Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Implementation of the Transmission Control Protocol(TCP). | |
7 | * | |
8 | * Version: $Id: tcp_input.c,v 1.243 2002/02/01 22:01:04 davem Exp $ | |
9 | * | |
02c30a84 | 10 | * Authors: Ross Biro |
1da177e4 LT |
11 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
12 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
13 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
14 | * Florian La Roche, <flla@stud.uni-sb.de> | |
15 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
16 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
17 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
18 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
19 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
20 | * Jorge Cwik, <jorge@laser.satlink.net> | |
21 | */ | |
22 | ||
23 | /* | |
24 | * Changes: | |
25 | * Pedro Roque : Fast Retransmit/Recovery. | |
26 | * Two receive queues. | |
27 | * Retransmit queue handled by TCP. | |
28 | * Better retransmit timer handling. | |
29 | * New congestion avoidance. | |
30 | * Header prediction. | |
31 | * Variable renaming. | |
32 | * | |
33 | * Eric : Fast Retransmit. | |
34 | * Randy Scott : MSS option defines. | |
35 | * Eric Schenk : Fixes to slow start algorithm. | |
36 | * Eric Schenk : Yet another double ACK bug. | |
37 | * Eric Schenk : Delayed ACK bug fixes. | |
38 | * Eric Schenk : Floyd style fast retrans war avoidance. | |
39 | * David S. Miller : Don't allow zero congestion window. | |
40 | * Eric Schenk : Fix retransmitter so that it sends | |
41 | * next packet on ack of previous packet. | |
42 | * Andi Kleen : Moved open_request checking here | |
43 | * and process RSTs for open_requests. | |
44 | * Andi Kleen : Better prune_queue, and other fixes. | |
45 | * Andrey Savochkin: Fix RTT measurements in the presnce of | |
46 | * timestamps. | |
47 | * Andrey Savochkin: Check sequence numbers correctly when | |
48 | * removing SACKs due to in sequence incoming | |
49 | * data segments. | |
50 | * Andi Kleen: Make sure we never ack data there is not | |
51 | * enough room for. Also make this condition | |
52 | * a fatal error if it might still happen. | |
53 | * Andi Kleen: Add tcp_measure_rcv_mss to make | |
54 | * connections with MSS<min(MTU,ann. MSS) | |
55 | * work without delayed acks. | |
56 | * Andi Kleen: Process packets with PSH set in the | |
57 | * fast path. | |
58 | * J Hadi Salim: ECN support | |
59 | * Andrei Gurtov, | |
60 | * Pasi Sarolahti, | |
61 | * Panu Kuhlberg: Experimental audit of TCP (re)transmission | |
62 | * engine. Lots of bugs are found. | |
63 | * Pasi Sarolahti: F-RTO for dealing with spurious RTOs | |
1da177e4 LT |
64 | */ |
65 | ||
66 | #include <linux/config.h> | |
67 | #include <linux/mm.h> | |
68 | #include <linux/module.h> | |
69 | #include <linux/sysctl.h> | |
70 | #include <net/tcp.h> | |
71 | #include <net/inet_common.h> | |
72 | #include <linux/ipsec.h> | |
73 | #include <asm/unaligned.h> | |
74 | ||
75 | int sysctl_tcp_timestamps = 1; | |
76 | int sysctl_tcp_window_scaling = 1; | |
77 | int sysctl_tcp_sack = 1; | |
78 | int sysctl_tcp_fack = 1; | |
79 | int sysctl_tcp_reordering = TCP_FASTRETRANS_THRESH; | |
80 | int sysctl_tcp_ecn; | |
81 | int sysctl_tcp_dsack = 1; | |
82 | int sysctl_tcp_app_win = 31; | |
83 | int sysctl_tcp_adv_win_scale = 2; | |
84 | ||
85 | int sysctl_tcp_stdurg; | |
86 | int sysctl_tcp_rfc1337; | |
87 | int sysctl_tcp_max_orphans = NR_FILE; | |
88 | int sysctl_tcp_frto; | |
89 | int sysctl_tcp_nometrics_save; | |
1da177e4 LT |
90 | |
91 | int sysctl_tcp_moderate_rcvbuf = 1; | |
9772efb9 | 92 | int sysctl_tcp_abc = 1; |
1da177e4 | 93 | |
1da177e4 LT |
94 | #define FLAG_DATA 0x01 /* Incoming frame contained data. */ |
95 | #define FLAG_WIN_UPDATE 0x02 /* Incoming ACK was a window update. */ | |
96 | #define FLAG_DATA_ACKED 0x04 /* This ACK acknowledged new data. */ | |
97 | #define FLAG_RETRANS_DATA_ACKED 0x08 /* "" "" some of which was retransmitted. */ | |
98 | #define FLAG_SYN_ACKED 0x10 /* This ACK acknowledged SYN. */ | |
99 | #define FLAG_DATA_SACKED 0x20 /* New SACK. */ | |
100 | #define FLAG_ECE 0x40 /* ECE in this ACK */ | |
101 | #define FLAG_DATA_LOST 0x80 /* SACK detected data lossage. */ | |
102 | #define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/ | |
103 | ||
104 | #define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED) | |
105 | #define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED) | |
106 | #define FLAG_CA_ALERT (FLAG_DATA_SACKED|FLAG_ECE) | |
107 | #define FLAG_FORWARD_PROGRESS (FLAG_ACKED|FLAG_DATA_SACKED) | |
108 | ||
109 | #define IsReno(tp) ((tp)->rx_opt.sack_ok == 0) | |
110 | #define IsFack(tp) ((tp)->rx_opt.sack_ok & 2) | |
111 | #define IsDSack(tp) ((tp)->rx_opt.sack_ok & 4) | |
112 | ||
113 | #define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH) | |
114 | ||
115 | /* Adapt the MSS value used to make delayed ack decision to the | |
116 | * real world. | |
117 | */ | |
463c84b9 ACM |
118 | static inline void tcp_measure_rcv_mss(struct sock *sk, |
119 | const struct sk_buff *skb) | |
1da177e4 | 120 | { |
463c84b9 ACM |
121 | struct inet_connection_sock *icsk = inet_csk(sk); |
122 | const unsigned int lss = icsk->icsk_ack.last_seg_size; | |
123 | unsigned int len; | |
1da177e4 | 124 | |
463c84b9 | 125 | icsk->icsk_ack.last_seg_size = 0; |
1da177e4 LT |
126 | |
127 | /* skb->len may jitter because of SACKs, even if peer | |
128 | * sends good full-sized frames. | |
129 | */ | |
130 | len = skb->len; | |
463c84b9 ACM |
131 | if (len >= icsk->icsk_ack.rcv_mss) { |
132 | icsk->icsk_ack.rcv_mss = len; | |
1da177e4 LT |
133 | } else { |
134 | /* Otherwise, we make more careful check taking into account, | |
135 | * that SACKs block is variable. | |
136 | * | |
137 | * "len" is invariant segment length, including TCP header. | |
138 | */ | |
139 | len += skb->data - skb->h.raw; | |
140 | if (len >= TCP_MIN_RCVMSS + sizeof(struct tcphdr) || | |
141 | /* If PSH is not set, packet should be | |
142 | * full sized, provided peer TCP is not badly broken. | |
143 | * This observation (if it is correct 8)) allows | |
144 | * to handle super-low mtu links fairly. | |
145 | */ | |
146 | (len >= TCP_MIN_MSS + sizeof(struct tcphdr) && | |
147 | !(tcp_flag_word(skb->h.th)&TCP_REMNANT))) { | |
148 | /* Subtract also invariant (if peer is RFC compliant), | |
149 | * tcp header plus fixed timestamp option length. | |
150 | * Resulting "len" is MSS free of SACK jitter. | |
151 | */ | |
463c84b9 ACM |
152 | len -= tcp_sk(sk)->tcp_header_len; |
153 | icsk->icsk_ack.last_seg_size = len; | |
1da177e4 | 154 | if (len == lss) { |
463c84b9 | 155 | icsk->icsk_ack.rcv_mss = len; |
1da177e4 LT |
156 | return; |
157 | } | |
158 | } | |
463c84b9 | 159 | icsk->icsk_ack.pending |= ICSK_ACK_PUSHED; |
1da177e4 LT |
160 | } |
161 | } | |
162 | ||
463c84b9 | 163 | static void tcp_incr_quickack(struct sock *sk) |
1da177e4 | 164 | { |
463c84b9 ACM |
165 | struct inet_connection_sock *icsk = inet_csk(sk); |
166 | unsigned quickacks = tcp_sk(sk)->rcv_wnd / (2 * icsk->icsk_ack.rcv_mss); | |
1da177e4 LT |
167 | |
168 | if (quickacks==0) | |
169 | quickacks=2; | |
463c84b9 ACM |
170 | if (quickacks > icsk->icsk_ack.quick) |
171 | icsk->icsk_ack.quick = min(quickacks, TCP_MAX_QUICKACKS); | |
1da177e4 LT |
172 | } |
173 | ||
463c84b9 | 174 | void tcp_enter_quickack_mode(struct sock *sk) |
1da177e4 | 175 | { |
463c84b9 ACM |
176 | struct inet_connection_sock *icsk = inet_csk(sk); |
177 | tcp_incr_quickack(sk); | |
178 | icsk->icsk_ack.pingpong = 0; | |
179 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 LT |
180 | } |
181 | ||
182 | /* Send ACKs quickly, if "quick" count is not exhausted | |
183 | * and the session is not interactive. | |
184 | */ | |
185 | ||
463c84b9 | 186 | static inline int tcp_in_quickack_mode(const struct sock *sk) |
1da177e4 | 187 | { |
463c84b9 ACM |
188 | const struct inet_connection_sock *icsk = inet_csk(sk); |
189 | return icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong; | |
1da177e4 LT |
190 | } |
191 | ||
192 | /* Buffer size and advertised window tuning. | |
193 | * | |
194 | * 1. Tuning sk->sk_sndbuf, when connection enters established state. | |
195 | */ | |
196 | ||
197 | static void tcp_fixup_sndbuf(struct sock *sk) | |
198 | { | |
199 | int sndmem = tcp_sk(sk)->rx_opt.mss_clamp + MAX_TCP_HEADER + 16 + | |
200 | sizeof(struct sk_buff); | |
201 | ||
202 | if (sk->sk_sndbuf < 3 * sndmem) | |
203 | sk->sk_sndbuf = min(3 * sndmem, sysctl_tcp_wmem[2]); | |
204 | } | |
205 | ||
206 | /* 2. Tuning advertised window (window_clamp, rcv_ssthresh) | |
207 | * | |
208 | * All tcp_full_space() is split to two parts: "network" buffer, allocated | |
209 | * forward and advertised in receiver window (tp->rcv_wnd) and | |
210 | * "application buffer", required to isolate scheduling/application | |
211 | * latencies from network. | |
212 | * window_clamp is maximal advertised window. It can be less than | |
213 | * tcp_full_space(), in this case tcp_full_space() - window_clamp | |
214 | * is reserved for "application" buffer. The less window_clamp is | |
215 | * the smoother our behaviour from viewpoint of network, but the lower | |
216 | * throughput and the higher sensitivity of the connection to losses. 8) | |
217 | * | |
218 | * rcv_ssthresh is more strict window_clamp used at "slow start" | |
219 | * phase to predict further behaviour of this connection. | |
220 | * It is used for two goals: | |
221 | * - to enforce header prediction at sender, even when application | |
222 | * requires some significant "application buffer". It is check #1. | |
223 | * - to prevent pruning of receive queue because of misprediction | |
224 | * of receiver window. Check #2. | |
225 | * | |
226 | * The scheme does not work when sender sends good segments opening | |
227 | * window and then starts to feed us spagetti. But it should work | |
228 | * in common situations. Otherwise, we have to rely on queue collapsing. | |
229 | */ | |
230 | ||
231 | /* Slow part of check#2. */ | |
463c84b9 ACM |
232 | static int __tcp_grow_window(const struct sock *sk, struct tcp_sock *tp, |
233 | const struct sk_buff *skb) | |
1da177e4 LT |
234 | { |
235 | /* Optimize this! */ | |
236 | int truesize = tcp_win_from_space(skb->truesize)/2; | |
237 | int window = tcp_full_space(sk)/2; | |
238 | ||
239 | while (tp->rcv_ssthresh <= window) { | |
240 | if (truesize <= skb->len) | |
463c84b9 | 241 | return 2 * inet_csk(sk)->icsk_ack.rcv_mss; |
1da177e4 LT |
242 | |
243 | truesize >>= 1; | |
244 | window >>= 1; | |
245 | } | |
246 | return 0; | |
247 | } | |
248 | ||
249 | static inline void tcp_grow_window(struct sock *sk, struct tcp_sock *tp, | |
250 | struct sk_buff *skb) | |
251 | { | |
252 | /* Check #1 */ | |
253 | if (tp->rcv_ssthresh < tp->window_clamp && | |
254 | (int)tp->rcv_ssthresh < tcp_space(sk) && | |
255 | !tcp_memory_pressure) { | |
256 | int incr; | |
257 | ||
258 | /* Check #2. Increase window, if skb with such overhead | |
259 | * will fit to rcvbuf in future. | |
260 | */ | |
261 | if (tcp_win_from_space(skb->truesize) <= skb->len) | |
262 | incr = 2*tp->advmss; | |
263 | else | |
264 | incr = __tcp_grow_window(sk, tp, skb); | |
265 | ||
266 | if (incr) { | |
267 | tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr, tp->window_clamp); | |
463c84b9 | 268 | inet_csk(sk)->icsk_ack.quick |= 1; |
1da177e4 LT |
269 | } |
270 | } | |
271 | } | |
272 | ||
273 | /* 3. Tuning rcvbuf, when connection enters established state. */ | |
274 | ||
275 | static void tcp_fixup_rcvbuf(struct sock *sk) | |
276 | { | |
277 | struct tcp_sock *tp = tcp_sk(sk); | |
278 | int rcvmem = tp->advmss + MAX_TCP_HEADER + 16 + sizeof(struct sk_buff); | |
279 | ||
280 | /* Try to select rcvbuf so that 4 mss-sized segments | |
281 | * will fit to window and correspoding skbs will fit to our rcvbuf. | |
282 | * (was 3; 4 is minimum to allow fast retransmit to work.) | |
283 | */ | |
284 | while (tcp_win_from_space(rcvmem) < tp->advmss) | |
285 | rcvmem += 128; | |
286 | if (sk->sk_rcvbuf < 4 * rcvmem) | |
287 | sk->sk_rcvbuf = min(4 * rcvmem, sysctl_tcp_rmem[2]); | |
288 | } | |
289 | ||
290 | /* 4. Try to fixup all. It is made iimediately after connection enters | |
291 | * established state. | |
292 | */ | |
293 | static void tcp_init_buffer_space(struct sock *sk) | |
294 | { | |
295 | struct tcp_sock *tp = tcp_sk(sk); | |
296 | int maxwin; | |
297 | ||
298 | if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) | |
299 | tcp_fixup_rcvbuf(sk); | |
300 | if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK)) | |
301 | tcp_fixup_sndbuf(sk); | |
302 | ||
303 | tp->rcvq_space.space = tp->rcv_wnd; | |
304 | ||
305 | maxwin = tcp_full_space(sk); | |
306 | ||
307 | if (tp->window_clamp >= maxwin) { | |
308 | tp->window_clamp = maxwin; | |
309 | ||
310 | if (sysctl_tcp_app_win && maxwin > 4 * tp->advmss) | |
311 | tp->window_clamp = max(maxwin - | |
312 | (maxwin >> sysctl_tcp_app_win), | |
313 | 4 * tp->advmss); | |
314 | } | |
315 | ||
316 | /* Force reservation of one segment. */ | |
317 | if (sysctl_tcp_app_win && | |
318 | tp->window_clamp > 2 * tp->advmss && | |
319 | tp->window_clamp + tp->advmss > maxwin) | |
320 | tp->window_clamp = max(2 * tp->advmss, maxwin - tp->advmss); | |
321 | ||
322 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, tp->window_clamp); | |
323 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
324 | } | |
325 | ||
1da177e4 LT |
326 | /* 5. Recalculate window clamp after socket hit its memory bounds. */ |
327 | static void tcp_clamp_window(struct sock *sk, struct tcp_sock *tp) | |
328 | { | |
6687e988 | 329 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
330 | struct sk_buff *skb; |
331 | unsigned int app_win = tp->rcv_nxt - tp->copied_seq; | |
332 | int ofo_win = 0; | |
333 | ||
6687e988 | 334 | icsk->icsk_ack.quick = 0; |
1da177e4 LT |
335 | |
336 | skb_queue_walk(&tp->out_of_order_queue, skb) { | |
337 | ofo_win += skb->len; | |
338 | } | |
339 | ||
340 | /* If overcommit is due to out of order segments, | |
341 | * do not clamp window. Try to expand rcvbuf instead. | |
342 | */ | |
343 | if (ofo_win) { | |
344 | if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] && | |
345 | !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) && | |
346 | !tcp_memory_pressure && | |
347 | atomic_read(&tcp_memory_allocated) < sysctl_tcp_mem[0]) | |
348 | sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc), | |
349 | sysctl_tcp_rmem[2]); | |
350 | } | |
351 | if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) { | |
352 | app_win += ofo_win; | |
353 | if (atomic_read(&sk->sk_rmem_alloc) >= 2 * sk->sk_rcvbuf) | |
354 | app_win >>= 1; | |
6687e988 ACM |
355 | if (app_win > icsk->icsk_ack.rcv_mss) |
356 | app_win -= icsk->icsk_ack.rcv_mss; | |
1da177e4 LT |
357 | app_win = max(app_win, 2U*tp->advmss); |
358 | ||
1da177e4 LT |
359 | tp->rcv_ssthresh = min(tp->window_clamp, 2U*tp->advmss); |
360 | } | |
361 | } | |
362 | ||
363 | /* Receiver "autotuning" code. | |
364 | * | |
365 | * The algorithm for RTT estimation w/o timestamps is based on | |
366 | * Dynamic Right-Sizing (DRS) by Wu Feng and Mike Fisk of LANL. | |
367 | * <http://www.lanl.gov/radiant/website/pubs/drs/lacsi2001.ps> | |
368 | * | |
369 | * More detail on this code can be found at | |
370 | * <http://www.psc.edu/~jheffner/senior_thesis.ps>, | |
371 | * though this reference is out of date. A new paper | |
372 | * is pending. | |
373 | */ | |
374 | static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep) | |
375 | { | |
376 | u32 new_sample = tp->rcv_rtt_est.rtt; | |
377 | long m = sample; | |
378 | ||
379 | if (m == 0) | |
380 | m = 1; | |
381 | ||
382 | if (new_sample != 0) { | |
383 | /* If we sample in larger samples in the non-timestamp | |
384 | * case, we could grossly overestimate the RTT especially | |
385 | * with chatty applications or bulk transfer apps which | |
386 | * are stalled on filesystem I/O. | |
387 | * | |
388 | * Also, since we are only going for a minimum in the | |
389 | * non-timestamp case, we do not smoothe things out | |
390 | * else with timestamps disabled convergance takes too | |
391 | * long. | |
392 | */ | |
393 | if (!win_dep) { | |
394 | m -= (new_sample >> 3); | |
395 | new_sample += m; | |
396 | } else if (m < new_sample) | |
397 | new_sample = m << 3; | |
398 | } else { | |
399 | /* No previous mesaure. */ | |
400 | new_sample = m << 3; | |
401 | } | |
402 | ||
403 | if (tp->rcv_rtt_est.rtt != new_sample) | |
404 | tp->rcv_rtt_est.rtt = new_sample; | |
405 | } | |
406 | ||
407 | static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp) | |
408 | { | |
409 | if (tp->rcv_rtt_est.time == 0) | |
410 | goto new_measure; | |
411 | if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq)) | |
412 | return; | |
413 | tcp_rcv_rtt_update(tp, | |
414 | jiffies - tp->rcv_rtt_est.time, | |
415 | 1); | |
416 | ||
417 | new_measure: | |
418 | tp->rcv_rtt_est.seq = tp->rcv_nxt + tp->rcv_wnd; | |
419 | tp->rcv_rtt_est.time = tcp_time_stamp; | |
420 | } | |
421 | ||
463c84b9 | 422 | static inline void tcp_rcv_rtt_measure_ts(struct sock *sk, const struct sk_buff *skb) |
1da177e4 | 423 | { |
463c84b9 | 424 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
425 | if (tp->rx_opt.rcv_tsecr && |
426 | (TCP_SKB_CB(skb)->end_seq - | |
463c84b9 | 427 | TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss)) |
1da177e4 LT |
428 | tcp_rcv_rtt_update(tp, tcp_time_stamp - tp->rx_opt.rcv_tsecr, 0); |
429 | } | |
430 | ||
431 | /* | |
432 | * This function should be called every time data is copied to user space. | |
433 | * It calculates the appropriate TCP receive buffer space. | |
434 | */ | |
435 | void tcp_rcv_space_adjust(struct sock *sk) | |
436 | { | |
437 | struct tcp_sock *tp = tcp_sk(sk); | |
438 | int time; | |
439 | int space; | |
440 | ||
441 | if (tp->rcvq_space.time == 0) | |
442 | goto new_measure; | |
443 | ||
444 | time = tcp_time_stamp - tp->rcvq_space.time; | |
445 | if (time < (tp->rcv_rtt_est.rtt >> 3) || | |
446 | tp->rcv_rtt_est.rtt == 0) | |
447 | return; | |
448 | ||
449 | space = 2 * (tp->copied_seq - tp->rcvq_space.seq); | |
450 | ||
451 | space = max(tp->rcvq_space.space, space); | |
452 | ||
453 | if (tp->rcvq_space.space != space) { | |
454 | int rcvmem; | |
455 | ||
456 | tp->rcvq_space.space = space; | |
457 | ||
458 | if (sysctl_tcp_moderate_rcvbuf) { | |
459 | int new_clamp = space; | |
460 | ||
461 | /* Receive space grows, normalize in order to | |
462 | * take into account packet headers and sk_buff | |
463 | * structure overhead. | |
464 | */ | |
465 | space /= tp->advmss; | |
466 | if (!space) | |
467 | space = 1; | |
468 | rcvmem = (tp->advmss + MAX_TCP_HEADER + | |
469 | 16 + sizeof(struct sk_buff)); | |
470 | while (tcp_win_from_space(rcvmem) < tp->advmss) | |
471 | rcvmem += 128; | |
472 | space *= rcvmem; | |
473 | space = min(space, sysctl_tcp_rmem[2]); | |
474 | if (space > sk->sk_rcvbuf) { | |
475 | sk->sk_rcvbuf = space; | |
476 | ||
477 | /* Make the window clamp follow along. */ | |
478 | tp->window_clamp = new_clamp; | |
479 | } | |
480 | } | |
481 | } | |
482 | ||
483 | new_measure: | |
484 | tp->rcvq_space.seq = tp->copied_seq; | |
485 | tp->rcvq_space.time = tcp_time_stamp; | |
486 | } | |
487 | ||
488 | /* There is something which you must keep in mind when you analyze the | |
489 | * behavior of the tp->ato delayed ack timeout interval. When a | |
490 | * connection starts up, we want to ack as quickly as possible. The | |
491 | * problem is that "good" TCP's do slow start at the beginning of data | |
492 | * transmission. The means that until we send the first few ACK's the | |
493 | * sender will sit on his end and only queue most of his data, because | |
494 | * he can only send snd_cwnd unacked packets at any given time. For | |
495 | * each ACK we send, he increments snd_cwnd and transmits more of his | |
496 | * queue. -DaveM | |
497 | */ | |
498 | static void tcp_event_data_recv(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) | |
499 | { | |
463c84b9 | 500 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
501 | u32 now; |
502 | ||
463c84b9 | 503 | inet_csk_schedule_ack(sk); |
1da177e4 | 504 | |
463c84b9 | 505 | tcp_measure_rcv_mss(sk, skb); |
1da177e4 LT |
506 | |
507 | tcp_rcv_rtt_measure(tp); | |
508 | ||
509 | now = tcp_time_stamp; | |
510 | ||
463c84b9 | 511 | if (!icsk->icsk_ack.ato) { |
1da177e4 LT |
512 | /* The _first_ data packet received, initialize |
513 | * delayed ACK engine. | |
514 | */ | |
463c84b9 ACM |
515 | tcp_incr_quickack(sk); |
516 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
1da177e4 | 517 | } else { |
463c84b9 | 518 | int m = now - icsk->icsk_ack.lrcvtime; |
1da177e4 LT |
519 | |
520 | if (m <= TCP_ATO_MIN/2) { | |
521 | /* The fastest case is the first. */ | |
463c84b9 ACM |
522 | icsk->icsk_ack.ato = (icsk->icsk_ack.ato >> 1) + TCP_ATO_MIN / 2; |
523 | } else if (m < icsk->icsk_ack.ato) { | |
524 | icsk->icsk_ack.ato = (icsk->icsk_ack.ato >> 1) + m; | |
525 | if (icsk->icsk_ack.ato > icsk->icsk_rto) | |
526 | icsk->icsk_ack.ato = icsk->icsk_rto; | |
527 | } else if (m > icsk->icsk_rto) { | |
1da177e4 LT |
528 | /* Too long gap. Apparently sender falled to |
529 | * restart window, so that we send ACKs quickly. | |
