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.
6 * Definitions for the TCP protocol.
8 * Version: @(#)tcp.h 1.0.2 04/28/93
10 * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
21 #include <linux/skbuff.h>
23 #include <net/inet_connection_sock.h>
24 #include <net/inet_timewait_sock.h>
25 #include <uapi/linux/tcp.h>
27 static inline struct tcphdr
*tcp_hdr(const struct sk_buff
*skb
)
29 return (struct tcphdr
*)skb_transport_header(skb
);
32 static inline unsigned int __tcp_hdrlen(const struct tcphdr
*th
)
37 static inline unsigned int tcp_hdrlen(const struct sk_buff
*skb
)
39 return __tcp_hdrlen(tcp_hdr(skb
));
42 static inline struct tcphdr
*inner_tcp_hdr(const struct sk_buff
*skb
)
44 return (struct tcphdr
*)skb_inner_transport_header(skb
);
47 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff
*skb
)
49 return inner_tcp_hdr(skb
)->doff
* 4;
52 static inline unsigned int tcp_optlen(const struct sk_buff
*skb
)
54 return (tcp_hdr(skb
)->doff
- 5) * 4;
58 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
59 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
60 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
62 /* TCP Fast Open Cookie as stored in memory */
63 struct tcp_fastopen_cookie
{
65 u8 val
[TCP_FASTOPEN_COOKIE_MAX
];
66 bool exp
; /* In RFC6994 experimental option format */
69 /* This defines a selective acknowledgement block. */
70 struct tcp_sack_block_wire
{
75 struct tcp_sack_block
{
80 /*These are used to set the sack_ok field in struct tcp_options_received */
81 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
82 #define TCP_FACK_ENABLED (1 << 1) /*1 = FACK is enabled locally*/
83 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
85 struct tcp_options_received
{
87 long ts_recent_stamp
;/* Time we stored ts_recent (for aging) */
88 u32 ts_recent
; /* Time stamp to echo next */
89 u32 rcv_tsval
; /* Time stamp value */
90 u32 rcv_tsecr
; /* Time stamp echo reply */
91 u16 saw_tstamp
: 1, /* Saw TIMESTAMP on last packet */
92 tstamp_ok
: 1, /* TIMESTAMP seen on SYN packet */
93 dsack
: 1, /* D-SACK is scheduled */
94 wscale_ok
: 1, /* Wscale seen on SYN packet */
95 sack_ok
: 4, /* SACK seen on SYN packet */
96 snd_wscale
: 4, /* Window scaling received from sender */
97 rcv_wscale
: 4; /* Window scaling to send to receiver */
98 u8 num_sacks
; /* Number of SACK blocks */
99 u16 user_mss
; /* mss requested by user in ioctl */
100 u16 mss_clamp
; /* Maximal mss, negotiated at connection setup */
103 static inline void tcp_clear_options(struct tcp_options_received
*rx_opt
)
105 rx_opt
->tstamp_ok
= rx_opt
->sack_ok
= 0;
106 rx_opt
->wscale_ok
= rx_opt
->snd_wscale
= 0;
109 /* This is the max number of SACKS that we'll generate and process. It's safe
110 * to increase this, although since:
111 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
112 * only four options will fit in a standard TCP header */
113 #define TCP_NUM_SACKS 4
115 struct tcp_request_sock_ops
;
117 struct tcp_request_sock
{
118 struct inet_request_sock req
;
119 const struct tcp_request_sock_ops
*af_specific
;
120 struct skb_mstamp snt_synack
; /* first SYNACK sent time */
125 u32 last_oow_ack_time
; /* last SYNACK */
126 u32 rcv_nxt
; /* the ack # by SYNACK. For
127 * FastOpen it's the seq#
132 static inline struct tcp_request_sock
*tcp_rsk(const struct request_sock
*req
)
134 return (struct tcp_request_sock
*)req
;
138 /* inet_connection_sock has to be the first member of tcp_sock */
139 struct inet_connection_sock inet_conn
;
140 u16 tcp_header_len
; /* Bytes of tcp header to send */
141 u16 gso_segs
; /* Max number of segs per GSO packet */
144 * Header prediction flags
145 * 0x5?10 << 16 + snd_wnd in net byte order
150 * RFC793 variables by their proper names. This means you can
151 * read the code and the spec side by side (and laugh ...)
152 * See RFC793 and RFC1122. The RFC writes these in capitals.
154 u64 bytes_received
; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
155 * sum(delta(rcv_nxt)), or how many bytes
158 u32 segs_in
; /* RFC4898 tcpEStatsPerfSegsIn
159 * total number of segments in.
