Merge branch 'drm-patches' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied...
[linux-2.6] / 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/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 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 u32 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
87                 if (dccp_insert_options(sk, skb)) {
88                         kfree_skb(skb);
89                         return -EPROTO;
90                 }
91                 
92                 skb->h.raw = skb_push(skb, dccp_header_size);
93                 dh = dccp_hdr(skb);
94
95                 /* Build DCCP header and checksum it. */
96                 memset(dh, 0, dccp_header_size);
97                 dh->dccph_type  = dcb->dccpd_type;
98                 dh->dccph_sport = inet->sport;
99                 dh->dccph_dport = inet->dport;
100                 dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
101                 dh->dccph_ccval = dcb->dccpd_ccval;
102                 /* XXX For now we're using only 48 bits sequence numbers */
103                 dh->dccph_x     = 1;
104
105                 dp->dccps_awh = dp->dccps_gss;
106                 dccp_hdr_set_seq(dh, dp->dccps_gss);
107                 if (set_ack)
108                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
109
110                 switch (dcb->dccpd_type) {
111                 case DCCP_PKT_REQUEST:
112                         dccp_hdr_request(skb)->dccph_req_service =
113                                                         dp->dccps_service;
114                         break;
115                 case DCCP_PKT_RESET:
116                         dccp_hdr_reset(skb)->dccph_reset_code =
117                                                         dcb->dccpd_reset_code;
118                         break;
119                 }
120
121                 icsk->icsk_af_ops->send_check(sk, skb->len, skb);
122
123                 if (set_ack)
124                         dccp_event_ack_sent(sk);
125
126                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
127
128                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
129                 err = icsk->icsk_af_ops->queue_xmit(skb, 0);
130                 if (err <= 0)
131                         return err;
132
133                 /* NET_XMIT_CN is special. It does not guarantee,
134                  * that this packet is lost. It tells that device
135                  * is about to start to drop packets or already
136                  * drops some packets of the same priority and
137                  * invokes us to send less aggressively.
138                  */
139                 return err == NET_XMIT_CN ? 0 : err;
140         }
141         return -ENOBUFS;
142 }
143
144 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
145 {
146         struct inet_connection_sock *icsk = inet_csk(sk);
147         struct dccp_sock *dp = dccp_sk(sk);
148         int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
149                        sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
150
151         /* Now subtract optional transport overhead */
152         mss_now -= icsk->icsk_ext_hdr_len;
153
154         /*
155          * FIXME: this should come from the CCID infrastructure, where, say,
156          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
157          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
158          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
159          * make it a multiple of 4
160          */
161
162         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
163
164         /* And store cached results */
165         icsk->icsk_pmtu_cookie = pmtu;
166         dp->dccps_mss_cache = mss_now;
167
168         return mss_now;
169 }
170
171 EXPORT_SYMBOL_GPL(dccp_sync_mss);
172
173 void dccp_write_space(struct sock *sk)
174 {
175         read_lock(&sk->sk_callback_lock);
176
177         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
178                 wake_up_interruptible(sk->sk_sleep);
179         /* Should agree with poll, otherwise some programs break */
180         if (sock_writeable(sk))
181                 sk_wake_async(sk, 2, POLL_OUT);
182
183         read_unlock(&sk->sk_callback_lock);
184 }
185
186 /**
187  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
188  * @sk: socket to wait for
189  * @timeo: for how long
190  */
191 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
192                               long *timeo)
193 {
194         struct dccp_sock *dp = dccp_sk(sk);
195         DEFINE_WAIT(wait);
196         long delay;
197         int rc;
198
199         while (1) {
200                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
201
202                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
203                         goto do_error;
204                 if (!*timeo)
205                         goto do_nonblock;
206                 if (signal_pending(current))
207                         goto do_interrupted;
208
209                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
210                                             skb->len);
211                 if (rc <= 0)
212                         break;
213                 delay = msecs_to_jiffies(rc);
214                 if (delay > *timeo || delay < 0)
215                         goto do_nonblock;
216
217                 sk->sk_write_pending++;
218                 release_sock(sk);
219                 *timeo -= schedule_timeout(delay);
220                 lock_sock(sk);
221                 sk->sk_write_pending--;
222         }
223 out:
224         finish_wait(sk->sk_sleep, &wait);
225         return rc;
226
227 do_error:
228         rc = -EPIPE;
229         goto out;
230 do_nonblock:
231         rc = -EAGAIN;
232         goto out;
233 do_interrupted:
234         rc = sock_intr_errno(*timeo);
235         goto out;
236 }
237
238 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
239 {
240         const struct dccp_sock *dp = dccp_sk(sk);
241         int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
242                                          skb->len);
243
244         if (err > 0)
245                 err = dccp_wait_for_ccid(sk, skb, timeo);