530 | */ | |
463c84b9 | 531 | tcp_incr_quickack(sk); |
1da177e4 LT |
532 | sk_stream_mem_reclaim(sk); |
533 | } | |
534 | } | |
463c84b9 | 535 | icsk->icsk_ack.lrcvtime = now; |
1da177e4 LT |
536 | |
537 | TCP_ECN_check_ce(tp, skb); | |
538 | ||
539 | if (skb->len >= 128) | |
540 | tcp_grow_window(sk, tp, skb); | |
541 | } | |
542 | ||
1da177e4 LT |
543 | /* Called to compute a smoothed rtt estimate. The data fed to this |
544 | * routine either comes from timestamps, or from segments that were | |
545 | * known _not_ to have been retransmitted [see Karn/Partridge | |
546 | * Proceedings SIGCOMM 87]. The algorithm is from the SIGCOMM 88 | |
547 | * piece by Van Jacobson. | |
548 | * NOTE: the next three routines used to be one big routine. | |
549 | * To save cycles in the RFC 1323 implementation it was better to break | |
550 | * it up into three procedures. -- erics | |
551 | */ | |
2d2abbab | 552 | static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt) |
1da177e4 | 553 | { |
6687e988 | 554 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
555 | long m = mrtt; /* RTT */ |
556 | ||
1da177e4 LT |
557 | /* The following amusing code comes from Jacobson's |
558 | * article in SIGCOMM '88. Note that rtt and mdev | |
559 | * are scaled versions of rtt and mean deviation. | |
560 | * This is designed to be as fast as possible | |
561 | * m stands for "measurement". | |
562 | * | |
563 | * On a 1990 paper the rto value is changed to: | |
564 | * RTO = rtt + 4 * mdev | |
565 | * | |
566 | * Funny. This algorithm seems to be very broken. | |
567 | * These formulae increase RTO, when it should be decreased, increase | |
568 | * too slowly, when it should be incresed fastly, decrease too fastly | |
569 | * etc. I guess in BSD RTO takes ONE value, so that it is absolutely | |
570 | * does not matter how to _calculate_ it. Seems, it was trap | |
571 | * that VJ failed to avoid. 8) | |
572 | */ | |
573 | if(m == 0) | |
574 | m = 1; | |
575 | if (tp->srtt != 0) { | |
576 | m -= (tp->srtt >> 3); /* m is now error in rtt est */ | |
577 | tp->srtt += m; /* rtt = 7/8 rtt + 1/8 new */ | |
578 | if (m < 0) { | |
579 | m = -m; /* m is now abs(error) */ | |
580 | m -= (tp->mdev >> 2); /* similar update on mdev */ | |
581 | /* This is similar to one of Eifel findings. | |
582 | * Eifel blocks mdev updates when rtt decreases. | |
583 | * This solution is a bit different: we use finer gain | |
584 | * for mdev in this case (alpha*beta). | |
585 | * Like Eifel it also prevents growth of rto, | |
586 | * but also it limits too fast rto decreases, | |
587 | * happening in pure Eifel. | |
588 | */ | |
589 | if (m > 0) | |
590 | m >>= 3; | |
591 | } else { | |
592 | m -= (tp->mdev >> 2); /* similar update on mdev */ | |
593 | } | |
594 | tp->mdev += m; /* mdev = 3/4 mdev + 1/4 new */ | |
595 | if (tp->mdev > tp->mdev_max) { | |
596 | tp->mdev_max = tp->mdev; | |
597 | if (tp->mdev_max > tp->rttvar) | |
598 | tp->rttvar = tp->mdev_max; | |
599 | } | |
600 | if (after(tp->snd_una, tp->rtt_seq)) { | |
601 | if (tp->mdev_max < tp->rttvar) | |
602 | tp->rttvar -= (tp->rttvar-tp->mdev_max)>>2; | |
603 | tp->rtt_seq = tp->snd_nxt; | |
604 | tp->mdev_max = TCP_RTO_MIN; | |
605 | } | |
606 | } else { | |
607 | /* no previous measure. */ | |
608 | tp->srtt = m<<3; /* take the measured time to be rtt */ | |
609 | tp->mdev = m<<1; /* make sure rto = 3*rtt */ | |
610 | tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN); | |
611 | tp->rtt_seq = tp->snd_nxt; | |
612 | } | |
1da177e4 LT |
613 | } |
614 | ||
615 | /* Calculate rto without backoff. This is the second half of Van Jacobson's | |
616 | * routine referred to above. | |
617 | */ | |
463c84b9 | 618 | static inline void tcp_set_rto(struct sock *sk) |
1da177e4 | 619 | { |
463c84b9 | 620 | const struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
621 | /* Old crap is replaced with new one. 8) |
622 | * | |
623 | * More seriously: | |
624 | * 1. If rtt variance happened to be less 50msec, it is hallucination. | |
625 | * It cannot be less due to utterly erratic ACK generation made | |
626 | * at least by solaris and freebsd. "Erratic ACKs" has _nothing_ | |
627 | * to do with delayed acks, because at cwnd>2 true delack timeout | |
628 | * is invisible. Actually, Linux-2.4 also generates erratic | |
629 | * ACKs in some curcumstances. | |
630 | */ | |
463c84b9 | 631 | inet_csk(sk)->icsk_rto = (tp->srtt >> 3) + tp->rttvar; |
1da177e4 LT |
632 | |
633 | /* 2. Fixups made earlier cannot be right. | |
634 | * If we do not estimate RTO correctly without them, | |
635 | * all the algo is pure shit and should be replaced | |
636 | * with correct one. It is exaclty, which we pretend to do. | |
637 | */ | |
638 | } | |
639 | ||
640 | /* NOTE: clamping at TCP_RTO_MIN is not required, current algo | |
641 | * guarantees that rto is higher. | |
642 | */ | |
463c84b9 | 643 | static inline void tcp_bound_rto(struct sock *sk) |
1da177e4 | 644 | { |
463c84b9 ACM |
645 | if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) |
646 | inet_csk(sk)->icsk_rto = TCP_RTO_MAX; | |
1da177e4 LT |
647 | } |
648 | ||
649 | /* Save metrics learned by this TCP session. | |
650 | This function is called only, when TCP finishes successfully | |
651 | i.e. when it enters TIME-WAIT or goes from LAST-ACK to CLOSE. | |
652 | */ | |
653 | void tcp_update_metrics(struct sock *sk) | |
654 | { | |
655 | struct tcp_sock *tp = tcp_sk(sk); | |
656 | struct dst_entry *dst = __sk_dst_get(sk); | |
657 | ||
658 | if (sysctl_tcp_nometrics_save) | |
659 | return; | |
660 | ||
661 | dst_confirm(dst); | |
662 | ||
663 | if (dst && (dst->flags&DST_HOST)) { | |
6687e988 | 664 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
665 | int m; |
666 | ||
6687e988 | 667 | if (icsk->icsk_backoff || !tp->srtt) { |
1da177e4 LT |
668 | /* This session failed to estimate rtt. Why? |
669 | * Probably, no packets returned in time. | |
670 | * Reset our results. | |
671 | */ | |
672 | if (!(dst_metric_locked(dst, RTAX_RTT))) | |
673 | dst->metrics[RTAX_RTT-1] = 0; | |
674 | return; | |
675 | } | |
676 | ||
677 | m = dst_metric(dst, RTAX_RTT) - tp->srtt; | |
678 | ||
679 | /* If newly calculated rtt larger than stored one, | |
680 | * store new one. Otherwise, use EWMA. Remember, | |
681 | * rtt overestimation is always better than underestimation. | |
682 | */ | |
683 | if (!(dst_metric_locked(dst, RTAX_RTT))) { | |
684 | if (m <= 0) | |
685 | dst->metrics[RTAX_RTT-1] = tp->srtt; | |
686 | else | |
687 | dst->metrics[RTAX_RTT-1] -= (m>>3); | |
688 | } | |
689 | ||
690 | if (!(dst_metric_locked(dst, RTAX_RTTVAR))) { | |
691 | if (m < 0) | |
692 | m = -m; | |
693 | ||
694 | /* Scale deviation to rttvar fixed point */ | |
695 | m >>= 1; | |
696 | if (m < tp->mdev) | |
697 | m = tp->mdev; | |
698 | ||
699 | if (m >= dst_metric(dst, RTAX_RTTVAR)) | |
700 | dst->metrics[RTAX_RTTVAR-1] = m; | |
701 | else | |
702 | dst->metrics[RTAX_RTTVAR-1] -= | |
703 | (dst->metrics[RTAX_RTTVAR-1] - m)>>2; | |
704 | } | |
705 | ||
706 | if (tp->snd_ssthresh >= 0xFFFF) { | |
707 | /* Slow start still did not finish. */ | |
708 | if (dst_metric(dst, RTAX_SSTHRESH) && | |
709 | !dst_metric_locked(dst, RTAX_SSTHRESH) && | |
710 | (tp->snd_cwnd >> 1) > dst_metric(dst, RTAX_SSTHRESH)) | |
711 | dst->metrics[RTAX_SSTHRESH-1] = tp->snd_cwnd >> 1; | |
712 | if (!dst_metric_locked(dst, RTAX_CWND) && | |
713 | tp->snd_cwnd > dst_metric(dst, RTAX_CWND)) | |
714 | dst->metrics[RTAX_CWND-1] = tp->snd_cwnd; | |
715 | } else if (tp->snd_cwnd > tp->snd_ssthresh && | |
6687e988 | 716 | icsk->icsk_ca_state == TCP_CA_Open) { |
1da177e4 LT |
717 | /* Cong. avoidance phase, cwnd is reliable. */ |
718 | if (!dst_metric_locked(dst, RTAX_SSTHRESH)) | |
719 | dst->metrics[RTAX_SSTHRESH-1] = | |
720 | max(tp->snd_cwnd >> 1, tp->snd_ssthresh); | |
721 | if (!dst_metric_locked(dst, RTAX_CWND)) | |
722 | dst->metrics[RTAX_CWND-1] = (dst->metrics[RTAX_CWND-1] + tp->snd_cwnd) >> 1; | |
723 | } else { | |
724 | /* Else slow start did not finish, cwnd is non-sense, | |
725 | ssthresh may be also invalid. | |
726 | */ | |
727 | if (!dst_metric_locked(dst, RTAX_CWND)) | |
728 | dst->metrics[RTAX_CWND-1] = (dst->metrics[RTAX_CWND-1] + tp->snd_ssthresh) >> 1; | |
729 | if (dst->metrics[RTAX_SSTHRESH-1] && | |
730 | !dst_metric_locked(dst, RTAX_SSTHRESH) && | |
731 | tp->snd_ssthresh > dst->metrics[RTAX_SSTHRESH-1]) | |
732 | dst->metrics[RTAX_SSTHRESH-1] = tp->snd_ssthresh; | |
733 | } | |
734 | ||
735 | if (!dst_metric_locked(dst, RTAX_REORDERING)) { | |
736 | if (dst->metrics[RTAX_REORDERING-1] < tp->reordering && | |
737 | tp->reordering != sysctl_tcp_reordering) | |
738 | dst->metrics[RTAX_REORDERING-1] = tp->reordering; | |
739 | } | |
740 | } | |
741 | } | |
742 | ||
743 | /* Numbers are taken from RFC2414. */ | |
744 | __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst) | |
745 | { | |
746 | __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0); | |
747 | ||
748 | if (!cwnd) { | |
c1b4a7e6 | 749 | if (tp->mss_cache > 1460) |
1da177e4 LT |
750 | cwnd = 2; |
751 | else | |
c1b4a7e6 | 752 | cwnd = (tp->mss_cache > 1095) ? 3 : 4; |
1da177e4 LT |
753 | } |
754 | return min_t(__u32, cwnd, tp->snd_cwnd_clamp); | |
755 | } | |
756 | ||
757 | /* Initialize metrics on socket. */ | |
758 | ||
759 | static void tcp_init_metrics(struct sock *sk) | |
760 | { | |
761 | struct tcp_sock *tp = tcp_sk(sk); | |
762 | struct dst_entry *dst = __sk_dst_get(sk); | |
763 | ||
764 | if (dst == NULL) | |
765 | goto reset; | |
766 | ||
767 | dst_confirm(dst); | |
768 | ||
769 | if (dst_metric_locked(dst, RTAX_CWND)) | |
770 | tp->snd_cwnd_clamp = dst_metric(dst, RTAX_CWND); | |
771 | if (dst_metric(dst, RTAX_SSTHRESH)) { | |
772 | tp->snd_ssthresh = dst_metric(dst, RTAX_SSTHRESH); | |
773 | if (tp->snd_ssthresh > tp->snd_cwnd_clamp) | |
774 | tp->snd_ssthresh = tp->snd_cwnd_clamp; | |
775 | } | |
776 | if (dst_metric(dst, RTAX_REORDERING) && | |
777 | tp->reordering != dst_metric(dst, RTAX_REORDERING)) { | |
778 | tp->rx_opt.sack_ok &= ~2; | |
779 | tp->reordering = dst_metric(dst, RTAX_REORDERING); | |
780 | } | |
781 | ||
782 | if (dst_metric(dst, RTAX_RTT) == 0) | |
783 | goto reset; | |
784 | ||
785 | if (!tp->srtt && dst_metric(dst, RTAX_RTT) < (TCP_TIMEOUT_INIT << 3)) | |
786 | goto reset; | |
787 | ||
788 | /* Initial rtt is determined from SYN,SYN-ACK. | |
789 | * The segment is small and rtt may appear much | |
790 | * less than real one. Use per-dst memory | |
791 | * to make it more realistic. | |
792 | * | |
793 | * A bit of theory. RTT is time passed after "normal" sized packet | |
794 | * is sent until it is ACKed. In normal curcumstances sending small | |
795 | * packets force peer to delay ACKs and calculation is correct too. | |
796 | * The algorithm is adaptive and, provided we follow specs, it | |
797 | * NEVER underestimate RTT. BUT! If peer tries to make some clever | |
798 | * tricks sort of "quick acks" for time long enough to decrease RTT | |
799 | * to low value, and then abruptly stops to do it and starts to delay | |
800 | * ACKs, wait for troubles. | |
801 | */ | |
802 | if (dst_metric(dst, RTAX_RTT) > tp->srtt) { | |
803 | tp->srtt = dst_metric(dst, RTAX_RTT); | |
804 | tp->rtt_seq = tp->snd_nxt; | |
805 | } | |
806 | if (dst_metric(dst, RTAX_RTTVAR) > tp->mdev) { | |
807 | tp->mdev = dst_metric(dst, RTAX_RTTVAR); | |
808 | tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN); | |
809 | } | |
463c84b9 ACM |
810 | tcp_set_rto(sk); |
811 | tcp_bound_rto(sk); | |
812 | if (inet_csk(sk)->icsk_rto < TCP_TIMEOUT_INIT && !tp->rx_opt.saw_tstamp) | |
1da177e4 LT |
813 | goto reset; |
814 | tp->snd_cwnd = tcp_init_cwnd(tp, dst); | |
815 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
816 | return; | |
817 | ||
818 | reset: | |
819 | /* Play conservative. If timestamps are not | |
820 | * supported, TCP will fail to recalculate correct | |
821 | * rtt, if initial rto is too small. FORGET ALL AND RESET! | |
822 | */ | |
823 | if (!tp->rx_opt.saw_tstamp && tp->srtt) { | |
824 | tp->srtt = 0; | |
825 | tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_INIT; | |
463c84b9 | 826 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
1da177e4 LT |
827 | } |
828 | } | |
829 | ||
6687e988 ACM |
830 | static void tcp_update_reordering(struct sock *sk, const int metric, |
831 | const int ts) | |
1da177e4 | 832 | { |
6687e988 | 833 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
834 | if (metric > tp->reordering) { |
835 | tp->reordering = min(TCP_MAX_REORDERING, metric); | |
836 | ||
837 | /* This exciting event is worth to be remembered. 8) */ | |
838 | if (ts) | |
839 | NET_INC_STATS_BH(LINUX_MIB_TCPTSREORDER); | |
840 | else if (IsReno(tp)) | |
841 | NET_INC_STATS_BH(LINUX_MIB_TCPRENOREORDER); | |
842 | else if (IsFack(tp)) | |
843 | NET_INC_STATS_BH(LINUX_MIB_TCPFACKREORDER); | |
844 | else | |
845 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKREORDER); | |
846 | #if FASTRETRANS_DEBUG > 1 | |
847 | printk(KERN_DEBUG "Disorder%d %d %u f%u s%u rr%d\n", | |
6687e988 | 848 | tp->rx_opt.sack_ok, inet_csk(sk)->icsk_ca_state, |
1da177e4 LT |
849 | tp->reordering, |
850 | tp->fackets_out, | |
851 | tp->sacked_out, | |
852 | tp->undo_marker ? tp->undo_retrans : 0); | |
853 | #endif | |
854 | /* Disable FACK yet. */ | |
855 | tp->rx_opt.sack_ok &= ~2; | |
856 | } | |
857 | } | |
858 | ||
859 | /* This procedure tags the retransmission queue when SACKs arrive. | |
860 | * | |
861 | * We have three tag bits: SACKED(S), RETRANS(R) and LOST(L). | |
862 | * Packets in queue with these bits set are counted in variables | |
863 | * sacked_out, retrans_out and lost_out, correspondingly. | |
864 | * | |
865 | * Valid combinations are: | |
866 | * Tag InFlight Description | |
867 | * 0 1 - orig segment is in flight. | |
868 | * S 0 - nothing flies, orig reached receiver. | |
869 | * L 0 - nothing flies, orig lost by net. | |
870 | * R 2 - both orig and retransmit are in flight. | |
871 | * L|R 1 - orig is lost, retransmit is in flight. | |
872 | * S|R 1 - orig reached receiver, retrans is still in flight. | |
873 | * (L|S|R is logically valid, it could occur when L|R is sacked, | |
874 | * but it is equivalent to plain S and code short-curcuits it to S. | |
875 | * L|S is logically invalid, it would mean -1 packet in flight 8)) | |
876 | * | |
877 | * These 6 states form finite state machine, controlled by the following events: | |
878 | * 1. New ACK (+SACK) arrives. (tcp_sacktag_write_queue()) | |
879 | * 2. Retransmission. (tcp_retransmit_skb(), tcp_xmit_retransmit_queue()) | |
880 | * 3. Loss detection event of one of three flavors: | |
881 | * A. Scoreboard estimator decided the packet is lost. | |
882 | * A'. Reno "three dupacks" marks head of queue lost. | |
883 | * A''. Its FACK modfication, head until snd.fack is lost. | |
884 | * B. SACK arrives sacking data transmitted after never retransmitted | |
885 | * hole was sent out. | |
886 | * C. SACK arrives sacking SND.NXT at the moment, when the | |
887 | * segment was retransmitted. | |
888 | * 4. D-SACK added new rule: D-SACK changes any tag to S. | |
889 | * | |
890 | * It is pleasant to note, that state diagram turns out to be commutative, | |
891 | * so that we are allowed not to be bothered by order of our actions, | |
892 | * when multiple events arrive simultaneously. (see the function below). | |
893 | * | |
894 | * Reordering detection. | |
895 | * -------------------- | |
896 | * Reordering metric is maximal distance, which a packet can be displaced | |
897 | * in packet stream. With SACKs we can estimate it: | |
898 | * | |
899 | * 1. SACK fills old hole and the corresponding segment was not | |
900 | * ever retransmitted -> reordering. Alas, we cannot use it | |
901 | * when segment was retransmitted. | |
902 | * 2. The last flaw is solved with D-SACK. D-SACK arrives | |
903 | * for retransmitted and already SACKed segment -> reordering.. | |
904 | * Both of these heuristics are not used in Loss state, when we cannot | |
905 | * account for retransmits accurately. | |
906 | */ | |
907 | static int | |
908 | tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_una) | |
909 | { | |
6687e988 | 910 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
911 | struct tcp_sock *tp = tcp_sk(sk); |
912 | unsigned char *ptr = ack_skb->h.raw + TCP_SKB_CB(ack_skb)->sacked; | |
913 | struct tcp_sack_block *sp = (struct tcp_sack_block *)(ptr+2); | |
914 | int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3; | |
915 | int reord = tp->packets_out; | |
916 | int prior_fackets; | |
917 | u32 lost_retrans = 0; | |
918 | int flag = 0; | |
919 | int i; | |
920 | ||
1da177e4 LT |
921 | if (!tp->sacked_out) |
922 | tp->fackets_out = 0; | |
923 | prior_fackets = tp->fackets_out; | |
924 | ||
925 | for (i=0; i<num_sacks; i++, sp++) { | |
926 | struct sk_buff *skb; | |
927 | __u32 start_seq = ntohl(sp->start_seq); | |
928 | __u32 end_seq = ntohl(sp->end_seq); | |
929 | int fack_count = 0; | |
930 | int dup_sack = 0; | |
931 | ||
932 | /* Check for D-SACK. */ | |
933 | if (i == 0) { | |
934 | u32 ack = TCP_SKB_CB(ack_skb)->ack_seq; | |
935 | ||
936 | if (before(start_seq, ack)) { | |
937 | dup_sack = 1; | |
938 | tp->rx_opt.sack_ok |= 4; | |
939 | NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV); | |
940 | } else if (num_sacks > 1 && | |
941 | !after(end_seq, ntohl(sp[1].end_seq)) && | |
942 | !before(start_seq, ntohl(sp[1].start_seq))) { | |
943 | dup_sack = 1; | |
944 | tp->rx_opt.sack_ok |= 4; | |
945 | NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV); | |
946 | } | |
947 | ||
948 | /* D-SACK for already forgotten data... | |
949 | * Do dumb counting. */ | |
950 | if (dup_sack && | |
951 | !after(end_seq, prior_snd_una) && | |
952 | after(end_seq, tp->undo_marker)) | |
953 | tp->undo_retrans--; | |
954 | ||
955 | /* Eliminate too old ACKs, but take into | |
956 | * account more or less fresh ones, they can | |
957 | * contain valid SACK info. | |
958 | */ | |
959 | if (before(ack, prior_snd_una - tp->max_window)) | |
960 | return 0; | |
961 | } | |
962 | ||
963 | /* Event "B" in the comment above. */ | |
964 | if (after(end_seq, tp->high_seq)) | |
965 | flag |= FLAG_DATA_LOST; | |
966 | ||
967 | sk_stream_for_retrans_queue(skb, sk) { | |
6475be16 DM |
968 | int in_sack, pcount; |
969 | u8 sacked; | |
1da177e4 LT |
970 | |
971 | /* The retransmission queue is always in order, so | |
972 | * we can short-circuit the walk early. | |
973 | */ | |
6475be16 | 974 | if (!before(TCP_SKB_CB(skb)->seq, end_seq)) |
1da177e4 LT |
975 | break; |
976 | ||
3c05d92e HX |
977 | in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) && |
978 | !before(end_seq, TCP_SKB_CB(skb)->end_seq); | |
979 | ||
6475be16 DM |
980 | pcount = tcp_skb_pcount(skb); |
981 | ||
3c05d92e HX |
982 | if (pcount > 1 && !in_sack && |
983 | after(TCP_SKB_CB(skb)->end_seq, start_seq)) { | |
6475be16 DM |
984 | unsigned int pkt_len; |
985 | ||
3c05d92e HX |
986 | in_sack = !after(start_seq, |
987 | TCP_SKB_CB(skb)->seq); | |
988 | ||
989 | if (!in_sack) | |
6475be16 DM |
990 | pkt_len = (start_seq - |
991 | TCP_SKB_CB(skb)->seq); | |
992 | else | |
993 | pkt_len = (end_seq - | |
994 | TCP_SKB_CB(skb)->seq); | |
995 | if (tcp_fragment(sk, skb, pkt_len, skb_shinfo(skb)->tso_size)) | |
996 | break; | |
997 | pcount = tcp_skb_pcount(skb); | |
998 | } | |
999 | ||
1000 | fack_count += pcount; | |
1da177e4 | 1001 | |
6475be16 DM |
1002 | sacked = TCP_SKB_CB(skb)->sacked; |
1003 | ||
1da177e4 LT |
1004 | /* Account D-SACK for retransmitted packet. */ |
1005 | if ((dup_sack && in_sack) && | |
1006 | (sacked & TCPCB_RETRANS) && | |
1007 | after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker)) | |
1008 | tp->undo_retrans--; | |
1009 | ||
1010 | /* The frame is ACKed. */ | |
1011 | if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) { | |
1012 | if (sacked&TCPCB_RETRANS) { | |
1013 | if ((dup_sack && in_sack) && | |
1014 | (sacked&TCPCB_SACKED_ACKED)) | |
1015 | reord = min(fack_count, reord); | |
1016 | } else { | |
1017 | /* If it was in a hole, we detected reordering. */ | |
1018 | if (fack_count < prior_fackets && | |
1019 | !(sacked&TCPCB_SACKED_ACKED)) | |
1020 | reord = min(fack_count, reord); | |
1021 | } | |
1022 | ||
1023 | /* Nothing to do; acked frame is about to be dropped. */ | |
1024 | continue; | |
1025 | } | |
1026 | ||
1027 | if ((sacked&TCPCB_SACKED_RETRANS) && | |
1028 | after(end_seq, TCP_SKB_CB(skb)->ack_seq) && | |
1029 | (!lost_retrans || after(end_seq, lost_retrans))) | |
1030 | lost_retrans = end_seq; | |
1031 | ||
1032 | if (!in_sack) | |
1033 | continue; | |
1034 | ||
1035 | if (!(sacked&TCPCB_SACKED_ACKED)) { | |
1036 | if (sacked & TCPCB_SACKED_RETRANS) { | |
1037 | /* If the segment is not tagged as lost, | |
1038 | * we do not clear RETRANS, believing | |
1039 | * that retransmission is still in flight. | |
1040 | */ | |
1041 | if (sacked & TCPCB_LOST) { | |
1042 | TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS); | |
1043 | tp->lost_out -= tcp_skb_pcount(skb); | |
1044 | tp->retrans_out -= tcp_skb_pcount(skb); | |
1045 | } | |
1046 | } else { | |
1047 | /* New sack for not retransmitted frame, | |
1048 | * which was in hole. It is reordering. | |
1049 | */ | |
1050 | if (!(sacked & TCPCB_RETRANS) && | |
1051 | fack_count < prior_fackets) | |
