4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 #include <linux/config.h>
14 #include <linux/dccp.h>
15 #include <linux/skbuff.h>
23 static inline void dccp_event_ack_sent(struct sock
*sk
)
25 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
29 * All SKB's seen here are completely headerless. It is our
30 * job to build the DCCP header, and pass the packet down to
31 * IP so it can do the same plus pass the packet off to the
34 int dccp_transmit_skb(struct sock
*sk
, struct sk_buff
*skb
)
36 if (likely(skb
!= NULL
)) {
37 const struct inet_sock
*inet
= inet_sk(sk
);
38 struct dccp_sock
*dp
= dccp_sk(sk
);
39 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
41 /* XXX For now we're using only 48 bits sequence numbers */
42 const int dccp_header_size
= sizeof(*dh
) +
43 sizeof(struct dccp_hdr_ext
) +
44 dccp_packet_hdr_len(dcb
->dccpd_type
);
46 u64 ackno
= dp
->dccps_gsr
;
48 dccp_inc_seqno(&dp
->dccps_gss
);
50 switch (dcb
->dccpd_type
) {
55 case DCCP_PKT_SYNCACK
:
56 ackno
= dcb
->dccpd_seq
;
60 dcb
->dccpd_seq
= dp
->dccps_gss
;
61 dccp_insert_options(sk
, skb
);
63 skb
->h
.raw
= skb_push(skb
, dccp_header_size
);
67 skb_set_owner_w(skb
, sk
);
69 /* Build DCCP header and checksum it. */
70 memset(dh
, 0, dccp_header_size
);
71 dh
->dccph_type
= dcb
->dccpd_type
;
72 dh
->dccph_sport
= inet
->sport
;
73 dh
->dccph_dport
= inet
->dport
;
74 dh
->dccph_doff
= (dccp_header_size
+ dcb
->dccpd_opt_len
) / 4;
75 dh
->dccph_ccval
= dcb
->dccpd_ccval
;
76 /* XXX For now we're using only 48 bits sequence numbers */
79 dp
->dccps_awh
= dp
->dccps_gss
;
80 dccp_hdr_set_seq(dh
, dp
->dccps_gss
);
82 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), ackno
);
84 switch (dcb
->dccpd_type
) {
85 case DCCP_PKT_REQUEST
:
86 dccp_hdr_request(skb
)->dccph_req_service
=
90 dccp_hdr_reset(skb
)->dccph_reset_code
=
91 dcb
->dccpd_reset_code
;
95 dh
->dccph_checksum
= dccp_v4_checksum(skb
, inet
->saddr
,
99 dccp_event_ack_sent(sk
);
101 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
103 err
= ip_queue_xmit(skb
, 0);
107 /* NET_XMIT_CN is special. It does not guarantee,
108 * that this packet is lost. It tells that device
109 * is about to start to drop packets or already
110 * drops some packets of the same priority and
111 * invokes us to send less aggressively.
