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/dccp.h>
14 #include <linux/kernel.h>
15 #include <linux/skbuff.h>
17 #include <net/inet_sock.h>
24 static inline void dccp_event_ack_sent(struct sock
*sk
)
26 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
29 static void dccp_skb_entail(struct sock
*sk
, struct sk_buff
*skb
)
31 skb_set_owner_w(skb
, sk
);
32 WARN_ON(sk
->sk_send_head
);
33 sk
->sk_send_head
= skb
;
37 * All SKB's seen here are completely headerless. It is our
38 * job to build the DCCP header, and pass the packet down to
39 * IP so it can do the same plus pass the packet off to the
42 static int dccp_transmit_skb(struct sock
*sk
, struct sk_buff
*skb
)
44 if (likely(skb
!= NULL
)) {
45 const struct inet_sock
*inet
= inet_sk(sk
);
46 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
47 struct dccp_sock
*dp
= dccp_sk(sk
);
48 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
50 /* XXX For now we're using only 48 bits sequence numbers */
51 const u32 dccp_header_size
= sizeof(*dh
) +
52 sizeof(struct dccp_hdr_ext
) +
53 dccp_packet_hdr_len(dcb
->dccpd_type
);
55 u64 ackno
= dp
->dccps_gsr
;
57 dccp_inc_seqno(&dp
->dccps_gss
);
59 switch (dcb
->dccpd_type
) {
63 case DCCP_PKT_DATAACK
:
66 case DCCP_PKT_REQUEST
:
71 case DCCP_PKT_SYNCACK
:
72 ackno
= dcb
->dccpd_seq
;
76 * Only data packets should come through with skb->sk
80 skb_set_owner_w(skb
, sk
);
84 dcb
->dccpd_seq
= dp
->dccps_gss
;
86 if (dccp_insert_options(sk
, skb
)) {
92 /* Build DCCP header and checksum it. */
93 dh
= dccp_zeroed_hdr(skb
, dccp_header_size
);
94 dh
->dccph_type
= dcb
->dccpd_type
;
95 dh
->dccph_sport
= inet
->sport
;
96 dh
->dccph_dport
= inet
->dport
;
97 dh
->dccph_doff
= (dccp_header_size
+ dcb
->dccpd_opt_len
) / 4;
98 dh
->dccph_ccval
= dcb
->dccpd_ccval
;
99 dh
->dccph_cscov
= dp
->dccps_pcslen
;
100 /* XXX For now we're using only 48 bits sequence numbers */
103 dp
->dccps_awh
= dp
->dccps_gss
;
104 dccp_hdr_set_seq(dh
, dp
->dccps_gss
);
106 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), ackno
);
108 switch (dcb
->dccpd_type
) {
109 case DCCP_PKT_REQUEST
:
110 dccp_hdr_request(skb
)->dccph_req_service
=
114 dccp_hdr_reset(skb
)->dccph_reset_code
=
115 dcb
->dccpd_reset_code
;
119 icsk
->icsk_af_ops
->send_check(sk
, 0, skb
);
122 dccp_event_ack_sent(sk
);
124 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
126 memset(&(IPCB(skb
)->opt
), 0, sizeof(IPCB(skb
)->opt
));
127 err
= icsk
->icsk_af_ops
->queue_xmit(skb
, sk
, 0);
131 /* NET_XMIT_CN is special. It does not guarantee,
132 * that this packet is lost. It tells that device
133 * is about to start to drop packets or already
134 * drops some packets of the same priority and
135 * invokes us to send less aggressively.
