4786bdcddcc92a4082b3dc7d30d77560b171e541
[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/config.h>
14 #include <linux/dccp.h>
15 #include <linux/skbuff.h>
16
17 #include <net/sock.h>
18
19 #include "ackvec.h"
20 #include "ccid.h"
21 #include "dccp.h"
22
23 static inline void dccp_event_ack_sent(struct sock *sk)
24 {
25         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
26 }
27
28 /*
29  * All SKB's seen here are completely headerless. It is our
30  * job to build the DCCP header, and pass the packet down to
31  * IP so it can do the same plus pass the packet off to the
32  * device.
33  */
34 int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
35 {
36         if (likely(skb != NULL)) {
37                 const struct inet_sock *inet = inet_sk(sk);
38                 struct dccp_sock *dp = dccp_sk(sk);
39                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
40                 struct dccp_hdr *dh;
41                 /* XXX For now we're using only 48 bits sequence numbers */
42                 const int dccp_header_size = sizeof(*dh) +
43                                              sizeof(struct dccp_hdr_ext) +
44                                           dccp_packet_hdr_len(dcb->dccpd_type);
45                 int err, set_ack = 1;
46                 u64 ackno = dp->dccps_gsr;
47
48                 dccp_inc_seqno(&dp->dccps_gss);
49
50                 switch (dcb->dccpd_type) {
51                 case DCCP_PKT_DATA:
52                         set_ack = 0;
53                         break;
54                 case DCCP_PKT_SYNC:
55                 case DCCP_PKT_SYNCACK:
56                         ackno = dcb->dccpd_seq;
57                         break;
58                 }
59
60                 dcb->dccpd_seq = dp->dccps_gss;
61                 dccp_insert_options(sk, skb);
62                 
63                 skb->h.raw = skb_push(skb, dccp_header_size);
64                 dh = dccp_hdr(skb);
65                 /*
66                  * Data packets are not cloned as they are never retransmitted
67                  */
68                 if (skb_cloned(skb))
69                         skb_set_owner_w(skb, sk);
70
71                 /* Build DCCP header and checksum it. */
72                 memset(dh, 0, dccp_header_size);
73                 dh->dccph_type  = dcb->dccpd_type;
74                 dh->dccph_sport = inet->sport;
75                 dh->dccph_dport = inet->dport;
76                 dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
77                 dh->dccph_ccval = dcb->dccpd_ccval;
78                 /* XXX For now we're using only 48 bits sequence numbers */
79                 dh->dccph_x     = 1;
80
81                 dp->dccps_awh = dp->dccps_gss;
82                 dccp_hdr_set_seq(dh, dp->dccps_gss);
83                 if (set_ack)
84                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
85
86                 switch (dcb->dccpd_type) {
87                 case DCCP_PKT_REQUEST:
88                         dccp_hdr_request(skb)->dccph_req_service =
89                                                         dp->dccps_service;
90                         break;
91                 case DCCP_PKT_RESET:
92                         dccp_hdr_reset(skb)->dccph_reset_code =
93                                                         dcb->dccpd_reset_code;
94                         break;
95                 }
96
97                 dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
98                                                       inet->daddr);
99
100                 if (set_ack)
101                         dccp_event_ack_sent(sk);
102
103                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
104
105                 err = ip_queue_xmit(skb, 0);
106                 if (err <= 0)
107                         return err;
108
109                 /* NET_XMIT_CN is special. It does not guarantee,
110                  * that this packet is lost. It tells that device
111                  * is about to start to drop packets or already
112                  * drops some packets of the same priority and
113                  * invokes us to send less aggressively.
114                  */
115                 return err == NET_XMIT_CN ? 0 : err;
116         }
117         return -ENOBUFS;
118 }
119
120 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
121 {
122         struct dccp_sock *dp = dccp_sk(sk);
123         int mss_now;
124
125         /*
126          * FIXME: we really should be using the af_specific thing to support
127          *        IPv6.
