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/kernel.h>
16 #include <linux/skbuff.h>
24 static inline void dccp_event_ack_sent(struct sock
*sk
)
26 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
29 static inline 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 struct dccp_sock
*dp
= dccp_sk(sk
);
47 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
49 /* XXX For now we're using only 48 bits sequence numbers */
50 const int dccp_header_size
= sizeof(*dh
) +
51 sizeof(struct dccp_hdr_ext
) +
52 dccp_packet_hdr_len(dcb
->dccpd_type
);
54 u64 ackno
= dp
->dccps_gsr
;
56 dccp_inc_seqno(&dp
->dccps_gss
);
58 switch (dcb
->dccpd_type
) {
62 case DCCP_PKT_DATAACK
:
66 case DCCP_PKT_SYNCACK
:
67 ackno
= dcb
->dccpd_seq
;
71 * Only data packets should come through with skb->sk
75 skb_set_owner_w(skb
, sk
);
79 dcb
->dccpd_seq
= dp
->dccps_gss
;
80 dccp_insert_options(sk
, skb
);
82 skb
->h
.raw
= skb_push(skb
, dccp_header_size
);
85 /* Build DCCP header and checksum it. */
86 memset(dh
, 0, dccp_header_size
);
87 dh
->dccph_type
= dcb
->dccpd_type
;
88 dh
->dccph_sport
= inet
->sport
;
89 dh
->dccph_dport
= inet
->dport
;
90 dh
->dccph_doff
= (dccp_header_size
+ dcb
->dccpd_opt_len
) / 4;
91 dh
->dccph_ccval
= dcb
->dccpd_ccval
;
92 /* XXX For now we're using only 48 bits sequence numbers */
95 dp
->dccps_awh
= dp
->dccps_gss
;
96 dccp_hdr_set_seq(dh
, dp
->dccps_gss
);
98 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), ackno
);
100 switch (dcb
->dccpd_type
) {
101 case DCCP_PKT_REQUEST
:
102 dccp_hdr_request(skb
)->dccph_req_service
=
106 dccp_hdr_reset(skb
)->dccph_reset_code
=
107 dcb
->dccpd_reset_code
;
111 dh
->dccph_checksum
= dccp_v4_checksum(skb
, inet
->saddr
,
115 dccp_event_ack_sent(sk
);
117 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
119 memset(&(IPCB(skb
)->opt
), 0, sizeof(IPCB(skb
)->opt
));
120 err
= ip_queue_xmit(skb
, 0);
124 /* NET_XMIT_CN is special. It does not guarantee,
125 * that this packet is lost. It tells that device
126 * is about to start to drop packets or already
127 * drops some packets of the same priority and
128 * invokes us to send less aggressively.
130 return err
== NET_XMIT_CN
? 0 : err
;
135 unsigned int dccp_sync_mss(struct sock
*sk
, u32 pmtu
)
137 struct dccp_sock
*dp
= dccp_sk(sk
);
141 * FIXME: we really should be using the af_specific thing to support
143 * mss_now = pmtu - tp->af_specific->net_header_len -
144 * sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
146 mss_now
= pmtu
- sizeof(struct iphdr
) - sizeof(struct dccp_hdr
) -
147 sizeof(struct dccp_hdr_ext
);
149 /* Now subtract optional transport overhead */
150 mss_now
-= dp
->dccps_ext_header_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 dp
->dccps_pmtu_cookie
= pmtu
;
164 dp
->dccps_mss_cache
= mss_now
;
169 void dccp_write_space(struct sock
*sk
)
171 read_lock(&sk
->sk_callback_lock
);
173 if (sk
->sk_sleep
&& waitqueue_active(sk
->sk_sleep
))
174 wake_up_interruptible(sk
->sk_sleep
);
175 /* Should agree with poll, otherwise some programs break */
176 if (sock_writeable(sk
))
177 sk_wake_async(sk
, 2, POLL_OUT
);
179 read_unlock(&sk
->sk_callback_lock
);
183 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
184 * @sk: socket to wait for
185 * @timeo: for how long
187 static int dccp_wait_for_ccid(struct sock
*sk
, struct sk_buff
*skb
,
190 struct dccp_sock
*dp
= dccp_sk(sk
);
196 prepare_to_wait(sk
->sk_sleep
, &wait
, TASK_INTERRUPTIBLE
);
198 if (sk
->sk_err
|| (sk
->sk_shutdown
& SEND_SHUTDOWN
))
202 if (signal_pending(current
))
205 rc
= ccid_hc_tx_send_packet(dp
->dccps_hc_tx_ccid
, sk
, skb
,
209 delay
= msecs_to_jiffies(rc
);
210 if (delay
> *timeo
|| delay
< 0)
213 sk
->sk_write_pending
++;
215 *timeo
-= schedule_timeout(delay
);
217 sk
->sk_write_pending
--;
220 finish_wait(sk
->sk_sleep
, &wait
);
230 rc
= sock_intr_errno(*timeo
);
234 int dccp_write_xmit(struct sock
*sk
, struct sk_buff
*skb
, long *timeo
)
236 const struct dccp_sock
*dp
= dccp_sk(sk
);
237 int err
= ccid_hc_tx_send_packet(dp
->dccps_hc_tx_ccid
, sk
, skb
,
241 err
= dccp_wait_for_ccid(sk
, skb
, timeo
);
244 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
245 const int len
= skb
->len
;
247 if (sk
->sk_state
== DCCP_PARTOPEN
) {
248 /* See 8.1.5. Handshake Completion */
249 inet_csk_schedule_ack(sk
);
250 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
251 inet_csk(sk
)->icsk_rto
,
253 dcb
->dccpd_type
= DCCP_PKT_DATAACK
;
254 } else if (dccp_ack_pending(sk
))
255 dcb
->dccpd_type
= DCCP_PKT_DATAACK
;
257 dcb
->dccpd_type
= DCCP_PKT_DATA
;
259 err
= dccp_transmit_skb(sk
, skb
);
260 ccid_hc_tx_packet_sent(dp
->dccps_hc_tx_ccid
, sk
, 0, len
);
267 int dccp_retransmit_skb(struct sock
*sk
, struct sk_buff
*skb
)
269 if (inet_sk_rebuild_header(sk
) != 0)
270 return -EHOSTUNREACH
; /* Routing failure or similar. */
272 return dccp_transmit_skb(sk
, (skb_cloned(skb
) ?