1052 | reord = min(fack_count, reord); | |
1053 | ||
1054 | if (sacked & TCPCB_LOST) { | |
1055 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST; | |
1056 | tp->lost_out -= tcp_skb_pcount(skb); | |
1057 | } | |
1058 | } | |
1059 | ||
1060 | TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED; | |
1061 | flag |= FLAG_DATA_SACKED; | |
1062 | tp->sacked_out += tcp_skb_pcount(skb); | |
1063 | ||
1064 | if (fack_count > tp->fackets_out) | |
1065 | tp->fackets_out = fack_count; | |
1066 | } else { | |
1067 | if (dup_sack && (sacked&TCPCB_RETRANS)) | |
1068 | reord = min(fack_count, reord); | |
1069 | } | |
1070 | ||
1071 | /* D-SACK. We can detect redundant retransmission | |
1072 | * in S|R and plain R frames and clear it. | |
1073 | * undo_retrans is decreased above, L|R frames | |
1074 | * are accounted above as well. | |
1075 | */ | |
1076 | if (dup_sack && | |
1077 | (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS)) { | |
1078 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; | |
1079 | tp->retrans_out -= tcp_skb_pcount(skb); | |
1080 | } | |
1081 | } | |
1082 | } | |
1083 | ||
1084 | /* Check for lost retransmit. This superb idea is | |
1085 | * borrowed from "ratehalving". Event "C". | |
1086 | * Later note: FACK people cheated me again 8), | |
1087 | * we have to account for reordering! Ugly, | |
1088 | * but should help. | |
1089 | */ | |
6687e988 | 1090 | if (lost_retrans && icsk->icsk_ca_state == TCP_CA_Recovery) { |
1da177e4 LT |
1091 | struct sk_buff *skb; |
1092 | ||
1093 | sk_stream_for_retrans_queue(skb, sk) { | |
1094 | if (after(TCP_SKB_CB(skb)->seq, lost_retrans)) | |
1095 | break; | |
1096 | if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
1097 | continue; | |
1098 | if ((TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) && | |
1099 | after(lost_retrans, TCP_SKB_CB(skb)->ack_seq) && | |
1100 | (IsFack(tp) || | |
1101 | !before(lost_retrans, | |
1102 | TCP_SKB_CB(skb)->ack_seq + tp->reordering * | |
c1b4a7e6 | 1103 | tp->mss_cache))) { |
1da177e4 LT |
1104 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; |
1105 | tp->retrans_out -= tcp_skb_pcount(skb); | |
1106 | ||
1107 | if (!(TCP_SKB_CB(skb)->sacked&(TCPCB_LOST|TCPCB_SACKED_ACKED))) { | |
1108 | tp->lost_out += tcp_skb_pcount(skb); | |
1109 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1110 | flag |= FLAG_DATA_SACKED; | |
1111 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSTRETRANSMIT); | |
1112 | } | |
1113 | } | |
1114 | } | |
1115 | } | |
1116 | ||
1117 | tp->left_out = tp->sacked_out + tp->lost_out; | |
1118 | ||
6687e988 ACM |
1119 | if ((reord < tp->fackets_out) && icsk->icsk_ca_state != TCP_CA_Loss) |
1120 | tcp_update_reordering(sk, ((tp->fackets_out + 1) - reord), 0); | |
1da177e4 LT |
1121 | |
1122 | #if FASTRETRANS_DEBUG > 0 | |
1123 | BUG_TRAP((int)tp->sacked_out >= 0); | |
1124 | BUG_TRAP((int)tp->lost_out >= 0); | |
1125 | BUG_TRAP((int)tp->retrans_out >= 0); | |
1126 | BUG_TRAP((int)tcp_packets_in_flight(tp) >= 0); | |
1127 | #endif | |
1128 | return flag; | |
1129 | } | |
1130 | ||
1131 | /* RTO occurred, but do not yet enter loss state. Instead, transmit two new | |
1132 | * segments to see from the next ACKs whether any data was really missing. | |
1133 | * If the RTO was spurious, new ACKs should arrive. | |
1134 | */ | |
1135 | void tcp_enter_frto(struct sock *sk) | |
1136 | { | |
6687e988 | 1137 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1138 | struct tcp_sock *tp = tcp_sk(sk); |
1139 | struct sk_buff *skb; | |
1140 | ||
1141 | tp->frto_counter = 1; | |
1142 | ||
6687e988 | 1143 | if (icsk->icsk_ca_state <= TCP_CA_Disorder || |
1da177e4 | 1144 | tp->snd_una == tp->high_seq || |
6687e988 ACM |
1145 | (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) { |
1146 | tp->prior_ssthresh = tcp_current_ssthresh(sk); | |
1147 | tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); | |
1148 | tcp_ca_event(sk, CA_EVENT_FRTO); | |
1da177e4 LT |
1149 | } |
1150 | ||
1151 | /* Have to clear retransmission markers here to keep the bookkeeping | |
1152 | * in shape, even though we are not yet in Loss state. | |
1153 | * If something was really lost, it is eventually caught up | |
1154 | * in tcp_enter_frto_loss. | |
1155 | */ | |
1156 | tp->retrans_out = 0; | |
1157 | tp->undo_marker = tp->snd_una; | |
1158 | tp->undo_retrans = 0; | |
1159 | ||
1160 | sk_stream_for_retrans_queue(skb, sk) { | |
1161 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_RETRANS; | |
1162 | } | |
1163 | tcp_sync_left_out(tp); | |
1164 | ||
6687e988 | 1165 | tcp_set_ca_state(sk, TCP_CA_Open); |
1da177e4 LT |
1166 | tp->frto_highmark = tp->snd_nxt; |
1167 | } | |
1168 | ||
1169 | /* Enter Loss state after F-RTO was applied. Dupack arrived after RTO, | |
1170 | * which indicates that we should follow the traditional RTO recovery, | |
1171 | * i.e. mark everything lost and do go-back-N retransmission. | |
1172 | */ | |
1173 | static void tcp_enter_frto_loss(struct sock *sk) | |
1174 | { | |
1175 | struct tcp_sock *tp = tcp_sk(sk); | |
1176 | struct sk_buff *skb; | |
1177 | int cnt = 0; | |
1178 | ||
1179 | tp->sacked_out = 0; | |
1180 | tp->lost_out = 0; | |
1181 | tp->fackets_out = 0; | |
1182 | ||
1183 | sk_stream_for_retrans_queue(skb, sk) { | |
1184 | cnt += tcp_skb_pcount(skb); | |
1185 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST; | |
1186 | if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) { | |
1187 | ||
1188 | /* Do not mark those segments lost that were | |
1189 | * forward transmitted after RTO | |
1190 | */ | |
1191 | if (!after(TCP_SKB_CB(skb)->end_seq, | |
1192 | tp->frto_highmark)) { | |
1193 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1194 | tp->lost_out += tcp_skb_pcount(skb); | |
1195 | } | |
1196 | } else { | |
1197 | tp->sacked_out += tcp_skb_pcount(skb); | |
1198 | tp->fackets_out = cnt; | |
1199 | } | |
1200 | } | |
1201 | tcp_sync_left_out(tp); | |
1202 | ||
1203 | tp->snd_cwnd = tp->frto_counter + tcp_packets_in_flight(tp)+1; | |
1204 | tp->snd_cwnd_cnt = 0; | |
1205 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1206 | tp->undo_marker = 0; | |
1207 | tp->frto_counter = 0; | |
1208 | ||
1209 | tp->reordering = min_t(unsigned int, tp->reordering, | |
1210 | sysctl_tcp_reordering); | |
6687e988 | 1211 | tcp_set_ca_state(sk, TCP_CA_Loss); |
1da177e4 LT |
1212 | tp->high_seq = tp->frto_highmark; |
1213 | TCP_ECN_queue_cwr(tp); | |
1da177e4 LT |
1214 | } |
1215 | ||
1216 | void tcp_clear_retrans(struct tcp_sock *tp) | |
1217 | { | |
1218 | tp->left_out = 0; | |
1219 | tp->retrans_out = 0; | |
1220 | ||
1221 | tp->fackets_out = 0; | |
1222 | tp->sacked_out = 0; | |
1223 | tp->lost_out = 0; | |
1224 | ||
1225 | tp->undo_marker = 0; | |
1226 | tp->undo_retrans = 0; | |
1227 | } | |
1228 | ||
1229 | /* Enter Loss state. If "how" is not zero, forget all SACK information | |
1230 | * and reset tags completely, otherwise preserve SACKs. If receiver | |
1231 | * dropped its ofo queue, we will know this due to reneging detection. | |
1232 | */ | |
1233 | void tcp_enter_loss(struct sock *sk, int how) | |
1234 | { | |
6687e988 | 1235 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1236 | struct tcp_sock *tp = tcp_sk(sk); |
1237 | struct sk_buff *skb; | |
1238 | int cnt = 0; | |
1239 | ||
1240 | /* Reduce ssthresh if it has not yet been made inside this window. */ | |
6687e988 ACM |
1241 | if (icsk->icsk_ca_state <= TCP_CA_Disorder || tp->snd_una == tp->high_seq || |
1242 | (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) { | |
1243 | tp->prior_ssthresh = tcp_current_ssthresh(sk); | |
1244 | tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); | |
1245 | tcp_ca_event(sk, CA_EVENT_LOSS); | |
1da177e4 LT |
1246 | } |
1247 | tp->snd_cwnd = 1; | |
1248 | tp->snd_cwnd_cnt = 0; | |
1249 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1250 | ||
9772efb9 | 1251 | tp->bytes_acked = 0; |
1da177e4 LT |
1252 | tcp_clear_retrans(tp); |
1253 | ||
1254 | /* Push undo marker, if it was plain RTO and nothing | |
1255 | * was retransmitted. */ | |
1256 | if (!how) | |
1257 | tp->undo_marker = tp->snd_una; | |
1258 | ||
1259 | sk_stream_for_retrans_queue(skb, sk) { | |
1260 | cnt += tcp_skb_pcount(skb); | |
1261 | if (TCP_SKB_CB(skb)->sacked&TCPCB_RETRANS) | |
1262 | tp->undo_marker = 0; | |
1263 | TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED; | |
1264 | if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || how) { | |
1265 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED; | |
1266 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1267 | tp->lost_out += tcp_skb_pcount(skb); | |
1268 | } else { | |
1269 | tp->sacked_out += tcp_skb_pcount(skb); | |
1270 | tp->fackets_out = cnt; | |
1271 | } | |
1272 | } | |
1273 | tcp_sync_left_out(tp); | |
1274 | ||
1275 | tp->reordering = min_t(unsigned int, tp->reordering, | |
1276 | sysctl_tcp_reordering); | |
6687e988 | 1277 | tcp_set_ca_state(sk, TCP_CA_Loss); |
1da177e4 LT |
1278 | tp->high_seq = tp->snd_nxt; |
1279 | TCP_ECN_queue_cwr(tp); | |
1280 | } | |
1281 | ||
463c84b9 | 1282 | static int tcp_check_sack_reneging(struct sock *sk) |
1da177e4 LT |
1283 | { |
1284 | struct sk_buff *skb; | |
1285 | ||
1286 | /* If ACK arrived pointing to a remembered SACK, | |
1287 | * it means that our remembered SACKs do not reflect | |
1288 | * real state of receiver i.e. | |
1289 | * receiver _host_ is heavily congested (or buggy). | |
1290 | * Do processing similar to RTO timeout. | |
1291 | */ | |
1292 | if ((skb = skb_peek(&sk->sk_write_queue)) != NULL && | |
1293 | (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) { | |
6687e988 | 1294 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1295 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKRENEGING); |
1296 | ||
1297 | tcp_enter_loss(sk, 1); | |
6687e988 | 1298 | icsk->icsk_retransmits++; |
1da177e4 | 1299 | tcp_retransmit_skb(sk, skb_peek(&sk->sk_write_queue)); |
463c84b9 | 1300 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
6687e988 | 1301 | icsk->icsk_rto, TCP_RTO_MAX); |
1da177e4 LT |
1302 | return 1; |
1303 | } | |
1304 | return 0; | |
1305 | } | |
1306 | ||
1307 | static inline int tcp_fackets_out(struct tcp_sock *tp) | |
1308 | { | |
1309 | return IsReno(tp) ? tp->sacked_out+1 : tp->fackets_out; | |
1310 | } | |
1311 | ||
463c84b9 | 1312 | static inline int tcp_skb_timedout(struct sock *sk, struct sk_buff *skb) |
1da177e4 | 1313 | { |
463c84b9 | 1314 | return (tcp_time_stamp - TCP_SKB_CB(skb)->when > inet_csk(sk)->icsk_rto); |
1da177e4 LT |
1315 | } |
1316 | ||
1317 | static inline int tcp_head_timedout(struct sock *sk, struct tcp_sock *tp) | |
1318 | { | |
1319 | return tp->packets_out && | |
463c84b9 | 1320 | tcp_skb_timedout(sk, skb_peek(&sk->sk_write_queue)); |
1da177e4 LT |
1321 | } |
1322 | ||
1323 | /* Linux NewReno/SACK/FACK/ECN state machine. | |
1324 | * -------------------------------------- | |
1325 | * | |
1326 | * "Open" Normal state, no dubious events, fast path. | |
1327 | * "Disorder" In all the respects it is "Open", | |
1328 | * but requires a bit more attention. It is entered when | |
1329 | * we see some SACKs or dupacks. It is split of "Open" | |
1330 | * mainly to move some processing from fast path to slow one. | |
1331 | * "CWR" CWND was reduced due to some Congestion Notification event. | |
1332 | * It can be ECN, ICMP source quench, local device congestion. | |
1333 | * "Recovery" CWND was reduced, we are fast-retransmitting. | |
1334 | * "Loss" CWND was reduced due to RTO timeout or SACK reneging. | |
1335 | * | |
1336 | * tcp_fastretrans_alert() is entered: | |
1337 | * - each incoming ACK, if state is not "Open" | |
1338 | * - when arrived ACK is unusual, namely: | |
1339 | * * SACK | |
1340 | * * Duplicate ACK. | |
1341 | * * ECN ECE. | |
1342 | * | |
1343 | * Counting packets in flight is pretty simple. | |
1344 | * | |
1345 | * in_flight = packets_out - left_out + retrans_out | |
1346 | * | |
1347 | * packets_out is SND.NXT-SND.UNA counted in packets. | |
1348 | * | |
1349 | * retrans_out is number of retransmitted segments. | |
1350 | * | |
1351 | * left_out is number of segments left network, but not ACKed yet. | |
1352 | * | |
1353 | * left_out = sacked_out + lost_out | |
1354 | * | |
1355 | * sacked_out: Packets, which arrived to receiver out of order | |
1356 | * and hence not ACKed. With SACKs this number is simply | |
1357 | * amount of SACKed data. Even without SACKs | |
1358 | * it is easy to give pretty reliable estimate of this number, | |
1359 | * counting duplicate ACKs. | |
1360 | * | |
1361 | * lost_out: Packets lost by network. TCP has no explicit | |
1362 | * "loss notification" feedback from network (for now). | |
1363 | * It means that this number can be only _guessed_. | |
1364 | * Actually, it is the heuristics to predict lossage that | |
1365 | * distinguishes different algorithms. | |
1366 | * | |
1367 | * F.e. after RTO, when all the queue is considered as lost, | |
1368 | * lost_out = packets_out and in_flight = retrans_out. | |
1369 | * | |
1370 | * Essentially, we have now two algorithms counting | |
1371 | * lost packets. | |
1372 | * | |
1373 | * FACK: It is the simplest heuristics. As soon as we decided | |
1374 | * that something is lost, we decide that _all_ not SACKed | |
1375 | * packets until the most forward SACK are lost. I.e. | |
1376 | * lost_out = fackets_out - sacked_out and left_out = fackets_out. | |
1377 | * It is absolutely correct estimate, if network does not reorder | |
1378 | * packets. And it loses any connection to reality when reordering | |
1379 | * takes place. We use FACK by default until reordering | |
1380 | * is suspected on the path to this destination. | |
1381 | * | |
1382 | * NewReno: when Recovery is entered, we assume that one segment | |
1383 | * is lost (classic Reno). While we are in Recovery and | |
1384 | * a partial ACK arrives, we assume that one more packet | |
1385 | * is lost (NewReno). This heuristics are the same in NewReno | |
1386 | * and SACK. | |
1387 | * | |
1388 | * Imagine, that's all! Forget about all this shamanism about CWND inflation | |
1389 | * deflation etc. CWND is real congestion window, never inflated, changes | |
1390 | * only according to classic VJ rules. | |
1391 | * | |
1392 | * Really tricky (and requiring careful tuning) part of algorithm | |
1393 | * is hidden in functions tcp_time_to_recover() and tcp_xmit_retransmit_queue(). | |
1394 | * The first determines the moment _when_ we should reduce CWND and, | |
1395 | * hence, slow down forward transmission. In fact, it determines the moment | |
1396 | * when we decide that hole is caused by loss, rather than by a reorder. | |
1397 | * | |
1398 | * tcp_xmit_retransmit_queue() decides, _what_ we should retransmit to fill | |
1399 | * holes, caused by lost packets. | |
1400 | * | |
1401 | * And the most logically complicated part of algorithm is undo | |
1402 | * heuristics. We detect false retransmits due to both too early | |
1403 | * fast retransmit (reordering) and underestimated RTO, analyzing | |
1404 | * timestamps and D-SACKs. When we detect that some segments were | |
1405 | * retransmitted by mistake and CWND reduction was wrong, we undo | |
1406 | * window reduction and abort recovery phase. This logic is hidden | |
1407 | * inside several functions named tcp_try_undo_<something>. | |
1408 | */ | |
1409 | ||
1410 | /* This function decides, when we should leave Disordered state | |
1411 | * and enter Recovery phase, reducing congestion window. | |
1412 | * | |
1413 | * Main question: may we further continue forward transmission | |
1414 | * with the same cwnd? | |
1415 | */ | |
1416 | static int tcp_time_to_recover(struct sock *sk, struct tcp_sock *tp) | |
1417 | { | |
1418 | __u32 packets_out; | |
1419 | ||
1420 | /* Trick#1: The loss is proven. */ | |
1421 | if (tp->lost_out) | |
1422 | return 1; | |
1423 | ||
1424 | /* Not-A-Trick#2 : Classic rule... */ | |
1425 | if (tcp_fackets_out(tp) > tp->reordering) | |
1426 | return 1; | |
1427 | ||
1428 | /* Trick#3 : when we use RFC2988 timer restart, fast | |
1429 | * retransmit can be triggered by timeout of queue head. | |
1430 | */ | |
1431 | if (tcp_head_timedout(sk, tp)) | |
1432 | return 1; | |
1433 | ||
1434 | /* Trick#4: It is still not OK... But will it be useful to delay | |
1435 | * recovery more? | |
1436 | */ | |
1437 | packets_out = tp->packets_out; | |
1438 | if (packets_out <= tp->reordering && | |
1439 | tp->sacked_out >= max_t(__u32, packets_out/2, sysctl_tcp_reordering) && | |
1440 | !tcp_may_send_now(sk, tp)) { | |
1441 | /* We have nothing to send. This connection is limited | |
1442 | * either by receiver window or by application. | |
1443 | */ | |
1444 | return 1; | |
1445 | } | |
1446 | ||
1447 | return 0; | |
1448 | } | |
1449 | ||
1450 | /* If we receive more dupacks than we expected counting segments | |
1451 | * in assumption of absent reordering, interpret this as reordering. | |
1452 | * The only another reason could be bug in receiver TCP. | |
1453 | */ | |
6687e988 | 1454 | static void tcp_check_reno_reordering(struct sock *sk, const int addend) |
1da177e4 | 1455 | { |
6687e988 | 1456 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
1457 | u32 holes; |
1458 | ||
1459 | holes = max(tp->lost_out, 1U); | |
1460 | holes = min(holes, tp->packets_out); | |
1461 | ||
1462 | if ((tp->sacked_out + holes) > tp->packets_out) { | |
1463 | tp->sacked_out = tp->packets_out - holes; | |
6687e988 | 1464 | tcp_update_reordering(sk, tp->packets_out + addend, 0); |
1da177e4 LT |
1465 | } |
1466 | } | |
1467 | ||
1468 | /* Emulate SACKs for SACKless connection: account for a new dupack. */ | |
1469 | ||
6687e988 | 1470 | static void tcp_add_reno_sack(struct sock *sk) |
1da177e4 | 1471 | { |
6687e988 | 1472 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 | 1473 | tp->sacked_out++; |
6687e988 | 1474 | tcp_check_reno_reordering(sk, 0); |
1da177e4 LT |
1475 | tcp_sync_left_out(tp); |
1476 | } | |
1477 | ||
1478 | /* Account for ACK, ACKing some data in Reno Recovery phase. */ | |
1479 | ||
1480 | static void tcp_remove_reno_sacks(struct sock *sk, struct tcp_sock *tp, int acked) | |
1481 | { | |
1482 | if (acked > 0) { | |
1483 | /* One ACK acked hole. The rest eat duplicate ACKs. */ | |
1484 | if (acked-1 >= tp->sacked_out) | |
1485 | tp->sacked_out = 0; | |
1486 | else | |
1487 | tp->sacked_out -= acked-1; | |
1488 | } | |
6687e988 | 1489 | tcp_check_reno_reordering(sk, acked); |
1da177e4 LT |
1490 | tcp_sync_left_out(tp); |
1491 | } | |
1492 | ||
1493 | static inline void tcp_reset_reno_sack(struct tcp_sock *tp) | |
1494 | { | |
1495 | tp->sacked_out = 0; | |
1496 | tp->left_out = tp->lost_out; | |
1497 | } | |
1498 | ||
1499 | /* Mark head of queue up as lost. */ | |
1500 | static void tcp_mark_head_lost(struct sock *sk, struct tcp_sock *tp, | |
1501 | int packets, u32 high_seq) | |
1502 | { | |
1503 | struct sk_buff *skb; | |
1504 | int cnt = packets; | |
1505 | ||
1506 | BUG_TRAP(cnt <= tp->packets_out); | |
1507 | ||
1508 | sk_stream_for_retrans_queue(skb, sk) { | |
1509 | cnt -= tcp_skb_pcount(skb); | |
1510 | if (cnt < 0 || after(TCP_SKB_CB(skb)->end_seq, high_seq)) | |
1511 | break; | |
1512 | if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) { | |
1513 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1514 | tp->lost_out += tcp_skb_pcount(skb); | |
1515 | } | |
1516 | } | |
1517 | tcp_sync_left_out(tp); | |
1518 | } | |
1519 | ||
1520 | /* Account newly detected lost packet(s) */ | |
1521 | ||
1522 | static void tcp_update_scoreboard(struct sock *sk, struct tcp_sock *tp) | |
1523 | { | |
1524 | if (IsFack(tp)) { | |
1525 | int lost = tp->fackets_out - tp->reordering; | |
1526 | if (lost <= 0) | |
1527 | lost = 1; | |
1528 | tcp_mark_head_lost(sk, tp, lost, tp->high_seq); | |
1529 | } else { | |
1530 | tcp_mark_head_lost(sk, tp, 1, tp->high_seq); | |
1531 | } | |
1532 | ||
1533 | /* New heuristics: it is possible only after we switched | |
1534 | * to restart timer each time when something is ACKed. | |
1535 | * Hence, we can detect timed out packets during fast | |
1536 | * retransmit without falling to slow start. | |
1537 | */ | |
1538 | if (tcp_head_timedout(sk, tp)) { | |
1539 | struct sk_buff *skb; | |
1540 | ||
1541 | sk_stream_for_retrans_queue(skb, sk) { | |
463c84b9 | 1542 | if (tcp_skb_timedout(sk, skb) && |
1da177e4 LT |
1543 | !(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) { |
1544 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1545 | tp->lost_out += tcp_skb_pcount(skb); | |
1546 | } | |
1547 | } | |
1548 | tcp_sync_left_out(tp); | |
1549 | } | |
1550 | } | |
1551 | ||
1552 | /* CWND moderation, preventing bursts due to too big ACKs | |
1553 | * in dubious situations. | |
1554 | */ | |
1555 | static inline void tcp_moderate_cwnd(struct tcp_sock *tp) | |
1556 | { | |
1557 | tp->snd_cwnd = min(tp->snd_cwnd, | |
1558 | tcp_packets_in_flight(tp)+tcp_max_burst(tp)); | |
1559 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1560 | } | |
1561 | ||
1562 | /* Decrease cwnd each second ack. */ | |
6687e988 | 1563 | static void tcp_cwnd_down(struct sock *sk) |
1da177e4 | 1564 | { |
6687e988 ACM |
1565 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1566 | struct tcp_sock *tp = tcp_sk(sk); | |
