[DCCP]: Use skb_set_owner_w in dccp_transmit_skb when skb->sk is NULL
[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                 if (!skb->sk)
67                         skb_set_owner_w(skb, sk);
68
69                 /* Build DCCP header and checksum it. */
70                 memset(dh, 0, dccp_header_size);
71                 dh->dccph_type  = dcb->dccpd_type;
72                 dh->dccph_sport = inet->sport;
73                 dh->dccph_dport = inet->dport;
74                 dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
75                 dh->dccph_ccval = dcb->dccpd_ccval;
76                 /* XXX For now we're using only 48 bits sequence numbers */
77                 dh->dccph_x     = 1;
78
79                 dp->dccps_awh = dp->dccps_gss;
80                 dccp_hdr_set_seq(dh, dp->dccps_gss);
81                 if (set_ack)
82                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
83
84                 switch (dcb->dccpd_type) {
85                 case DCCP_PKT_REQUEST:
86                         dccp_hdr_request(skb)->dccph_req_service =
87                                                         dp->dccps_service;
88                         break;
89                 case DCCP_PKT_RESET:
90                         dccp_hdr_reset(skb)->dccph_reset_code =
91                                                         dcb->dccpd_reset_code;
92                         break;
93                 }
94
95                 dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
96                                                       inet->daddr);
97
98                 if (set_ack)
99                         dccp_event_ack_sent(sk);
100
101                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
102
103                 err = ip_queue_xmit(skb, 0);
104                 if (err <= 0)
105                         return err;
106
107                 /* NET_XMIT_CN is special. It does not guarantee,
108                  * that this packet is lost. It tells that device
109                  * is about to start to drop packets or already
110                  * drops some packets of the same priority and
111                  * invokes us to send less aggressively.
112                  */
113                 return err == NET_XMIT_CN ? 0 : err;
114         }
115         return -ENOBUFS;
116 }
117
118 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
119 {
120         struct dccp_sock *dp = dccp_sk(sk);
121         int mss_now;
122
123         /*
124          * FIXME: we really should be using the af_specific thing to support
125          *        IPv6.
126          * mss_now = pmtu - tp->af_specific->net_header_len -
127          *           sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
128          */
129         mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
130                   sizeof(struct dccp_hdr_ext);
131
132         /* Now subtract optional transport overhead */
133         mss_now -= dp->dccps_ext_header_len;
134
135         /*
136          * FIXME: this should come from the CCID infrastructure, where, say,
137          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
138          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
139          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
140          * make it a multiple of 4
141          */
142
143         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
144
145         /* And store cached results */
146         dp->dccps_pmtu_cookie = pmtu;
147         dp->dccps_mss_cache = mss_now;
148
149         return mss_now;
150 }
151
152 void dccp_write_space(struct sock *sk)
153 {
154         read_lock(&sk->sk_callback_lock);
155
156         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
157                 wake_up_interruptible(sk->sk_sleep);
158         /* Should agree with poll, otherwise some programs break */
159         if (sock_writeable(sk))
160                 sk_wake_async(sk, 2, POLL_OUT);
161
162         read_unlock(&sk->sk_callback_lock);
163 }
164
165 /**
166  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
167  * @sk: socket to wait for
168  * @timeo: for how long
169  */
170 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
171                               long *timeo)
172 {
173         struct dccp_sock *dp = dccp_sk(sk);
174         DEFINE_WAIT(wait);
175         long delay;
176         int rc;
177
178         while (1) {
179                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
180
181                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
182                         goto do_error;
183                 if (!*timeo)
184                         goto do_nonblock;
185                 if (signal_pending(current))
186                         goto do_interrupted;
187
188                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
189                                             skb->len);
190                 if (rc <= 0)
191                         break;
192                 delay = msecs_to_jiffies(rc);
193                 if (delay > *timeo || delay < 0)
194                         goto do_nonblock;
195
196                 sk->sk_write_pending++;
197                 release_sock(sk);
198                 *timeo -= schedule_timeout(delay);
199                 lock_sock(sk);
200                 sk->sk_write_pending--;
201         }
202 out:
203         finish_wait(sk->sk_sleep, &wait);
204         return rc;
205
206 do_error:
207         rc = -EPIPE;
208         goto out;
209 do_nonblock:
210         rc = -EAGAIN;
211         goto out;
212 do_interrupted:
213         rc = sock_intr_errno(*timeo);
214         goto out;
215 }
216
217 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
218 {