273 pskb_copy(skb
, GFP_ATOMIC
):
274 skb_clone(skb
, GFP_ATOMIC
)));
277 struct sk_buff
*dccp_make_response(struct sock
*sk
, struct dst_entry
*dst
,
278 struct request_sock
*req
)
281 struct dccp_request_sock
*dreq
;
282 const int dccp_header_size
= sizeof(struct dccp_hdr
) +
283 sizeof(struct dccp_hdr_ext
) +
284 sizeof(struct dccp_hdr_response
);
285 struct sk_buff
*skb
= sock_wmalloc(sk
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+
291 /* Reserve space for headers. */
292 skb_reserve(skb
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+ dccp_header_size
);
294 skb
->dst
= dst_clone(dst
);
297 dreq
= dccp_rsk(req
);
298 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_RESPONSE
;
299 DCCP_SKB_CB(skb
)->dccpd_seq
= dreq
->dreq_iss
;
300 dccp_insert_options(sk
, skb
);
302 skb
->h
.raw
= skb_push(skb
, dccp_header_size
);
305 memset(dh
, 0, dccp_header_size
);
307 dh
->dccph_sport
= inet_sk(sk
)->sport
;
308 dh
->dccph_dport
= inet_rsk(req
)->rmt_port
;
309 dh
->dccph_doff
= (dccp_header_size
+
310 DCCP_SKB_CB(skb
)->dccpd_opt_len
) / 4;
311 dh
->dccph_type
= DCCP_PKT_RESPONSE
;
313 dccp_hdr_set_seq(dh
, dreq
->dreq_iss
);
314 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), dreq
->dreq_isr
);
315 dccp_hdr_response(skb
)->dccph_resp_service
= dreq
->dreq_service
;
317 dh
->dccph_checksum
= dccp_v4_checksum(skb
, inet_rsk(req
)->loc_addr
,
318 inet_rsk(req
)->rmt_addr
);
320 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
324 struct sk_buff
*dccp_make_reset(struct sock
*sk
, struct dst_entry
*dst
,
325 const enum dccp_reset_codes code
)
329 struct dccp_sock
*dp
= dccp_sk(sk
);
330 const int dccp_header_size
= sizeof(struct dccp_hdr
) +
331 sizeof(struct dccp_hdr_ext
) +
332 sizeof(struct dccp_hdr_reset
);
333 struct sk_buff
*skb
= sock_wmalloc(sk
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+
339 /* Reserve space for headers. */
340 skb_reserve(skb
, MAX_HEADER
+ DCCP_MAX_OPT_LEN
+ dccp_header_size
);
342 skb
->dst
= dst_clone(dst
);
345 dccp_inc_seqno(&dp
->dccps_gss
);
347 DCCP_SKB_CB(skb
)->dccpd_reset_code
= code
;
348 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_RESET
;
349 DCCP_SKB_CB(skb
)->dccpd_seq
= dp
->dccps_gss
;
350 dccp_insert_options(sk
, skb
);
352 skb
->h
.raw
= skb_push(skb
, dccp_header_size
);
355 memset(dh
, 0, dccp_header_size
);
357 dh
->dccph_sport
= inet_sk(sk
)->sport
;
358 dh
->dccph_dport
= inet_sk(sk
)->dport
;
359 dh
->dccph_doff
= (dccp_header_size
+
360 DCCP_SKB_CB(skb
)->dccpd_opt_len
) / 4;
361 dh
->dccph_type
= DCCP_PKT_RESET
;
363 dccp_hdr_set_seq(dh
, dp
->dccps_gss
);
364 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb
), dp
->dccps_gsr
);
366 dccp_hdr_reset(skb
)->dccph_reset_code
= code
;
368 dh
->dccph_checksum
= dccp_v4_checksum(skb
, inet_sk(sk
)->saddr
,
371 DCCP_INC_STATS(DCCP_MIB_OUTSEGS
);
376 * Do all connect socket setups that can be done AF independent.