1da177e4 | 1567 | int decr = tp->snd_cwnd_cnt + 1; |
1da177e4 LT |
1568 | |
1569 | tp->snd_cwnd_cnt = decr&1; | |
1570 | decr >>= 1; | |
1571 | ||
6687e988 | 1572 | if (decr && tp->snd_cwnd > icsk->icsk_ca_ops->min_cwnd(sk)) |
1da177e4 LT |
1573 | tp->snd_cwnd -= decr; |
1574 | ||
1575 | tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)+1); | |
1576 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1577 | } | |
1578 | ||
1579 | /* Nothing was retransmitted or returned timestamp is less | |
1580 | * than timestamp of the first retransmission. | |
1581 | */ | |
1582 | static inline int tcp_packet_delayed(struct tcp_sock *tp) | |
1583 | { | |
1584 | return !tp->retrans_stamp || | |
1585 | (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr && | |
1586 | (__s32)(tp->rx_opt.rcv_tsecr - tp->retrans_stamp) < 0); | |
1587 | } | |
1588 | ||
1589 | /* Undo procedures. */ | |
1590 | ||
1591 | #if FASTRETRANS_DEBUG > 1 | |
1592 | static void DBGUNDO(struct sock *sk, struct tcp_sock *tp, const char *msg) | |
1593 | { | |
1594 | struct inet_sock *inet = inet_sk(sk); | |
1595 | printk(KERN_DEBUG "Undo %s %u.%u.%u.%u/%u c%u l%u ss%u/%u p%u\n", | |
1596 | msg, | |
1597 | NIPQUAD(inet->daddr), ntohs(inet->dport), | |
1598 | tp->snd_cwnd, tp->left_out, | |
1599 | tp->snd_ssthresh, tp->prior_ssthresh, | |
1600 | tp->packets_out); | |
1601 | } | |
1602 | #else | |
1603 | #define DBGUNDO(x...) do { } while (0) | |
1604 | #endif | |
1605 | ||
6687e988 | 1606 | static void tcp_undo_cwr(struct sock *sk, const int undo) |
1da177e4 | 1607 | { |
6687e988 ACM |
1608 | struct tcp_sock *tp = tcp_sk(sk); |
1609 | ||
1da177e4 | 1610 | if (tp->prior_ssthresh) { |
6687e988 ACM |
1611 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1612 | ||
1613 | if (icsk->icsk_ca_ops->undo_cwnd) | |
1614 | tp->snd_cwnd = icsk->icsk_ca_ops->undo_cwnd(sk); | |
1da177e4 LT |
1615 | else |
1616 | tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh<<1); | |
1617 | ||
1618 | if (undo && tp->prior_ssthresh > tp->snd_ssthresh) { | |
1619 | tp->snd_ssthresh = tp->prior_ssthresh; | |
1620 | TCP_ECN_withdraw_cwr(tp); | |
1621 | } | |
1622 | } else { | |
1623 | tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh); | |
1624 | } | |
1625 | tcp_moderate_cwnd(tp); | |
1626 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1627 | } | |
1628 | ||
1629 | static inline int tcp_may_undo(struct tcp_sock *tp) | |
1630 | { | |
1631 | return tp->undo_marker && | |
1632 | (!tp->undo_retrans || tcp_packet_delayed(tp)); | |
1633 | } | |
1634 | ||
1635 | /* People celebrate: "We love our President!" */ | |
1636 | static int tcp_try_undo_recovery(struct sock *sk, struct tcp_sock *tp) | |
1637 | { | |
1638 | if (tcp_may_undo(tp)) { | |
1639 | /* Happy end! We did not retransmit anything | |
1640 | * or our original transmission succeeded. | |
1641 | */ | |
6687e988 ACM |
1642 | DBGUNDO(sk, tp, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans"); |
1643 | tcp_undo_cwr(sk, 1); | |
1644 | if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss) | |
1da177e4 LT |
1645 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO); |
1646 | else | |
1647 | NET_INC_STATS_BH(LINUX_MIB_TCPFULLUNDO); | |
1648 | tp->undo_marker = 0; | |
1649 | } | |
1650 | if (tp->snd_una == tp->high_seq && IsReno(tp)) { | |
1651 | /* Hold old state until something *above* high_seq | |
1652 | * is ACKed. For Reno it is MUST to prevent false | |
1653 | * fast retransmits (RFC2582). SACK TCP is safe. */ | |
1654 | tcp_moderate_cwnd(tp); | |
1655 | return 1; | |
1656 | } | |
6687e988 | 1657 | tcp_set_ca_state(sk, TCP_CA_Open); |
1da177e4 LT |
1658 | return 0; |
1659 | } | |
1660 | ||
1661 | /* Try to undo cwnd reduction, because D-SACKs acked all retransmitted data */ | |
1662 | static void tcp_try_undo_dsack(struct sock *sk, struct tcp_sock *tp) | |
1663 | { | |
1664 | if (tp->undo_marker && !tp->undo_retrans) { | |
1665 | DBGUNDO(sk, tp, "D-SACK"); | |
6687e988 | 1666 | tcp_undo_cwr(sk, 1); |
1da177e4 LT |
1667 | tp->undo_marker = 0; |
1668 | NET_INC_STATS_BH(LINUX_MIB_TCPDSACKUNDO); | |
1669 | } | |
1670 | } | |
1671 | ||
1672 | /* Undo during fast recovery after partial ACK. */ | |
1673 | ||
1674 | static int tcp_try_undo_partial(struct sock *sk, struct tcp_sock *tp, | |
1675 | int acked) | |
1676 | { | |
1677 | /* Partial ACK arrived. Force Hoe's retransmit. */ | |
1678 | int failed = IsReno(tp) || tp->fackets_out>tp->reordering; | |
1679 | ||
1680 | if (tcp_may_undo(tp)) { | |
1681 | /* Plain luck! Hole if filled with delayed | |
1682 | * packet, rather than with a retransmit. | |
1683 | */ | |
1684 | if (tp->retrans_out == 0) | |
1685 | tp->retrans_stamp = 0; | |
1686 | ||
6687e988 | 1687 | tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1); |
1da177e4 LT |
1688 | |
1689 | DBGUNDO(sk, tp, "Hoe"); | |
6687e988 | 1690 | tcp_undo_cwr(sk, 0); |
1da177e4 LT |
1691 | NET_INC_STATS_BH(LINUX_MIB_TCPPARTIALUNDO); |
1692 | ||
1693 | /* So... Do not make Hoe's retransmit yet. | |
1694 | * If the first packet was delayed, the rest | |
1695 | * ones are most probably delayed as well. | |
1696 | */ | |
1697 | failed = 0; | |
1698 | } | |
1699 | return failed; | |
1700 | } | |
1701 | ||
1702 | /* Undo during loss recovery after partial ACK. */ | |
1703 | static int tcp_try_undo_loss(struct sock *sk, struct tcp_sock *tp) | |
1704 | { | |
1705 | if (tcp_may_undo(tp)) { | |
1706 | struct sk_buff *skb; | |
1707 | sk_stream_for_retrans_queue(skb, sk) { | |
1708 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST; | |
1709 | } | |
1710 | DBGUNDO(sk, tp, "partial loss"); | |
1711 | tp->lost_out = 0; | |
1712 | tp->left_out = tp->sacked_out; | |
6687e988 | 1713 | tcp_undo_cwr(sk, 1); |
1da177e4 | 1714 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO); |
463c84b9 | 1715 | inet_csk(sk)->icsk_retransmits = 0; |
1da177e4 LT |
1716 | tp->undo_marker = 0; |
1717 | if (!IsReno(tp)) | |
6687e988 | 1718 | tcp_set_ca_state(sk, TCP_CA_Open); |
1da177e4 LT |
1719 | return 1; |
1720 | } | |
1721 | return 0; | |
1722 | } | |
1723 | ||
6687e988 | 1724 | static inline void tcp_complete_cwr(struct sock *sk) |
1da177e4 | 1725 | { |
6687e988 | 1726 | struct tcp_sock *tp = tcp_sk(sk); |
317a76f9 | 1727 | tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh); |
1da177e4 | 1728 | tp->snd_cwnd_stamp = tcp_time_stamp; |
6687e988 | 1729 | tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR); |
1da177e4 LT |
1730 | } |
1731 | ||
1732 | static void tcp_try_to_open(struct sock *sk, struct tcp_sock *tp, int flag) | |
1733 | { | |
1734 | tp->left_out = tp->sacked_out; | |
1735 | ||
1736 | if (tp->retrans_out == 0) | |
1737 | tp->retrans_stamp = 0; | |
1738 | ||
1739 | if (flag&FLAG_ECE) | |
6687e988 | 1740 | tcp_enter_cwr(sk); |
1da177e4 | 1741 | |
6687e988 | 1742 | if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) { |
1da177e4 LT |
1743 | int state = TCP_CA_Open; |
1744 | ||
1745 | if (tp->left_out || tp->retrans_out || tp->undo_marker) | |
1746 | state = TCP_CA_Disorder; | |
1747 | ||
6687e988 ACM |
1748 | if (inet_csk(sk)->icsk_ca_state != state) { |
1749 | tcp_set_ca_state(sk, state); | |
1da177e4 LT |
1750 | tp->high_seq = tp->snd_nxt; |
1751 | } | |
1752 | tcp_moderate_cwnd(tp); | |
1753 | } else { | |
6687e988 | 1754 | tcp_cwnd_down(sk); |
1da177e4 LT |
1755 | } |
1756 | } | |
1757 | ||
1758 | /* Process an event, which can update packets-in-flight not trivially. | |
1759 | * Main goal of this function is to calculate new estimate for left_out, | |
1760 | * taking into account both packets sitting in receiver's buffer and | |
1761 | * packets lost by network. | |
1762 | * | |
1763 | * Besides that it does CWND reduction, when packet loss is detected | |
1764 | * and changes state of machine. | |
1765 | * | |
1766 | * It does _not_ decide what to send, it is made in function | |
1767 | * tcp_xmit_retransmit_queue(). | |
1768 | */ | |
1769 | static void | |
1770 | tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una, | |
1771 | int prior_packets, int flag) | |
1772 | { | |
6687e988 | 1773 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1774 | struct tcp_sock *tp = tcp_sk(sk); |
1775 | int is_dupack = (tp->snd_una == prior_snd_una && !(flag&FLAG_NOT_DUP)); | |
1776 | ||
1777 | /* Some technical things: | |
1778 | * 1. Reno does not count dupacks (sacked_out) automatically. */ | |
1779 | if (!tp->packets_out) | |
1780 | tp->sacked_out = 0; | |
1781 | /* 2. SACK counts snd_fack in packets inaccurately. */ | |
1782 | if (tp->sacked_out == 0) | |
1783 | tp->fackets_out = 0; | |
1784 | ||
1785 | /* Now state machine starts. | |
1786 | * A. ECE, hence prohibit cwnd undoing, the reduction is required. */ | |
1787 | if (flag&FLAG_ECE) | |
1788 | tp->prior_ssthresh = 0; | |
1789 | ||
1790 | /* B. In all the states check for reneging SACKs. */ | |
463c84b9 | 1791 | if (tp->sacked_out && tcp_check_sack_reneging(sk)) |
1da177e4 LT |
1792 | return; |
1793 | ||
1794 | /* C. Process data loss notification, provided it is valid. */ | |
1795 | if ((flag&FLAG_DATA_LOST) && | |
1796 | before(tp->snd_una, tp->high_seq) && | |
6687e988 | 1797 | icsk->icsk_ca_state != TCP_CA_Open && |
1da177e4 LT |
1798 | tp->fackets_out > tp->reordering) { |
1799 | tcp_mark_head_lost(sk, tp, tp->fackets_out-tp->reordering, tp->high_seq); | |
1800 | NET_INC_STATS_BH(LINUX_MIB_TCPLOSS); | |
1801 | } | |
1802 | ||
1803 | /* D. Synchronize left_out to current state. */ | |
1804 | tcp_sync_left_out(tp); | |
1805 | ||
1806 | /* E. Check state exit conditions. State can be terminated | |
1807 | * when high_seq is ACKed. */ | |
6687e988 | 1808 | if (icsk->icsk_ca_state == TCP_CA_Open) { |
1da177e4 LT |
1809 | if (!sysctl_tcp_frto) |
1810 | BUG_TRAP(tp->retrans_out == 0); | |
1811 | tp->retrans_stamp = 0; | |
1812 | } else if (!before(tp->snd_una, tp->high_seq)) { | |
6687e988 | 1813 | switch (icsk->icsk_ca_state) { |
1da177e4 | 1814 | case TCP_CA_Loss: |
6687e988 | 1815 | icsk->icsk_retransmits = 0; |
1da177e4 LT |
1816 | if (tcp_try_undo_recovery(sk, tp)) |
1817 | return; | |
1818 | break; | |
1819 | ||
1820 | case TCP_CA_CWR: | |
1821 | /* CWR is to be held something *above* high_seq | |
1822 | * is ACKed for CWR bit to reach receiver. */ | |
1823 | if (tp->snd_una != tp->high_seq) { | |
6687e988 ACM |
1824 | tcp_complete_cwr(sk); |
1825 | tcp_set_ca_state(sk, TCP_CA_Open); | |
1da177e4 LT |
1826 | } |
1827 | break; | |
1828 | ||
1829 | case TCP_CA_Disorder: | |
1830 | tcp_try_undo_dsack(sk, tp); | |
1831 | if (!tp->undo_marker || | |
1832 | /* For SACK case do not Open to allow to undo | |
1833 | * catching for all duplicate ACKs. */ | |
1834 | IsReno(tp) || tp->snd_una != tp->high_seq) { | |
1835 | tp->undo_marker = 0; | |
6687e988 | 1836 | tcp_set_ca_state(sk, TCP_CA_Open); |
1da177e4 LT |
1837 | } |
1838 | break; | |
1839 | ||
1840 | case TCP_CA_Recovery: | |
1841 | if (IsReno(tp)) | |
1842 | tcp_reset_reno_sack(tp); | |
1843 | if (tcp_try_undo_recovery(sk, tp)) | |
1844 | return; | |
6687e988 | 1845 | tcp_complete_cwr(sk); |
1da177e4 LT |
1846 | break; |
1847 | } | |
1848 | } | |
1849 | ||
1850 | /* F. Process state. */ | |
6687e988 | 1851 | switch (icsk->icsk_ca_state) { |
1da177e4 LT |
1852 | case TCP_CA_Recovery: |
1853 | if (prior_snd_una == tp->snd_una) { | |
1854 | if (IsReno(tp) && is_dupack) | |
6687e988 | 1855 | tcp_add_reno_sack(sk); |
1da177e4 LT |
1856 | } else { |
1857 | int acked = prior_packets - tp->packets_out; | |
1858 | if (IsReno(tp)) | |
1859 | tcp_remove_reno_sacks(sk, tp, acked); | |
1860 | is_dupack = tcp_try_undo_partial(sk, tp, acked); | |
1861 | } | |
1862 | break; | |
1863 | case TCP_CA_Loss: | |
1864 | if (flag&FLAG_DATA_ACKED) | |
6687e988 | 1865 | icsk->icsk_retransmits = 0; |
1da177e4 LT |
1866 | if (!tcp_try_undo_loss(sk, tp)) { |
1867 | tcp_moderate_cwnd(tp); | |
1868 | tcp_xmit_retransmit_queue(sk); | |
1869 | return; | |
1870 | } | |
6687e988 | 1871 | if (icsk->icsk_ca_state != TCP_CA_Open) |
1da177e4 LT |
1872 | return; |
1873 | /* Loss is undone; fall through to processing in Open state. */ | |
1874 | default: | |
1875 | if (IsReno(tp)) { | |
1876 | if (tp->snd_una != prior_snd_una) | |
1877 | tcp_reset_reno_sack(tp); | |
1878 | if (is_dupack) | |
6687e988 | 1879 | tcp_add_reno_sack(sk); |
1da177e4 LT |
1880 | } |
1881 | ||
6687e988 | 1882 | if (icsk->icsk_ca_state == TCP_CA_Disorder) |
1da177e4 LT |
1883 | tcp_try_undo_dsack(sk, tp); |
1884 | ||
1885 | if (!tcp_time_to_recover(sk, tp)) { | |
1886 | tcp_try_to_open(sk, tp, flag); | |
1887 | return; | |
1888 | } | |
1889 | ||
1890 | /* Otherwise enter Recovery state */ | |
1891 | ||
1892 | if (IsReno(tp)) | |
1893 | NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERY); | |
1894 | else | |
1895 | NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERY); | |
1896 | ||
1897 | tp->high_seq = tp->snd_nxt; | |
1898 | tp->prior_ssthresh = 0; | |
1899 | tp->undo_marker = tp->snd_una; | |
1900 | tp->undo_retrans = tp->retrans_out; | |
1901 | ||
6687e988 | 1902 | if (icsk->icsk_ca_state < TCP_CA_CWR) { |
1da177e4 | 1903 | if (!(flag&FLAG_ECE)) |
6687e988 ACM |
1904 | tp->prior_ssthresh = tcp_current_ssthresh(sk); |
1905 | tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); | |
1da177e4 LT |
1906 | TCP_ECN_queue_cwr(tp); |
1907 | } | |
1908 | ||
9772efb9 | 1909 | tp->bytes_acked = 0; |
1da177e4 | 1910 | tp->snd_cwnd_cnt = 0; |
6687e988 | 1911 | tcp_set_ca_state(sk, TCP_CA_Recovery); |
1da177e4 LT |
1912 | } |
1913 | ||
1914 | if (is_dupack || tcp_head_timedout(sk, tp)) | |
1915 | tcp_update_scoreboard(sk, tp); | |
6687e988 | 1916 | tcp_cwnd_down(sk); |
1da177e4 LT |
1917 | tcp_xmit_retransmit_queue(sk); |
1918 | } | |
1919 | ||
1920 | /* Read draft-ietf-tcplw-high-performance before mucking | |
1921 | * with this code. (Superceeds RFC1323) | |
1922 | */ | |
2d2abbab | 1923 | static void tcp_ack_saw_tstamp(struct sock *sk, int flag) |
1da177e4 | 1924 | { |
1da177e4 LT |
1925 | /* RTTM Rule: A TSecr value received in a segment is used to |
1926 | * update the averaged RTT measurement only if the segment | |
1927 | * acknowledges some new data, i.e., only if it advances the | |
1928 | * left edge of the send window. | |
1929 | * | |
1930 | * See draft-ietf-tcplw-high-performance-00, section 3.3. | |
1931 | * 1998/04/10 Andrey V. Savochkin <saw@msu.ru> | |
1932 | * | |
1933 | * Changed: reset backoff as soon as we see the first valid sample. | |
1934 | * If we do not, we get strongly overstimated rto. With timestamps | |
1935 | * samples are accepted even from very old segments: f.e., when rtt=1 | |
1936 | * increases to 8, we retransmit 5 times and after 8 seconds delayed | |
1937 | * answer arrives rto becomes 120 seconds! If at least one of segments | |
1938 | * in window is lost... Voila. --ANK (010210) | |
1939 | */ | |
463c84b9 ACM |
1940 | struct tcp_sock *tp = tcp_sk(sk); |
1941 | const __u32 seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr; | |
2d2abbab | 1942 | tcp_rtt_estimator(sk, seq_rtt); |
463c84b9 ACM |
1943 | tcp_set_rto(sk); |
1944 | inet_csk(sk)->icsk_backoff = 0; | |
1945 | tcp_bound_rto(sk); | |
1da177e4 LT |
1946 | } |
1947 | ||
2d2abbab | 1948 | static void tcp_ack_no_tstamp(struct sock *sk, u32 seq_rtt, int flag) |
1da177e4 LT |
1949 | { |
1950 | /* We don't have a timestamp. Can only use | |
1951 | * packets that are not retransmitted to determine | |
1952 | * rtt estimates. Also, we must not reset the | |
1953 | * backoff for rto until we get a non-retransmitted | |
1954 | * packet. This allows us to deal with a situation | |
1955 | * where the network delay has increased suddenly. | |
1956 | * I.e. Karn's algorithm. (SIGCOMM '87, p5.) | |
1957 | */ | |
1958 | ||
1959 | if (flag & FLAG_RETRANS_DATA_ACKED) | |
1960 | return; | |
1961 | ||
2d2abbab | 1962 | tcp_rtt_estimator(sk, seq_rtt); |
463c84b9 ACM |
1963 | tcp_set_rto(sk); |
1964 | inet_csk(sk)->icsk_backoff = 0; | |
1965 | tcp_bound_rto(sk); | |
1da177e4 LT |
1966 | } |
1967 | ||
463c84b9 | 1968 | static inline void tcp_ack_update_rtt(struct sock *sk, const int flag, |
2d2abbab | 1969 | const s32 seq_rtt) |
1da177e4 | 1970 | { |
463c84b9 | 1971 | const struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
1972 | /* Note that peer MAY send zero echo. In this case it is ignored. (rfc1323) */ |
1973 | if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) | |
2d2abbab | 1974 | tcp_ack_saw_tstamp(sk, flag); |
1da177e4 | 1975 | else if (seq_rtt >= 0) |
2d2abbab | 1976 | tcp_ack_no_tstamp(sk, seq_rtt, flag); |
1da177e4 LT |
1977 | } |
1978 | ||
6687e988 | 1979 | static inline void tcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt, |
317a76f9 | 1980 | u32 in_flight, int good) |
1da177e4 | 1981 | { |
6687e988 ACM |
1982 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1983 | icsk->icsk_ca_ops->cong_avoid(sk, ack, rtt, in_flight, good); | |
1984 | tcp_sk(sk)->snd_cwnd_stamp = tcp_time_stamp; | |
1da177e4 LT |
1985 | } |
1986 | ||
1da177e4 LT |
1987 | /* Restart timer after forward progress on connection. |
1988 | * RFC2988 recommends to restart timer to now+rto. | |
1989 | */ | |
1990 | ||
1991 | static inline void tcp_ack_packets_out(struct sock *sk, struct tcp_sock *tp) | |
1992 | { | |
1993 | if (!tp->packets_out) { | |
463c84b9 | 1994 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); |
1da177e4 | 1995 | } else { |
3f421baa | 1996 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, inet_csk(sk)->icsk_rto, TCP_RTO_MAX); |
1da177e4 LT |
1997 | } |
1998 | } | |
1999 | ||
1da177e4 LT |
2000 | static int tcp_tso_acked(struct sock *sk, struct sk_buff *skb, |
2001 | __u32 now, __s32 *seq_rtt) | |
2002 | { | |
2003 | struct tcp_sock *tp = tcp_sk(sk); | |
2004 | struct tcp_skb_cb *scb = TCP_SKB_CB(skb); | |
2005 | __u32 seq = tp->snd_una; | |
2006 | __u32 packets_acked; | |
2007 | int acked = 0; | |
2008 | ||
2009 | /* If we get here, the whole TSO packet has not been | |
2010 | * acked. | |
2011 | */ | |
2012 | BUG_ON(!after(scb->end_seq, seq)); | |
2013 | ||
2014 | packets_acked = tcp_skb_pcount(skb); | |
2015 | if (tcp_trim_head(sk, skb, seq - scb->seq)) | |
2016 | return 0; | |
2017 | packets_acked -= tcp_skb_pcount(skb); | |
2018 | ||
2019 | if (packets_acked) { | |
2020 | __u8 sacked = scb->sacked; | |
2021 | ||
2022 | acked |= FLAG_DATA_ACKED; | |
2023 | if (sacked) { | |
2024 | if (sacked & TCPCB_RETRANS) { | |
2025 | if (sacked & TCPCB_SACKED_RETRANS) | |
2026 | tp->retrans_out -= packets_acked; | |
2027 | acked |= FLAG_RETRANS_DATA_ACKED; | |
2028 | *seq_rtt = -1; | |
2029 | } else if (*seq_rtt < 0) | |
2030 | *seq_rtt = now - scb->when; | |
2031 | if (sacked & TCPCB_SACKED_ACKED) | |
2032 | tp->sacked_out -= packets_acked; | |
2033 | if (sacked & TCPCB_LOST) | |
2034 | tp->lost_out -= packets_acked; | |
2035 | if (sacked & TCPCB_URG) { | |
2036 | if (tp->urg_mode && | |
2037 | !before(seq, tp->snd_up)) | |
2038 | tp->urg_mode = 0; | |
2039 | } | |
2040 | } else if (*seq_rtt < 0) | |
2041 | *seq_rtt = now - scb->when; | |
2042 | ||
2043 | if (tp->fackets_out) { | |
2044 | __u32 dval = min(tp->fackets_out, packets_acked); | |
2045 | tp->fackets_out -= dval; | |
2046 | } | |
2047 | tp->packets_out -= packets_acked; | |
2048 | ||
2049 | BUG_ON(tcp_skb_pcount(skb) == 0); | |
2050 | BUG_ON(!before(scb->seq, scb->end_seq)); | |
2051 | } | |
2052 | ||
2053 | return acked; | |
2054 | } | |
2055 | ||
2d2abbab SH |
2056 | static inline u32 tcp_usrtt(const struct sk_buff *skb) |
2057 | { | |
2058 | struct timeval tv, now; | |
2059 | ||
2060 | do_gettimeofday(&now); | |
2061 | skb_get_timestamp(skb, &tv); | |
2062 | return (now.tv_sec - tv.tv_sec) * 1000000 + (now.tv_usec - tv.tv_usec); | |
2063 | } | |
1da177e4 LT |
2064 | |
2065 | /* Remove acknowledged frames from the retransmission queue. */ | |
2d2abbab | 2066 | static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p) |
1da177e4 LT |
2067 | { |
2068 | struct tcp_sock *tp = tcp_sk(sk); | |
2d2abbab | 2069 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2070 | struct sk_buff *skb; |
2071 | __u32 now = tcp_time_stamp; | |
2072 | int acked = 0; | |
2073 | __s32 seq_rtt = -1; | |
317a76f9 | 2074 | u32 pkts_acked = 0; |
2d2abbab SH |
2075 | void (*rtt_sample)(struct sock *sk, u32 usrtt) |
2076 | = icsk->icsk_ca_ops->rtt_sample; | |
1da177e4 LT |
2077 | |
2078 | while ((skb = skb_peek(&sk->sk_write_queue)) && | |
2079 | skb != sk->sk_send_head) { | |
2080 | struct tcp_skb_cb *scb = TCP_SKB_CB(skb); | |
2081 | __u8 sacked = scb->sacked; | |
2082 | ||
2083 | /* If our packet is before the ack sequence we can | |
2084 | * discard it as it's confirmed to have arrived at | |
2085 | * the other end. | |
2086 | */ | |
2087 | if (after(scb->end_seq, tp->snd_una)) { | |
cb83199a DM |
2088 | if (tcp_skb_pcount(skb) > 1 && |
2089 | after(tp->snd_una, scb->seq)) | |
1da177e4 LT |
2090 | acked |= tcp_tso_acked(sk, skb, |
2091 | now, &seq_rtt); | |
2092 | break; | |
2093 | } | |
2094 | ||
2095 | /* Initial outgoing SYN's get put onto the write_queue | |
2096 | * just like anything else we transmit. It is not | |
2097 | * true data, and if we misinform our callers that | |
2098 | * this ACK acks real data, we will erroneously exit | |
2099 | * connection startup slow start one packet too | |
2100 | * quickly. This is severely frowned upon behavior. | |
2101 | */ | |
2102 | if (!(scb->flags & TCPCB_FLAG_SYN)) { | |
2103 | acked |= FLAG_DATA_ACKED; | |
