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[DCCP]: Generalize dccp_v4_send_reset
[linux-2.6.git] / net / dccp / output.c
blob9922d2696b9c7036592605df04fdd99fd9f71ccd
1 /*
2 * net/dccp/output.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
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.
11 */
12
13 #include <linux/config.h>
14 #include <linux/dccp.h>
15 #include <linux/kernel.h>
16 #include <linux/skbuff.h>
17
18 #include <net/inet_sock.h>
19 #include <net/sock.h>
20
21 #include "ackvec.h"
22 #include "ccid.h"
23 #include "dccp.h"
24
25 static inline void dccp_event_ack_sent(struct sock *sk)
26 {
27 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
28 }
29
30 static inline void dccp_skb_entail(struct sock *sk, struct sk_buff *skb)
31 {
32 skb_set_owner_w(skb, sk);
33 WARN_ON(sk->sk_send_head);
34 sk->sk_send_head = skb;
35 }
36
37 /*
38 * All SKB's seen here are completely headerless. It is our
39 * job to build the DCCP header, and pass the packet down to
40 * IP so it can do the same plus pass the packet off to the
41 * device.
42 */
43 static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
44 {
45 if (likely(skb != NULL)) {
46 const struct inet_sock *inet = inet_sk(sk);
47 const struct inet_connection_sock *icsk = inet_csk(sk);
48 struct dccp_sock *dp = dccp_sk(sk);
49 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
50 struct dccp_hdr *dh;
51 /* XXX For now we're using only 48 bits sequence numbers */
52 const int dccp_header_size = sizeof(*dh) +
53 sizeof(struct dccp_hdr_ext) +
54 dccp_packet_hdr_len(dcb->dccpd_type);
55 int err, set_ack = 1;
56 u64 ackno = dp->dccps_gsr;
57
58 dccp_inc_seqno(&dp->dccps_gss);
59
60 switch (dcb->dccpd_type) {
61 case DCCP_PKT_DATA:
62 set_ack = 0;
63 /* fall through */
64 case DCCP_PKT_DATAACK:
65 break;
66
67 case DCCP_PKT_REQUEST:
68 set_ack = 0;
69 /* fall through */
70
71 case DCCP_PKT_SYNC:
72 case DCCP_PKT_SYNCACK:
73 ackno = dcb->dccpd_seq;
74 /* fall through */
75 default:
76 /*
77 * Only data packets should come through with skb->sk
78 * set.
79 */
80 WARN_ON(skb->sk);
81 skb_set_owner_w(skb, sk);
82 break;
83 }
84
85 dcb->dccpd_seq = dp->dccps_gss;
86 dccp_insert_options(sk, skb);
87
88 skb->h.raw = skb_push(skb, dccp_header_size);
89 dh = dccp_hdr(skb);
90
91 /* Build DCCP header and checksum it. */
92 memset(dh, 0, dccp_header_size);
93 dh->dccph_type = dcb->dccpd_type;
94 dh->dccph_sport = inet->sport;
95 dh->dccph_dport = inet->dport;
96 dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
97 dh->dccph_ccval = dcb->dccpd_ccval;
98 /* XXX For now we're using only 48 bits sequence numbers */
99 dh->dccph_x = 1;
100
101 dp->dccps_awh = dp->dccps_gss;
102 dccp_hdr_set_seq(dh, dp->dccps_gss);
103 if (set_ack)
104 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
105
106 switch (dcb->dccpd_type) {
107 case DCCP_PKT_REQUEST:
108 dccp_hdr_request(skb)->dccph_req_service =
109 dp->dccps_service;
110 break;
111 case DCCP_PKT_RESET:
112 dccp_hdr_reset(skb)->dccph_reset_code =
113 dcb->dccpd_reset_code;
114 break;
115 }
116
117 icsk->icsk_af_ops->send_check(sk, skb->len, skb);
118
119 if (set_ack)
120 dccp_event_ack_sent(sk);
121
122 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
123
124 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
125 err = icsk->icsk_af_ops->queue_xmit(skb, 0);
126 if (err <= 0)
127 return err;
128
129 /* NET_XMIT_CN is special. It does not guarantee,
130 * that this packet is lost. It tells that device
131 * is about to start to drop packets or already
132 * drops some packets of the same priority and
133 * invokes us to send less aggressively.