137 return err
== NET_XMIT_CN
? 0 : err
;
142 unsigned int dccp_sync_mss(struct sock
*sk
, u32 pmtu
)
144 struct inet_connection_sock
*icsk
= inet_csk(sk
);
145 struct dccp_sock
*dp
= dccp_sk(sk
);
146 int mss_now
= (pmtu
- icsk
->icsk_af_ops
->net_header_len
-
147 sizeof(struct dccp_hdr
) - sizeof(struct dccp_hdr_ext
));
149 /* Now subtract optional transport overhead */
150 mss_now
-= icsk
->icsk_ext_hdr_len
;
153 * FIXME: this should come from the CCID infrastructure, where, say,
154 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
155 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
156 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
157 * make it a multiple of 4
160 mss_now
-= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
162 /* And store cached results */
163 icsk
->icsk_pmtu_cookie
= pmtu
;
164 dp
->dccps_mss_cache
= mss_now
;
169 EXPORT_SYMBOL_GPL(dccp_sync_mss
);
171 void dccp_write_space(struct sock
*sk
)
173 read_lock(&sk
->sk_callback_lock
);
175 if (sk
->sk_sleep
&& waitqueue_active(sk
->sk_sleep
))
176 wake_up_interruptible(sk
->sk_sleep
);
177 /* Should agree with poll, otherwise some programs break */
178 if (sock_writeable(sk
))
179 sk_wake_async(sk
, 2, POLL_OUT
);
181 read_unlock(&sk
->sk_callback_lock
);
185 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
186 * @sk: socket to wait for
187 * @timeo: for how long
189 static int dccp_wait_for_ccid(struct sock
*sk
, struct sk_buff
*skb
,
192 struct dccp_sock
*dp
= dccp_sk(sk
);
198 prepare_to_wait(sk
->sk_sleep
, &wait
, TASK_INTERRUPTIBLE
);
204 if (signal_pending(current
))
207 rc
= ccid_hc_tx_send_packet(dp
->dccps_hc_tx_ccid
, sk
, skb
,
211 delay
= msecs_to_jiffies(rc
);
212 if (delay
> *timeo
|| delay
< 0)
215 sk
->sk_write_pending
++;
217 *timeo
-= schedule_timeout(delay
);
219 sk
->sk_write_pending
--;
222 finish_wait(sk
->sk_sleep
, &wait
);
232 rc
= sock_intr_errno(*timeo
);
236 static void dccp_write_xmit_timer(unsigned long data
) {
237 struct sock
*sk
= (struct sock
*)data
;
238 struct dccp_sock
*dp
= dccp_sk(sk
);
241 if (sock_owned_by_user(sk
))
242 sk_reset_timer(sk
, &dp
->dccps_xmit_timer
, jiffies
+1);
244 dccp_write_xmit(sk
, 0);
249 void dccp_write_xmit(struct sock
*sk
, int block
)
251 struct dccp_sock
*dp
= dccp_sk(sk
);
253 long timeo
= DCCP_XMIT_TIMEO
; /* If a packet is taking longer than
254 this we have other issues */
256 while ((skb
= skb_peek(&sk
->sk_write_queue
))) {
257 int err
= ccid_hc_tx_send_packet(dp
->dccps_hc_tx_ccid
, sk
, skb
,
262 sk_reset_timer(sk
, &dp
->dccps_xmit_timer
,
263 msecs_to_jiffies(err
)+jiffies
);
266 err
= dccp_wait_for_ccid(sk
, skb
, &timeo
);
267 timeo
= DCCP_XMIT_TIMEO
;
270 printk(KERN_CRIT
"%s:err at dccp_wait_for_ccid"
271 " %d\n", __FUNCTION__
, err
);
276 skb_dequeue(&sk
->sk_write_queue
);
278 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
279 const int len
= skb
->len
;
281 if (sk
->sk_state
== DCCP_PARTOPEN
) {
282 /* See 8.1.5. Handshake Completion */
283 inet_csk_schedule_ack(sk
);
284 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
285 inet_csk(sk
)->icsk_rto
,
287 dcb
->dccpd_type
= DCCP_PKT_DATAACK
;
288 } else if (dccp_ack_pending(sk
))
289 dcb
->dccpd_type
= DCCP_PKT_DATAACK
;
291 dcb
->dccpd_type
= DCCP_PKT_DATA
;
293 err
= dccp_transmit_skb(sk
, skb
);
294 ccid_hc_tx_packet_sent(dp
->dccps_hc_tx_ccid
, sk
, 0, len
);
296 printk(KERN_CRIT
"%s:err from "
297 "ccid_hc_tx_packet_sent %d\n",
306 int dccp_retransmit_skb(struct sock
*sk
, struct sk_buff
*skb
)
308 if (inet_csk(sk
)->icsk_af_ops
->rebuild_header(sk
) != 0)
309 return -EHOSTUNREACH
; /* Routing failure or similar. */
311 return dccp_transmit_skb(sk
, (skb_cloned(skb
) ?