317a76f9 | 2104 | ++pkts_acked; |
1da177e4 LT |
2105 | } else { |
2106 | acked |= FLAG_SYN_ACKED; | |
2107 | tp->retrans_stamp = 0; | |
2108 | } | |
2109 | ||
2110 | if (sacked) { | |
2111 | if (sacked & TCPCB_RETRANS) { | |
2112 | if(sacked & TCPCB_SACKED_RETRANS) | |
2113 | tp->retrans_out -= tcp_skb_pcount(skb); | |
2114 | acked |= FLAG_RETRANS_DATA_ACKED; | |
2115 | seq_rtt = -1; | |
2d2abbab | 2116 | } else if (seq_rtt < 0) { |
1da177e4 | 2117 | seq_rtt = now - scb->when; |
2d2abbab SH |
2118 | if (rtt_sample) |
2119 | (*rtt_sample)(sk, tcp_usrtt(skb)); | |
a61bbcf2 | 2120 | } |
1da177e4 LT |
2121 | if (sacked & TCPCB_SACKED_ACKED) |
2122 | tp->sacked_out -= tcp_skb_pcount(skb); | |
2123 | if (sacked & TCPCB_LOST) | |
2124 | tp->lost_out -= tcp_skb_pcount(skb); | |
2125 | if (sacked & TCPCB_URG) { | |
2126 | if (tp->urg_mode && | |
2127 | !before(scb->end_seq, tp->snd_up)) | |
2128 | tp->urg_mode = 0; | |
2129 | } | |
2d2abbab | 2130 | } else if (seq_rtt < 0) { |
1da177e4 | 2131 | seq_rtt = now - scb->when; |
2d2abbab SH |
2132 | if (rtt_sample) |
2133 | (*rtt_sample)(sk, tcp_usrtt(skb)); | |
2134 | } | |
1da177e4 LT |
2135 | tcp_dec_pcount_approx(&tp->fackets_out, skb); |
2136 | tcp_packets_out_dec(tp, skb); | |
8728b834 | 2137 | __skb_unlink(skb, &sk->sk_write_queue); |
1da177e4 LT |
2138 | sk_stream_free_skb(sk, skb); |
2139 | } | |
2140 | ||
2141 | if (acked&FLAG_ACKED) { | |
2d2abbab | 2142 | tcp_ack_update_rtt(sk, acked, seq_rtt); |
1da177e4 | 2143 | tcp_ack_packets_out(sk, tp); |
317a76f9 | 2144 | |
6687e988 ACM |
2145 | if (icsk->icsk_ca_ops->pkts_acked) |
2146 | icsk->icsk_ca_ops->pkts_acked(sk, pkts_acked); | |
1da177e4 LT |
2147 | } |
2148 | ||
2149 | #if FASTRETRANS_DEBUG > 0 | |
2150 | BUG_TRAP((int)tp->sacked_out >= 0); | |
2151 | BUG_TRAP((int)tp->lost_out >= 0); | |
2152 | BUG_TRAP((int)tp->retrans_out >= 0); | |
2153 | if (!tp->packets_out && tp->rx_opt.sack_ok) { | |
6687e988 | 2154 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2155 | if (tp->lost_out) { |
2156 | printk(KERN_DEBUG "Leak l=%u %d\n", | |
6687e988 | 2157 | tp->lost_out, icsk->icsk_ca_state); |
1da177e4 LT |
2158 | tp->lost_out = 0; |
2159 | } | |
2160 | if (tp->sacked_out) { | |
2161 | printk(KERN_DEBUG "Leak s=%u %d\n", | |
6687e988 | 2162 | tp->sacked_out, icsk->icsk_ca_state); |
1da177e4 LT |
2163 | tp->sacked_out = 0; |
2164 | } | |
2165 | if (tp->retrans_out) { | |
2166 | printk(KERN_DEBUG "Leak r=%u %d\n", | |
6687e988 | 2167 | tp->retrans_out, icsk->icsk_ca_state); |
1da177e4 LT |
2168 | tp->retrans_out = 0; |
2169 | } | |
2170 | } | |
2171 | #endif | |
2172 | *seq_rtt_p = seq_rtt; | |
2173 | return acked; | |
2174 | } | |
2175 | ||
2176 | static void tcp_ack_probe(struct sock *sk) | |
2177 | { | |
463c84b9 ACM |
2178 | const struct tcp_sock *tp = tcp_sk(sk); |
2179 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1da177e4 LT |
2180 | |
2181 | /* Was it a usable window open? */ | |
2182 | ||
2183 | if (!after(TCP_SKB_CB(sk->sk_send_head)->end_seq, | |
2184 | tp->snd_una + tp->snd_wnd)) { | |
463c84b9 ACM |
2185 | icsk->icsk_backoff = 0; |
2186 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_PROBE0); | |
1da177e4 LT |
2187 | /* Socket must be waked up by subsequent tcp_data_snd_check(). |
2188 | * This function is not for random using! | |
2189 | */ | |
2190 | } else { | |
463c84b9 | 2191 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
3f421baa ACM |
2192 | min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), |
2193 | TCP_RTO_MAX); | |
1da177e4 LT |
2194 | } |
2195 | } | |
2196 | ||
6687e988 | 2197 | static inline int tcp_ack_is_dubious(const struct sock *sk, const int flag) |
1da177e4 LT |
2198 | { |
2199 | return (!(flag & FLAG_NOT_DUP) || (flag & FLAG_CA_ALERT) || | |
6687e988 | 2200 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open); |
1da177e4 LT |
2201 | } |
2202 | ||
6687e988 | 2203 | static inline int tcp_may_raise_cwnd(const struct sock *sk, const int flag) |
1da177e4 | 2204 | { |
6687e988 | 2205 | const struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 | 2206 | return (!(flag & FLAG_ECE) || tp->snd_cwnd < tp->snd_ssthresh) && |
6687e988 | 2207 | !((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_Recovery | TCPF_CA_CWR)); |
1da177e4 LT |
2208 | } |
2209 | ||
2210 | /* Check that window update is acceptable. | |
2211 | * The function assumes that snd_una<=ack<=snd_next. | |
2212 | */ | |
463c84b9 ACM |
2213 | static inline int tcp_may_update_window(const struct tcp_sock *tp, const u32 ack, |
2214 | const u32 ack_seq, const u32 nwin) | |
1da177e4 LT |
2215 | { |
2216 | return (after(ack, tp->snd_una) || | |
2217 | after(ack_seq, tp->snd_wl1) || | |
2218 | (ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd)); | |
2219 | } | |
2220 | ||
2221 | /* Update our send window. | |
2222 | * | |
2223 | * Window update algorithm, described in RFC793/RFC1122 (used in linux-2.2 | |
2224 | * and in FreeBSD. NetBSD's one is even worse.) is wrong. | |
2225 | */ | |
2226 | static int tcp_ack_update_window(struct sock *sk, struct tcp_sock *tp, | |
2227 | struct sk_buff *skb, u32 ack, u32 ack_seq) | |
2228 | { | |
2229 | int flag = 0; | |
2230 | u32 nwin = ntohs(skb->h.th->window); | |
2231 | ||
2232 | if (likely(!skb->h.th->syn)) | |
2233 | nwin <<= tp->rx_opt.snd_wscale; | |
2234 | ||
2235 | if (tcp_may_update_window(tp, ack, ack_seq, nwin)) { | |
2236 | flag |= FLAG_WIN_UPDATE; | |
2237 | tcp_update_wl(tp, ack, ack_seq); | |
2238 | ||
2239 | if (tp->snd_wnd != nwin) { | |
2240 | tp->snd_wnd = nwin; | |
2241 | ||
2242 | /* Note, it is the only place, where | |
2243 | * fast path is recovered for sending TCP. | |
2244 | */ | |
2ad41065 | 2245 | tp->pred_flags = 0; |
1da177e4 LT |
2246 | tcp_fast_path_check(sk, tp); |
2247 | ||
2248 | if (nwin > tp->max_window) { | |
2249 | tp->max_window = nwin; | |
2250 | tcp_sync_mss(sk, tp->pmtu_cookie); | |
2251 | } | |
2252 | } | |
2253 | } | |
2254 | ||
2255 | tp->snd_una = ack; | |
2256 | ||
2257 | return flag; | |
2258 | } | |
2259 | ||
2260 | static void tcp_process_frto(struct sock *sk, u32 prior_snd_una) | |
2261 | { | |
2262 | struct tcp_sock *tp = tcp_sk(sk); | |
2263 | ||
2264 | tcp_sync_left_out(tp); | |
2265 | ||
2266 | if (tp->snd_una == prior_snd_una || | |
2267 | !before(tp->snd_una, tp->frto_highmark)) { | |
2268 | /* RTO was caused by loss, start retransmitting in | |
2269 | * go-back-N slow start | |
2270 | */ | |
2271 | tcp_enter_frto_loss(sk); | |
2272 | return; | |
2273 | } | |
2274 | ||
2275 | if (tp->frto_counter == 1) { | |
2276 | /* First ACK after RTO advances the window: allow two new | |
2277 | * segments out. | |
2278 | */ | |
2279 | tp->snd_cwnd = tcp_packets_in_flight(tp) + 2; | |
2280 | } else { | |
2281 | /* Also the second ACK after RTO advances the window. | |
2282 | * The RTO was likely spurious. Reduce cwnd and continue | |
2283 | * in congestion avoidance | |
2284 | */ | |
2285 | tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh); | |
2286 | tcp_moderate_cwnd(tp); | |
2287 | } | |
2288 | ||
2289 | /* F-RTO affects on two new ACKs following RTO. | |
2290 | * At latest on third ACK the TCP behavor is back to normal. | |
2291 | */ | |
2292 | tp->frto_counter = (tp->frto_counter + 1) % 3; | |
2293 | } | |
2294 | ||
1da177e4 LT |
2295 | /* This routine deals with incoming acks, but not outgoing ones. */ |
2296 | static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag) | |
2297 | { | |
6687e988 | 2298 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2299 | struct tcp_sock *tp = tcp_sk(sk); |
2300 | u32 prior_snd_una = tp->snd_una; | |
2301 | u32 ack_seq = TCP_SKB_CB(skb)->seq; | |
2302 | u32 ack = TCP_SKB_CB(skb)->ack_seq; | |
2303 | u32 prior_in_flight; | |
2304 | s32 seq_rtt; | |
2305 | int prior_packets; | |
2306 | ||
2307 | /* If the ack is newer than sent or older than previous acks | |
2308 | * then we can probably ignore it. | |
2309 | */ | |
2310 | if (after(ack, tp->snd_nxt)) | |
2311 | goto uninteresting_ack; | |
2312 | ||
2313 | if (before(ack, prior_snd_una)) | |
2314 | goto old_ack; | |
2315 | ||
9772efb9 SH |
2316 | if (sysctl_tcp_abc && icsk->icsk_ca_state < TCP_CA_CWR) |
2317 | tp->bytes_acked += ack - prior_snd_una; | |
2318 | ||
1da177e4 LT |
2319 | if (!(flag&FLAG_SLOWPATH) && after(ack, prior_snd_una)) { |
2320 | /* Window is constant, pure forward advance. | |
2321 | * No more checks are required. | |
2322 | * Note, we use the fact that SND.UNA>=SND.WL2. | |
2323 | */ | |
2324 | tcp_update_wl(tp, ack, ack_seq); | |
2325 | tp->snd_una = ack; | |
1da177e4 LT |
2326 | flag |= FLAG_WIN_UPDATE; |
2327 | ||
6687e988 | 2328 | tcp_ca_event(sk, CA_EVENT_FAST_ACK); |
317a76f9 | 2329 | |
1da177e4 LT |
2330 | NET_INC_STATS_BH(LINUX_MIB_TCPHPACKS); |
2331 | } else { | |
2332 | if (ack_seq != TCP_SKB_CB(skb)->end_seq) | |
2333 | flag |= FLAG_DATA; | |
2334 | else | |
2335 | NET_INC_STATS_BH(LINUX_MIB_TCPPUREACKS); | |
2336 | ||
2337 | flag |= tcp_ack_update_window(sk, tp, skb, ack, ack_seq); | |
2338 | ||
2339 | if (TCP_SKB_CB(skb)->sacked) | |
2340 | flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una); | |
2341 | ||
2342 | if (TCP_ECN_rcv_ecn_echo(tp, skb->h.th)) | |
2343 | flag |= FLAG_ECE; | |
2344 | ||
6687e988 | 2345 | tcp_ca_event(sk, CA_EVENT_SLOW_ACK); |
1da177e4 LT |
2346 | } |
2347 | ||
2348 | /* We passed data and got it acked, remove any soft error | |
2349 | * log. Something worked... | |
2350 | */ | |
2351 | sk->sk_err_soft = 0; | |
2352 | tp->rcv_tstamp = tcp_time_stamp; | |
2353 | prior_packets = tp->packets_out; | |
2354 | if (!prior_packets) | |
2355 | goto no_queue; | |
2356 | ||
2357 | prior_in_flight = tcp_packets_in_flight(tp); | |
2358 | ||
2359 | /* See if we can take anything off of the retransmit queue. */ | |
2d2abbab | 2360 | flag |= tcp_clean_rtx_queue(sk, &seq_rtt); |
1da177e4 LT |
2361 | |
2362 | if (tp->frto_counter) | |
2363 | tcp_process_frto(sk, prior_snd_una); | |
2364 | ||
6687e988 | 2365 | if (tcp_ack_is_dubious(sk, flag)) { |
1da177e4 | 2366 | /* Advanve CWND, if state allows this. */ |
6687e988 ACM |
2367 | if ((flag & FLAG_DATA_ACKED) && tcp_may_raise_cwnd(sk, flag)) |
2368 | tcp_cong_avoid(sk, ack, seq_rtt, prior_in_flight, 0); | |
1da177e4 LT |
2369 | tcp_fastretrans_alert(sk, prior_snd_una, prior_packets, flag); |
2370 | } else { | |
317a76f9 | 2371 | if ((flag & FLAG_DATA_ACKED)) |
6687e988 | 2372 | tcp_cong_avoid(sk, ack, seq_rtt, prior_in_flight, 1); |
1da177e4 LT |
2373 | } |
2374 | ||
2375 | if ((flag & FLAG_FORWARD_PROGRESS) || !(flag&FLAG_NOT_DUP)) | |
2376 | dst_confirm(sk->sk_dst_cache); | |
2377 | ||
2378 | return 1; | |
2379 | ||
2380 | no_queue: | |
6687e988 | 2381 | icsk->icsk_probes_out = 0; |
1da177e4 LT |
2382 | |
2383 | /* If this ack opens up a zero window, clear backoff. It was | |
2384 | * being used to time the probes, and is probably far higher than | |
2385 | * it needs to be for normal retransmission. | |
2386 | */ | |
2387 | if (sk->sk_send_head) | |
2388 | tcp_ack_probe(sk); | |
2389 | return 1; | |
2390 | ||
2391 | old_ack: | |
2392 | if (TCP_SKB_CB(skb)->sacked) | |
2393 | tcp_sacktag_write_queue(sk, skb, prior_snd_una); | |
2394 | ||
2395 | uninteresting_ack: | |
2396 | SOCK_DEBUG(sk, "Ack %u out of %u:%u\n", ack, tp->snd_una, tp->snd_nxt); | |
2397 | return 0; | |
2398 | } | |
2399 | ||
2400 | ||
2401 | /* Look for tcp options. Normally only called on SYN and SYNACK packets. | |
2402 | * But, this can also be called on packets in the established flow when | |
2403 | * the fast version below fails. | |
2404 | */ | |
2405 | void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx, int estab) | |
2406 | { | |
2407 | unsigned char *ptr; | |
2408 | struct tcphdr *th = skb->h.th; | |
2409 | int length=(th->doff*4)-sizeof(struct tcphdr); | |
2410 | ||
2411 | ptr = (unsigned char *)(th + 1); | |
2412 | opt_rx->saw_tstamp = 0; | |
2413 | ||
2414 | while(length>0) { | |
2415 | int opcode=*ptr++; | |
2416 | int opsize; | |
2417 | ||
2418 | switch (opcode) { | |
2419 | case TCPOPT_EOL: | |
2420 | return; | |
2421 | case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ | |
2422 | length--; | |
2423 | continue; | |
2424 | default: | |
2425 | opsize=*ptr++; | |
2426 | if (opsize < 2) /* "silly options" */ | |
2427 | return; | |
2428 | if (opsize > length) | |
2429 | return; /* don't parse partial options */ | |
2430 | switch(opcode) { | |
2431 | case TCPOPT_MSS: | |
2432 | if(opsize==TCPOLEN_MSS && th->syn && !estab) { | |
2433 | u16 in_mss = ntohs(get_unaligned((__u16 *)ptr)); | |
2434 | if (in_mss) { | |
2435 | if (opt_rx->user_mss && opt_rx->user_mss < in_mss) | |
2436 | in_mss = opt_rx->user_mss; | |
2437 | opt_rx->mss_clamp = in_mss; | |
2438 | } | |
2439 | } | |
2440 | break; | |
2441 | case TCPOPT_WINDOW: | |
2442 | if(opsize==TCPOLEN_WINDOW && th->syn && !estab) | |
2443 | if (sysctl_tcp_window_scaling) { | |
2444 | __u8 snd_wscale = *(__u8 *) ptr; | |
2445 | opt_rx->wscale_ok = 1; | |
2446 | if (snd_wscale > 14) { | |
2447 | if(net_ratelimit()) | |
2448 | printk(KERN_INFO "tcp_parse_options: Illegal window " | |
2449 | "scaling value %d >14 received.\n", | |
2450 | snd_wscale); | |
2451 | snd_wscale = 14; | |
2452 | } | |
2453 | opt_rx->snd_wscale = snd_wscale; | |
2454 | } | |
2455 | break; | |
2456 | case TCPOPT_TIMESTAMP: | |
2457 | if(opsize==TCPOLEN_TIMESTAMP) { | |
2458 | if ((estab && opt_rx->tstamp_ok) || | |
2459 | (!estab && sysctl_tcp_timestamps)) { | |
2460 | opt_rx->saw_tstamp = 1; | |
2461 | opt_rx->rcv_tsval = ntohl(get_unaligned((__u32 *)ptr)); | |
2462 | opt_rx->rcv_tsecr = ntohl(get_unaligned((__u32 *)(ptr+4))); | |
2463 | } | |
2464 | } | |
2465 | break; | |
2466 | case TCPOPT_SACK_PERM: | |
2467 | if(opsize==TCPOLEN_SACK_PERM && th->syn && !estab) { | |
2468 | if (sysctl_tcp_sack) { | |
2469 | opt_rx->sack_ok = 1; | |
2470 | tcp_sack_reset(opt_rx); | |
2471 | } | |
2472 | } | |
2473 | break; | |
2474 | ||
2475 | case TCPOPT_SACK: | |
2476 | if((opsize >= (TCPOLEN_SACK_BASE + TCPOLEN_SACK_PERBLOCK)) && | |
2477 | !((opsize - TCPOLEN_SACK_BASE) % TCPOLEN_SACK_PERBLOCK) && | |
2478 | opt_rx->sack_ok) { | |
2479 | TCP_SKB_CB(skb)->sacked = (ptr - 2) - (unsigned char *)th; | |
2480 | } | |
2481 | }; | |
2482 | ptr+=opsize-2; | |
2483 | length-=opsize; | |
2484 | }; | |
2485 | } | |
2486 | } | |
2487 | ||
2488 | /* Fast parse options. This hopes to only see timestamps. | |
2489 | * If it is wrong it falls back on tcp_parse_options(). | |
2490 | */ | |
2491 | static inline int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th, | |
2492 | struct tcp_sock *tp) | |
2493 | { | |
2494 | if (th->doff == sizeof(struct tcphdr)>>2) { | |
2495 | tp->rx_opt.saw_tstamp = 0; | |
2496 | return 0; | |
2497 | } else if (tp->rx_opt.tstamp_ok && | |
2498 | th->doff == (sizeof(struct tcphdr)>>2)+(TCPOLEN_TSTAMP_ALIGNED>>2)) { | |
2499 | __u32 *ptr = (__u32 *)(th + 1); | |
2500 | if (*ptr == ntohl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
2501 | | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP)) { | |
2502 | tp->rx_opt.saw_tstamp = 1; | |
2503 | ++ptr; | |
2504 | tp->rx_opt.rcv_tsval = ntohl(*ptr); | |
2505 | ++ptr; | |
2506 | tp->rx_opt.rcv_tsecr = ntohl(*ptr); | |
2507 | return 1; | |
2508 | } | |
2509 | } | |
2510 | tcp_parse_options(skb, &tp->rx_opt, 1); | |
2511 | return 1; | |
2512 | } | |
2513 | ||
2514 | static inline void tcp_store_ts_recent(struct tcp_sock *tp) | |
2515 | { | |
2516 | tp->rx_opt.ts_recent = tp->rx_opt.rcv_tsval; | |
2517 | tp->rx_opt.ts_recent_stamp = xtime.tv_sec; | |
2518 | } | |
2519 | ||
2520 | static inline void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq) | |
2521 | { | |
2522 | if (tp->rx_opt.saw_tstamp && !after(seq, tp->rcv_wup)) { | |
2523 | /* PAWS bug workaround wrt. ACK frames, the PAWS discard | |
2524 | * extra check below makes sure this can only happen | |
2525 | * for pure ACK frames. -DaveM | |
2526 | * | |
2527 | * Not only, also it occurs for expired timestamps. | |
2528 | */ | |
2529 | ||
2530 | if((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) >= 0 || | |
2531 | xtime.tv_sec >= tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS) | |
2532 | tcp_store_ts_recent(tp); | |
2533 | } | |
2534 | } | |
2535 | ||
2536 | /* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM | |
2537 | * | |
2538 | * It is not fatal. If this ACK does _not_ change critical state (seqs, window) | |
2539 | * it can pass through stack. So, the following predicate verifies that | |
2540 | * this segment is not used for anything but congestion avoidance or | |
2541 | * fast retransmit. Moreover, we even are able to eliminate most of such | |
2542 | * second order effects, if we apply some small "replay" window (~RTO) | |
2543 | * to timestamp space. | |
2544 | * | |
2545 | * All these measures still do not guarantee that we reject wrapped ACKs | |
2546 | * on networks with high bandwidth, when sequence space is recycled fastly, | |
2547 | * but it guarantees that such events will be very rare and do not affect | |
2548 | * connection seriously. This doesn't look nice, but alas, PAWS is really | |
2549 | * buggy extension. | |
2550 | * | |
2551 | * [ Later note. Even worse! It is buggy for segments _with_ data. RFC | |
2552 | * states that events when retransmit arrives after original data are rare. | |
2553 | * It is a blatant lie. VJ forgot about fast retransmit! 8)8) It is | |
2554 | * the biggest problem on large power networks even with minor reordering. | |
2555 | * OK, let's give it small replay window. If peer clock is even 1hz, it is safe | |
2556 | * up to bandwidth of 18Gigabit/sec. 8) ] | |
2557 | */ | |
2558 | ||
463c84b9 | 2559 | static int tcp_disordered_ack(const struct sock *sk, const struct sk_buff *skb) |
1da177e4 | 2560 | { |
463c84b9 | 2561 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
2562 | struct tcphdr *th = skb->h.th; |
2563 | u32 seq = TCP_SKB_CB(skb)->seq; | |
2564 | u32 ack = TCP_SKB_CB(skb)->ack_seq; | |
2565 | ||
2566 | return (/* 1. Pure ACK with correct sequence number. */ | |
2567 | (th->ack && seq == TCP_SKB_CB(skb)->end_seq && seq == tp->rcv_nxt) && | |
2568 | ||
2569 | /* 2. ... and duplicate ACK. */ | |
2570 | ack == tp->snd_una && | |
2571 | ||
2572 | /* 3. ... and does not update window. */ | |
2573 | !tcp_may_update_window(tp, ack, seq, ntohs(th->window) << tp->rx_opt.snd_wscale) && | |
2574 | ||
2575 | /* 4. ... and sits in replay window. */ | |
463c84b9 | 2576 | (s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) <= (inet_csk(sk)->icsk_rto * 1024) / HZ); |
1da177e4 LT |
2577 | } |
2578 | ||
463c84b9 | 2579 | static inline int tcp_paws_discard(const struct sock *sk, const struct sk_buff *skb) |
1da177e4 | 2580 | { |
463c84b9 | 2581 | const struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
2582 | return ((s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) > TCP_PAWS_WINDOW && |
2583 | xtime.tv_sec < tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS && | |
463c84b9 | 2584 | !tcp_disordered_ack(sk, skb)); |
1da177e4 LT |
2585 | } |
2586 | ||
2587 | /* Check segment sequence number for validity. | |
2588 | * | |
2589 | * Segment controls are considered valid, if the segment | |
2590 | * fits to the window after truncation to the window. Acceptability | |
2591 | * of data (and SYN, FIN, of course) is checked separately. | |
2592 | * See tcp_data_queue(), for example. | |
2593 | * | |
2594 | * Also, controls (RST is main one) are accepted using RCV.WUP instead | |
2595 | * of RCV.NXT. Peer still did not advance his SND.UNA when we | |
2596 | * delayed ACK, so that hisSND.UNA<=ourRCV.WUP. | |
2597 | * (borrowed from freebsd) | |
2598 | */ | |
2599 | ||
2600 | static inline int tcp_sequence(struct tcp_sock *tp, u32 seq, u32 end_seq) | |
2601 | { | |
2602 | return !before(end_seq, tp->rcv_wup) && | |
2603 | !after(seq, tp->rcv_nxt + tcp_receive_window(tp)); | |
2604 | } | |
2605 | ||
2606 | /* When we get a reset we do this. */ | |
2607 | static void tcp_reset(struct sock *sk) | |
2608 | { | |
2609 | /* We want the right error as BSD sees it (and indeed as we do). */ | |
2610 | switch (sk->sk_state) { | |
2611 | case TCP_SYN_SENT: | |
2612 | sk->sk_err = ECONNREFUSED; | |
2613 | break; | |
2614 | case TCP_CLOSE_WAIT: | |
2615 | sk->sk_err = EPIPE; | |
2616 | break; | |
2617 | case TCP_CLOSE: | |
2618 | return; | |
2619 | default: | |
2620 | sk->sk_err = ECONNRESET; | |
2621 | } | |
2622 | ||
2623 | if (!sock_flag(sk, SOCK_DEAD)) | |
2624 | sk->sk_error_report(sk); | |
2625 | ||
2626 | tcp_done(sk); | |
2627 | } | |
2628 | ||
2629 | /* | |
2630 | * Process the FIN bit. This now behaves as it is supposed to work | |
2631 | * and the FIN takes effect when it is validly part of sequence | |
2632 | * space. Not before when we get holes. | |
2633 | * | |
2634 | * If we are ESTABLISHED, a received fin moves us to CLOSE-WAIT | |
2635 | * (and thence onto LAST-ACK and finally, CLOSE, we never enter | |
2636 | * TIME-WAIT) | |
2637 | * | |
2638 | * If we are in FINWAIT-1, a received FIN indicates simultaneous | |
2639 | * close and we go into CLOSING (and later onto TIME-WAIT) | |
2640 | * | |
2641 | * If we are in FINWAIT-2, a received FIN moves us to TIME-WAIT. | |
2642 | */ | |
2643 | static void tcp_fin(struct sk_buff *skb, struct sock *sk, struct tcphdr *th) | |
2644 | { | |