246
247         if (err == 0) {
248                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
249                 const int len = skb->len;
250
251                 if (sk->sk_state == DCCP_PARTOPEN) {
252                         /* See 8.1.5.  Handshake Completion */
253                         inet_csk_schedule_ack(sk);
254                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
255                                                   inet_csk(sk)->icsk_rto,
256                                                   DCCP_RTO_MAX);
257                         dcb->dccpd_type = DCCP_PKT_DATAACK;
258                 } else if (dccp_ack_pending(sk))
259                         dcb->dccpd_type = DCCP_PKT_DATAACK;
260                 else
261                         dcb->dccpd_type = DCCP_PKT_DATA;
262
263                 err = dccp_transmit_skb(sk, skb);
264                 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
265         } else
266                 kfree_skb(skb);
267
268         return err;
269 }
270
271 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
272 {
273         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
274                 return -EHOSTUNREACH; /* Routing failure or similar. */
275
276         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
277                                       pskb_copy(skb, GFP_ATOMIC):
278                                       skb_clone(skb, GFP_ATOMIC)));
279 }
280
281 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
282                                    struct request_sock *req)
283 {
284         struct dccp_hdr *dh;
285         struct dccp_request_sock *dreq;
286         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
287                                      sizeof(struct dccp_hdr_ext) +
288                                      sizeof(struct dccp_hdr_response);
289         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
290                                            GFP_ATOMIC);
291         if (skb == NULL)
292                 return NULL;
293
294         /* Reserve space for headers. */
295         skb_reserve(skb, sk->sk_prot->max_header);
296
297         skb->dst = dst_clone(dst);
298         skb->csum = 0;
299
300         dreq = dccp_rsk(req);
301         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
302         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
303
304         if (dccp_insert_options(sk, skb)) {
305                 kfree_skb(skb);
306                 return NULL;
307         }
308
309         skb->h.raw = skb_push(skb, dccp_header_size);
310
311         dh = dccp_hdr(skb);
312         memset(dh, 0, dccp_header_size);
313
314         dh->dccph_sport = inet_sk(sk)->sport;
315         dh->dccph_dport = inet_rsk(req)->rmt_port;
316         dh->dccph_doff  = (dccp_header_size +
317                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
318         dh->dccph_type  = DCCP_PKT_RESPONSE;
319         dh->dccph_x     = 1;
320         dccp_hdr_set_seq(dh, dreq->dreq_iss);
321         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
322         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
323
324         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
325         return skb;
326 }
327
328 EXPORT_SYMBOL_GPL(dccp_make_response);
329
330 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
331                                        const enum dccp_reset_codes code)
332                                    
333 {
334         struct dccp_hdr *dh;
335         struct dccp_sock *dp = dccp_sk(sk);
336         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
337                                      sizeof(struct dccp_hdr_ext) +
338                                      sizeof(struct dccp_hdr_reset);
339         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
340                                            GFP_ATOMIC);
341         if (skb == NULL)
342                 return NULL;
343
344         /* Reserve space for headers. */
345         skb_reserve(skb, sk->sk_prot->max_header);
346
347         skb->dst = dst_clone(dst);
348         skb->csum = 0;
349
350         dccp_inc_seqno(&dp->dccps_gss);
351
352         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
353         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
354         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
355
356         if (dccp_insert_options(sk, skb)) {
357                 kfree_skb(skb);
358                 return NULL;
359         }
360
361         skb->h.raw = skb_push(skb, dccp_header_size);
362
363         dh = dccp_hdr(skb);
364         memset(dh, 0, dccp_header_size);
365
366         dh->dccph_sport = inet_sk(sk)->sport;
367         dh->dccph_dport = inet_sk(sk)->dport;
368         dh->dccph_doff  = (dccp_header_size +
369                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
370         dh->dccph_type  = DCCP_PKT_RESET;
371         dh->dccph_x     = 1;
372         dccp_hdr_set_seq(dh, dp->dccps_gss);
373         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
374
375         dccp_hdr_reset(skb)->dccph_reset_code = code;
376         inet_csk(sk)->icsk_af_ops->send_check(sk, skb->len, skb);
377
378         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
379         return skb;
380 }
381
382 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
383 {
384         /*
385          * FIXME: what if rebuild_header fails?
386          * Should we be doing a rebuild_header here?
387          */
388         int err = inet_sk_rebuild_header(sk);
389
390         if (err == 0) {
391                 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache,
392                                                       code);
393                 if (skb != NULL) {
394                         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
395                         err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, 0);
396                         if (err == NET_XMIT_CN)
397                                 err = 0;
398                 }
399         }
400
401         return err;
402 }
403
404 /*
405  * Do all connect socket setups that can be done AF independent.