128          * mss_now = pmtu - tp->af_specific->net_header_len -
129          *           sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
130          */
131         mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
132                   sizeof(struct dccp_hdr_ext);
133
134         /* Now subtract optional transport overhead */
135         mss_now -= dp->dccps_ext_header_len;
136
137         /*
138          * FIXME: this should come from the CCID infrastructure, where, say,
139          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
140          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
141          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
142          * make it a multiple of 4
143          */
144
145         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
146
147         /* And store cached results */
148         dp->dccps_pmtu_cookie = pmtu;
149         dp->dccps_mss_cache = mss_now;
150
151         return mss_now;
152 }
153
154 void dccp_write_space(struct sock *sk)
155 {
156         read_lock(&sk->sk_callback_lock);
157
158         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
159                 wake_up_interruptible(sk->sk_sleep);
160         /* Should agree with poll, otherwise some programs break */
161         if (sock_writeable(sk))
162                 sk_wake_async(sk, 2, POLL_OUT);
163
164         read_unlock(&sk->sk_callback_lock);
165 }
166
167 /**
168  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
169  * @sk: socket to wait for
170  * @timeo: for how long
171  */
172 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
173                               long *timeo)
174 {
175         struct dccp_sock *dp = dccp_sk(sk);
176         DEFINE_WAIT(wait);
177         long delay;
178         int rc;
179
180         while (1) {
181                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
182
183                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
184                         goto do_error;
185                 if (!*timeo)
186                         goto do_nonblock;
187                 if (signal_pending(current))
188                         goto do_interrupted;
189
190                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
191                                             skb->len);
192                 if (rc <= 0)
193                         break;
194                 delay = msecs_to_jiffies(rc);
195                 if (delay > *timeo || delay < 0)
196                         goto do_nonblock;
197
198                 sk->sk_write_pending++;
199                 release_sock(sk);
200                 *timeo -= 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_nonblock:
212         rc = -EAGAIN;
213         goto out;
214 do_interrupted:
215         rc = sock_intr_errno(*timeo);
216         goto out;
217 }
218
219 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
220 {
221         const struct dccp_sock *dp = dccp_sk(sk);
222         int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
223                                          skb->len);
224
225         if (err > 0)
226                 err = dccp_wait_for_ccid(sk, skb, timeo);
227
228         if (err == 0) {
229                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
230                 const int len = skb->len;
231
232                 if (sk->sk_state == DCCP_PARTOPEN) {
233                         /* See 8.1.5.  Handshake Completion */
234                         inet_csk_schedule_ack(sk);
235                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
236                                                   inet_csk(sk)->icsk_rto,
237                                                   DCCP_RTO_MAX);
238                         dcb->dccpd_type = DCCP_PKT_DATAACK;
239                 } else if (dccp_ack_pending(sk))
240                         dcb->dccpd_type = DCCP_PKT_DATAACK;
241                 else
242                         dcb->dccpd_type = DCCP_PKT_DATA;
243
244                 err = dccp_transmit_skb(sk, skb);
245                 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
246         }
247
248         return err;
249 }
250
251 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
252 {
253         if (inet_sk_rebuild_header(sk) != 0)
254                 return -EHOSTUNREACH; /* Routing failure or similar. */
255
256         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
257                                       pskb_copy(skb, GFP_ATOMIC):
258                                       skb_clone(skb, GFP_ATOMIC)));
259 }
260
261 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
262                                    struct request_sock *req)
263 {
264         struct dccp_hdr *dh;
265         struct dccp_request_sock *dreq;
266         const int dccp_header_size = sizeof(struct dccp_hdr) +
267                                      sizeof(struct dccp_hdr_ext) +
268                                      sizeof(struct dccp_hdr_response);
269         struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
270                                                dccp_header_size, 1,
271                                            GFP_ATOMIC);
272         if (skb == NULL)
273                 return NULL;
274
275         /* Reserve space for headers. */
276         skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
277
278         skb->dst = dst_clone(dst);
279         skb->csum = 0;
280
281         dreq = dccp_rsk(req);
282         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
283         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
284         dccp_insert_options(sk, skb);
285
286         skb->h.raw = skb_push(skb, dccp_header_size);
287
288         dh = dccp_hdr(skb);
289         memset(dh, 0, dccp_header_size);
290
291         dh->dccph_sport = inet_sk(sk)->sport;
292         dh->dccph_dport = inet_rsk(req)->rmt_port;
293         dh->dccph_doff  = (dccp_header_size +
294                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
295         dh->dccph_type  = DCCP_PKT_RESPONSE;
296         dh->dccph_x     = 1;
297         dccp_hdr_set_seq(dh, dreq->dreq_iss);
298         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
299         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
300
301         dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
302                                               inet_rsk(req)->rmt_addr);
303
304         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
305         return skb;
306 }
307
308 struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
309                                 const enum dccp_reset_codes code)
310                                    
311 {
312         struct dccp_hdr *dh;
313         struct dccp_sock *dp = dccp_sk(sk);
314         const int dccp_header_size = sizeof(struct dccp_hdr) +
315                                      sizeof(struct dccp_hdr_ext) +
316                                      sizeof(struct dccp_hdr_reset);
317         struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
318                                                dccp_header_size, 1,
319                                            GFP_ATOMIC);
320         if (skb == NULL)
321                 return NULL;
322
323         /* Reserve space for headers. */
324         skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
325
326         skb->dst = dst_clone(dst);
327         skb->csum = 0;
328
329         dccp_inc_seqno(&dp->dccps_gss);
330
331         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
332         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
333         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
334         dccp_insert_options(sk, skb);
335
336         skb->h.raw = skb_push(skb, dccp_header_size);
337
338         dh = dccp_hdr(skb);
339         memset(dh, 0, dccp_header_size);
340
341         dh->dccph_sport = inet_sk(sk)->sport;
342         dh->dccph_dport = inet_sk(sk)->dport;
343         dh->dccph_doff  = (dccp_header_size +
344                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
345         dh->dccph_type  = DCCP_PKT_RESET;
346         dh->dccph_x     = 1;
347         dccp_hdr_set_seq(dh, dp->dccps_gss);
348         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
349
350         dccp_hdr_reset(skb)->dccph_reset_code = code;
351
352         dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
353                                               inet_sk(sk)->daddr);
354
355         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
356         return skb;
357 }
358
359 /*
360  * Do all connect socket setups that can be done AF independent.