2645 | struct tcp_sock *tp = tcp_sk(sk); | |
2646 | ||
463c84b9 | 2647 | inet_csk_schedule_ack(sk); |
1da177e4 LT |
2648 | |
2649 | sk->sk_shutdown |= RCV_SHUTDOWN; | |
2650 | sock_set_flag(sk, SOCK_DONE); | |
2651 | ||
2652 | switch (sk->sk_state) { | |
2653 | case TCP_SYN_RECV: | |
2654 | case TCP_ESTABLISHED: | |
2655 | /* Move to CLOSE_WAIT */ | |
2656 | tcp_set_state(sk, TCP_CLOSE_WAIT); | |
463c84b9 | 2657 | inet_csk(sk)->icsk_ack.pingpong = 1; |
1da177e4 LT |
2658 | break; |
2659 | ||
2660 | case TCP_CLOSE_WAIT: | |
2661 | case TCP_CLOSING: | |
2662 | /* Received a retransmission of the FIN, do | |
2663 | * nothing. | |
2664 | */ | |
2665 | break; | |
2666 | case TCP_LAST_ACK: | |
2667 | /* RFC793: Remain in the LAST-ACK state. */ | |
2668 | break; | |
2669 | ||
2670 | case TCP_FIN_WAIT1: | |
2671 | /* This case occurs when a simultaneous close | |
2672 | * happens, we must ack the received FIN and | |
2673 | * enter the CLOSING state. | |
2674 | */ | |
2675 | tcp_send_ack(sk); | |
2676 | tcp_set_state(sk, TCP_CLOSING); | |
2677 | break; | |
2678 | case TCP_FIN_WAIT2: | |
2679 | /* Received a FIN -- send ACK and enter TIME_WAIT. */ | |
2680 | tcp_send_ack(sk); | |
2681 | tcp_time_wait(sk, TCP_TIME_WAIT, 0); | |
2682 | break; | |
2683 | default: | |
2684 | /* Only TCP_LISTEN and TCP_CLOSE are left, in these | |
2685 | * cases we should never reach this piece of code. | |
2686 | */ | |
2687 | printk(KERN_ERR "%s: Impossible, sk->sk_state=%d\n", | |
2688 | __FUNCTION__, sk->sk_state); | |
2689 | break; | |
2690 | }; | |
2691 | ||
2692 | /* It _is_ possible, that we have something out-of-order _after_ FIN. | |
2693 | * Probably, we should reset in this case. For now drop them. | |
2694 | */ | |
2695 | __skb_queue_purge(&tp->out_of_order_queue); | |
2696 | if (tp->rx_opt.sack_ok) | |
2697 | tcp_sack_reset(&tp->rx_opt); | |
2698 | sk_stream_mem_reclaim(sk); | |
2699 | ||
2700 | if (!sock_flag(sk, SOCK_DEAD)) { | |
2701 | sk->sk_state_change(sk); | |
2702 | ||
2703 | /* Do not send POLL_HUP for half duplex close. */ | |
2704 | if (sk->sk_shutdown == SHUTDOWN_MASK || | |
2705 | sk->sk_state == TCP_CLOSE) | |
2706 | sk_wake_async(sk, 1, POLL_HUP); | |
2707 | else | |
2708 | sk_wake_async(sk, 1, POLL_IN); | |
2709 | } | |
2710 | } | |
2711 | ||
2712 | static __inline__ int | |
2713 | tcp_sack_extend(struct tcp_sack_block *sp, u32 seq, u32 end_seq) | |
2714 | { | |
2715 | if (!after(seq, sp->end_seq) && !after(sp->start_seq, end_seq)) { | |
2716 | if (before(seq, sp->start_seq)) | |
2717 | sp->start_seq = seq; | |
2718 | if (after(end_seq, sp->end_seq)) | |
2719 | sp->end_seq = end_seq; | |
2720 | return 1; | |
2721 | } | |
2722 | return 0; | |
2723 | } | |
2724 | ||
2725 | static inline void tcp_dsack_set(struct tcp_sock *tp, u32 seq, u32 end_seq) | |
2726 | { | |
2727 | if (tp->rx_opt.sack_ok && sysctl_tcp_dsack) { | |
2728 | if (before(seq, tp->rcv_nxt)) | |
2729 | NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOLDSENT); | |
2730 | else | |
2731 | NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFOSENT); | |
2732 | ||
2733 | tp->rx_opt.dsack = 1; | |
2734 | tp->duplicate_sack[0].start_seq = seq; | |
2735 | tp->duplicate_sack[0].end_seq = end_seq; | |
2736 | tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + 1, 4 - tp->rx_opt.tstamp_ok); | |
2737 | } | |
2738 | } | |
2739 | ||
2740 | static inline void tcp_dsack_extend(struct tcp_sock *tp, u32 seq, u32 end_seq) | |
2741 | { | |
2742 | if (!tp->rx_opt.dsack) | |
2743 | tcp_dsack_set(tp, seq, end_seq); | |
2744 | else | |
2745 | tcp_sack_extend(tp->duplicate_sack, seq, end_seq); | |
2746 | } | |
2747 | ||
2748 | static void tcp_send_dupack(struct sock *sk, struct sk_buff *skb) | |
2749 | { | |
2750 | struct tcp_sock *tp = tcp_sk(sk); | |
2751 | ||
2752 | if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq && | |
2753 | before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) { | |
2754 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOST); | |
463c84b9 | 2755 | tcp_enter_quickack_mode(sk); |
1da177e4 LT |
2756 | |
2757 | if (tp->rx_opt.sack_ok && sysctl_tcp_dsack) { | |
2758 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
2759 | ||
2760 | if (after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) | |
2761 | end_seq = tp->rcv_nxt; | |
2762 | tcp_dsack_set(tp, TCP_SKB_CB(skb)->seq, end_seq); | |
2763 | } | |
2764 | } | |
2765 | ||
2766 | tcp_send_ack(sk); | |
2767 | } | |
2768 | ||
2769 | /* These routines update the SACK block as out-of-order packets arrive or | |
2770 | * in-order packets close up the sequence space. | |
2771 | */ | |
2772 | static void tcp_sack_maybe_coalesce(struct tcp_sock *tp) | |
2773 | { | |
2774 | int this_sack; | |
2775 | struct tcp_sack_block *sp = &tp->selective_acks[0]; | |
2776 | struct tcp_sack_block *swalk = sp+1; | |
2777 | ||
2778 | /* See if the recent change to the first SACK eats into | |
2779 | * or hits the sequence space of other SACK blocks, if so coalesce. | |
2780 | */ | |
2781 | for (this_sack = 1; this_sack < tp->rx_opt.num_sacks; ) { | |
2782 | if (tcp_sack_extend(sp, swalk->start_seq, swalk->end_seq)) { | |
2783 | int i; | |
2784 | ||
2785 | /* Zap SWALK, by moving every further SACK up by one slot. | |
2786 | * Decrease num_sacks. | |
2787 | */ | |
2788 | tp->rx_opt.num_sacks--; | |
2789 | tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, 4 - tp->rx_opt.tstamp_ok); | |
2790 | for(i=this_sack; i < tp->rx_opt.num_sacks; i++) | |
2791 | sp[i] = sp[i+1]; | |
2792 | continue; | |
2793 | } | |
2794 | this_sack++, swalk++; | |
2795 | } | |
2796 | } | |
2797 | ||
2798 | static __inline__ void tcp_sack_swap(struct tcp_sack_block *sack1, struct tcp_sack_block *sack2) | |
2799 | { | |
2800 | __u32 tmp; | |
2801 | ||
2802 | tmp = sack1->start_seq; | |
2803 | sack1->start_seq = sack2->start_seq; | |
2804 | sack2->start_seq = tmp; | |
2805 | ||
2806 | tmp = sack1->end_seq; | |
2807 | sack1->end_seq = sack2->end_seq; | |
2808 | sack2->end_seq = tmp; | |
2809 | } | |
2810 | ||
2811 | static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq) | |
2812 | { | |
2813 | struct tcp_sock *tp = tcp_sk(sk); | |
2814 | struct tcp_sack_block *sp = &tp->selective_acks[0]; | |
2815 | int cur_sacks = tp->rx_opt.num_sacks; | |
2816 | int this_sack; | |
2817 | ||
2818 | if (!cur_sacks) | |
2819 | goto new_sack; | |
2820 | ||
2821 | for (this_sack=0; this_sack<cur_sacks; this_sack++, sp++) { | |
2822 | if (tcp_sack_extend(sp, seq, end_seq)) { | |
2823 | /* Rotate this_sack to the first one. */ | |
2824 | for (; this_sack>0; this_sack--, sp--) | |
2825 | tcp_sack_swap(sp, sp-1); | |
2826 | if (cur_sacks > 1) | |
2827 | tcp_sack_maybe_coalesce(tp); | |
2828 | return; | |
2829 | } | |
2830 | } | |
2831 | ||
2832 | /* Could not find an adjacent existing SACK, build a new one, | |
2833 | * put it at the front, and shift everyone else down. We | |
2834 | * always know there is at least one SACK present already here. | |
2835 | * | |
2836 | * If the sack array is full, forget about the last one. | |
2837 | */ | |
2838 | if (this_sack >= 4) { | |
2839 | this_sack--; | |
2840 | tp->rx_opt.num_sacks--; | |
2841 | sp--; | |
2842 | } | |
2843 | for(; this_sack > 0; this_sack--, sp--) | |
2844 | *sp = *(sp-1); | |
2845 | ||
2846 | new_sack: | |
2847 | /* Build the new head SACK, and we're done. */ | |
2848 | sp->start_seq = seq; | |
2849 | sp->end_seq = end_seq; | |
2850 | tp->rx_opt.num_sacks++; | |
2851 | tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, 4 - tp->rx_opt.tstamp_ok); | |
2852 | } | |
2853 | ||
2854 | /* RCV.NXT advances, some SACKs should be eaten. */ | |
2855 | ||
2856 | static void tcp_sack_remove(struct tcp_sock *tp) | |
2857 | { | |
2858 | struct tcp_sack_block *sp = &tp->selective_acks[0]; | |
2859 | int num_sacks = tp->rx_opt.num_sacks; | |
2860 | int this_sack; | |
2861 | ||
2862 | /* Empty ofo queue, hence, all the SACKs are eaten. Clear. */ | |
b03efcfb | 2863 | if (skb_queue_empty(&tp->out_of_order_queue)) { |
1da177e4 LT |
2864 | tp->rx_opt.num_sacks = 0; |
2865 | tp->rx_opt.eff_sacks = tp->rx_opt.dsack; | |
2866 | return; | |
2867 | } | |
2868 | ||
2869 | for(this_sack = 0; this_sack < num_sacks; ) { | |
2870 | /* Check if the start of the sack is covered by RCV.NXT. */ | |
2871 | if (!before(tp->rcv_nxt, sp->start_seq)) { | |
2872 | int i; | |
2873 | ||
2874 | /* RCV.NXT must cover all the block! */ | |
2875 | BUG_TRAP(!before(tp->rcv_nxt, sp->end_seq)); | |
2876 | ||
2877 | /* Zap this SACK, by moving forward any other SACKS. */ | |
2878 | for (i=this_sack+1; i < num_sacks; i++) | |
2879 | tp->selective_acks[i-1] = tp->selective_acks[i]; | |
2880 | num_sacks--; | |
2881 | continue; | |
2882 | } | |
2883 | this_sack++; | |
2884 | sp++; | |
2885 | } | |
2886 | if (num_sacks != tp->rx_opt.num_sacks) { | |
2887 | tp->rx_opt.num_sacks = num_sacks; | |
2888 | tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, 4 - tp->rx_opt.tstamp_ok); | |
2889 | } | |
2890 | } | |
2891 | ||
2892 | /* This one checks to see if we can put data from the | |
2893 | * out_of_order queue into the receive_queue. | |
2894 | */ | |
2895 | static void tcp_ofo_queue(struct sock *sk) | |
2896 | { | |
2897 | struct tcp_sock *tp = tcp_sk(sk); | |
2898 | __u32 dsack_high = tp->rcv_nxt; | |
2899 | struct sk_buff *skb; | |
2900 | ||
2901 | while ((skb = skb_peek(&tp->out_of_order_queue)) != NULL) { | |
2902 | if (after(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) | |
2903 | break; | |
2904 | ||
2905 | if (before(TCP_SKB_CB(skb)->seq, dsack_high)) { | |
2906 | __u32 dsack = dsack_high; | |
2907 | if (before(TCP_SKB_CB(skb)->end_seq, dsack_high)) | |
2908 | dsack_high = TCP_SKB_CB(skb)->end_seq; | |
2909 | tcp_dsack_extend(tp, TCP_SKB_CB(skb)->seq, dsack); | |
2910 | } | |
2911 | ||
2912 | if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) { | |
2913 | SOCK_DEBUG(sk, "ofo packet was already received \n"); | |
8728b834 | 2914 | __skb_unlink(skb, &tp->out_of_order_queue); |
1da177e4 LT |
2915 | __kfree_skb(skb); |
2916 | continue; | |
2917 | } | |
2918 | SOCK_DEBUG(sk, "ofo requeuing : rcv_next %X seq %X - %X\n", | |
2919 | tp->rcv_nxt, TCP_SKB_CB(skb)->seq, | |
2920 | TCP_SKB_CB(skb)->end_seq); | |
2921 | ||
8728b834 | 2922 | __skb_unlink(skb, &tp->out_of_order_queue); |
1da177e4 LT |
2923 | __skb_queue_tail(&sk->sk_receive_queue, skb); |
2924 | tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; | |
2925 | if(skb->h.th->fin) | |
2926 | tcp_fin(skb, sk, skb->h.th); | |
2927 | } | |
2928 | } | |
2929 | ||
2930 | static int tcp_prune_queue(struct sock *sk); | |
2931 | ||
2932 | static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) | |
2933 | { | |
2934 | struct tcphdr *th = skb->h.th; | |
2935 | struct tcp_sock *tp = tcp_sk(sk); | |
2936 | int eaten = -1; | |
2937 | ||
2938 | if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) | |
2939 | goto drop; | |
2940 | ||
1da177e4 LT |
2941 | __skb_pull(skb, th->doff*4); |
2942 | ||
2943 | TCP_ECN_accept_cwr(tp, skb); | |
2944 | ||
2945 | if (tp->rx_opt.dsack) { | |
2946 | tp->rx_opt.dsack = 0; | |
2947 | tp->rx_opt.eff_sacks = min_t(unsigned int, tp->rx_opt.num_sacks, | |
2948 | 4 - tp->rx_opt.tstamp_ok); | |
2949 | } | |
2950 | ||
2951 | /* Queue data for delivery to the user. | |
2952 | * Packets in sequence go to the receive queue. | |
2953 | * Out of sequence packets to the out_of_order_queue. | |
2954 | */ | |
2955 | if (TCP_SKB_CB(skb)->seq == tp->rcv_nxt) { | |
2956 | if (tcp_receive_window(tp) == 0) | |
2957 | goto out_of_window; | |
2958 | ||
2959 | /* Ok. In sequence. In window. */ | |
2960 | if (tp->ucopy.task == current && | |
2961 | tp->copied_seq == tp->rcv_nxt && tp->ucopy.len && | |
2962 | sock_owned_by_user(sk) && !tp->urg_data) { | |
2963 | int chunk = min_t(unsigned int, skb->len, | |
2964 | tp->ucopy.len); | |
2965 | ||
2966 | __set_current_state(TASK_RUNNING); | |
2967 | ||
2968 | local_bh_enable(); | |
2969 | if (!skb_copy_datagram_iovec(skb, 0, tp->ucopy.iov, chunk)) { | |
2970 | tp->ucopy.len -= chunk; | |
2971 | tp->copied_seq += chunk; | |
2972 | eaten = (chunk == skb->len && !th->fin); | |
2973 | tcp_rcv_space_adjust(sk); | |
2974 | } | |
2975 | local_bh_disable(); | |
2976 | } | |
2977 | ||
2978 | if (eaten <= 0) { | |
2979 | queue_and_out: | |
2980 | if (eaten < 0 && | |
2981 | (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || | |
2982 | !sk_stream_rmem_schedule(sk, skb))) { | |
2983 | if (tcp_prune_queue(sk) < 0 || | |
2984 | !sk_stream_rmem_schedule(sk, skb)) | |
2985 | goto drop; | |
2986 | } | |
2987 | sk_stream_set_owner_r(skb, sk); | |
2988 | __skb_queue_tail(&sk->sk_receive_queue, skb); | |
2989 | } | |
2990 | tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; | |
2991 | if(skb->len) | |
2992 | tcp_event_data_recv(sk, tp, skb); | |
2993 | if(th->fin) | |
2994 | tcp_fin(skb, sk, th); | |
2995 | ||
b03efcfb | 2996 | if (!skb_queue_empty(&tp->out_of_order_queue)) { |
1da177e4 LT |
2997 | tcp_ofo_queue(sk); |
2998 | ||
2999 | /* RFC2581. 4.2. SHOULD send immediate ACK, when | |
3000 | * gap in queue is filled. | |
3001 | */ | |
b03efcfb | 3002 | if (skb_queue_empty(&tp->out_of_order_queue)) |
463c84b9 | 3003 | inet_csk(sk)->icsk_ack.pingpong = 0; |
1da177e4 LT |
3004 | } |
3005 | ||
3006 | if (tp->rx_opt.num_sacks) | |
3007 | tcp_sack_remove(tp); | |
3008 | ||
3009 | tcp_fast_path_check(sk, tp); | |
3010 | ||
3011 | if (eaten > 0) | |
3012 | __kfree_skb(skb); | |
3013 | else if (!sock_flag(sk, SOCK_DEAD)) | |
3014 | sk->sk_data_ready(sk, 0); | |
3015 | return; | |
3016 | } | |
3017 | ||
3018 | if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) { | |
3019 | /* A retransmit, 2nd most common case. Force an immediate ack. */ | |
3020 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOST); | |
3021 | tcp_dsack_set(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq); | |
3022 | ||
3023 | out_of_window: | |
463c84b9 ACM |
3024 | tcp_enter_quickack_mode(sk); |
3025 | inet_csk_schedule_ack(sk); | |
1da177e4 LT |
3026 | drop: |
3027 | __kfree_skb(skb); | |
3028 | return; | |
3029 | } | |
3030 | ||
3031 | /* Out of window. F.e. zero window probe. */ | |
3032 | if (!before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt + tcp_receive_window(tp))) | |
3033 | goto out_of_window; | |
3034 | ||
463c84b9 | 3035 | tcp_enter_quickack_mode(sk); |
1da177e4 LT |
3036 | |
3037 | if (before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) { | |
3038 | /* Partial packet, seq < rcv_next < end_seq */ | |
3039 | SOCK_DEBUG(sk, "partial packet: rcv_next %X seq %X - %X\n", | |
3040 | tp->rcv_nxt, TCP_SKB_CB(skb)->seq, | |
3041 | TCP_SKB_CB(skb)->end_seq); | |
3042 | ||
3043 | tcp_dsack_set(tp, TCP_SKB_CB(skb)->seq, tp->rcv_nxt); | |
3044 | ||
3045 | /* If window is closed, drop tail of packet. But after | |
3046 | * remembering D-SACK for its head made in previous line. | |
3047 | */ | |
3048 | if (!tcp_receive_window(tp)) | |
3049 | goto out_of_window; | |
3050 | goto queue_and_out; | |
3051 | } | |
3052 | ||
3053 | TCP_ECN_check_ce(tp, skb); | |
3054 | ||
3055 | if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || | |
3056 | !sk_stream_rmem_schedule(sk, skb)) { | |
3057 | if (tcp_prune_queue(sk) < 0 || | |
3058 | !sk_stream_rmem_schedule(sk, skb)) | |
3059 | goto drop; | |
3060 | } | |
3061 | ||
3062 | /* Disable header prediction. */ | |
3063 | tp->pred_flags = 0; | |
463c84b9 | 3064 | inet_csk_schedule_ack(sk); |
1da177e4 LT |
3065 | |
3066 | SOCK_DEBUG(sk, "out of order segment: rcv_next %X seq %X - %X\n", | |
3067 | tp->rcv_nxt, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq); | |
3068 | ||
3069 | sk_stream_set_owner_r(skb, sk); | |
3070 | ||
3071 | if (!skb_peek(&tp->out_of_order_queue)) { | |
3072 | /* Initial out of order segment, build 1 SACK. */ | |
3073 | if (tp->rx_opt.sack_ok) { | |
3074 | tp->rx_opt.num_sacks = 1; | |
3075 | tp->rx_opt.dsack = 0; | |
3076 | tp->rx_opt.eff_sacks = 1; | |
3077 | tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq; | |
3078 | tp->selective_acks[0].end_seq = | |
3079 | TCP_SKB_CB(skb)->end_seq; | |
3080 | } | |
3081 | __skb_queue_head(&tp->out_of_order_queue,skb); | |
3082 | } else { | |
3083 | struct sk_buff *skb1 = tp->out_of_order_queue.prev; | |
3084 | u32 seq = TCP_SKB_CB(skb)->seq; | |
3085 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
3086 | ||
3087 | if (seq == TCP_SKB_CB(skb1)->end_seq) { | |
8728b834 | 3088 | __skb_append(skb1, skb, &tp->out_of_order_queue); |
1da177e4 LT |
3089 | |
3090 | if (!tp->rx_opt.num_sacks || | |
3091 | tp->selective_acks[0].end_seq != seq) | |
3092 | goto add_sack; | |
3093 | ||
3094 | /* Common case: data arrive in order after hole. */ | |
3095 | tp->selective_acks[0].end_seq = end_seq; | |
3096 | return; | |
3097 | } | |
3098 | ||
3099 | /* Find place to insert this segment. */ | |
3100 | do { | |
3101 | if (!after(TCP_SKB_CB(skb1)->seq, seq)) | |
3102 | break; | |
3103 | } while ((skb1 = skb1->prev) != | |
3104 | (struct sk_buff*)&tp->out_of_order_queue); | |
3105 | ||
3106 | /* Do skb overlap to previous one? */ | |
3107 | if (skb1 != (struct sk_buff*)&tp->out_of_order_queue && | |
3108 | before(seq, TCP_SKB_CB(skb1)->end_seq)) { | |
3109 | if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) { | |
3110 | /* All the bits are present. Drop. */ | |
3111 | __kfree_skb(skb); | |
3112 | tcp_dsack_set(tp, seq, end_seq); | |
3113 | goto add_sack; | |
3114 | } | |
3115 | if (after(seq, TCP_SKB_CB(skb1)->seq)) { | |
3116 | /* Partial overlap. */ | |
3117 | tcp_dsack_set(tp, seq, TCP_SKB_CB(skb1)->end_seq); | |
3118 | } else { | |
3119 | skb1 = skb1->prev; | |
3120 | } | |
3121 | } | |
3122 | __skb_insert(skb, skb1, skb1->next, &tp->out_of_order_queue); | |
3123 | ||
3124 | /* And clean segments covered by new one as whole. */ | |
3125 | while ((skb1 = skb->next) != | |
3126 | (struct sk_buff*)&tp->out_of_order_queue && | |
3127 | after(end_seq, TCP_SKB_CB(skb1)->seq)) { | |
3128 | if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) { | |
3129 | tcp_dsack_extend(tp, TCP_SKB_CB(skb1)->seq, end_seq); | |
3130 | break; | |
3131 | } | |
8728b834 | 3132 | __skb_unlink(skb1, &tp->out_of_order_queue); |
1da177e4 LT |
3133 | tcp_dsack_extend(tp, TCP_SKB_CB(skb1)->seq, TCP_SKB_CB(skb1)->end_seq); |
3134 | __kfree_skb(skb1); | |
3135 | } | |
3136 | ||
3137 | add_sack: | |
3138 | if (tp->rx_opt.sack_ok) | |
3139 | tcp_sack_new_ofo_skb(sk, seq, end_seq); | |
3140 | } | |
3141 | } | |
3142 | ||
3143 | /* Collapse contiguous sequence of skbs head..tail with | |
3144 | * sequence numbers start..end. | |
3145 | * Segments with FIN/SYN are not collapsed (only because this | |
3146 | * simplifies code) | |
3147 | */ | |
3148 | static void | |
8728b834 DM |
3149 | tcp_collapse(struct sock *sk, struct sk_buff_head *list, |
3150 | struct sk_buff *head, struct sk_buff *tail, | |
3151 | u32 start, u32 end) | |
1da177e4 LT |
3152 | { |
3153 | struct sk_buff *skb; | |
3154 | ||
3155 | /* First, check that queue is collapsable and find | |
3156 | * the point where collapsing can be useful. */ | |
3157 | for (skb = head; skb != tail; ) { | |
3158 | /* No new bits? It is possible on ofo queue. */ | |
3159 | if (!before(start, TCP_SKB_CB(skb)->end_seq)) { | |
3160 | struct sk_buff *next = skb->next; | |
8728b834 | 3161 | __skb_unlink(skb, list); |
1da177e4 LT |
3162 | __kfree_skb(skb); |
3163 | NET_INC_STATS_BH(LINUX_MIB_TCPRCVCOLLAPSED); | |
3164 | skb = next; | |
3165 | continue; | |
3166 | } | |
3167 | ||
3168 | /* The first skb to collapse is: | |
3169 | * - not SYN/FIN and | |
3170 | * - bloated or contains data before "start" or | |
3171 | * overlaps to the next one. | |
3172 | */ | |
3173 | if (!skb->h.th->syn && !skb->h.th->fin && | |
3174 | (tcp_win_from_space(skb->truesize) > skb->len || | |
3175 | before(TCP_SKB_CB(skb)->seq, start) || | |
3176 | (skb->next != tail && | |
3177 | TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb->next)->seq))) | |
3178 | break; | |
3179 | ||
3180 | /* Decided to skip this, advance start seq. */ | |
3181 | start = TCP_SKB_CB(skb)->end_seq; | |
3182 | skb = skb->next; | |
3183 | } | |
3184 | if (skb == tail || skb->h.th->syn || skb->h.th->fin) | |
3185 | return; | |
3186 | ||
3187 | while (before(start, end)) { | |
3188 | struct sk_buff *nskb; | |
3189 | int header = skb_headroom(skb); | |
3190 | int copy = SKB_MAX_ORDER(header, 0); | |
3191 | ||
3192 | /* Too big header? This can happen with IPv6. */ | |
3193 | if (copy < 0) | |
3194 | return; | |
3195 | if (end-start < copy) | |
3196 | copy = end-start; | |
3197 | nskb = alloc_skb(copy+header, GFP_ATOMIC); | |
3198 | if (!nskb) | |
3199 | return; | |
3200 | skb_reserve(nskb, header); | |
3201 | memcpy(nskb->head, skb->head, header); | |
3202 | nskb->nh.raw = nskb->head + (skb->nh.raw-skb->head); | |
3203 | nskb->h.raw = nskb->head + (skb->h.raw-skb->head); | |
3204 | nskb->mac.raw = nskb->head + (skb->mac.raw-skb->head); | |
3205 | memcpy(nskb->cb, skb->cb, sizeof(skb->cb)); | |
3206 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(nskb)->end_seq = start; | |
8728b834 | 3207 | __skb_insert(nskb, skb->prev, skb, list); |
1da177e4 LT |
3208 | sk_stream_set_owner_r(nskb, sk); |
3209 | ||
3210 | /* Copy data, releasing collapsed skbs. */ | |
3211 | while (copy > 0) { | |
3212 | int offset = start - TCP_SKB_CB(skb)->seq; | |