113 return err
== NET_XMIT_CN
? 0 : err
;
118 unsigned int dccp_sync_mss(struct sock
*sk
, u32 pmtu
)
120 struct dccp_sock
*dp
= dccp_sk(sk
);
124 * FIXME: we really should be using the af_specific thing to support
126 * mss_now = pmtu - tp->af_specific->net_header_len -
127 * sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
129 mss_now
= pmtu
- sizeof(struct iphdr
) - sizeof(struct dccp_hdr
) -
130 sizeof(struct dccp_hdr_ext
);
132 /* Now subtract optional transport overhead */
133 mss_now
-= dp
->dccps_ext_header_len
;
136 * FIXME: this should come from the CCID infrastructure, where, say,
137 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
138 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
139 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
140 * make it a multiple of 4
143 mss_now
-= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
145 /* And store cached results */
146 dp
->dccps_pmtu_cookie
= pmtu
;
147 dp
->dccps_mss_cache
= mss_now
;
152 void dccp_write_space(struct sock
*sk
)
154 read_lock(&sk
->sk_callback_lock
);
156 if (sk
->sk_sleep
&& waitqueue_active(sk
->sk_sleep
))
157 wake_up_interruptible(sk
->sk_sleep
);
158 /* Should agree with poll, otherwise some programs break */
159 if (sock_writeable(sk
))
160 sk_wake_async(sk
, 2, POLL_OUT
);
162 read_unlock(&sk
->sk_callback_lock
);
166 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
167 * @sk: socket to wait for
168 * @timeo: for how long
170 static int dccp_wait_for_ccid(struct sock
*sk
, struct sk_buff
*skb
,
173 struct dccp_sock
*dp
= dccp_sk(sk
);
179 prepare_to_wait(sk
->sk_sleep
, &wait
, TASK_INTERRUPTIBLE
);
181 if (sk
->sk_err
|| (sk
->sk_shutdown
& SEND_SHUTDOWN
))
185 if (signal_pending(current
))
188 rc
= ccid_hc_tx_send_packet(dp
->dccps_hc_tx_ccid
, sk
, skb
,
192 delay
= msecs_to_jiffies(rc
);
193 if (delay
> *timeo
|| delay
< 0)
196 sk
->sk_write_pending
++;
198 *timeo
-= schedule_timeout(delay
);
200 sk
->sk_write_pending
--;
203 finish_wait(sk
->sk_sleep
, &wait
);
213 rc
= sock_intr_errno(*timeo
);
217 int dccp_write_xmit(struct sock
*sk
, struct sk_buff
*skb
, long *timeo
)
219 const struct dccp_sock
*dp
= dccp_sk(sk
);
220 int err
= ccid_hc_tx_send_packet(dp
->dccps_hc_tx_ccid
, sk
, skb
,
224 err
= dccp_wait_for_ccid(sk
, skb
, timeo
);
227 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
228 const int len
= skb
->len
;
230 if (sk
->sk_state
== DCCP_PARTOPEN
) {
231 /* See 8.1.5. Handshake Completion */
232 inet_csk_schedule_ack(sk
);
233 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
234 inet_csk(sk
)->icsk_rto
,
236 dcb
->dccpd_type
= DCCP_PKT_DATAACK
;
237 } else if (dccp_ack_pending(sk
))
238 dcb
->dccpd_type
= DCCP_PKT_DATAACK
;
240 dcb
->dccpd_type
= DCCP_PKT_DATA
;
242 err
= dccp_transmit_skb(sk
, skb
);
243 ccid_hc_tx_packet_sent(dp
->dccps_hc_tx_ccid
, sk
, 0, len
);
250 int dccp_retransmit_skb(struct sock
*sk
, struct sk_buff
*skb
)
252 if (inet_sk_rebuild_header(sk
) != 0)
253 return -EHOSTUNREACH
; /* Routing failure or similar. */
255 return dccp_transmit_skb(sk
, (skb_cloned(skb
) ?
