~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/dccp/output.c

Version: ~ [ linux-5.9-rc6 ] ~ [ linux-5.8.10 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.66 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.146 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.198 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.236 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.236 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  *  net/dccp/output.c
  4  *
  5  *  An implementation of the DCCP protocol
  6  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  7  */
  8 
  9 #include <linux/dccp.h>
 10 #include <linux/kernel.h>
 11 #include <linux/skbuff.h>
 12 #include <linux/slab.h>
 13 #include <linux/sched/signal.h>
 14 
 15 #include <net/inet_sock.h>
 16 #include <net/sock.h>
 17 
 18 #include "ackvec.h"
 19 #include "ccid.h"
 20 #include "dccp.h"
 21 
 22 static inline void dccp_event_ack_sent(struct sock *sk)
 23 {
 24         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 25 }
 26 
 27 /* enqueue @skb on sk_send_head for retransmission, return clone to send now */
 28 static struct sk_buff *dccp_skb_entail(struct sock *sk, struct sk_buff *skb)
 29 {
 30         skb_set_owner_w(skb, sk);
 31         WARN_ON(sk->sk_send_head);
 32         sk->sk_send_head = skb;
 33         return skb_clone(sk->sk_send_head, gfp_any());
 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                 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                  * Increment GSS here already in case the option code needs it.
 58                  * Update GSS for real only if option processing below succeeds.
 59                  */
 60                 dcb->dccpd_seq = ADD48(dp->dccps_gss, 1);
 61 
 62                 switch (dcb->dccpd_type) {
 63                 case DCCP_PKT_DATA:
 64                         set_ack = 0;
 65                         /* fall through */
 66                 case DCCP_PKT_DATAACK:
 67                 case DCCP_PKT_RESET:
 68                         break;
 69 
 70                 case DCCP_PKT_REQUEST:
 71                         set_ack = 0;
 72                         /* Use ISS on the first (non-retransmitted) Request. */
 73                         if (icsk->icsk_retransmits == 0)
 74                                 dcb->dccpd_seq = dp->dccps_iss;
 75                         /* fall through */
 76 
 77                 case DCCP_PKT_SYNC:
 78                 case DCCP_PKT_SYNCACK:
 79                         ackno = dcb->dccpd_ack_seq;
 80                         /* fall through */
 81                 default:
 82                         /*
 83                          * Set owner/destructor: some skbs are allocated via
 84                          * alloc_skb (e.g. when retransmission may happen).
 85                          * Only Data, DataAck, and Reset packets should come
 86                          * through here with skb->sk set.
 87                          */
 88                         WARN_ON(skb->sk);
 89                         skb_set_owner_w(skb, sk);
 90                         break;
 91                 }
 92 
 93                 if (dccp_insert_options(sk, skb)) {
 94                         kfree_skb(skb);
 95                         return -EPROTO;
 96                 }
 97 
 98 
 99                 /* Build DCCP header and checksum it. */
100                 dh = dccp_zeroed_hdr(skb, dccp_header_size);
101                 dh->dccph_type  = dcb->dccpd_type;
102                 dh->dccph_sport = inet->inet_sport;
103                 dh->dccph_dport = inet->inet_dport;
104                 dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
105                 dh->dccph_ccval = dcb->dccpd_ccval;
106                 dh->dccph_cscov = dp->dccps_pcslen;
107                 /* XXX For now we're using only 48 bits sequence numbers */
108                 dh->dccph_x     = 1;
109 
110                 dccp_update_gss(sk, dcb->dccpd_seq);
111                 dccp_hdr_set_seq(dh, dp->dccps_gss);
112                 if (set_ack)
113                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
114 
115                 switch (dcb->dccpd_type) {
116                 case DCCP_PKT_REQUEST:
117                         dccp_hdr_request(skb)->dccph_req_service =
118                                                         dp->dccps_service;
119                         /*
120                          * Limit Ack window to ISS <= P.ackno <= GSS, so that
121                          * only Responses to Requests we sent are considered.
122                          */
123                         dp->dccps_awl = dp->dccps_iss;
124                         break;
125                 case DCCP_PKT_RESET:
126                         dccp_hdr_reset(skb)->dccph_reset_code =
127                                                         dcb->dccpd_reset_code;
128                         break;
129                 }
130 
131                 icsk->icsk_af_ops->send_check(sk, skb);
132 
133                 if (set_ack)
134                         dccp_event_ack_sent(sk);
135 
136                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
137 
138                 err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl);
139                 return net_xmit_eval(err);
140         }
141         return -ENOBUFS;
142 }
143 
144 /**
145  * dccp_determine_ccmps  -  Find out about CCID-specific packet-size limits
146  * We only consider the HC-sender CCID for setting the CCMPS (RFC 4340, 14.),
147  * since the RX CCID is restricted to feedback packets (Acks), which are small
148  * in comparison with the data traffic. A value of 0 means "no current CCMPS".