3213 | int size = TCP_SKB_CB(skb)->end_seq - start; | |
3214 | ||
3215 | if (offset < 0) BUG(); | |
3216 | if (size > 0) { | |
3217 | size = min(copy, size); | |
3218 | if (skb_copy_bits(skb, offset, skb_put(nskb, size), size)) | |
3219 | BUG(); | |
3220 | TCP_SKB_CB(nskb)->end_seq += size; | |
3221 | copy -= size; | |
3222 | start += size; | |
3223 | } | |
3224 | if (!before(start, TCP_SKB_CB(skb)->end_seq)) { | |
3225 | struct sk_buff *next = skb->next; | |
8728b834 | 3226 | __skb_unlink(skb, list); |
1da177e4 LT |
3227 | __kfree_skb(skb); |
3228 | NET_INC_STATS_BH(LINUX_MIB_TCPRCVCOLLAPSED); | |
3229 | skb = next; | |
3230 | if (skb == tail || skb->h.th->syn || skb->h.th->fin) | |
3231 | return; | |
3232 | } | |
3233 | } | |
3234 | } | |
3235 | } | |
3236 | ||
3237 | /* Collapse ofo queue. Algorithm: select contiguous sequence of skbs | |
3238 | * and tcp_collapse() them until all the queue is collapsed. | |
3239 | */ | |
3240 | static void tcp_collapse_ofo_queue(struct sock *sk) | |
3241 | { | |
3242 | struct tcp_sock *tp = tcp_sk(sk); | |
3243 | struct sk_buff *skb = skb_peek(&tp->out_of_order_queue); | |
3244 | struct sk_buff *head; | |
3245 | u32 start, end; | |
3246 | ||
3247 | if (skb == NULL) | |
3248 | return; | |
3249 | ||
3250 | start = TCP_SKB_CB(skb)->seq; | |
3251 | end = TCP_SKB_CB(skb)->end_seq; | |
3252 | head = skb; | |
3253 | ||
3254 | for (;;) { | |
3255 | skb = skb->next; | |
3256 | ||
3257 | /* Segment is terminated when we see gap or when | |
3258 | * we are at the end of all the queue. */ | |
3259 | if (skb == (struct sk_buff *)&tp->out_of_order_queue || | |
3260 | after(TCP_SKB_CB(skb)->seq, end) || | |
3261 | before(TCP_SKB_CB(skb)->end_seq, start)) { | |
8728b834 DM |
3262 | tcp_collapse(sk, &tp->out_of_order_queue, |
3263 | head, skb, start, end); | |
1da177e4 LT |
3264 | head = skb; |
3265 | if (skb == (struct sk_buff *)&tp->out_of_order_queue) | |
3266 | break; | |
3267 | /* Start new segment */ | |
3268 | start = TCP_SKB_CB(skb)->seq; | |
3269 | end = TCP_SKB_CB(skb)->end_seq; | |
3270 | } else { | |
3271 | if (before(TCP_SKB_CB(skb)->seq, start)) | |
3272 | start = TCP_SKB_CB(skb)->seq; | |
3273 | if (after(TCP_SKB_CB(skb)->end_seq, end)) | |
3274 | end = TCP_SKB_CB(skb)->end_seq; | |
3275 | } | |
3276 | } | |
3277 | } | |
3278 | ||
3279 | /* Reduce allocated memory if we can, trying to get | |
3280 | * the socket within its memory limits again. | |
3281 | * | |
3282 | * Return less than zero if we should start dropping frames | |
3283 | * until the socket owning process reads some of the data | |
3284 | * to stabilize the situation. | |
3285 | */ | |
3286 | static int tcp_prune_queue(struct sock *sk) | |
3287 | { | |
3288 | struct tcp_sock *tp = tcp_sk(sk); | |
3289 | ||
3290 | SOCK_DEBUG(sk, "prune_queue: c=%x\n", tp->copied_seq); | |
3291 | ||
3292 | NET_INC_STATS_BH(LINUX_MIB_PRUNECALLED); | |
3293 | ||
3294 | if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) | |
3295 | tcp_clamp_window(sk, tp); | |
3296 | else if (tcp_memory_pressure) | |
3297 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss); | |
3298 | ||
3299 | tcp_collapse_ofo_queue(sk); | |
8728b834 DM |
3300 | tcp_collapse(sk, &sk->sk_receive_queue, |
3301 | sk->sk_receive_queue.next, | |
1da177e4 LT |
3302 | (struct sk_buff*)&sk->sk_receive_queue, |
3303 | tp->copied_seq, tp->rcv_nxt); | |
3304 | sk_stream_mem_reclaim(sk); | |
3305 | ||
3306 | if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) | |
3307 | return 0; | |
3308 | ||
3309 | /* Collapsing did not help, destructive actions follow. | |
3310 | * This must not ever occur. */ | |
3311 | ||
3312 | /* First, purge the out_of_order queue. */ | |
b03efcfb DM |
3313 | if (!skb_queue_empty(&tp->out_of_order_queue)) { |
3314 | NET_INC_STATS_BH(LINUX_MIB_OFOPRUNED); | |
1da177e4 LT |
3315 | __skb_queue_purge(&tp->out_of_order_queue); |
3316 | ||
3317 | /* Reset SACK state. A conforming SACK implementation will | |
3318 | * do the same at a timeout based retransmit. When a connection | |
3319 | * is in a sad state like this, we care only about integrity | |
3320 | * of the connection not performance. | |
3321 | */ | |
3322 | if (tp->rx_opt.sack_ok) | |
3323 | tcp_sack_reset(&tp->rx_opt); | |
3324 | sk_stream_mem_reclaim(sk); | |
3325 | } | |
3326 | ||
3327 | if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) | |
3328 | return 0; | |
3329 | ||
3330 | /* If we are really being abused, tell the caller to silently | |
3331 | * drop receive data on the floor. It will get retransmitted | |
3332 | * and hopefully then we'll have sufficient space. | |
3333 | */ | |
3334 | NET_INC_STATS_BH(LINUX_MIB_RCVPRUNED); | |
3335 | ||
3336 | /* Massive buffer overcommit. */ | |
3337 | tp->pred_flags = 0; | |
3338 | return -1; | |
3339 | } | |
3340 | ||
3341 | ||
3342 | /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. | |
3343 | * As additional protections, we do not touch cwnd in retransmission phases, | |
3344 | * and if application hit its sndbuf limit recently. | |
3345 | */ | |
3346 | void tcp_cwnd_application_limited(struct sock *sk) | |
3347 | { | |
3348 | struct tcp_sock *tp = tcp_sk(sk); | |
3349 | ||
6687e988 | 3350 | if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && |
1da177e4 LT |
3351 | sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { |
3352 | /* Limited by application or receiver window. */ | |
3353 | u32 win_used = max(tp->snd_cwnd_used, 2U); | |
3354 | if (win_used < tp->snd_cwnd) { | |
6687e988 | 3355 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
3356 | tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; |
3357 | } | |
3358 | tp->snd_cwnd_used = 0; | |
3359 | } | |
3360 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
3361 | } | |
3362 | ||
0d9901df DM |
3363 | static inline int tcp_should_expand_sndbuf(struct sock *sk, struct tcp_sock *tp) |
3364 | { | |
3365 | /* If the user specified a specific send buffer setting, do | |
3366 | * not modify it. | |
3367 | */ | |
3368 | if (sk->sk_userlocks & SOCK_SNDBUF_LOCK) | |
3369 | return 0; | |
3370 | ||
3371 | /* If we are under global TCP memory pressure, do not expand. */ | |
3372 | if (tcp_memory_pressure) | |
3373 | return 0; | |
3374 | ||
3375 | /* If we are under soft global TCP memory pressure, do not expand. */ | |
3376 | if (atomic_read(&tcp_memory_allocated) >= sysctl_tcp_mem[0]) | |
3377 | return 0; | |
3378 | ||
3379 | /* If we filled the congestion window, do not expand. */ | |
3380 | if (tp->packets_out >= tp->snd_cwnd) | |
3381 | return 0; | |
3382 | ||
3383 | return 1; | |
3384 | } | |
1da177e4 LT |
3385 | |
3386 | /* When incoming ACK allowed to free some skb from write_queue, | |
3387 | * we remember this event in flag SOCK_QUEUE_SHRUNK and wake up socket | |
3388 | * on the exit from tcp input handler. | |
3389 | * | |
3390 | * PROBLEM: sndbuf expansion does not work well with largesend. | |
3391 | */ | |
3392 | static void tcp_new_space(struct sock *sk) | |
3393 | { | |
3394 | struct tcp_sock *tp = tcp_sk(sk); | |
3395 | ||
0d9901df | 3396 | if (tcp_should_expand_sndbuf(sk, tp)) { |
c1b4a7e6 | 3397 | int sndmem = max_t(u32, tp->rx_opt.mss_clamp, tp->mss_cache) + |
1da177e4 LT |
3398 | MAX_TCP_HEADER + 16 + sizeof(struct sk_buff), |
3399 | demanded = max_t(unsigned int, tp->snd_cwnd, | |
3400 | tp->reordering + 1); | |
3401 | sndmem *= 2*demanded; | |
3402 | if (sndmem > sk->sk_sndbuf) | |
3403 | sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]); | |
3404 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
3405 | } | |
3406 | ||
3407 | sk->sk_write_space(sk); | |
3408 | } | |
3409 | ||
3410 | static inline void tcp_check_space(struct sock *sk) | |
3411 | { | |
3412 | if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) { | |
3413 | sock_reset_flag(sk, SOCK_QUEUE_SHRUNK); | |
3414 | if (sk->sk_socket && | |
3415 | test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) | |
3416 | tcp_new_space(sk); | |
3417 | } | |
3418 | } | |
3419 | ||
55c97f3e | 3420 | static __inline__ void tcp_data_snd_check(struct sock *sk, struct tcp_sock *tp) |
1da177e4 | 3421 | { |
55c97f3e | 3422 | tcp_push_pending_frames(sk, tp); |
1da177e4 LT |
3423 | tcp_check_space(sk); |
3424 | } | |
3425 | ||
3426 | /* | |
3427 | * Check if sending an ack is needed. | |
3428 | */ | |
3429 | static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible) | |
3430 | { | |
3431 | struct tcp_sock *tp = tcp_sk(sk); | |
3432 | ||
3433 | /* More than one full frame received... */ | |
463c84b9 | 3434 | if (((tp->rcv_nxt - tp->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss |
1da177e4 LT |
3435 | /* ... and right edge of window advances far enough. |
3436 | * (tcp_recvmsg() will send ACK otherwise). Or... | |
3437 | */ | |
3438 | && __tcp_select_window(sk) >= tp->rcv_wnd) || | |
3439 | /* We ACK each frame or... */ | |
463c84b9 | 3440 | tcp_in_quickack_mode(sk) || |
1da177e4 LT |
3441 | /* We have out of order data. */ |
3442 | (ofo_possible && | |
3443 | skb_peek(&tp->out_of_order_queue))) { | |
3444 | /* Then ack it now */ | |
3445 | tcp_send_ack(sk); | |
3446 | } else { | |
3447 | /* Else, send delayed ack. */ | |
3448 | tcp_send_delayed_ack(sk); | |
3449 | } | |
3450 | } | |
3451 | ||
3452 | static __inline__ void tcp_ack_snd_check(struct sock *sk) | |
3453 | { | |
463c84b9 | 3454 | if (!inet_csk_ack_scheduled(sk)) { |
1da177e4 LT |
3455 | /* We sent a data segment already. */ |
3456 | return; | |
3457 | } | |
3458 | __tcp_ack_snd_check(sk, 1); | |
3459 | } | |
3460 | ||
3461 | /* | |
3462 | * This routine is only called when we have urgent data | |
3463 | * signalled. Its the 'slow' part of tcp_urg. It could be | |
3464 | * moved inline now as tcp_urg is only called from one | |
3465 | * place. We handle URGent data wrong. We have to - as | |
3466 | * BSD still doesn't use the correction from RFC961. | |
3467 | * For 1003.1g we should support a new option TCP_STDURG to permit | |
3468 | * either form (or just set the sysctl tcp_stdurg). | |
3469 | */ | |
3470 | ||
3471 | static void tcp_check_urg(struct sock * sk, struct tcphdr * th) | |
3472 | { | |
3473 | struct tcp_sock *tp = tcp_sk(sk); | |
3474 | u32 ptr = ntohs(th->urg_ptr); | |
3475 | ||
3476 | if (ptr && !sysctl_tcp_stdurg) | |
3477 | ptr--; | |
3478 | ptr += ntohl(th->seq); | |
3479 | ||
3480 | /* Ignore urgent data that we've already seen and read. */ | |
3481 | if (after(tp->copied_seq, ptr)) | |
3482 | return; | |
3483 | ||
3484 | /* Do not replay urg ptr. | |
3485 | * | |
3486 | * NOTE: interesting situation not covered by specs. | |
3487 | * Misbehaving sender may send urg ptr, pointing to segment, | |
3488 | * which we already have in ofo queue. We are not able to fetch | |
3489 | * such data and will stay in TCP_URG_NOTYET until will be eaten | |
3490 | * by recvmsg(). Seems, we are not obliged to handle such wicked | |
3491 | * situations. But it is worth to think about possibility of some | |
3492 | * DoSes using some hypothetical application level deadlock. | |
3493 | */ | |
3494 | if (before(ptr, tp->rcv_nxt)) | |
3495 | return; | |
3496 | ||
3497 | /* Do we already have a newer (or duplicate) urgent pointer? */ | |
3498 | if (tp->urg_data && !after(ptr, tp->urg_seq)) | |
3499 | return; | |
3500 | ||
3501 | /* Tell the world about our new urgent pointer. */ | |
3502 | sk_send_sigurg(sk); | |
3503 | ||
3504 | /* We may be adding urgent data when the last byte read was | |
3505 | * urgent. To do this requires some care. We cannot just ignore | |
3506 | * tp->copied_seq since we would read the last urgent byte again | |
3507 | * as data, nor can we alter copied_seq until this data arrives | |
3508 | * or we break the sematics of SIOCATMARK (and thus sockatmark()) | |
3509 | * | |
3510 | * NOTE. Double Dutch. Rendering to plain English: author of comment | |
3511 | * above did something sort of send("A", MSG_OOB); send("B", MSG_OOB); | |
3512 | * and expect that both A and B disappear from stream. This is _wrong_. | |
3513 | * Though this happens in BSD with high probability, this is occasional. | |
3514 | * Any application relying on this is buggy. Note also, that fix "works" | |
3515 | * only in this artificial test. Insert some normal data between A and B and we will | |
3516 | * decline of BSD again. Verdict: it is better to remove to trap | |
3517 | * buggy users. | |
3518 | */ | |
3519 | if (tp->urg_seq == tp->copied_seq && tp->urg_data && | |
3520 | !sock_flag(sk, SOCK_URGINLINE) && | |
3521 | tp->copied_seq != tp->rcv_nxt) { | |
3522 | struct sk_buff *skb = skb_peek(&sk->sk_receive_queue); | |
3523 | tp->copied_seq++; | |
3524 | if (skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq)) { | |
8728b834 | 3525 | __skb_unlink(skb, &sk->sk_receive_queue); |
1da177e4 LT |
3526 | __kfree_skb(skb); |
3527 | } | |
3528 | } | |
3529 | ||
3530 | tp->urg_data = TCP_URG_NOTYET; | |
3531 | tp->urg_seq = ptr; | |
3532 | ||
3533 | /* Disable header prediction. */ | |
3534 | tp->pred_flags = 0; | |
3535 | } | |
3536 | ||
3537 | /* This is the 'fast' part of urgent handling. */ | |
3538 | static void tcp_urg(struct sock *sk, struct sk_buff *skb, struct tcphdr *th) | |
3539 | { | |
3540 | struct tcp_sock *tp = tcp_sk(sk); | |
3541 | ||
3542 | /* Check if we get a new urgent pointer - normally not. */ | |
3543 | if (th->urg) | |
3544 | tcp_check_urg(sk,th); | |
3545 | ||
3546 | /* Do we wait for any urgent data? - normally not... */ | |
3547 | if (tp->urg_data == TCP_URG_NOTYET) { | |
3548 | u32 ptr = tp->urg_seq - ntohl(th->seq) + (th->doff * 4) - | |
3549 | th->syn; | |
3550 | ||
3551 | /* Is the urgent pointer pointing into this packet? */ | |
3552 | if (ptr < skb->len) { | |
3553 | u8 tmp; | |
3554 | if (skb_copy_bits(skb, ptr, &tmp, 1)) | |
3555 | BUG(); | |
3556 | tp->urg_data = TCP_URG_VALID | tmp; | |
3557 | if (!sock_flag(sk, SOCK_DEAD)) | |
3558 | sk->sk_data_ready(sk, 0); | |
3559 | } | |
3560 | } | |
3561 | } | |
3562 | ||
3563 | static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen) | |
3564 | { | |
3565 | struct tcp_sock *tp = tcp_sk(sk); | |
3566 | int chunk = skb->len - hlen; | |
3567 | int err; | |
3568 | ||
3569 | local_bh_enable(); | |
3570 | if (skb->ip_summed==CHECKSUM_UNNECESSARY) | |
3571 | err = skb_copy_datagram_iovec(skb, hlen, tp->ucopy.iov, chunk); | |
3572 | else | |
3573 | err = skb_copy_and_csum_datagram_iovec(skb, hlen, | |
3574 | tp->ucopy.iov); | |
3575 | ||
3576 | if (!err) { | |
3577 | tp->ucopy.len -= chunk; | |
3578 | tp->copied_seq += chunk; | |
3579 | tcp_rcv_space_adjust(sk); | |
3580 | } | |
3581 | ||
3582 | local_bh_disable(); | |
3583 | return err; | |
3584 | } | |
3585 | ||
3586 | static int __tcp_checksum_complete_user(struct sock *sk, struct sk_buff *skb) | |
3587 | { | |
3588 | int result; | |
3589 | ||
3590 | if (sock_owned_by_user(sk)) { | |
3591 | local_bh_enable(); | |
3592 | result = __tcp_checksum_complete(skb); | |
3593 | local_bh_disable(); | |
3594 | } else { | |
3595 | result = __tcp_checksum_complete(skb); | |
3596 | } | |
3597 | return result; | |
3598 | } | |
3599 | ||
3600 | static __inline__ int | |
3601 | tcp_checksum_complete_user(struct sock *sk, struct sk_buff *skb) | |
3602 | { | |
3603 | return skb->ip_summed != CHECKSUM_UNNECESSARY && | |
3604 | __tcp_checksum_complete_user(sk, skb); | |
3605 | } | |
3606 | ||
3607 | /* | |
3608 | * TCP receive function for the ESTABLISHED state. | |
3609 | * | |
3610 | * It is split into a fast path and a slow path. The fast path is | |
3611 | * disabled when: | |
3612 | * - A zero window was announced from us - zero window probing | |
3613 | * is only handled properly in the slow path. | |
3614 | * - Out of order segments arrived. | |
3615 | * - Urgent data is expected. | |
3616 | * - There is no buffer space left | |
3617 | * - Unexpected TCP flags/window values/header lengths are received | |
3618 | * (detected by checking the TCP header against pred_flags) | |
3619 | * - Data is sent in both directions. Fast path only supports pure senders | |
3620 | * or pure receivers (this means either the sequence number or the ack | |
3621 | * value must stay constant) | |
3622 | * - Unexpected TCP option. | |
3623 | * | |
3624 | * When these conditions are not satisfied it drops into a standard | |
3625 | * receive procedure patterned after RFC793 to handle all cases. | |
3626 | * The first three cases are guaranteed by proper pred_flags setting, | |
3627 | * the rest is checked inline. Fast processing is turned on in | |
3628 | * tcp_data_queue when everything is OK. | |
3629 | */ | |
3630 | int tcp_rcv_established(struct sock *sk, struct sk_buff *skb, | |
3631 | struct tcphdr *th, unsigned len) | |
3632 | { | |
3633 | struct tcp_sock *tp = tcp_sk(sk); | |
3634 | ||
3635 | /* | |
3636 | * Header prediction. | |
3637 | * The code loosely follows the one in the famous | |
3638 | * "30 instruction TCP receive" Van Jacobson mail. | |
3639 | * | |
3640 | * Van's trick is to deposit buffers into socket queue | |
3641 | * on a device interrupt, to call tcp_recv function | |
3642 | * on the receive process context and checksum and copy | |
3643 | * the buffer to user space. smart... | |
3644 | * | |
3645 | * Our current scheme is not silly either but we take the | |
3646 | * extra cost of the net_bh soft interrupt processing... | |
3647 | * We do checksum and copy also but from device to kernel. | |
3648 | */ | |
3649 | ||
3650 | tp->rx_opt.saw_tstamp = 0; | |
3651 | ||
3652 | /* pred_flags is 0xS?10 << 16 + snd_wnd | |
3653 | * if header_predition is to be made | |
3654 | * 'S' will always be tp->tcp_header_len >> 2 | |
3655 | * '?' will be 0 for the fast path, otherwise pred_flags is 0 to | |
3656 | * turn it off (when there are holes in the receive | |
3657 | * space for instance) | |
3658 | * PSH flag is ignored. | |
3659 | */ | |
3660 | ||
3661 | if ((tcp_flag_word(th) & TCP_HP_BITS) == tp->pred_flags && | |
3662 | TCP_SKB_CB(skb)->seq == tp->rcv_nxt) { | |
3663 | int tcp_header_len = tp->tcp_header_len; | |
3664 | ||
3665 | /* Timestamp header prediction: tcp_header_len | |
3666 | * is automatically equal to th->doff*4 due to pred_flags | |
3667 | * match. | |
3668 | */ | |
3669 | ||
3670 | /* Check timestamp */ | |
3671 | if (tcp_header_len == sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) { | |
3672 | __u32 *ptr = (__u32 *)(th + 1); | |
3673 | ||
3674 | /* No? Slow path! */ | |
3675 | if (*ptr != ntohl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
3676 | | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP)) | |
3677 | goto slow_path; | |
3678 | ||
3679 | tp->rx_opt.saw_tstamp = 1; | |
3680 | ++ptr; | |
3681 | tp->rx_opt.rcv_tsval = ntohl(*ptr); | |
3682 | ++ptr; | |
3683 | tp->rx_opt.rcv_tsecr = ntohl(*ptr); | |
3684 | ||
3685 | /* If PAWS failed, check it more carefully in slow path */ | |
3686 | if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) < 0) | |
3687 | goto slow_path; | |
3688 | ||
3689 | /* DO NOT update ts_recent here, if checksum fails | |
3690 | * and timestamp was corrupted part, it will result | |
3691 | * in a hung connection since we will drop all | |
3692 | * future packets due to the PAWS test. | |
3693 | */ | |
3694 | } | |
3695 | ||
3696 | if (len <= tcp_header_len) { | |
3697 | /* Bulk data transfer: sender */ | |
3698 | if (len == tcp_header_len) { | |
3699 | /* Predicted packet is in window by definition. | |
3700 | * seq == rcv_nxt and rcv_wup <= rcv_nxt. | |
3701 | * Hence, check seq<=rcv_wup reduces to: | |
3702 | */ | |
3703 | if (tcp_header_len == | |
3704 | (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) && | |
3705 | tp->rcv_nxt == tp->rcv_wup) | |
3706 | tcp_store_ts_recent(tp); | |
3707 | ||
463c84b9 | 3708 | tcp_rcv_rtt_measure_ts(sk, skb); |
1da177e4 LT |
3709 | |
3710 | /* We know that such packets are checksummed | |
3711 | * on entry. | |
3712 | */ | |
3713 | tcp_ack(sk, skb, 0); | |
3714 | __kfree_skb(skb); | |
55c97f3e | 3715 | tcp_data_snd_check(sk, tp); |
1da177e4 LT |
3716 | return 0; |
3717 | } else { /* Header too small */ | |
3718 | TCP_INC_STATS_BH(TCP_MIB_INERRS); | |
3719 | goto discard; | |
3720 | } | |
3721 | } else { | |
3722 | int eaten = 0; | |
3723 | ||
3724 | if (tp->ucopy.task == current && | |
3725 | tp->copied_seq == tp->rcv_nxt && | |
3726 | len - tcp_header_len <= tp->ucopy.len && | |
3727 | sock_owned_by_user(sk)) { | |
3728 | __set_current_state(TASK_RUNNING); | |
3729 | ||
3730 | if (!tcp_copy_to_iovec(sk, skb, tcp_header_len)) { | |
3731 | /* Predicted packet is in window by definition. | |
3732 | * seq == rcv_nxt and rcv_wup <= rcv_nxt. | |
3733 | * Hence, check seq<=rcv_wup reduces to: | |
3734 | */ | |
3735 | if (tcp_header_len == | |
3736 | (sizeof(struct tcphdr) + | |
3737 | TCPOLEN_TSTAMP_ALIGNED) && | |
3738 | tp->rcv_nxt == tp->rcv_wup) | |
3739 | tcp_store_ts_recent(tp); | |
3740 | ||
463c84b9 | 3741 | tcp_rcv_rtt_measure_ts(sk, skb); |
1da177e4 LT |
3742 | |
3743 | __skb_pull(skb, tcp_header_len); | |
3744 | tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; | |
3745 | NET_INC_STATS_BH(LINUX_MIB_TCPHPHITSTOUSER); | |
3746 | eaten = 1; | |
3747 | } | |
3748 | } | |
3749 | if (!eaten) { | |
3750 | if (tcp_checksum_complete_user(sk, skb)) | |
3751 | goto csum_error; | |
3752 | ||
3753 | /* Predicted packet is in window by definition. | |
3754 | * seq == rcv_nxt and rcv_wup <= rcv_nxt. | |
3755 | * Hence, check seq<=rcv_wup reduces to: | |