361  */
362 static inline void dccp_connect_init(struct sock *sk)
363 {
364         struct dst_entry *dst = __sk_dst_get(sk);
365         struct inet_connection_sock *icsk = inet_csk(sk);
366
367         sk->sk_err = 0;
368         sock_reset_flag(sk, SOCK_DONE);
369         
370         dccp_sync_mss(sk, dst_mtu(dst));
371
372         /*
373          * FIXME: set dp->{dccps_swh,dccps_swl}, with
374          * something like dccp_inc_seq
375          */
376
377         icsk->icsk_retransmits = 0;
378 }
379
380 int dccp_connect(struct sock *sk)
381 {
382         struct sk_buff *skb;
383         struct inet_connection_sock *icsk = inet_csk(sk);
384
385         dccp_connect_init(sk);
386
387         skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
388         if (unlikely(skb == NULL))
389                 return -ENOBUFS;
390
391         /* Reserve space for headers. */
392         skb_reserve(skb, MAX_DCCP_HEADER);
393
394         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
395         skb->csum = 0;
396         skb_set_owner_w(skb, sk);
397
398         BUG_TRAP(sk->sk_send_head == NULL);
399         sk->sk_send_head = skb;
400         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
401         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
402
403         /* Timer for repeating the REQUEST until an answer. */
404         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
405                                   icsk->icsk_rto, DCCP_RTO_MAX);
406         return 0;
407 }
408
409 void dccp_send_ack(struct sock *sk)
410 {
411         /* If we have been reset, we may not send again. */
412         if (sk->sk_state != DCCP_CLOSED) {
413                 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
414
415                 if (skb == NULL) {
416                         inet_csk_schedule_ack(sk);
417                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
418                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
419                                                   TCP_DELACK_MAX,
420                                                   DCCP_RTO_MAX);
421                         return;
422                 }
423
424                 /* Reserve space for headers */
425                 skb_reserve(skb, MAX_DCCP_HEADER);
426                 skb->csum = 0;
427                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
428                 skb_set_owner_w(skb, sk);
429                 dccp_transmit_skb(sk, skb);
430         }
431 }
432
433 EXPORT_SYMBOL_GPL(dccp_send_ack);
434
435 void dccp_send_delayed_ack(struct sock *sk)
436 {
437         struct inet_connection_sock *icsk = inet_csk(sk);
438         /*
439          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
440          * with using 2s, and active senders also piggyback the ACK into a
441          * DATAACK packet, so this is really for quiescent senders.
442          */
443         unsigned long timeout = jiffies + 2 * HZ;
444
445         /* Use new timeout only if there wasn't a older one earlier. */
446         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
447                 /* If delack timer was blocked or is about to expire,
448                  * send ACK now.
449                  *
450                  * FIXME: check the "about to expire" part
451                  */
452                 if (icsk->icsk_ack.blocked) {
453                         dccp_send_ack(sk);
454                         return;
455                 }
456
457                 if (!time_before(timeout, icsk->icsk_ack.timeout))
458                         timeout = icsk->icsk_ack.timeout;
459         }
460         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
461         icsk->icsk_ack.timeout = timeout;
462         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
463 }
464
465 void dccp_send_sync(struct sock *sk, const u64 seq,
466                     const enum dccp_pkt_type pkt_type)
467 {
468         /*
469          * We are not putting this on the write queue, so
470          * dccp_transmit_skb() will set the ownership to this
471          * sock.
472          */
473         struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
474
475         if (skb == NULL)
476                 /* FIXME: how to make sure the sync is sent? */
477                 return;
478
479         /* Reserve space for headers and prepare control bits. */
480         skb_reserve(skb, MAX_DCCP_HEADER);
481         skb->csum = 0;
482         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
483         DCCP_SKB_CB(skb)->dccpd_seq = seq;
484
485         skb_set_owner_w(skb, sk);
486         dccp_transmit_skb(sk, skb);
487 }
488
489 /*
490  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
491  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
492  * any circumstances.
493  */
494 void dccp_send_close(struct sock *sk, const int active)
495 {
496         struct dccp_sock *dp = dccp_sk(sk);
497         struct sk_buff *skb;
498         const unsigned int prio = active ? GFP_KERNEL : GFP_ATOMIC;
499
500         skb = alloc_skb(sk->sk_prot->max_header, prio);
501         if (skb == NULL)
502                 return;
503
504         /* Reserve space for headers and prepare control bits. */
505         skb_reserve(skb, sk->sk_prot->max_header);
506         skb->csum = 0;
507         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
508                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
509
510         skb_set_owner_w(skb, sk);
511         if (active) {
512                 BUG_TRAP(sk->sk_send_head == NULL);
513                 sk->sk_send_head = skb;
514                 dccp_transmit_skb(sk, skb_clone(skb, prio));
515         } else
516                 dccp_transmit_skb(sk, skb);
517 }