312 pskb_copy(skb
, GFP_ATOMIC
):
313 skb_clone(skb
, GFP_ATOMIC
)));
316 struct sk_buff
*dccp_make_response(struct sock
*sk
, struct dst_entry
*dst
,
317 struct request_sock
*req
)
320 struct dccp_request_sock
*dreq
;
321 const u32 dccp_header_size
= sizeof(struct dccp_hdr
) +
322 sizeof(struct dccp_hdr_ext
) +
323 sizeof(struct dccp_hdr_response
);
324 struct sk_buff
*skb
= sock_wmalloc(sk
, sk
->sk_prot
->max_header
, 1,
329 /* Reserve space for headers. */
330 skb_reserve(skb
, sk
->sk_prot
->max_header
);
332 skb
->dst
= dst_clone(dst
);
334 dreq
= dccp_rsk(req
);
335 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_RESPONSE
;
336 DCCP_SKB_CB(skb
)->dccpd_seq
= dreq
->dreq_iss
;
338 if (dccp_insert_options(sk
, skb
)) {
343 dh
= dccp_zeroed_hdr(skb
, dccp_header_size
);
345 dh
->dccph_sport
= inet_sk(sk
)->sport
;
346 dh
->dccph_dport
= inet_rsk(req
)->rmt_port
;
347 dh
->dccph_doff
= (dccp_header_size
+
348 DCCP_SKB_CB(skb
)->dccpd_opt_len
) / 4;
349 dh
->dccph_type
= DCCP_PKT_RESPONSE
;
351 dccp_hdr_set_seq(dh
, dreq
->dreq_iss
);
352 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), dreq
->dreq_isr
);
353 dccp_hdr_response(skb
)->dccph_resp_service
= dreq
->dreq_service
;
355 dccp_csum_outgoing(skb
);
357 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
361 EXPORT_SYMBOL_GPL(dccp_make_response
);
363 static struct sk_buff
*dccp_make_reset(struct sock
*sk
, struct dst_entry
*dst
,
364 const enum dccp_reset_codes code
)
368 struct dccp_sock
*dp
= dccp_sk(sk
);
369 const u32 dccp_header_size
= sizeof(struct dccp_hdr
) +
370 sizeof(struct dccp_hdr_ext
) +
371 sizeof(struct dccp_hdr_reset
);
372 struct sk_buff
*skb
= sock_wmalloc(sk
, sk
->sk_prot
->max_header
, 1,
377 /* Reserve space for headers. */
378 skb_reserve(skb
, sk
->sk_prot
->max_header
);
380 skb
->dst
= dst_clone(dst
);
382 dccp_inc_seqno(&dp
->dccps_gss
);
384 DCCP_SKB_CB(skb
)->dccpd_reset_code
= code
;
385 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_RESET
;
386 DCCP_SKB_CB(skb
)->dccpd_seq
= dp
->dccps_gss
;
388 if (dccp_insert_options(sk
, skb
)) {
393 dh
= dccp_zeroed_hdr(skb
, dccp_header_size
);
395 dh
->dccph_sport
= inet_sk(sk
)->sport
;
396 dh
->dccph_dport
= inet_sk(sk
)->dport
;
397 dh
->dccph_doff
= (dccp_header_size
+
398 DCCP_SKB_CB(skb
)->dccpd_opt_len
) / 4;
399 dh
->dccph_type
= DCCP_PKT_RESET
;
401 dccp_hdr_set_seq(dh
, dp
->dccps_gss
);
402 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), dp
->dccps_gsr
);
404 dccp_hdr_reset(skb
)->dccph_reset_code
= code
;
405 inet_csk(sk
)->icsk_af_ops
->send_check(sk
, 0, skb
);
407 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
411 int dccp_send_reset(struct sock
*sk
, enum dccp_reset_codes code
)
414 * FIXME: what if rebuild_header fails?
415 * Should we be doing a rebuild_header here?
417 int err
= inet_sk_rebuild_header(sk
);
420 struct sk_buff
*skb
= dccp_make_reset(sk
, sk
->sk_dst_cache
,
423 memset(&(IPCB(skb
)->opt
), 0, sizeof(IPCB(skb
)->opt
));
424 err
= inet_csk(sk
)->icsk_af_ops
->queue_xmit(skb
, sk
, 0);
425 if (err
== NET_XMIT_CN
)
434 * Do all connect socket setups that can be done AF independent.
436 static inline void dccp_connect_init(struct sock
*sk
)
438 struct dccp_sock
*dp
= dccp_sk(sk
);
439 struct dst_entry
*dst
= __sk_dst_get(sk
);
440 struct inet_connection_sock
*icsk
= inet_csk(sk
);
443 sock_reset_flag(sk
, SOCK_DONE
);
445 dccp_sync_mss(sk
, dst_mtu(dst
));
447 dccp_update_gss(sk
, dp
->dccps_iss
);
449 * SWL and AWL are initially adjusted so that they are not less than
450 * the initial Sequence Numbers received and sent, respectively:
451 * SWL := max(GSR + 1 - floor(W/4), ISR),
452 * AWL := max(GSS - W' + 1, ISS).
