51654975e8eafbbc80894bf58d2a30ae54420bd7
[linux-2.6.git] / net / dccp / output.c
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/dccp.h>
14 #include <linux/kernel.h>
15 #include <linux/skbuff.h>
16
17 #include <net/inet_sock.h>
18 #include <net/sock.h>
19
20 #include "ackvec.h"
21 #include "ccid.h"
22 #include "dccp.h"
23
24 static inline void dccp_event_ack_sent(struct sock *sk)
25 {
26         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
27 }
28
29 static void dccp_skb_entail(struct sock *sk, struct sk_buff *skb)
30 {
31         skb_set_owner_w(skb, sk);
32         WARN_ON(sk->sk_send_head);
33         sk->sk_send_head = skb;
34 }
35
36 /*
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
40  * device.
41  */
42 static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
43 {
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);
49                 struct dccp_hdr *dh;
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);
54                 int err, set_ack = 1;
55                 u64 ackno = dp->dccps_gsr;
56
57                 dccp_inc_seqno(&dp->dccps_gss);
58
59                 switch (dcb->dccpd_type) {
60                 case DCCP_PKT_DATA:
61                         set_ack = 0;
62                         /* fall through */
63                 case DCCP_PKT_DATAACK:
64                         break;
65
66                 case DCCP_PKT_REQUEST:
67                         set_ack = 0;
68                         /* fall through */
69
70                 case DCCP_PKT_SYNC:
71                 case DCCP_PKT_SYNCACK:
72                         ackno = dcb->dccpd_seq;
73                         /* fall through */
74                 default:
75                         /*
76                          * Only data packets should come through with skb->sk
77                          * set.
78                          */
79                         WARN_ON(skb->sk);
80                         skb_set_owner_w(skb, sk);
81                         break;
82                 }
83
84                 dcb->dccpd_seq = dp->dccps_gss;
85
86                 if (dccp_insert_options(sk, skb)) {
87                         kfree_skb(skb);
88                         return -EPROTO;
89                 }
90                 
91
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                 /* XXX For now we're using only 48 bits sequence numbers */
100                 dh->dccph_x     = 1;
101
102                 dp->dccps_awh = dp->dccps_gss;
103                 dccp_hdr_set_seq(dh, dp->dccps_gss);
104                 if (set_ack)
105                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
106
107                 switch (dcb->dccpd_type) {
108                 case DCCP_PKT_REQUEST:
109                         dccp_hdr_request(skb)->dccph_req_service =
110                                                         dp->dccps_service;
111                         break;
112                 case DCCP_PKT_RESET:
113                         dccp_hdr_reset(skb)->dccph_reset_code =
114                                                         dcb->dccpd_reset_code;
115                         break;
116                 }
117
118                 icsk->icsk_af_ops->send_check(sk, skb->len, skb);
119
120                 if (set_ack)
121                         dccp_event_ack_sent(sk);
122
123                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
124
125                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
126                 err = icsk->icsk_af_ops->queue_xmit(skb, sk, 0);
127                 if (err <= 0)
128                         return err;
129
130                 /* NET_XMIT_CN is special. It does not guarantee,
131                  * that this packet is lost. It tells that device
132                  * is about to start to drop packets or already
133                  * drops some packets of the same priority and
134                  * invokes us to send less aggressively.
