b4df12b24161c56bb6a0412ab05a3fbb8585c73a
[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                 dh->dccph_cscov = dp->dccps_pcslen;
100                 /* XXX For now we're using only 48 bits sequence numbers */
101                 dh->dccph_x     = 1;
102
103                 dp->dccps_awh = dp->dccps_gss;
104                 dccp_hdr_set_seq(dh, dp->dccps_gss);
105                 if (set_ack)
106                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
107
108                 switch (dcb->dccpd_type) {
109                 case DCCP_PKT_REQUEST:
110                         dccp_hdr_request(skb)->dccph_req_service =
111                                                         dp->dccps_service;
112                         break;
113                 case DCCP_PKT_RESET:
114                         dccp_hdr_reset(skb)->dccph_reset_code =
115                                                         dcb->dccpd_reset_code;
116                         break;
117                 }
118
119                 icsk->icsk_af_ops->send_check(sk, 0, skb);
120
121                 if (set_ack)
122                         dccp_event_ack_sent(sk);
123
124                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
125
126                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
127                 err = icsk->icsk_af_ops->queue_xmit(skb, sk, 0);
128                 return net_xmit_eval(err);
129         }
130         return -ENOBUFS;
131 }
132
133 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
134 {
135         struct inet_connection_sock *icsk = inet_csk(sk);
136         struct dccp_sock *dp = dccp_sk(sk);
137         int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
138                        sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
139
140         /* Now subtract optional transport overhead */
141         mss_now -= icsk->icsk_ext_hdr_len;
142
143         /*
144          * FIXME: this should come from the CCID infrastructure, where, say,
145          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
146          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
147          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
148          * make it a multiple of 4
149          */
150
151         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
152
153         /* And store cached results */
154         icsk->icsk_pmtu_cookie = pmtu;
155         dp->dccps_mss_cache = mss_now;
156
157         return mss_now;
158 }
159
160 EXPORT_SYMBOL_GPL(dccp_sync_mss);
161
162 void dccp_write_space(struct sock *sk)
163 {
164         read_lock(&sk->sk_callback_lock);
165
166         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
167                 wake_up_interruptible(sk->sk_sleep);
168         /* Should agree with poll, otherwise some programs break */
169         if (sock_writeable(sk))
170                 sk_wake_async(sk, 2, POLL_OUT);
171
172         read_unlock(&sk->sk_callback_lock);
173 }
174
175 /**
176  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
177  * @sk: socket to wait for
178  */
179 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb)
180 {
181         struct dccp_sock *dp = dccp_sk(sk);
182         DEFINE_WAIT(wait);
183         unsigned long delay;
184         int rc;
185
186         while (1) {
187                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
188
189                 if (sk->sk_err)
190                         goto do_error;
191                 if (signal_pending(current))
192                         goto do_interrupted;
193
194                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
195                 if (rc <= 0)
196                         break;
197                 delay = msecs_to_jiffies(rc);
198                 sk->sk_write_pending++;
199                 release_sock(sk);
200                 schedule_timeout(delay);
201                 lock_sock(sk);
202                 sk->sk_write_pending--;
203         }
204 out:
205         finish_wait(sk->sk_sleep, &wait);
206         return rc;
207
208 do_error:
209         rc = -EPIPE;
210         goto out;
211 do_interrupted:
212         rc = -EINTR;
213         goto out;
214 }
215
216 static void dccp_write_xmit_timer(unsigned long data) {
217         struct sock *sk = (struct sock *)data;
218         struct dccp_sock *dp = dccp_sk(sk);
219
220         bh_lock_sock(sk);
221         if (sock_owned_by_user(sk))
222                 sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1);
223         else
224                 dccp_write_xmit(sk, 0);
225         bh_unlock_sock(sk);
226         sock_put(sk);
227 }
228
229 void dccp_write_xmit(struct sock *sk, int block)
230 {
231         struct dccp_sock *dp = dccp_sk(sk);
232         struct sk_buff *skb;
233
234         while ((skb = skb_peek(&sk->sk_write_queue))) {
235                 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
236
237                 if (err > 0) {
238                         if (!block) {
239                                 sk_reset_timer(sk, &dp->dccps_xmit_timer,
240                                                 msecs_to_jiffies(err)+jiffies);
241                                 break;
242                         } else
243                                 err = dccp_wait_for_ccid(sk, skb);
244                         if (err && err != -EINTR)
245                                 DCCP_BUG("err=%d after dccp_wait_for_ccid", err);
246                 }
247
248                 skb_dequeue(&sk->sk_write_queue);
249                 if (err == 0) {
250                         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
251                         const int len = skb->len;
252
253                         if (sk->sk_state == DCCP_PARTOPEN) {
254                                 /* See 8.1.5.  Handshake Completion */
255                                 inet_csk_schedule_ack(sk);
256                                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
257                                                   inet_csk(sk)->icsk_rto,
258                                                   DCCP_RTO_MAX);
259                                 dcb->dccpd_type = DCCP_PKT_DATAACK;
260                         } else if (dccp_ack_pending(sk))
261                                 dcb->dccpd_type = DCCP_PKT_DATAACK;
262                         else
263                                 dcb->dccpd_type = DCCP_PKT_DATA;