161 u32 rcv_nxt
; /* What we want to receive next */
162 u32 copied_seq
; /* Head of yet unread data */
163 u32 rcv_wup
; /* rcv_nxt on last window update sent */
164 u32 snd_nxt
; /* Next sequence we send */
165 u32 segs_out
; /* RFC4898 tcpEStatsPerfSegsOut
166 * The total number of segments sent.
168 u64 bytes_acked
; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
169 * sum(delta(snd_una)), or how many bytes
172 struct u64_stats_sync syncp
; /* protects 64bit vars (cf tcp_get_info()) */
174 u32 snd_una
; /* First byte we want an ack for */
175 u32 snd_sml
; /* Last byte of the most recently transmitted small packet */
176 u32 rcv_tstamp
; /* timestamp of last received ACK (for keepalives) */
177 u32 lsndtime
; /* timestamp of last sent data packet (for restart window) */
178 u32 last_oow_ack_time
; /* timestamp of last out-of-window ACK */
180 u32 tsoffset
; /* timestamp offset */
182 struct list_head tsq_node
; /* anchor in tsq_tasklet.head list */
183 unsigned long tsq_flags
;
185 /* Data for direct copy to user */
187 struct sk_buff_head prequeue
;
188 struct task_struct
*task
;
194 u32 snd_wl1
; /* Sequence for window update */
195 u32 snd_wnd
; /* The window we expect to receive */
196 u32 max_window
; /* Maximal window ever seen from peer */
197 u32 mss_cache
; /* Cached effective mss, not including SACKS */
199 u32 window_clamp
; /* Maximal window to advertise */
200 u32 rcv_ssthresh
; /* Current window clamp */
202 /* Information of the most recently (s)acked skb */
204 struct skb_mstamp mstamp
; /* (Re)sent time of the skb */
205 u8 advanced
; /* mstamp advanced since last lost marking */
206 u8 reord
; /* reordering detected */
208 u16 advmss
; /* Advertised MSS */
210 u8 nonagle
: 4,/* Disable Nagle algorithm? */
211 thin_lto
: 1,/* Use linear timeouts for thin streams */
212 thin_dupack
: 1,/* Fast retransmit on first dupack */
214 frto
: 1;/* F-RTO (RFC5682) activated in CA_Loss */
216 u8 do_early_retrans
:1,/* Enable RFC5827 early-retransmit */
217 syn_data
:1, /* SYN includes data */
218 syn_fastopen
:1, /* SYN includes Fast Open option */
219 syn_fastopen_exp
:1,/* SYN includes Fast Open exp. option */
220 syn_data_acked
:1,/* data in SYN is acked by SYN-ACK */
221 save_syn
:1, /* Save headers of SYN packet */
222 is_cwnd_limited
:1;/* forward progress limited by snd_cwnd? */
223 u32 tlp_high_seq
; /* snd_nxt at the time of TLP retransmit. */
225 /* RTT measurement */
226 u32 srtt_us
; /* smoothed round trip time << 3 in usecs */
227 u32 mdev_us
; /* medium deviation */
228 u32 mdev_max_us
; /* maximal mdev for the last rtt period */
229 u32 rttvar_us
; /* smoothed mdev_max */
230 u32 rtt_seq
; /* sequence number to update rttvar */
232 u32 rtt
, ts
; /* RTT in usec and sampling time in jiffies. */
235 u32 packets_out
; /* Packets which are "in flight" */
236 u32 retrans_out
; /* Retransmitted packets out */
237 u32 max_packets_out
; /* max packets_out in last window */
238 u32 max_packets_seq
; /* right edge of max_packets_out flight */
240 u16 urg_data
; /* Saved octet of OOB data and control flags */
241 u8 ecn_flags
; /* ECN status bits. */
242 u8 keepalive_probes
; /* num of allowed keep alive probes */
243 u32 reordering
; /* Packet reordering metric. */
244 u32 snd_up
; /* Urgent pointer */
247 * Options received (usually on last packet, some only on SYN packets).
249 struct tcp_options_received rx_opt
;
252 * Slow start and congestion control (see also Nagle, and Karn & Partridge)
254 u32 snd_ssthresh
; /* Slow start size threshold */
255 u32 snd_cwnd
; /* Sending congestion window */
256 u32 snd_cwnd_cnt
; /* Linear increase counter */
257 u32 snd_cwnd_clamp
; /* Do not allow snd_cwnd to grow above this */
260 u32 prior_cwnd
; /* Congestion window at start of Recovery. */
261 u32 prr_delivered
; /* Number of newly delivered packets to
262 * receiver in Recovery. */
263 u32 prr_out
; /* Total number of pkts sent during Recovery. */
264 u32 delivered
; /* Total data packets delivered incl. rexmits */
266 u32 rcv_wnd
; /* Current receiver window */
267 u32 write_seq
; /* Tail(+1) of data held in tcp send buffer */
268 u32 notsent_lowat
; /* TCP_NOTSENT_LOWAT */
269 u32 pushed_seq
; /* Last pushed seq, required to talk to windows */
270 u32 lost_out
; /* Lost packets */
271 u32 sacked_out
; /* SACK'd packets */
272 u32 fackets_out
; /* FACK'd packets */
274 /* from STCP, retrans queue hinting */
275 struct sk_buff
* lost_skb_hint
;
276 struct sk_buff
*retransmit_skb_hint
;
278 /* OOO segments go in this list. Note that socket lock must be held,
279 * as we do not use sk_buff_head lock.