453 * These adjustments MUST be applied only at the beginning of the
456 dccp_set_seqno(&dp
->dccps_awl
, max48(dp
->dccps_awl
, dp
->dccps_iss
));
458 icsk
->icsk_retransmits
= 0;
459 init_timer(&dp
->dccps_xmit_timer
);
460 dp
->dccps_xmit_timer
.data
= (unsigned long)sk
;
461 dp
->dccps_xmit_timer
.function
= dccp_write_xmit_timer
;
464 int dccp_connect(struct sock
*sk
)
467 struct inet_connection_sock
*icsk
= inet_csk(sk
);
469 dccp_connect_init(sk
);
471 skb
= alloc_skb(sk
->sk_prot
->max_header
, sk
->sk_allocation
);
472 if (unlikely(skb
== NULL
))
475 /* Reserve space for headers. */
476 skb_reserve(skb
, sk
->sk_prot
->max_header
);
478 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_REQUEST
;
480 dccp_skb_entail(sk
, skb
);
481 dccp_transmit_skb(sk
, skb_clone(skb
, GFP_KERNEL
));
482 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS
);
484 /* Timer for repeating the REQUEST until an answer. */
485 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_RETRANS
,
486 icsk
->icsk_rto
, DCCP_RTO_MAX
);
490 EXPORT_SYMBOL_GPL(dccp_connect
);
492 void dccp_send_ack(struct sock
*sk
)
494 /* If we have been reset, we may not send again. */
495 if (sk
->sk_state
!= DCCP_CLOSED
) {
496 struct sk_buff
*skb
= alloc_skb(sk
->sk_prot
->max_header
,
500 inet_csk_schedule_ack(sk
);
501 inet_csk(sk
)->icsk_ack
.ato
= TCP_ATO_MIN
;
502 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
508 /* Reserve space for headers */
509 skb_reserve(skb
, sk
->sk_prot
->max_header
);
510 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_ACK
;
511 dccp_transmit_skb(sk
, skb
);
515 EXPORT_SYMBOL_GPL(dccp_send_ack
);
517 void dccp_send_delayed_ack(struct sock
*sk
)
519 struct inet_connection_sock
*icsk
= inet_csk(sk
);
521 * FIXME: tune this timer. elapsed time fixes the skew, so no problem
522 * with using 2s, and active senders also piggyback the ACK into a
523 * DATAACK packet, so this is really for quiescent senders.
525 unsigned long timeout
= jiffies
+ 2 * HZ
;
527 /* Use new timeout only if there wasn't a older one earlier. */
528 if (icsk
->icsk_ack
.pending
& ICSK_ACK_TIMER
) {
529 /* If delack timer was blocked or is about to expire,
532 * FIXME: check the "about to expire" part
534 if (icsk
->icsk_ack
.blocked
) {
539 if (!time_before(timeout
, icsk
->icsk_ack
.timeout
))
540 timeout
= icsk
->icsk_ack
.timeout
;
542 icsk
->icsk_ack
.pending
|= ICSK_ACK_SCHED
| ICSK_ACK_TIMER
;
543 icsk
->icsk_ack
.timeout
= timeout
;
544 sk_reset_timer(sk
, &icsk
->icsk_delack_timer
, timeout
);
547 void dccp_send_sync(struct sock
*sk
, const u64 seq
,
548 const enum dccp_pkt_type pkt_type
)
551 * We are not putting this on the write queue, so
552 * dccp_transmit_skb() will set the ownership to this
555 struct sk_buff
*skb
= alloc_skb(sk
->sk_prot
->max_header
, GFP_ATOMIC
);
558 /* FIXME: how to make sure the sync is sent? */
561 /* Reserve space for headers and prepare control bits. */
562 skb_reserve(skb
, sk
->sk_prot
->max_header
);
563 DCCP_SKB_CB(skb
)->dccpd_type
= pkt_type
;
564 DCCP_SKB_CB(skb
)->dccpd_seq
= seq
;
566 dccp_transmit_skb(sk
, skb
);
569 EXPORT_SYMBOL_GPL(dccp_send_sync
);
572 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
573 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
576 void dccp_send_close(struct sock
*sk
, const int active
)
578 struct dccp_sock
*dp
= dccp_sk(sk
);
580 const gfp_t prio
= active
? GFP_KERNEL
: GFP_ATOMIC
;
582 skb
= alloc_skb(sk
->sk_prot
->max_header
, prio
);
586 /* Reserve space for headers and prepare control bits. */
587 skb_reserve(skb
, sk
->sk_prot
->max_header
);
588 DCCP_SKB_CB(skb
)->dccpd_type
= dp
->dccps_role
== DCCP_ROLE_CLIENT
?
589 DCCP_PKT_CLOSE
: DCCP_PKT_CLOSEREQ
;
592 dccp_write_xmit(sk
, 1);
593 dccp_skb_entail(sk
, skb
);
594 dccp_transmit_skb(sk
, skb_clone(skb
, prio
));
595 /* FIXME do we need a retransmit timer here? */
597 dccp_transmit_skb(sk
, skb
);
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