264
265                         err = dccp_transmit_skb(sk, skb);
266                         ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
267                         if (err)
268                                 DCCP_BUG("err=%d after ccid_hc_tx_packet_sent",
269                                          err);
270                 } else {
271                         dccp_pr_debug("packet discarded\n");
272                         kfree(skb);
273                 }
274         }
275 }
276
277 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
278 {
279         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
280                 return -EHOSTUNREACH; /* Routing failure or similar. */
281
282         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
283                                       pskb_copy(skb, GFP_ATOMIC):
284                                       skb_clone(skb, GFP_ATOMIC)));
285 }
286
287 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
288                                    struct request_sock *req)
289 {
290         struct dccp_hdr *dh;
291         struct dccp_request_sock *dreq;
292         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
293                                      sizeof(struct dccp_hdr_ext) +
294                                      sizeof(struct dccp_hdr_response);
295         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
296                                            GFP_ATOMIC);
297         if (skb == NULL)
298                 return NULL;
299
300         /* Reserve space for headers. */
301         skb_reserve(skb, sk->sk_prot->max_header);
302
303         skb->dst = dst_clone(dst);
304
305         dreq = dccp_rsk(req);
306         if (inet_rsk(req)->acked)       /* increase ISS upon retransmission */
307                 dccp_inc_seqno(&dreq->dreq_iss);
308         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
309         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
310
311         if (dccp_insert_options(sk, skb)) {
312                 kfree_skb(skb);
313                 return NULL;
314         }
315
316         /* Build and checksum header */
317         dh = dccp_zeroed_hdr(skb, dccp_header_size);
318
319         dh->dccph_sport = inet_sk(sk)->sport;
320         dh->dccph_dport = inet_rsk(req)->rmt_port;
321         dh->dccph_doff  = (dccp_header_size +
322                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
323         dh->dccph_type  = DCCP_PKT_RESPONSE;
324         dh->dccph_x     = 1;
325         dccp_hdr_set_seq(dh, dreq->dreq_iss);
326         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
327         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
328
329         dccp_csum_outgoing(skb);
330
331         /* We use `acked' to remember that a Response was already sent. */
332         inet_rsk(req)->acked = 1;
333         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
334         return skb;
335 }
336
337 EXPORT_SYMBOL_GPL(dccp_make_response);
338
339 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
340                                        const enum dccp_reset_codes code)
341                                    
342 {
343         struct dccp_hdr *dh;
344         struct dccp_sock *dp = dccp_sk(sk);
345         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
346                                      sizeof(struct dccp_hdr_ext) +
347                                      sizeof(struct dccp_hdr_reset);
348         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
349                                            GFP_ATOMIC);
350         if (skb == NULL)
351                 return NULL;
352
353         /* Reserve space for headers. */
354         skb_reserve(skb, sk->sk_prot->max_header);
355
356         skb->dst = dst_clone(dst);
357
358         dccp_inc_seqno(&dp->dccps_gss);
359
360         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
361         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
362         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
363
364         if (dccp_insert_options(sk, skb)) {
365                 kfree_skb(skb);
366                 return NULL;
367         }
368
369         dh = dccp_zeroed_hdr(skb, dccp_header_size);
370
371         dh->dccph_sport = inet_sk(sk)->sport;
372         dh->dccph_dport = inet_sk(sk)->dport;
373         dh->dccph_doff  = (dccp_header_size +
374                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
375         dh->dccph_type  = DCCP_PKT_RESET;
376         dh->dccph_x     = 1;
377         dccp_hdr_set_seq(dh, dp->dccps_gss);
378         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
379
380         dccp_hdr_reset(skb)->dccph_reset_code = code;
381         inet_csk(sk)->icsk_af_ops->send_check(sk, 0, skb);
382
383         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
384         return skb;
385 }
386
387 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
388 {
389         /*
390          * FIXME: what if rebuild_header fails?
391          * Should we be doing a rebuild_header here?
392          */
393         int err = inet_sk_rebuild_header(sk);
394
395         if (err == 0) {
396                 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache,
397                                                       code);
398                 if (skb != NULL) {
399                         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
400                         err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, sk, 0);
401                         return net_xmit_eval(err);
402                 }
403         }
404
405         return err;
406 }
407
408 /*
409  * Do all connect socket setups that can be done AF independent.
410  */
411 static inline void dccp_connect_init(struct sock *sk)
412 {
413         struct dccp_sock *dp = dccp_sk(sk);
414         struct dst_entry *dst = __sk_dst_get(sk);
415         struct inet_connection_sock *icsk = inet_csk(sk);
416
417         sk->sk_err = 0;
418         sock_reset_flag(sk, SOCK_DONE);
419         
420         dccp_sync_mss(sk, dst_mtu(dst));
421
422         /*
423          * SWL and AWL are initially adjusted so that they are not less than
424          * the initial Sequence Numbers received and sent, respectively:
425          *      SWL := max(GSR + 1 - floor(W/4), ISR),
426          *      AWL := max(GSS - W' + 1, ISS).