219         const struct dccp_sock *dp = dccp_sk(sk);
220         int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
221                                          skb->len);
222
223         if (err > 0)
224                 err = dccp_wait_for_ccid(sk, skb, timeo);
225
226         if (err == 0) {
227                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
228                 const int len = skb->len;
229
230                 if (sk->sk_state == DCCP_PARTOPEN) {
231                         /* See 8.1.5.  Handshake Completion */
232                         inet_csk_schedule_ack(sk);
233                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
234                                                   inet_csk(sk)->icsk_rto,
235                                                   DCCP_RTO_MAX);
236                         dcb->dccpd_type = DCCP_PKT_DATAACK;
237                 } else if (dccp_ack_pending(sk))
238                         dcb->dccpd_type = DCCP_PKT_DATAACK;
239                 else
240                         dcb->dccpd_type = DCCP_PKT_DATA;
241
242                 err = dccp_transmit_skb(sk, skb);
243                 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
244         }
245
246         return err;
247 }
248
249 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
250 {
251         if (inet_sk_rebuild_header(sk) != 0)
252                 return -EHOSTUNREACH; /* Routing failure or similar. */
253
254         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
255                                       pskb_copy(skb, GFP_ATOMIC):
256                                       skb_clone(skb, GFP_ATOMIC)));
257 }
258
259 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
260                                    struct request_sock *req)
261 {
262         struct dccp_hdr *dh;
263         struct dccp_request_sock *dreq;
264         const int dccp_header_size = sizeof(struct dccp_hdr) +
265                                      sizeof(struct dccp_hdr_ext) +
266                                      sizeof(struct dccp_hdr_response);
267         struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
268                                                dccp_header_size, 1,
269                                            GFP_ATOMIC);
270         if (skb == NULL)
271                 return NULL;
272
273         /* Reserve space for headers. */
274         skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
275
276         skb->dst = dst_clone(dst);
277         skb->csum = 0;
278
279         dreq = dccp_rsk(req);
280         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
281         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
282         dccp_insert_options(sk, skb);
283
284         skb->h.raw = skb_push(skb, dccp_header_size);
285
286         dh = dccp_hdr(skb);
287         memset(dh, 0, dccp_header_size);
288
289         dh->dccph_sport = inet_sk(sk)->sport;
290         dh->dccph_dport = inet_rsk(req)->rmt_port;
291         dh->dccph_doff  = (dccp_header_size +
292                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
293         dh->dccph_type  = DCCP_PKT_RESPONSE;
294         dh->dccph_x     = 1;
295         dccp_hdr_set_seq(dh, dreq->dreq_iss);
296         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
297         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
298
299         dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
300                                               inet_rsk(req)->rmt_addr);
301
302         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
303         return skb;
304 }
305
306 struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
307                                 const enum dccp_reset_codes code)
308                                    
309 {
310         struct dccp_hdr *dh;
311         struct dccp_sock *dp = dccp_sk(sk);
312         const int dccp_header_size = sizeof(struct dccp_hdr) +
313                                      sizeof(struct dccp_hdr_ext) +
314                                      sizeof(struct dccp_hdr_reset);
315         struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
316                                                dccp_header_size, 1,
317                                            GFP_ATOMIC);
318         if (skb == NULL)
319                 return NULL;
320
321         /* Reserve space for headers. */
322         skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
323
324         skb->dst = dst_clone(dst);
325         skb->csum = 0;
326
327         dccp_inc_seqno(&dp->dccps_gss);
328
329         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
330         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
331         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
332         dccp_insert_options(sk, skb);
333
334         skb->h.raw = skb_push(skb, dccp_header_size);
335
336         dh = dccp_hdr(skb);
337         memset(dh, 0, dccp_header_size);
338
339         dh->dccph_sport = inet_sk(sk)->sport;
340         dh->dccph_dport = inet_sk(sk)->dport;
341         dh->dccph_doff  = (dccp_header_size +
342                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
343         dh->dccph_type  = DCCP_PKT_RESET;
344         dh->dccph_x     = 1;
345         dccp_hdr_set_seq(dh, dp->dccps_gss);
346         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
347
348         dccp_hdr_reset(skb)->dccph_reset_code = code;
349
350         dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
351                                               inet_sk(sk)->daddr);
352
353         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
354         return skb;
355 }
356
357 /*
358  * Do all connect socket setups that can be done AF independent.