3756 | */ | |
3757 | if (tcp_header_len == | |
3758 | (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) && | |
3759 | tp->rcv_nxt == tp->rcv_wup) | |
3760 | tcp_store_ts_recent(tp); | |
3761 | ||
463c84b9 | 3762 | tcp_rcv_rtt_measure_ts(sk, skb); |
1da177e4 LT |
3763 | |
3764 | if ((int)skb->truesize > sk->sk_forward_alloc) | |
3765 | goto step5; | |
3766 | ||
3767 | NET_INC_STATS_BH(LINUX_MIB_TCPHPHITS); | |
3768 | ||
3769 | /* Bulk data transfer: receiver */ | |
3770 | __skb_pull(skb,tcp_header_len); | |
3771 | __skb_queue_tail(&sk->sk_receive_queue, skb); | |
3772 | sk_stream_set_owner_r(skb, sk); | |
3773 | tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; | |
3774 | } | |
3775 | ||
3776 | tcp_event_data_recv(sk, tp, skb); | |
3777 | ||
3778 | if (TCP_SKB_CB(skb)->ack_seq != tp->snd_una) { | |
3779 | /* Well, only one small jumplet in fast path... */ | |
3780 | tcp_ack(sk, skb, FLAG_DATA); | |
55c97f3e | 3781 | tcp_data_snd_check(sk, tp); |
463c84b9 | 3782 | if (!inet_csk_ack_scheduled(sk)) |
1da177e4 LT |
3783 | goto no_ack; |
3784 | } | |
3785 | ||
31432412 | 3786 | __tcp_ack_snd_check(sk, 0); |
1da177e4 LT |
3787 | no_ack: |
3788 | if (eaten) | |
3789 | __kfree_skb(skb); | |
3790 | else | |
3791 | sk->sk_data_ready(sk, 0); | |
3792 | return 0; | |
3793 | } | |
3794 | } | |
3795 | ||
3796 | slow_path: | |
3797 | if (len < (th->doff<<2) || tcp_checksum_complete_user(sk, skb)) | |
3798 | goto csum_error; | |
3799 | ||
3800 | /* | |
3801 | * RFC1323: H1. Apply PAWS check first. | |
3802 | */ | |
3803 | if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp && | |
463c84b9 | 3804 | tcp_paws_discard(sk, skb)) { |
1da177e4 LT |
3805 | if (!th->rst) { |
3806 | NET_INC_STATS_BH(LINUX_MIB_PAWSESTABREJECTED); | |
3807 | tcp_send_dupack(sk, skb); | |
3808 | goto discard; | |
3809 | } | |
3810 | /* Resets are accepted even if PAWS failed. | |
3811 | ||
3812 | ts_recent update must be made after we are sure | |
3813 | that the packet is in window. | |
3814 | */ | |
3815 | } | |
3816 | ||
3817 | /* | |
3818 | * Standard slow path. | |
3819 | */ | |
3820 | ||
3821 | if (!tcp_sequence(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq)) { | |
3822 | /* RFC793, page 37: "In all states except SYN-SENT, all reset | |
3823 | * (RST) segments are validated by checking their SEQ-fields." | |
3824 | * And page 69: "If an incoming segment is not acceptable, | |
3825 | * an acknowledgment should be sent in reply (unless the RST bit | |
3826 | * is set, if so drop the segment and return)". | |
3827 | */ | |
3828 | if (!th->rst) | |
3829 | tcp_send_dupack(sk, skb); | |
3830 | goto discard; | |
3831 | } | |
3832 | ||
3833 | if(th->rst) { | |
3834 | tcp_reset(sk); | |
3835 | goto discard; | |
3836 | } | |
3837 | ||
3838 | tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); | |
3839 | ||
3840 | if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) { | |
3841 | TCP_INC_STATS_BH(TCP_MIB_INERRS); | |
3842 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONSYN); | |
3843 | tcp_reset(sk); | |
3844 | return 1; | |
3845 | } | |
3846 | ||
3847 | step5: | |
3848 | if(th->ack) | |
3849 | tcp_ack(sk, skb, FLAG_SLOWPATH); | |
3850 | ||
463c84b9 | 3851 | tcp_rcv_rtt_measure_ts(sk, skb); |
1da177e4 LT |
3852 | |
3853 | /* Process urgent data. */ | |
3854 | tcp_urg(sk, skb, th); | |
3855 | ||
3856 | /* step 7: process the segment text */ | |
3857 | tcp_data_queue(sk, skb); | |
3858 | ||
55c97f3e | 3859 | tcp_data_snd_check(sk, tp); |
1da177e4 LT |
3860 | tcp_ack_snd_check(sk); |
3861 | return 0; | |
3862 | ||
3863 | csum_error: | |
3864 | TCP_INC_STATS_BH(TCP_MIB_INERRS); | |
3865 | ||
3866 | discard: | |
3867 | __kfree_skb(skb); | |
3868 | return 0; | |
3869 | } | |
3870 | ||
3871 | static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, | |
3872 | struct tcphdr *th, unsigned len) | |
3873 | { | |
3874 | struct tcp_sock *tp = tcp_sk(sk); | |
3875 | int saved_clamp = tp->rx_opt.mss_clamp; | |
3876 | ||
3877 | tcp_parse_options(skb, &tp->rx_opt, 0); | |
3878 | ||
3879 | if (th->ack) { | |
295f7324 | 3880 | struct inet_connection_sock *icsk; |
1da177e4 LT |
3881 | /* rfc793: |
3882 | * "If the state is SYN-SENT then | |
3883 | * first check the ACK bit | |
3884 | * If the ACK bit is set | |
3885 | * If SEG.ACK =< ISS, or SEG.ACK > SND.NXT, send | |
3886 | * a reset (unless the RST bit is set, if so drop | |
3887 | * the segment and return)" | |
3888 | * | |
3889 | * We do not send data with SYN, so that RFC-correct | |
3890 | * test reduces to: | |
3891 | */ | |
3892 | if (TCP_SKB_CB(skb)->ack_seq != tp->snd_nxt) | |
3893 | goto reset_and_undo; | |
3894 | ||
3895 | if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr && | |
3896 | !between(tp->rx_opt.rcv_tsecr, tp->retrans_stamp, | |
3897 | tcp_time_stamp)) { | |
3898 | NET_INC_STATS_BH(LINUX_MIB_PAWSACTIVEREJECTED); | |
3899 | goto reset_and_undo; | |
3900 | } | |
3901 | ||
3902 | /* Now ACK is acceptable. | |
3903 | * | |
3904 | * "If the RST bit is set | |
3905 | * If the ACK was acceptable then signal the user "error: | |
3906 | * connection reset", drop the segment, enter CLOSED state, | |
3907 | * delete TCB, and return." | |
3908 | */ | |
3909 | ||
3910 | if (th->rst) { | |
3911 | tcp_reset(sk); | |
3912 | goto discard; | |
3913 | } | |
3914 | ||
3915 | /* rfc793: | |
3916 | * "fifth, if neither of the SYN or RST bits is set then | |
3917 | * drop the segment and return." | |
3918 | * | |
3919 | * See note below! | |
3920 | * --ANK(990513) | |
3921 | */ | |
3922 | if (!th->syn) | |
3923 | goto discard_and_undo; | |
3924 | ||
3925 | /* rfc793: | |
3926 | * "If the SYN bit is on ... | |
3927 | * are acceptable then ... | |
3928 | * (our SYN has been ACKed), change the connection | |
3929 | * state to ESTABLISHED..." | |
3930 | */ | |
3931 | ||
3932 | TCP_ECN_rcv_synack(tp, th); | |
3933 | if (tp->ecn_flags&TCP_ECN_OK) | |
3934 | sock_set_flag(sk, SOCK_NO_LARGESEND); | |
3935 | ||
3936 | tp->snd_wl1 = TCP_SKB_CB(skb)->seq; | |
3937 | tcp_ack(sk, skb, FLAG_SLOWPATH); | |
3938 | ||
3939 | /* Ok.. it's good. Set up sequence numbers and | |
3940 | * move to established. | |
3941 | */ | |
3942 | tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; | |
3943 | tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1; | |
3944 | ||
3945 | /* RFC1323: The window in SYN & SYN/ACK segments is | |
3946 | * never scaled. | |
3947 | */ | |
3948 | tp->snd_wnd = ntohs(th->window); | |
3949 | tcp_init_wl(tp, TCP_SKB_CB(skb)->ack_seq, TCP_SKB_CB(skb)->seq); | |
3950 | ||
3951 | if (!tp->rx_opt.wscale_ok) { | |
3952 | tp->rx_opt.snd_wscale = tp->rx_opt.rcv_wscale = 0; | |
3953 | tp->window_clamp = min(tp->window_clamp, 65535U); | |
3954 | } | |
3955 | ||
3956 | if (tp->rx_opt.saw_tstamp) { | |
3957 | tp->rx_opt.tstamp_ok = 1; | |
3958 | tp->tcp_header_len = | |
3959 | sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED; | |
3960 | tp->advmss -= TCPOLEN_TSTAMP_ALIGNED; | |
3961 | tcp_store_ts_recent(tp); | |
3962 | } else { | |
3963 | tp->tcp_header_len = sizeof(struct tcphdr); | |
3964 | } | |
3965 | ||
3966 | if (tp->rx_opt.sack_ok && sysctl_tcp_fack) | |
3967 | tp->rx_opt.sack_ok |= 2; | |
3968 | ||
3969 | tcp_sync_mss(sk, tp->pmtu_cookie); | |
3970 | tcp_initialize_rcv_mss(sk); | |
3971 | ||
3972 | /* Remember, tcp_poll() does not lock socket! | |
3973 | * Change state from SYN-SENT only after copied_seq | |
3974 | * is initialized. */ | |
3975 | tp->copied_seq = tp->rcv_nxt; | |
3976 | mb(); | |
3977 | tcp_set_state(sk, TCP_ESTABLISHED); | |
3978 | ||
3979 | /* Make sure socket is routed, for correct metrics. */ | |
3980 | tp->af_specific->rebuild_header(sk); | |
3981 | ||
3982 | tcp_init_metrics(sk); | |
3983 | ||
6687e988 | 3984 | tcp_init_congestion_control(sk); |
317a76f9 | 3985 | |
1da177e4 LT |
3986 | /* Prevent spurious tcp_cwnd_restart() on first data |
3987 | * packet. | |
3988 | */ | |
3989 | tp->lsndtime = tcp_time_stamp; | |
3990 | ||
3991 | tcp_init_buffer_space(sk); | |
3992 | ||
3993 | if (sock_flag(sk, SOCK_KEEPOPEN)) | |
463c84b9 | 3994 | inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tp)); |
1da177e4 LT |
3995 | |
3996 | if (!tp->rx_opt.snd_wscale) | |
3997 | __tcp_fast_path_on(tp, tp->snd_wnd); | |
3998 | else | |
3999 | tp->pred_flags = 0; | |
4000 | ||
4001 | if (!sock_flag(sk, SOCK_DEAD)) { | |
4002 | sk->sk_state_change(sk); | |
4003 | sk_wake_async(sk, 0, POLL_OUT); | |
4004 | } | |
4005 | ||
295f7324 ACM |
4006 | icsk = inet_csk(sk); |
4007 | ||
4008 | if (sk->sk_write_pending || | |
4009 | icsk->icsk_accept_queue.rskq_defer_accept || | |
4010 | icsk->icsk_ack.pingpong) { | |
1da177e4 LT |
4011 | /* Save one ACK. Data will be ready after |
4012 | * several ticks, if write_pending is set. | |
4013 | * | |
4014 | * It may be deleted, but with this feature tcpdumps | |
4015 | * look so _wonderfully_ clever, that I was not able | |
4016 | * to stand against the temptation 8) --ANK | |
4017 | */ | |
463c84b9 | 4018 | inet_csk_schedule_ack(sk); |
295f7324 ACM |
4019 | icsk->icsk_ack.lrcvtime = tcp_time_stamp; |
4020 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
463c84b9 ACM |
4021 | tcp_incr_quickack(sk); |
4022 | tcp_enter_quickack_mode(sk); | |
3f421baa ACM |
4023 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, |
4024 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
1da177e4 LT |
4025 | |
4026 | discard: | |
4027 | __kfree_skb(skb); | |
4028 | return 0; | |
4029 | } else { | |
4030 | tcp_send_ack(sk); | |
4031 | } | |
4032 | return -1; | |
4033 | } | |
4034 | ||
4035 | /* No ACK in the segment */ | |
4036 | ||
4037 | if (th->rst) { | |
4038 | /* rfc793: | |
4039 | * "If the RST bit is set | |
4040 | * | |
4041 | * Otherwise (no ACK) drop the segment and return." | |
4042 | */ | |
4043 | ||
4044 | goto discard_and_undo; | |
4045 | } | |
4046 | ||
4047 | /* PAWS check. */ | |
4048 | if (tp->rx_opt.ts_recent_stamp && tp->rx_opt.saw_tstamp && tcp_paws_check(&tp->rx_opt, 0)) | |
4049 | goto discard_and_undo; | |
4050 | ||
4051 | if (th->syn) { | |
4052 | /* We see SYN without ACK. It is attempt of | |
4053 | * simultaneous connect with crossed SYNs. | |
4054 | * Particularly, it can be connect to self. | |
4055 | */ | |
4056 | tcp_set_state(sk, TCP_SYN_RECV); | |
4057 | ||
4058 | if (tp->rx_opt.saw_tstamp) { | |
4059 | tp->rx_opt.tstamp_ok = 1; | |
4060 | tcp_store_ts_recent(tp); | |
4061 | tp->tcp_header_len = | |
4062 | sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED; | |
4063 | } else { | |
4064 | tp->tcp_header_len = sizeof(struct tcphdr); | |
4065 | } | |
4066 | ||
4067 | tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; | |
4068 | tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1; | |
4069 | ||
4070 | /* RFC1323: The window in SYN & SYN/ACK segments is | |
4071 | * never scaled. | |
4072 | */ | |
4073 | tp->snd_wnd = ntohs(th->window); | |
4074 | tp->snd_wl1 = TCP_SKB_CB(skb)->seq; | |
4075 | tp->max_window = tp->snd_wnd; | |
4076 | ||
4077 | TCP_ECN_rcv_syn(tp, th); | |
4078 | if (tp->ecn_flags&TCP_ECN_OK) | |
4079 | sock_set_flag(sk, SOCK_NO_LARGESEND); | |
4080 | ||
4081 | tcp_sync_mss(sk, tp->pmtu_cookie); | |
4082 | tcp_initialize_rcv_mss(sk); | |
4083 | ||
4084 | ||
4085 | tcp_send_synack(sk); | |
4086 | #if 0 | |
4087 | /* Note, we could accept data and URG from this segment. | |
4088 | * There are no obstacles to make this. | |
4089 | * | |
4090 | * However, if we ignore data in ACKless segments sometimes, | |
4091 | * we have no reasons to accept it sometimes. | |
4092 | * Also, seems the code doing it in step6 of tcp_rcv_state_process | |
4093 | * is not flawless. So, discard packet for sanity. | |
4094 | * Uncomment this return to process the data. | |
4095 | */ | |
4096 | return -1; | |
4097 | #else | |
4098 | goto discard; | |
4099 | #endif | |
4100 | } | |
4101 | /* "fifth, if neither of the SYN or RST bits is set then | |
4102 | * drop the segment and return." | |
4103 | */ | |
4104 | ||
4105 | discard_and_undo: | |
4106 | tcp_clear_options(&tp->rx_opt); | |
4107 | tp->rx_opt.mss_clamp = saved_clamp; | |
4108 | goto discard; | |
4109 | ||
4110 | reset_and_undo: | |
4111 | tcp_clear_options(&tp->rx_opt); | |
4112 | tp->rx_opt.mss_clamp = saved_clamp; | |
4113 | return 1; | |
4114 | } | |
4115 | ||
4116 | ||
4117 | /* | |
4118 | * This function implements the receiving procedure of RFC 793 for | |
4119 | * all states except ESTABLISHED and TIME_WAIT. | |
4120 | * It's called from both tcp_v4_rcv and tcp_v6_rcv and should be | |
4121 | * address independent. | |
4122 | */ | |
4123 | ||
4124 | int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, | |
4125 | struct tcphdr *th, unsigned len) | |
4126 | { | |
4127 | struct tcp_sock *tp = tcp_sk(sk); | |
4128 | int queued = 0; | |
4129 | ||
4130 | tp->rx_opt.saw_tstamp = 0; | |
4131 | ||
4132 | switch (sk->sk_state) { | |
4133 | case TCP_CLOSE: | |
4134 | goto discard; | |
4135 | ||
4136 | case TCP_LISTEN: | |
4137 | if(th->ack) | |
4138 | return 1; | |
4139 | ||
4140 | if(th->rst) | |
4141 | goto discard; | |
4142 | ||
4143 | if(th->syn) { | |
4144 | if(tp->af_specific->conn_request(sk, skb) < 0) | |
4145 | return 1; | |
4146 | ||
1da177e4 LT |
4147 | /* Now we have several options: In theory there is |
4148 | * nothing else in the frame. KA9Q has an option to | |
4149 | * send data with the syn, BSD accepts data with the | |
4150 | * syn up to the [to be] advertised window and | |
4151 | * Solaris 2.1 gives you a protocol error. For now | |
4152 | * we just ignore it, that fits the spec precisely | |
4153 | * and avoids incompatibilities. It would be nice in | |
4154 | * future to drop through and process the data. | |
4155 | * | |
4156 | * Now that TTCP is starting to be used we ought to | |
4157 | * queue this data. | |
4158 | * But, this leaves one open to an easy denial of | |
4159 | * service attack, and SYN cookies can't defend | |
4160 | * against this problem. So, we drop the data | |
4161 | * in the interest of security over speed. | |
4162 | */ | |
4163 | goto discard; | |
4164 | } | |
4165 | goto discard; | |
4166 | ||
4167 | case TCP_SYN_SENT: | |
1da177e4 LT |
4168 | queued = tcp_rcv_synsent_state_process(sk, skb, th, len); |
4169 | if (queued >= 0) | |
4170 | return queued; | |
4171 | ||
4172 | /* Do step6 onward by hand. */ | |
4173 | tcp_urg(sk, skb, th); | |
4174 | __kfree_skb(skb); | |
55c97f3e | 4175 | tcp_data_snd_check(sk, tp); |
1da177e4 LT |
4176 | return 0; |
4177 | } | |
4178 | ||
4179 | if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp && | |
463c84b9 | 4180 | tcp_paws_discard(sk, skb)) { |
1da177e4 LT |
4181 | if (!th->rst) { |
4182 | NET_INC_STATS_BH(LINUX_MIB_PAWSESTABREJECTED); | |
4183 | tcp_send_dupack(sk, skb); | |
4184 | goto discard; | |
4185 | } | |
4186 | /* Reset is accepted even if it did not pass PAWS. */ | |
4187 | } | |
4188 | ||
4189 | /* step 1: check sequence number */ | |
4190 | if (!tcp_sequence(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq)) { | |
4191 | if (!th->rst) | |
4192 | tcp_send_dupack(sk, skb); | |
4193 | goto discard; | |
4194 | } | |
4195 | ||
4196 | /* step 2: check RST bit */ | |
4197 | if(th->rst) { | |
4198 | tcp_reset(sk); | |
4199 | goto discard; | |
4200 | } | |
4201 | ||
4202 | tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); | |
4203 | ||
4204 | /* step 3: check security and precedence [ignored] */ | |
4205 | ||
4206 | /* step 4: | |
4207 | * | |
4208 | * Check for a SYN in window. | |
4209 | */ | |
4210 | if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) { | |
4211 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONSYN); | |
4212 | tcp_reset(sk); | |
4213 | return 1; | |
4214 | } | |
4215 | ||
4216 | /* step 5: check the ACK field */ | |
4217 | if (th->ack) { | |
4218 | int acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH); | |
4219 | ||
4220 | switch(sk->sk_state) { | |
4221 | case TCP_SYN_RECV: | |
4222 | if (acceptable) { | |
4223 | tp->copied_seq = tp->rcv_nxt; | |
4224 | mb(); | |
4225 | tcp_set_state(sk, TCP_ESTABLISHED); | |
4226 | sk->sk_state_change(sk); | |
4227 | ||
4228 | /* Note, that this wakeup is only for marginal | |
4229 | * crossed SYN case. Passively open sockets | |
4230 | * are not waked up, because sk->sk_sleep == | |
4231 | * NULL and sk->sk_socket == NULL. | |
4232 | */ | |
4233 | if (sk->sk_socket) { | |
4234 | sk_wake_async(sk,0,POLL_OUT); | |
4235 | } | |
4236 | ||
4237 | tp->snd_una = TCP_SKB_CB(skb)->ack_seq; | |
4238 | tp->snd_wnd = ntohs(th->window) << | |
4239 | tp->rx_opt.snd_wscale; | |
4240 | tcp_init_wl(tp, TCP_SKB_CB(skb)->ack_seq, | |
4241 | TCP_SKB_CB(skb)->seq); | |
4242 | ||
4243 | /* tcp_ack considers this ACK as duplicate | |
4244 | * and does not calculate rtt. | |
4245 | * Fix it at least with timestamps. | |
4246 | */ | |
4247 | if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr && | |
4248 | !tp->srtt) | |
2d2abbab | 4249 | tcp_ack_saw_tstamp(sk, 0); |
1da177e4 LT |
4250 | |
4251 | if (tp->rx_opt.tstamp_ok) | |
4252 | tp->advmss -= TCPOLEN_TSTAMP_ALIGNED; | |
4253 | ||
4254 | /* Make sure socket is routed, for | |
4255 | * correct metrics. | |
4256 | */ | |
4257 | tp->af_specific->rebuild_header(sk); | |
4258 | ||
4259 | tcp_init_metrics(sk); | |
4260 | ||
6687e988 | 4261 | tcp_init_congestion_control(sk); |
317a76f9 | 4262 | |
1da177e4 LT |
4263 | /* Prevent spurious tcp_cwnd_restart() on |
4264 | * first data packet. | |
4265 | */ | |
4266 | tp->lsndtime = tcp_time_stamp; | |
4267 | ||
4268 | tcp_initialize_rcv_mss(sk); | |
4269 | tcp_init_buffer_space(sk); | |
4270 | tcp_fast_path_on(tp); | |
4271 | } else { | |
4272 | return 1; | |
4273 | } | |
4274 | break; | |
4275 | ||
4276 | case TCP_FIN_WAIT1: | |
4277 | if (tp->snd_una == tp->write_seq) { | |
4278 | tcp_set_state(sk, TCP_FIN_WAIT2); | |
4279 | sk->sk_shutdown |= SEND_SHUTDOWN; | |
4280 | dst_confirm(sk->sk_dst_cache); | |
4281 | ||
4282 | if (!sock_flag(sk, SOCK_DEAD)) | |
4283 | /* Wake up lingering close() */ | |
4284 | sk->sk_state_change(sk); | |
4285 | else { | |
4286 | int tmo; | |
4287 | ||
4288 | if (tp->linger2 < 0 || | |
4289 | (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq && | |
4290 | after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt))) { | |
4291 | tcp_done(sk); | |
4292 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONDATA); | |
4293 | return 1; | |
4294 | } | |
4295 | ||
463c84b9 | 4296 | tmo = tcp_fin_time(sk); |
1da177e4 | 4297 | if (tmo > TCP_TIMEWAIT_LEN) { |
463c84b9 | 4298 | inet_csk_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN); |
1da177e4 LT |
4299 | } else if (th->fin || sock_owned_by_user(sk)) { |
4300 | /* Bad case. We could lose such FIN otherwise. | |
4301 | * It is not a big problem, but it looks confusing | |
4302 | * and not so rare event. We still can lose it now, | |
4303 | * if it spins in bh_lock_sock(), but it is really | |
4304 | * marginal case. | |
4305 | */ | |
463c84b9 | 4306 | inet_csk_reset_keepalive_timer(sk, tmo); |
1da177e4 LT |
4307 | } else { |
4308 | tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); | |
4309 | goto discard; | |
4310 | } | |
4311 | } | |
4312 | } | |
4313 | break; | |
4314 | ||
4315 | case TCP_CLOSING: | |
4316 | if (tp->snd_una == tp->write_seq) { | |
4317 | tcp_time_wait(sk, TCP_TIME_WAIT, 0); | |
4318 | goto discard; | |
4319 | } | |
4320 | break; | |
4321 | ||
4322 | case TCP_LAST_ACK: | |
4323 | if (tp->snd_una == tp->write_seq) { | |
4324 | tcp_update_metrics(sk); | |
4325 | tcp_done(sk); | |
4326 | goto discard; | |
4327 | } | |
4328 | break; | |
4329 | } | |
4330 | } else | |
4331 | goto discard; | |
4332 | ||
4333 | /* step 6: check the URG bit */ | |
4334 | tcp_urg(sk, skb, th); | |
4335 | ||
4336 | /* step 7: process the segment text */ | |
4337 | switch (sk->sk_state) { | |
4338 | case TCP_CLOSE_WAIT: | |
4339 | case TCP_CLOSING: | |
4340 | case TCP_LAST_ACK: | |
4341 | if (!before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) | |
4342 | break; | |
4343 | case TCP_FIN_WAIT1: | |
4344 | case TCP_FIN_WAIT2: | |
4345 | /* RFC 793 says to queue data in these states, | |
4346 | * RFC 1122 says we MUST send a reset. | |
4347 | * BSD 4.4 also does reset. | |
4348 | */ | |
4349 | if (sk->sk_shutdown & RCV_SHUTDOWN) { | |
4350 | if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq && | |
4351 | after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) { | |
4352 | NET_INC_STATS_BH(LINUX_MIB_TCPABORTONDATA); | |
4353 | tcp_reset(sk); | |
4354 | return 1; | |
4355 | } | |
4356 | } | |
4357 | /* Fall through */ | |
4358 | case TCP_ESTABLISHED: | |
4359 | tcp_data_queue(sk, skb); | |
4360 | queued = 1; | |
4361 | break; | |
4362 | } | |
4363 | ||
4364 | /* tcp_data could move socket to TIME-WAIT */ | |
4365 | if (sk->sk_state != TCP_CLOSE) { | |
55c97f3e | 4366 | tcp_data_snd_check(sk, tp); |
1da177e4 LT |
4367 | tcp_ack_snd_check(sk); |
4368 | } | |
4369 | ||
4370 | if (!queued) { | |
4371 | discard: | |
4372 | __kfree_skb(skb); | |
4373 | } | |
4374 | return 0; | |
4375 | } | |
4376 | ||
4377 | EXPORT_SYMBOL(sysctl_tcp_ecn); | |
4378 | EXPORT_SYMBOL(sysctl_tcp_reordering); | |
9772efb9 | 4379 | EXPORT_SYMBOL(sysctl_tcp_abc); |
1da177e4 LT |
4380 | EXPORT_SYMBOL(tcp_parse_options); |
4381 | EXPORT_SYMBOL(tcp_rcv_established); | |
4382 | EXPORT_SYMBOL(tcp_rcv_state_process); |