406  */
407 static inline void dccp_connect_init(struct sock *sk)
408 {
409         struct dccp_sock *dp = dccp_sk(sk);
410         struct dst_entry *dst = __sk_dst_get(sk);
411         struct inet_connection_sock *icsk = inet_csk(sk);
412
413         sk->sk_err = 0;
414         sock_reset_flag(sk, SOCK_DONE);
415         
416         dccp_sync_mss(sk, dst_mtu(dst));
417
418         dccp_update_gss(sk, dp->dccps_iss);
419         /*
420          * SWL and AWL are initially adjusted so that they are not less than
421          * the initial Sequence Numbers received and sent, respectively:
422          *      SWL := max(GSR + 1 - floor(W/4), ISR),
423          *      AWL := max(GSS - W' + 1, ISS).
424          * These adjustments MUST be applied only at the beginning of the
425          * connection.
426          */
427         dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
428
429         icsk->icsk_retransmits = 0;
430 }
431
432 int dccp_connect(struct sock *sk)
433 {
434         struct sk_buff *skb;
435         struct inet_connection_sock *icsk = inet_csk(sk);
436
437         dccp_connect_init(sk);
438
439         skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
440         if (unlikely(skb == NULL))
441                 return -ENOBUFS;
442
443         /* Reserve space for headers. */
444         skb_reserve(skb, sk->sk_prot->max_header);
445
446         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
447         skb->csum = 0;
448
449         dccp_skb_entail(sk, skb);
450         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
451         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
452
453         /* Timer for repeating the REQUEST until an answer. */
454         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
455                                   icsk->icsk_rto, DCCP_RTO_MAX);
456         return 0;
457 }
458
459 EXPORT_SYMBOL_GPL(dccp_connect);
460
461 void dccp_send_ack(struct sock *sk)
462 {
463         /* If we have been reset, we may not send again. */
464         if (sk->sk_state != DCCP_CLOSED) {
465                 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header,
466                                                 GFP_ATOMIC);
467
468                 if (skb == NULL) {
469                         inet_csk_schedule_ack(sk);
470                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
471                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
472                                                   TCP_DELACK_MAX,
473                                                   DCCP_RTO_MAX);
474                         return;
475                 }
476
477                 /* Reserve space for headers */
478                 skb_reserve(skb, sk->sk_prot->max_header);
479                 skb->csum = 0;
480                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
481                 dccp_transmit_skb(sk, skb);
482         }
483 }
484
485 EXPORT_SYMBOL_GPL(dccp_send_ack);
486
487 void dccp_send_delayed_ack(struct sock *sk)
488 {
489         struct inet_connection_sock *icsk = inet_csk(sk);
490         /*
491          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
492          * with using 2s, and active senders also piggyback the ACK into a
493          * DATAACK packet, so this is really for quiescent senders.
494          */
495         unsigned long timeout = jiffies + 2 * HZ;
496
497         /* Use new timeout only if there wasn't a older one earlier. */
498         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
499                 /* If delack timer was blocked or is about to expire,
500                  * send ACK now.
501                  *
502                  * FIXME: check the "about to expire" part
503                  */
504                 if (icsk->icsk_ack.blocked) {
505                         dccp_send_ack(sk);
506                         return;
507                 }
508
509                 if (!time_before(timeout, icsk->icsk_ack.timeout))
510                         timeout = icsk->icsk_ack.timeout;
511         }
512         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
513         icsk->icsk_ack.timeout = timeout;
514         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
515 }
516
517 void dccp_send_sync(struct sock *sk, const u64 seq,
518                     const enum dccp_pkt_type pkt_type)
519 {
520         /*
521          * We are not putting this on the write queue, so
522          * dccp_transmit_skb() will set the ownership to this
523          * sock.
524          */
525         struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
526
527         if (skb == NULL)
528                 /* FIXME: how to make sure the sync is sent? */
529                 return;
530
531         /* Reserve space for headers and prepare control bits. */
532         skb_reserve(skb, sk->sk_prot->max_header);
533         skb->csum = 0;
534         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
535         DCCP_SKB_CB(skb)->dccpd_seq = seq;
536
537         dccp_transmit_skb(sk, skb);
538 }
539
540 EXPORT_SYMBOL_GPL(dccp_send_sync);
541
542 /*
543  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
544  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
545  * any circumstances.
546  */
547 void dccp_send_close(struct sock *sk, const int active)
548 {
549         struct dccp_sock *dp = dccp_sk(sk);
550         struct sk_buff *skb;
551         const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
552
553         skb = alloc_skb(sk->sk_prot->max_header, prio);
554         if (skb == NULL)
555                 return;
556
557         /* Reserve space for headers and prepare control bits. */
558         skb_reserve(skb, sk->sk_prot->max_header);
559         skb->csum = 0;
560         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
561                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
562
563         if (active) {
564                 dccp_skb_entail(sk, skb);
565                 dccp_transmit_skb(sk, skb_clone(skb, prio));
566         } else
567                 dccp_transmit_skb(sk, skb);
568 }