134 */
135 return err == NET_XMIT_CN ? 0 : err;
136 }
137 return -ENOBUFS;
138 }
139
140 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
141 {
142 struct inet_connection_sock *icsk = inet_csk(sk);
143 struct dccp_sock *dp = dccp_sk(sk);
144 int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
145 sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
146
147 /* Now subtract optional transport overhead */
148 mss_now -= icsk->icsk_ext_hdr_len;
149
150 /*
151 * FIXME: this should come from the CCID infrastructure, where, say,
152 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
153 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
154 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
155 * make it a multiple of 4
156 */
157
158 mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
159
160 /* And store cached results */
161 icsk->icsk_pmtu_cookie = pmtu;
162 dp->dccps_mss_cache = mss_now;
163
164 return mss_now;
165 }
166
167 EXPORT_SYMBOL_GPL(dccp_sync_mss);
168
169 void dccp_write_space(struct sock *sk)
170 {
171 read_lock(&sk->sk_callback_lock);
172
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);
178
179 read_unlock(&sk->sk_callback_lock);
180 }
181
182 /**
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
186 */
187 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
188 long *timeo)
189 {
190 struct dccp_sock *dp = dccp_sk(sk);
191 DEFINE_WAIT(wait);
192 long delay;
193 int rc;
194
195 while (1) {
196 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
197
198 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
199 goto do_error;
200 if (!*timeo)
201 goto do_nonblock;
202 if (signal_pending(current))
203 goto do_interrupted;
204
205 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
206 skb->len);
207 if (rc <= 0)
208 break;
209 delay = msecs_to_jiffies(rc);
210 if (delay > *timeo || delay < 0)
211 goto do_nonblock;
212
213 sk->sk_write_pending++;
214 release_sock(sk);
215 *timeo -= schedule_timeout(delay);
216 lock_sock(sk);
217 sk->sk_write_pending--;
218 }
219 out:
220 finish_wait(sk->sk_sleep, &wait);
221 return rc;
222
223 do_error:
224 rc = -EPIPE;
225 goto out;
226 do_nonblock:
227 rc = -EAGAIN;
228 goto out;
229 do_interrupted:
230 rc = sock_intr_errno(*timeo);
231 goto out;
232 }
233
234 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
235 {
236 const struct dccp_sock *dp = dccp_sk(sk);
237 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
238 skb->len);
239
240 if (err > 0)
241 err = dccp_wait_for_ccid(sk, skb, timeo);
242
243 if (err == 0) {
244 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
245 const int len = skb->len;
246
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,
252 DCCP_RTO_MAX);
253 dcb->dccpd_type = DCCP_PKT_DATAACK;
254 } else if (dccp_ack_pending(sk))
255 dcb->dccpd_type = DCCP_PKT_DATAACK;
256 else
257 dcb->dccpd_type = DCCP_PKT_DATA;
258
259 err = dccp_transmit_skb(sk, skb);
260 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
261 } else
262 kfree_skb(skb);
263
264 return err;
265 }
266
267 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
268 {
269 if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
270 return -EHOSTUNREACH; /* Routing failure or similar. */
271
272 return dccp_transmit_skb(sk, (skb_cloned(skb) ?
273 pskb_copy(skb, GFP_ATOMIC):
274 skb_clone(skb, GFP_ATOMIC)));
275 }
276
277 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
278 struct request_sock *req)
279 {
280 struct dccp_hdr *dh;
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 +
286 dccp_header_size, 1,
287 GFP_ATOMIC);
288 if (skb == NULL)
289 return NULL;
290
291 /* Reserve space for headers. */
292 skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
293
294 skb->dst = dst_clone(dst);
295 skb->csum = 0;
296
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);
301
302 skb->h.raw = skb_push(skb, dccp_header_size);
303
304 dh = dccp_hdr(skb);
305 memset(dh, 0, dccp_header_size);
306
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;
312 dh->dccph_x = 1;
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;
316
317 dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
318 inet_rsk(req)->rmt_addr);
319
320 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
321 return skb;
322 }
323
324 EXPORT_SYMBOL_GPL(dccp_make_response);
325
326 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
327 const enum dccp_reset_codes code)
328
329 {
330 struct dccp_hdr *dh;
331 struct dccp_sock *dp = dccp_sk(sk);
332 const int dccp_header_size = sizeof(struct dccp_hdr) +
333 sizeof(struct dccp_hdr_ext) +
334 sizeof(struct dccp_hdr_reset);
335 struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
336 dccp_header_size, 1,
337 GFP_ATOMIC);
338 if (skb == NULL)
339 return NULL;
340
341 /* Reserve space for headers. */
342 skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
343
344 skb->dst = dst_clone(dst);
345 skb->csum = 0;
346
347 dccp_inc_seqno(&dp->dccps_gss);
348
349 DCCP_SKB_CB(skb)->dccpd_reset_code = code;
350 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
351 DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
352 dccp_insert_options(sk, skb);
353
354 skb->h.raw = skb_push(skb, dccp_header_size);
355
356 dh = dccp_hdr(skb);
357 memset(dh, 0, dccp_header_size);
358
359 dh->dccph_sport = inet_sk(sk)->sport;
360 dh->dccph_dport = inet_sk(sk)->dport;
361 dh->dccph_doff = (dccp_header_size +
362 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
363 dh->dccph_type = DCCP_PKT_RESET;
364 dh->dccph_x = 1;
365 dccp_hdr_set_seq(dh, dp->dccps_gss);
366 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
367
368 dccp_hdr_reset(skb)->dccph_reset_code = code;
369 inet_csk(sk)->icsk_af_ops->send_check(sk, skb->len, skb);
370
371 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
372 return skb;
373 }
374
375 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
376 {
377 /*
378 * FIXME: what if rebuild_header fails?
379 * Should we be doing a rebuild_header here?