135                  */
136                 return err == NET_XMIT_CN ? 0 : err;
137         }
138         return -ENOBUFS;
139 }
140
141 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
142 {
143         struct inet_connection_sock *icsk = inet_csk(sk);
144         struct dccp_sock *dp = dccp_sk(sk);
145         int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
146                        sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
147
148         /* Now subtract optional transport overhead */
149         mss_now -= icsk->icsk_ext_hdr_len;
150
151         /*
152          * FIXME: this should come from the CCID infrastructure, where, say,
153          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
154          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
155          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
156          * make it a multiple of 4
157          */
158
159         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
160
161         /* And store cached results */
162         icsk->icsk_pmtu_cookie = pmtu;
163         dp->dccps_mss_cache = mss_now;
164
165         return mss_now;
166 }
167
168 EXPORT_SYMBOL_GPL(dccp_sync_mss);
169
170 void dccp_write_space(struct sock *sk)
171 {
172         read_lock(&sk->sk_callback_lock);
173
174         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
175                 wake_up_interruptible(sk->sk_sleep);
176         /* Should agree with poll, otherwise some programs break */
177         if (sock_writeable(sk))
178                 sk_wake_async(sk, 2, POLL_OUT);
179
180         read_unlock(&sk->sk_callback_lock);
181 }
182
183 /**
184  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
185  * @sk: socket to wait for
186  * @timeo: for how long
187  */
188 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
189                               long *timeo)
190 {
191         struct dccp_sock *dp = dccp_sk(sk);
192         DEFINE_WAIT(wait);
193         long delay;
194         int rc;
195
196         while (1) {
197                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
198
199                 if (sk->sk_err)
200                         goto do_error;
201                 if (!*timeo)
202                         goto do_nonblock;
203                 if (signal_pending(current))
204                         goto do_interrupted;
205
206                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
207                                             skb->len);
208                 if (rc <= 0)
209                         break;
210                 delay = msecs_to_jiffies(rc);
211                 if (delay > *timeo || delay < 0)
212                         goto do_nonblock;
213
214                 sk->sk_write_pending++;
215                 release_sock(sk);
216                 *timeo -= schedule_timeout(delay);
217                 lock_sock(sk);
218                 sk->sk_write_pending--;
219         }
220 out:
221         finish_wait(sk->sk_sleep, &wait);
222         return rc;
223
224 do_error:
225         rc = -EPIPE;
226         goto out;
227 do_nonblock:
228         rc = -EAGAIN;
229         goto out;
230 do_interrupted:
231         rc = sock_intr_errno(*timeo);
232         goto out;
233 }
234
235 static void dccp_write_xmit_timer(unsigned long data) {
236         struct sock *sk = (struct sock *)data;
237         struct dccp_sock *dp = dccp_sk(sk);
238
239         bh_lock_sock(sk);
240         if (sock_owned_by_user(sk))
241                 sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1);
242         else
243                 dccp_write_xmit(sk, 0);
244         bh_unlock_sock(sk);
245         sock_put(sk);
246 }
247
248 void dccp_write_xmit(struct sock *sk, int block)
249 {
250         struct dccp_sock *dp = dccp_sk(sk);
251         struct sk_buff *skb;
252         long timeo = DCCP_XMIT_TIMEO;   /* If a packet is taking longer than
253                                            this we have other issues */
254
255         while ((skb = skb_peek(&sk->sk_write_queue))) {
256                 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
257                                          skb->len);
258
259                 if (err > 0) {
260                         if (!block) {
261                                 sk_reset_timer(sk, &dp->dccps_xmit_timer,
262                                                 msecs_to_jiffies(err)+jiffies);
263                                 break;
264                         } else {
265                                 err = dccp_wait_for_ccid(sk, skb, &timeo);
266                                 timeo = DCCP_XMIT_TIMEO;
267                         }
268                         if (err) {
269                                 printk(KERN_CRIT "%s:err at dccp_wait_for_ccid"
270                                                  " %d\n", __FUNCTION__, err);
271                                 dump_stack();
272                         }
273                 }
274
275                 skb_dequeue(&sk->sk_write_queue);
276                 if (err == 0) {
277                         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
278                         const int len = skb->len;
279
280                         if (sk->sk_state == DCCP_PARTOPEN) {
281                                 /* See 8.1.5.  Handshake Completion */
282                                 inet_csk_schedule_ack(sk);
283                                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
284                                                   inet_csk(sk)->icsk_rto,
285                                                   DCCP_RTO_MAX);
286                                 dcb->dccpd_type = DCCP_PKT_DATAACK;
287                         } else if (dccp_ack_pending(sk))
288                                 dcb->dccpd_type = DCCP_PKT_DATAACK;
289                         else
290                                 dcb->dccpd_type = DCCP_PKT_DATA;