256 pskb_copy(skb
, GFP_ATOMIC
):
257 skb_clone(skb
, GFP_ATOMIC
)));
260 struct sk_buff
*dccp_make_response(struct sock
*sk
, struct dst_entry
*dst
,
261 struct request_sock
*req
)
264 struct dccp_request_sock
*dreq
;
265 const int dccp_header_size
= sizeof(struct dccp_hdr
) +
266 sizeof(struct dccp_hdr_ext
) +
267 sizeof(struct dccp_hdr_response
);
268 struct sk_buff
*skb
= sock_wmalloc(sk
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+
274 /* Reserve space for headers. */
275 skb_reserve(skb
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+ dccp_header_size
);
277 skb
->dst
= dst_clone(dst
);
280 dreq
= dccp_rsk(req
);
281 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_RESPONSE
;
282 DCCP_SKB_CB(skb
)->dccpd_seq
= dreq
->dreq_iss
;
283 dccp_insert_options(sk
, skb
);
285 skb
->h
.raw
= skb_push(skb
, dccp_header_size
);
288 memset(dh
, 0, dccp_header_size
);
290 dh
->dccph_sport
= inet_sk(sk
)->sport
;
291 dh
->dccph_dport
= inet_rsk(req
)->rmt_port
;
292 dh
->dccph_doff
= (dccp_header_size
+
293 DCCP_SKB_CB(skb
)->dccpd_opt_len
) / 4;
294 dh
->dccph_type
= DCCP_PKT_RESPONSE
;
296 dccp_hdr_set_seq(dh
, dreq
->dreq_iss
);
297 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), dreq
->dreq_isr
);
298 dccp_hdr_response(skb
)->dccph_resp_service
= dreq
->dreq_service
;
300 dh
->dccph_checksum
= dccp_v4_checksum(skb
, inet_rsk(req
)->loc_addr
,
301 inet_rsk(req
)->rmt_addr
);
303 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
307 struct sk_buff
*dccp_make_reset(struct sock
*sk
, struct dst_entry
*dst
,
308 const enum dccp_reset_codes code
)
312 struct dccp_sock
*dp
= dccp_sk(sk
);
313 const int dccp_header_size
= sizeof(struct dccp_hdr
) +
314 sizeof(struct dccp_hdr_ext
) +
315 sizeof(struct dccp_hdr_reset
);
316 struct sk_buff
*skb
= sock_wmalloc(sk
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+
322 /* Reserve space for headers. */
323 skb_reserve(skb
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+ dccp_header_size
);
325 skb
->dst
= dst_clone(dst
);
328 dccp_inc_seqno(&dp
->dccps_gss
);
330 DCCP_SKB_CB(skb
)->dccpd_reset_code
= code
;
331 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_RESET
;
332 DCCP_SKB_CB(skb
)->dccpd_seq
= dp
->dccps_gss
;
333 dccp_insert_options(sk
, skb
);
335 skb
->h
.raw
= skb_push(skb
, dccp_header_size
);
338 memset(dh
, 0, dccp_header_size
);
340 dh
->dccph_sport
= inet_sk(sk
)->sport
;
341 dh
->dccph_dport
= inet_sk(sk
)->dport
;
342 dh
->dccph_doff
= (dccp_header_size
+
343 DCCP_SKB_CB(skb
)->dccpd_opt_len
) / 4;
344 dh
->dccph_type
= DCCP_PKT_RESET
;
346 dccp_hdr_set_seq(dh
, dp
->dccps_gss
);
347 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), dp
->dccps_gsr
);
349 dccp_hdr_reset(skb
)->dccph_reset_code
= code
;
351 dh
->dccph_checksum
= dccp_v4_checksum(skb
, inet_sk(sk
)->saddr
,
354 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
359 * Do all connect socket setups that can be done AF independent.
361 static inline void dccp_connect_init(struct sock
*sk
)
363 struct dst_entry
*dst
= __sk_dst_get(sk
);
364 struct inet_connection_sock
*icsk
= inet_csk(sk
);
367 sock_reset_flag(sk
, SOCK_DONE
);
369 dccp_sync_mss(sk
, dst_mtu(dst
));
372 * FIXME: set dp->{dccps_swh,dccps_swl}, with
373 * something like dccp_inc_seq
376 icsk
->icsk_retransmits
= 0;
379 int dccp_connect(struct sock
*sk
)
382 struct inet_connection_sock
*icsk
= inet_csk(sk
);
384 dccp_connect_init(sk
);
386 skb
= alloc_skb(MAX_DCCP_HEADER
+ 15, sk