359  */
360 static inline void dccp_connect_init(struct sock *sk)
361 {
362         struct dst_entry *dst = __sk_dst_get(sk);
363         struct inet_connection_sock *icsk = inet_csk(sk);
364
365         sk->sk_err = 0;
366         sock_reset_flag(sk, SOCK_DONE);
367         
368         dccp_sync_mss(sk, dst_mtu(dst));
369
370         /*
371          * FIXME: set dp->{dccps_swh,dccps_swl}, with
372          * something like dccp_inc_seq
373          */
374
375         icsk->icsk_retransmits = 0;
376 }
377
378 int dccp_connect(struct sock *sk)
379 {
380         struct sk_buff *skb;
381         struct inet_connection_sock *icsk = inet_csk(sk);
382
383         dccp_connect_init(sk);
384
385         skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
386         if (unlikely(skb == NULL))
387                 return -ENOBUFS;
388
389         /* Reserve space for headers. */
390         skb_reserve(skb, MAX_DCCP_HEADER);
391
392         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
393         skb->csum = 0;
394         skb_set_owner_w(skb, sk);
395
396         BUG_TRAP(sk->sk_send_head == NULL);
397         sk->sk_send_head = skb;
398         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
399         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
400
401         /* Timer for repeating the REQUEST until an answer. */
402         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
403                                   icsk->icsk_rto, DCCP_RTO_MAX);
404         return 0;
405 }
406
407 void dccp_send_ack(struct sock *sk)
408 {
409         /* If we have been reset, we may not send again. */
410         if (sk->sk_state != DCCP_CLOSED) {
411                 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
412
413                 if (skb == NULL) {
414                         inet_csk_schedule_ack(sk);
415                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
416                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
417                                                   TCP_DELACK_MAX,
418                                                   DCCP_RTO_MAX);
419                         return;
420                 }
421
422                 /* Reserve space for headers */
423                 skb_reserve(skb, MAX_DCCP_HEADER);
424                 skb->csum = 0;
425                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
426                 skb_set_owner_w(skb, sk);
427                 dccp_transmit_skb(sk, skb);
428         }
429 }
430
431 EXPORT_SYMBOL_GPL(dccp_send_ack);
432
433 void dccp_send_delayed_ack(struct sock *sk)
434 {
435         struct inet_connection_sock *icsk = inet_csk(sk);
436         /*
437          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
438          * with using 2s, and active senders also piggyback the ACK into a
439          * DATAACK packet, so this is really for quiescent senders.
440          */
441         unsigned long timeout = jiffies + 2 * HZ;
442
443         /* Use new timeout only if there wasn't a older one earlier. */
444         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
445                 /* If delack timer was blocked or is about to expire,
446                  * send ACK now.
447                  *
448                  * FIXME: check the "about to expire" part
449                  */
450                 if (icsk->icsk_ack.blocked) {
451                         dccp_send_ack(sk);
452                         return;
453                 }
454
455                 if (!time_before(timeout, icsk->icsk_ack.timeout))
456                         timeout = icsk->icsk_ack.timeout;
457         }
458         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
459         icsk->icsk_ack.timeout = timeout;
460         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
461 }
462
463 void dccp_send_sync(struct sock *sk, const u64 seq,
464                     const enum dccp_pkt_type pkt_type)
465 {
466         /*
467          * We are not putting this on the write queue, so
468          * dccp_transmit_skb() will set the ownership to this
469          * sock.
470          */
471         struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
472
473         if (skb == NULL)
474                 /* FIXME: how to make sure the sync is sent? */
475                 return;
476
477         /* Reserve space for headers and prepare control bits. */
478         skb_reserve(skb, MAX_DCCP_HEADER);
479         skb->csum = 0;
480         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
481         DCCP_SKB_CB(skb)->dccpd_seq = seq;
482
483         skb_set_owner_w(skb, sk);
484         dccp_transmit_skb(sk, skb);
485 }
486
487 /*
488  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
489  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
490  * any circumstances.
491  */
492 void dccp_send_close(struct sock *sk, const int active)
493 {
494         struct dccp_sock *dp = dccp_sk(sk);
495         struct sk_buff *skb;
496         const unsigned int prio = active ? GFP_KERNEL : GFP_ATOMIC;
497
498         skb = alloc_skb(sk->sk_prot->max_header, prio);
499         if (skb == NULL)
500                 return;
501
502         /* Reserve space for headers and prepare control bits. */
503         skb_reserve(skb, sk->sk_prot->max_header);
504         skb->csum = 0;
505         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
506                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
507
508         skb_set_owner_w(skb, sk);
509         if (active) {
510                 BUG_TRAP(sk->sk_send_head == NULL);
511                 sk->sk_send_head = skb;
512                 dccp_transmit_skb(sk, skb_clone(skb, prio));
513         } else
514                 dccp_transmit_skb(sk, skb);
515 }