281 struct sk_buff_head out_of_order_queue
;
283 /* SACKs data, these 2 need to be together (see tcp_options_write) */
284 struct tcp_sack_block duplicate_sack
[1]; /* D-SACK block */
285 struct tcp_sack_block selective_acks
[4]; /* The SACKS themselves*/
287 struct tcp_sack_block recv_sack_cache
[4];
289 struct sk_buff
*highest_sack
; /* skb just after the highest
290 * skb with SACKed bit set
291 * (validity guaranteed only if
296 u32 retransmit_high
; /* L-bits may be on up to this seqno */
298 u32 prior_ssthresh
; /* ssthresh saved at recovery start */
299 u32 high_seq
; /* snd_nxt at onset of congestion */
301 u32 retrans_stamp
; /* Timestamp of the last retransmit,
302 * also used in SYN-SENT to remember stamp of
304 u32 undo_marker
; /* snd_una upon a new recovery episode. */
305 int undo_retrans
; /* number of undoable retransmissions. */
306 u32 total_retrans
; /* Total retransmits for entire connection */
308 u32 urg_seq
; /* Seq of received urgent pointer */
309 unsigned int keepalive_time
; /* time before keep alive takes place */
310 unsigned int keepalive_intvl
; /* time interval between keep alive probes */
314 /* Receiver side RTT estimation */
321 /* Receiver queue space */
328 /* TCP-specific MTU probe information. */
333 u32 mtu_info
; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
334 * while socket was owned by user.
337 #ifdef CONFIG_TCP_MD5SIG
338 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
339 const struct tcp_sock_af_ops
*af_specific
;
341 /* TCP MD5 Signature Option information */
342 struct tcp_md5sig_info __rcu
*md5sig_info
;
345 /* TCP fastopen related information */
346 struct tcp_fastopen_request
*fastopen_req
;
347 /* fastopen_rsk points to request_sock that resulted in this big
348 * socket. Used to retransmit SYNACKs etc.
350 struct request_sock
*fastopen_rsk
;
357 TCP_TSQ_DEFERRED
, /* tcp_tasklet_func() found socket was owned */
358 TCP_WRITE_TIMER_DEFERRED
, /* tcp_write_timer() found socket was owned */
359 TCP_DELACK_TIMER_DEFERRED
, /* tcp_delack_timer() found socket was owned */
360 TCP_MTU_REDUCED_DEFERRED
, /* tcp_v{4|6}_err() could not call
361 * tcp_v{4|6}_mtu_reduced()
365 static inline struct tcp_sock
*tcp_sk(const struct sock
*sk
)
367 return (struct tcp_sock
*)sk
;
370 struct tcp_timewait_sock
{
371 struct inet_timewait_sock tw_sk
;
372 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
373 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
378 /* The time we sent the last out-of-window ACK: */
379 u32 tw_last_oow_ack_time
;
381 long tw_ts_recent_stamp
;
382 #ifdef CONFIG_TCP_MD5SIG
383 struct tcp_md5sig_key
*tw_md5_key
;
387 static inline struct tcp_timewait_sock
*tcp_twsk(const struct sock
*sk
)
389 return (struct tcp_timewait_sock
*)sk
;
392 static inline bool tcp_passive_fastopen(const struct sock
*sk
)
394 return (sk
->sk_state
== TCP_SYN_RECV
&&
395 tcp_sk(sk
)->fastopen_rsk
!= NULL
);
398 static inline void fastopen_queue_tune(struct sock
*sk
, int backlog
)
400 struct request_sock_queue
*queue
= &inet_csk(sk
)->icsk_accept_queue
;
401 int somaxconn
= READ_ONCE(sock_net(sk
)->core
.sysctl_somaxconn
);
403 queue
->fastopenq
.max_qlen
= min_t(unsigned int, backlog
, somaxconn
);
406 static inline void tcp_move_syn(struct tcp_sock
*tp
,
407 struct request_sock
*req
)
409 tp
->saved_syn
= req
->saved_syn
;
410 req
->saved_syn
= NULL
;
413 static inline void tcp_saved_syn_free(struct tcp_sock
*tp
)
415 kfree(tp
->saved_syn
);
416 tp
->saved_syn
= NULL
;
419 #endif /* _LINUX_TCP_H */