->sk_allocation
);
387 if (unlikely(skb
== NULL
))
390 /* Reserve space for headers. */
391 skb_reserve(skb
, MAX_DCCP_HEADER
);
393 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_REQUEST
;
395 skb_set_owner_w(skb
, sk
);
397 BUG_TRAP(sk
->sk_send_head
== NULL
);
398 sk
->sk_send_head
= skb
;
399 dccp_transmit_skb(sk
, skb_clone(skb
, GFP_KERNEL
));
400 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS
);
402 /* Timer for repeating the REQUEST until an answer. */
403 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_RETRANS
,
404 icsk
->icsk_rto
, DCCP_RTO_MAX
);
408 void dccp_send_ack(struct sock
*sk
)
410 /* If we have been reset, we may not send again. */
411 if (sk
->sk_state
!= DCCP_CLOSED
) {
412 struct sk_buff
*skb
= alloc_skb(MAX_DCCP_HEADER
, GFP_ATOMIC
);
415 inet_csk_schedule_ack(sk
);
416 inet_csk(sk
)->icsk_ack
.ato
= TCP_ATO_MIN
;
417 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
423 /* Reserve space for headers */
424 skb_reserve(skb
, MAX_DCCP_HEADER
);
426 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_ACK
;
427 skb_set_owner_w(skb
, sk
);
428 dccp_transmit_skb(sk
, skb
);
432 EXPORT_SYMBOL_GPL(dccp_send_ack
);
434 void dccp_send_delayed_ack(struct sock
*sk
)
436 struct inet_connection_sock
*icsk
= inet_csk(sk
);
438 * FIXME: tune this timer. elapsed time fixes the skew, so no problem
439 * with using 2s, and active senders also piggyback the ACK into a
440 * DATAACK packet, so this is really for quiescent senders.
442 unsigned long timeout
= jiffies
+ 2 * HZ
;
444 /* Use new timeout only if there wasn't a older one earlier. */
445 if (icsk
->icsk_ack
.pending
& ICSK_ACK_TIMER
) {
446 /* If delack timer was blocked or is about to expire,
449 * FIXME: check the "about to expire" part
451 if (icsk
->icsk_ack
.blocked
) {
456 if (!time_before(timeout
, icsk
->icsk_ack
.timeout
))
457 timeout
= icsk
->icsk_ack
.timeout
;
459 icsk
->icsk_ack
.pending
|= ICSK_ACK_SCHED
| ICSK_ACK_TIMER
;
460 icsk
->icsk_ack
.timeout
= timeout
;
461 sk_reset_timer(sk
, &icsk
->icsk_delack_timer
, timeout
);
464 void dccp_send_sync(struct sock
*sk
, const u64 seq
,
465 const enum dccp_pkt_type pkt_type
)
468 * We are not putting this on the write queue, so
469 * dccp_transmit_skb() will set the ownership to this
472 struct sk_buff
*skb
= alloc_skb(MAX_DCCP_HEADER
, GFP_ATOMIC
);
475 /* FIXME: how to make sure the sync is sent? */
478 /* Reserve space for headers and prepare control bits. */
479 skb_reserve(skb
, MAX_DCCP_HEADER
);
481 DCCP_SKB_CB(skb
)->dccpd_type
= pkt_type
;
482 DCCP_SKB_CB(skb
)->dccpd_seq
= seq
;
484 skb_set_owner_w(skb
, sk
);
485 dccp_transmit_skb(sk
, skb
);
489 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
490 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
493 void dccp_send_close(struct sock
*sk
, const int active
)
495 struct dccp_sock
*dp
= dccp_sk(sk
);
497 const unsigned int prio
= active
? GFP_KERNEL
: GFP_ATOMIC
;
499 skb
= alloc_skb(sk
->sk_prot
->max_header
, prio
);
503 /* Reserve space for headers and prepare control bits. */
504 skb_reserve(skb
, sk
->sk_prot
->max_header
);
506 DCCP_SKB_CB(skb
)->dccpd_type
= dp
->dccps_role
== DCCP_ROLE_CLIENT
?
507 DCCP_PKT_CLOSE
: DCCP_PKT_CLOSEREQ
;
509 skb_set_owner_w(skb
, sk
);
511 BUG_TRAP(sk
->sk_send_head
== NULL
);
512 sk
->sk_send_head
= skb
;
513 dccp_transmit_skb(sk
, skb_clone(skb
, prio
));
515 dccp_transmit_skb(sk
, skb
);
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