378 static inline void dccp_connect_init(struct sock
*sk
)
380 struct dst_entry
*dst
= __sk_dst_get(sk
);
381 struct inet_connection_sock
*icsk
= inet_csk(sk
);
384 sock_reset_flag(sk
, SOCK_DONE
);
386 dccp_sync_mss(sk
, dst_mtu(dst
));
389 * FIXME: set dp->{dccps_swh,dccps_swl}, with
390 * something like dccp_inc_seq
393 icsk
->icsk_retransmits
= 0;
396 int dccp_connect(struct sock
*sk
)
399 struct inet_connection_sock
*icsk
= inet_csk(sk
);
401 dccp_connect_init(sk
);
403 skb
= alloc_skb(MAX_DCCP_HEADER
+ 15, sk
->sk_allocation
);
404 if (unlikely(skb
== NULL
))
407 /* Reserve space for headers. */
408 skb_reserve(skb
, MAX_DCCP_HEADER
);
410 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_REQUEST
;
413 dccp_skb_entail(sk
, skb
);
414 dccp_transmit_skb(sk
, skb_clone(skb
, GFP_KERNEL
));
415 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS
);
417 /* Timer for repeating the REQUEST until an answer. */
418 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_RETRANS
,
419 icsk
->icsk_rto
, DCCP_RTO_MAX
);
423 void dccp_send_ack(struct sock
*sk
)
425 /* If we have been reset, we may not send again. */
426 if (sk
->sk_state
!= DCCP_CLOSED
) {
427 struct sk_buff
*skb
= alloc_skb(MAX_DCCP_HEADER
, GFP_ATOMIC
);
430 inet_csk_schedule_ack(sk
);
431 inet_csk(sk
)->icsk_ack
.ato
= TCP_ATO_MIN
;
432 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
438 /* Reserve space for headers */
439 skb_reserve(skb
, MAX_DCCP_HEADER
);
441 DCCP_SKB_CB(skb
)->dccpd_type
= DCCP_PKT_ACK
;
442 dccp_transmit_skb(sk
, skb
);
446 EXPORT_SYMBOL_GPL(dccp_send_ack
);
448 void dccp_send_delayed_ack(struct sock
*sk
)
450 struct inet_connection_sock
*icsk
= inet_csk(sk
);
452 * FIXME: tune this timer. elapsed time fixes the skew, so no problem
453 * with using 2s, and active senders also piggyback the ACK into a
454 * DATAACK packet, so this is really for quiescent senders.
456 unsigned long timeout
= jiffies
+ 2 * HZ
;
458 /* Use new timeout only if there wasn't a older one earlier. */
459 if (icsk
->icsk_ack
.pending
& ICSK_ACK_TIMER
) {
460 /* If delack timer was blocked or is about to expire,
463 * FIXME: check the "about to expire" part
465 if (icsk
->icsk_ack
.blocked
) {
470 if (!time_before(timeout
, icsk
->icsk_ack
.timeout
))
471 timeout
= icsk
->icsk_ack
.timeout
;
473 icsk
->icsk_ack
.pending
|= ICSK_ACK_SCHED
| ICSK_ACK_TIMER
;
474 icsk
->icsk_ack
.timeout
= timeout
;
475 sk_reset_timer(sk
, &icsk
->icsk_delack_timer
, timeout
);
478 void dccp_send_sync(struct sock
*sk
, const u64 seq
,
479 const enum dccp_pkt_type pkt_type
)
482 * We are not putting this on the write queue, so
483 * dccp_transmit_skb() will set the ownership to this
486 struct sk_buff
*skb
= alloc_skb(MAX_DCCP_HEADER
, GFP_ATOMIC
);
489 /* FIXME: how to make sure the sync is sent? */
492 /* Reserve space for headers and prepare control bits. */
493 skb_reserve(skb
, MAX_DCCP_HEADER
);
495 DCCP_SKB_CB(skb
)->dccpd_type
= pkt_type
;
496 DCCP_SKB_CB(skb
)->dccpd_seq
= seq
;
498 dccp_transmit_skb(sk
, skb
);
502 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
503 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
506 void dccp_send_close(struct sock
*sk
, const int active
)
508 struct dccp_sock
*dp
= dccp_sk(sk
);
510 const gfp_t prio
= active
? GFP_KERNEL
: GFP_ATOMIC
;
512 skb
= alloc_skb(sk
->sk_prot
->max_header
, prio
);
516 /* Reserve space for headers and prepare control bits. */
517 skb_reserve(skb
, sk
->sk_prot
->max_header
);
519 DCCP_SKB_CB(skb
)->dccpd_type
= dp
->dccps_role
== DCCP_ROLE_CLIENT
?
520 DCCP_PKT_CLOSE
: DCCP_PKT_CLOSEREQ
;
523 dccp_skb_entail(sk
, skb
);
524 dccp_transmit_skb(sk
, skb_clone(skb
, prio
));
526 dccp_transmit_skb(sk
, skb
);