427          * These adjustments MUST be applied only at the beginning of the
428          * connection.
429          */
430         dccp_update_gss(sk, dp->dccps_iss);
431         dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
432
433         /* S.GAR - greatest valid acknowledgement number received on a non-Sync;
434          *         initialized to S.ISS (sec. 8.5)                            */
435         dp->dccps_gar = dp->dccps_iss;
436
437         icsk->icsk_retransmits = 0;
438         init_timer(&dp->dccps_xmit_timer);
439         dp->dccps_xmit_timer.data = (unsigned long)sk;
440         dp->dccps_xmit_timer.function = dccp_write_xmit_timer;
441 }
442
443 int dccp_connect(struct sock *sk)
444 {
445         struct sk_buff *skb;
446         struct inet_connection_sock *icsk = inet_csk(sk);
447
448         dccp_connect_init(sk);
449
450         skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
451         if (unlikely(skb == NULL))
452                 return -ENOBUFS;
453
454         /* Reserve space for headers. */
455         skb_reserve(skb, sk->sk_prot->max_header);
456
457         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
458
459         dccp_skb_entail(sk, skb);
460         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
461         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
462
463         /* Timer for repeating the REQUEST until an answer. */
464         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
465                                   icsk->icsk_rto, DCCP_RTO_MAX);
466         return 0;
467 }
468
469 EXPORT_SYMBOL_GPL(dccp_connect);
470
471 void dccp_send_ack(struct sock *sk)
472 {
473         /* If we have been reset, we may not send again. */
474         if (sk->sk_state != DCCP_CLOSED) {
475                 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header,
476                                                 GFP_ATOMIC);
477
478                 if (skb == NULL) {
479                         inet_csk_schedule_ack(sk);
480                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
481                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
482                                                   TCP_DELACK_MAX,
483                                                   DCCP_RTO_MAX);
484                         return;
485                 }
486
487                 /* Reserve space for headers */
488                 skb_reserve(skb, sk->sk_prot->max_header);
489                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
490                 dccp_transmit_skb(sk, skb);
491         }
492 }
493
494 EXPORT_SYMBOL_GPL(dccp_send_ack);
495
496 void dccp_send_delayed_ack(struct sock *sk)
497 {
498         struct inet_connection_sock *icsk = inet_csk(sk);
499         /*
500          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
501          * with using 2s, and active senders also piggyback the ACK into a
502          * DATAACK packet, so this is really for quiescent senders.
503          */
504         unsigned long timeout = jiffies + 2 * HZ;
505
506         /* Use new timeout only if there wasn't a older one earlier. */
507         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
508                 /* If delack timer was blocked or is about to expire,
509                  * send ACK now.
510                  *
511                  * FIXME: check the "about to expire" part
512                  */
513                 if (icsk->icsk_ack.blocked) {
514                         dccp_send_ack(sk);
515                         return;
516                 }
517
518                 if (!time_before(timeout, icsk->icsk_ack.timeout))
519                         timeout = icsk->icsk_ack.timeout;
520         }
521         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
522         icsk->icsk_ack.timeout = timeout;
523         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
524 }
525
526 void dccp_send_sync(struct sock *sk, const u64 seq,
527                     const enum dccp_pkt_type pkt_type)
528 {
529         /*
530          * We are not putting this on the write queue, so
531          * dccp_transmit_skb() will set the ownership to this
532          * sock.
533          */
534         struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
535
536         if (skb == NULL)
537                 /* FIXME: how to make sure the sync is sent? */
538                 return;
539
540         /* Reserve space for headers and prepare control bits. */
541         skb_reserve(skb, sk->sk_prot->max_header);
542         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
543         DCCP_SKB_CB(skb)->dccpd_seq = seq;
544
545         dccp_transmit_skb(sk, skb);
546 }
547
548 EXPORT_SYMBOL_GPL(dccp_send_sync);
549
550 /*
551  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
552  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
553  * any circumstances.
554  */
555 void dccp_send_close(struct sock *sk, const int active)
556 {
557         struct dccp_sock *dp = dccp_sk(sk);
558         struct sk_buff *skb;
559         const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
560
561         skb = alloc_skb(sk->sk_prot->max_header, prio);
562         if (skb == NULL)
563                 return;
564
565         /* Reserve space for headers and prepare control bits. */
566         skb_reserve(skb, sk->sk_prot->max_header);
567         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
568                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
569
570         if (active) {
571                 dccp_write_xmit(sk, 1);
572                 dccp_skb_entail(sk, skb);
573                 dccp_transmit_skb(sk, skb_clone(skb, prio));
574                 /* FIXME do we need a retransmit timer here? */
575         } else
576                 dccp_transmit_skb(sk, skb);
577 }