291
292                         err = dccp_transmit_skb(sk, skb);
293                         ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
294                         if (err) {
295                                 printk(KERN_CRIT "%s:err from "
296                                                  "ccid_hc_tx_packet_sent %d\n",
297                                                  __FUNCTION__, err);
298                                 dump_stack();
299                         }
300                 } else
301                         kfree(skb);
302         }
303 }
304
305 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
306 {
307         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
308                 return -EHOSTUNREACH; /* Routing failure or similar. */
309
310         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
311                                       pskb_copy(skb, GFP_ATOMIC):
312                                       skb_clone(skb, GFP_ATOMIC)));
313 }
314
315 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
316                                    struct request_sock *req)
317 {
318         struct dccp_hdr *dh;
319         struct dccp_request_sock *dreq;
320         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
321                                      sizeof(struct dccp_hdr_ext) +
322                                      sizeof(struct dccp_hdr_response);
323         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
324                                            GFP_ATOMIC);
325         if (skb == NULL)
326                 return NULL;
327
328         /* Reserve space for headers. */
329         skb_reserve(skb, sk->sk_prot->max_header);
330
331         skb->dst = dst_clone(dst);
332         skb->csum = 0;
333
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;
337
338         if (dccp_insert_options(sk, skb)) {
339                 kfree_skb(skb);
340                 return NULL;
341         }
342
343         dh = dccp_zeroed_hdr(skb, dccp_header_size);
344
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;
350         dh->dccph_x     = 1;
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;
354
355         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
356         return skb;
357 }
358
359 EXPORT_SYMBOL_GPL(dccp_make_response);
360
361 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
362                                        const enum dccp_reset_codes code)
363                                    
364 {
365         struct dccp_hdr *dh;
366         struct dccp_sock *dp = dccp_sk(sk);
367         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
368                                      sizeof(struct dccp_hdr_ext) +
369                                      sizeof(struct dccp_hdr_reset);
370         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
371                                            GFP_ATOMIC);
372         if (skb == NULL)
373                 return NULL;
374
375         /* Reserve space for headers. */
376         skb_reserve(skb, sk->sk_prot->max_header);
377
378         skb->dst = dst_clone(dst);
379         skb->csum = 0;
380
381         dccp_inc_seqno(&dp->dccps_gss);
382
383         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
384         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
385         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
386
387         if (dccp_insert_options(sk, skb)) {
388                 kfree_skb(skb);
389                 return NULL;
390         }
391
392         dh = dccp_zeroed_hdr(skb, dccp_header_size);
393
394         dh->dccph_sport = inet_sk(sk)->sport;
395         dh->dccph_dport = inet_sk(sk)->dport;
396         dh->dccph_doff  = (dccp_header_size +
397                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
398         dh->dccph_type  = DCCP_PKT_RESET;
399         dh->dccph_x     = 1;
400         dccp_hdr_set_seq(dh, dp->dccps_gss);
401         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
402
403         dccp_hdr_reset(skb)->dccph_reset_code = code;
404         inet_csk(sk)->icsk_af_ops->send_check(sk, skb->len, skb);
405
406         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
407         return skb;
408 }
409
410 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
411 {
412         /*
413          * FIXME: what if rebuild_header fails?
414          * Should we be doing a rebuild_header here?
415          */
416         int err = inet_sk_rebuild_header(sk);
417
418         if (err == 0) {
419                 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache,
420                                                       code);
421                 if (skb != NULL) {
422                         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
423                         err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, sk, 0);
424                         if (err == NET_XMIT_CN)
425                                 err = 0;
426                 }
427         }
428
429         return err;
430 }
431
432 /*
433  * Do all connect socket setups that can be done AF independent.
434  */
435 static inline void dccp_connect_init(struct sock *sk)
436 {
437         struct dccp_sock *dp = dccp_sk(sk);
438         struct dst_entry *dst = __sk_dst_get(sk);
439         struct inet_connection_sock *icsk = inet_csk(sk);
440
441         sk->sk_err = 0;
442         sock_reset_flag(sk, SOCK_DONE);
443         
444         dccp_sync_mss(sk, dst_mtu(dst));
445
446         dccp_update_gss(sk, dp->dccps_iss);
447         /*
448          * SWL and AWL are initially adjusted so that they are not less than
449          * the initial Sequence Numbers received and sent, respectively:
450          *      SWL := max(GSR + 1 - floor(W/4), ISR),
451          *      AWL := max(GSS - W' + 1, ISS).
452          * These adjustments MUST be applied only at the beginning of the
453          * connection.