380 */
381 int err = inet_sk_rebuild_header(sk);
382
383 if (err == 0) {
384 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache,
385 code);
386 if (skb != NULL) {
387 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
388 err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, 0);
389 if (err == NET_XMIT_CN)
390 err = 0;
391 }
392 }
393
394 return err;
395 }
396
397 /*
398 * Do all connect socket setups that can be done AF independent.
399 */
400 static inline void dccp_connect_init(struct sock *sk)
401 {
402 struct dccp_sock *dp = dccp_sk(sk);
403 struct dst_entry *dst = __sk_dst_get(sk);
404 struct inet_connection_sock *icsk = inet_csk(sk);
405
406 sk->sk_err = 0;
407 sock_reset_flag(sk, SOCK_DONE);
408
409 dccp_sync_mss(sk, dst_mtu(dst));
410
411 dccp_update_gss(sk, dp->dccps_iss);
412 /*
413 * SWL and AWL are initially adjusted so that they are not less than
414 * the initial Sequence Numbers received and sent, respectively:
415 * SWL := max(GSR + 1 - floor(W/4), ISR),
416 * AWL := max(GSS - W' + 1, ISS).
417 * These adjustments MUST be applied only at the beginning of the
418 * connection.
419 */
420 dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
421
422 icsk->icsk_retransmits = 0;
423 }
424
425 int dccp_connect(struct sock *sk)
426 {
427 struct sk_buff *skb;
428 struct inet_connection_sock *icsk = inet_csk(sk);
429
430 dccp_connect_init(sk);
431
432 skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
433 if (unlikely(skb == NULL))
434 return -ENOBUFS;
435
436 /* Reserve space for headers. */
437 skb_reserve(skb, MAX_DCCP_HEADER);
438
439 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
440 skb->csum = 0;
441
442 dccp_skb_entail(sk, skb);
443 dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
444 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
445
446 /* Timer for repeating the REQUEST until an answer. */
447 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
448 icsk->icsk_rto, DCCP_RTO_MAX);
449 return 0;
450 }
451
452 EXPORT_SYMBOL_GPL(dccp_connect);
453
454 void dccp_send_ack(struct sock *sk)
455 {
456 /* If we have been reset, we may not send again. */
457 if (sk->sk_state != DCCP_CLOSED) {
458 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
459
460 if (skb == NULL) {
461 inet_csk_schedule_ack(sk);
462 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
463 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
464 TCP_DELACK_MAX,
465 DCCP_RTO_MAX);
466 return;
467 }
468
469 /* Reserve space for headers */
470 skb_reserve(skb, MAX_DCCP_HEADER);
471 skb->csum = 0;
472 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
473 dccp_transmit_skb(sk, skb);
474 }
475 }
476
477 EXPORT_SYMBOL_GPL(dccp_send_ack);
478
479 void dccp_send_delayed_ack(struct sock *sk)
480 {
481 struct inet_connection_sock *icsk = inet_csk(sk);
482 /*
483 * FIXME: tune this timer. elapsed time fixes the skew, so no problem
484 * with using 2s, and active senders also piggyback the ACK into a
485 * DATAACK packet, so this is really for quiescent senders.
486 */
487 unsigned long timeout = jiffies + 2 * HZ;
488
489 /* Use new timeout only if there wasn't a older one earlier. */
490 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
491 /* If delack timer was blocked or is about to expire,
492 * send ACK now.
493 *
494 * FIXME: check the "about to expire" part
495 */
496 if (icsk->icsk_ack.blocked) {
497 dccp_send_ack(sk);
498 return;
499 }
500
501 if (!time_before(timeout, icsk->icsk_ack.timeout))
502 timeout = icsk->icsk_ack.timeout;
503 }
504 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
505 icsk->icsk_ack.timeout = timeout;
506 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
507 }
508
509 void dccp_send_sync(struct sock *sk, const u64 seq,
510 const enum dccp_pkt_type pkt_type)
511 {
512 /*
513 * We are not putting this on the write queue, so
514 * dccp_transmit_skb() will set the ownership to this
515 * sock.
516 */
517 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
518
519 if (skb == NULL)
520 /* FIXME: how to make sure the sync is sent? */
521 return;
522
523 /* Reserve space for headers and prepare control bits. */
524 skb_reserve(skb, MAX_DCCP_HEADER);
525 skb->csum = 0;
526 DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
527 DCCP_SKB_CB(skb)->dccpd_seq = seq;
528
529 dccp_transmit_skb(sk, skb);
530 }
531
532 /*
533 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
534 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
535 * any circumstances.
536 */
537 void dccp_send_close(struct sock *sk, const int active)
538 {
539 struct dccp_sock *dp = dccp_sk(sk);
540 struct sk_buff *skb;
541 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
542
543 skb = alloc_skb(sk->sk_prot->max_header, prio);
544 if (skb == NULL)
545 return;
546
547 /* Reserve space for headers and prepare control bits. */
548 skb_reserve(skb, sk->sk_prot->max_header);
549 skb->csum = 0;
550 DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
551 DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
552
553 if (active) {
554 dccp_skb_entail(sk, skb);
555 dccp_transmit_skb(sk, skb_clone(skb, prio));
556 } else
557 dccp_transmit_skb(sk, skb);
558 }
Linus' kernel tree