454          */
455         dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
456
457         icsk->icsk_retransmits = 0;
458         init_timer(&dp->dccps_xmit_timer);
459         dp->dccps_xmit_timer.data = (unsigned long)sk;
460         dp->dccps_xmit_timer.function = dccp_write_xmit_timer;
461 }
462
463 int dccp_connect(struct sock *sk)
464 {
465         struct sk_buff *skb;
466         struct inet_connection_sock *icsk = inet_csk(sk);
467
468         dccp_connect_init(sk);
469
470         skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
471         if (unlikely(skb == NULL))
472                 return -ENOBUFS;
473
474         /* Reserve space for headers. */
475         skb_reserve(skb, sk->sk_prot->max_header);
476
477         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
478         skb->csum = 0;
479
480         dccp_skb_entail(sk, skb);
481         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
482         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
483
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);
487         return 0;
488 }
489
490 EXPORT_SYMBOL_GPL(dccp_connect);
491
492 void dccp_send_ack(struct sock *sk)
493 {
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,
497                                                 GFP_ATOMIC);
498
499                 if (skb == NULL) {
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,
503                                                   TCP_DELACK_MAX,
504                                                   DCCP_RTO_MAX);
505                         return;
506                 }
507
508                 /* Reserve space for headers */
509                 skb_reserve(skb, sk->sk_prot->max_header);
510                 skb->csum = 0;
511                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
512                 dccp_transmit_skb(sk, skb);
513         }
514 }
515
516 EXPORT_SYMBOL_GPL(dccp_send_ack);
517
518 void dccp_send_delayed_ack(struct sock *sk)
519 {
520         struct inet_connection_sock *icsk = inet_csk(sk);
521         /*
522          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
523          * with using 2s, and active senders also piggyback the ACK into a
524          * DATAACK packet, so this is really for quiescent senders.
525          */
526         unsigned long timeout = jiffies + 2 * HZ;
527
528         /* Use new timeout only if there wasn't a older one earlier. */
529         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
530                 /* If delack timer was blocked or is about to expire,
531                  * send ACK now.
532                  *
533                  * FIXME: check the "about to expire" part
534                  */
535                 if (icsk->icsk_ack.blocked) {
536                         dccp_send_ack(sk);
537                         return;
538                 }
539
540                 if (!time_before(timeout, icsk->icsk_ack.timeout))
541                         timeout = icsk->icsk_ack.timeout;
542         }
543         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
544         icsk->icsk_ack.timeout = timeout;
545         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
546 }
547
548 void dccp_send_sync(struct sock *sk, const u64 seq,
549                     const enum dccp_pkt_type pkt_type)
550 {
551         /*
552          * We are not putting this on the write queue, so
553          * dccp_transmit_skb() will set the ownership to this
554          * sock.
555          */
556         struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
557
558         if (skb == NULL)
559                 /* FIXME: how to make sure the sync is sent? */
560                 return;
561
562         /* Reserve space for headers and prepare control bits. */
563         skb_reserve(skb, sk->sk_prot->max_header);
564         skb->csum = 0;
565         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
566         DCCP_SKB_CB(skb)->dccpd_seq = seq;
567
568         dccp_transmit_skb(sk, skb);
569 }
570
571 EXPORT_SYMBOL_GPL(dccp_send_sync);
572
573 /*
574  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
575  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
576  * any circumstances.
577  */
578 void dccp_send_close(struct sock *sk, const int active)
579 {
580         struct dccp_sock *dp = dccp_sk(sk);
581         struct sk_buff *skb;
582         const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
583
584         skb = alloc_skb(sk->sk_prot->max_header, prio);
585         if (skb == NULL)
586                 return;
587
588         /* Reserve space for headers and prepare control bits. */
589         skb_reserve(skb, sk->sk_prot->max_header);
590         skb->csum = 0;
591         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
592                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
593
594         if (active) {
595                 dccp_write_xmit(sk, 1);
596                 dccp_skb_entail(sk, skb);
597                 dccp_transmit_skb(sk, skb_clone(skb, prio));
598                 /* FIXME do we need a retransmit timer here? */
599         } else
600                 dccp_transmit_skb(sk, skb);
601 }