149  */
150 static u32 dccp_determine_ccmps(const struct dccp_sock *dp)
151 {
152         const struct ccid *tx_ccid = dp->dccps_hc_tx_ccid;
153 
154         if (tx_ccid == NULL || tx_ccid->ccid_ops == NULL)
155                 return 0;
156         return tx_ccid->ccid_ops->ccid_ccmps;
157 }
158 
159 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
160 {
161         struct inet_connection_sock *icsk = inet_csk(sk);
162         struct dccp_sock *dp = dccp_sk(sk);
163         u32 ccmps = dccp_determine_ccmps(dp);
164         u32 cur_mps = ccmps ? min(pmtu, ccmps) : pmtu;
165 
166         /* Account for header lengths and IPv4/v6 option overhead */
167         cur_mps -= (icsk->icsk_af_ops->net_header_len + icsk->icsk_ext_hdr_len +
168                     sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext));
169 
170         /*
171          * Leave enough headroom for common DCCP header options.
172          * This only considers options which may appear on DCCP-Data packets, as
173          * per table 3 in RFC 4340, 5.8. When running out of space for other
174          * options (eg. Ack Vector which can take up to 255 bytes), it is better
175          * to schedule a separate Ack. Thus we leave headroom for the following:
176          *  - 1 byte for Slow Receiver (11.6)
177          *  - 6 bytes for Timestamp (13.1)
178          *  - 10 bytes for Timestamp Echo (13.3)
179          *  - 8 bytes for NDP count (7.7, when activated)
180          *  - 6 bytes for Data Checksum (9.3)
181          *  - %DCCPAV_MIN_OPTLEN bytes for Ack Vector size (11.4, when enabled)
182          */
183         cur_mps -= roundup(1 + 6 + 10 + dp->dccps_send_ndp_count * 8 + 6 +
184                            (dp->dccps_hc_rx_ackvec ? DCCPAV_MIN_OPTLEN : 0), 4);
185 
186         /* And store cached results */
187         icsk->icsk_pmtu_cookie = pmtu;
188         dp->dccps_mss_cache = cur_mps;
189 
190         return cur_mps;
191 }
192 
193 EXPORT_SYMBOL_GPL(dccp_sync_mss);
194 
195 void dccp_write_space(struct sock *sk)
196 {
197         struct socket_wq *wq;
198 
199         rcu_read_lock();
200         wq = rcu_dereference(sk->sk_wq);
201         if (skwq_has_sleeper(wq))
202                 wake_up_interruptible(&wq->wait);
203         /* Should agree with poll, otherwise some programs break */
204         if (sock_writeable(sk))
205                 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
206 
207         rcu_read_unlock();
208 }
209 
210 /**
211  * dccp_wait_for_ccid  -  Await CCID send permission
212  * @sk:    socket to wait for
213  * @delay: timeout in jiffies
214  *
215  * This is used by CCIDs which need to delay the send time in process context.
216  */
217 static int dccp_wait_for_ccid(struct sock *sk, unsigned long delay)
218 {
219         DEFINE_WAIT(wait);
220         long remaining;
221 
222         prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
223         sk->sk_write_pending++;
224         release_sock(sk);
225 
226         remaining = schedule_timeout(delay);
227 
228         lock_sock(sk);
229         sk->sk_write_pending--;
230         finish_wait(sk_sleep(sk), &wait);
231 
232         if (signal_pending(current) || sk->sk_err)
233                 return -1;
234         return remaining;
235 }
236 
237 /**
238  * dccp_xmit_packet  -  Send data packet under control of CCID
239  * Transmits next-queued payload and informs CCID to account for the packet.
240  */
241 static void dccp_xmit_packet(struct sock *sk)
242 {
243         int err, len;
244         struct dccp_sock *dp = dccp_sk(sk);
245         struct sk_buff *skb = dccp_qpolicy_pop(sk);
246 
247         if (unlikely(skb == NULL))
248                 return;
249         len = skb->len;
250 
251         if (sk->sk_state == DCCP_PARTOPEN) {
252                 const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD;
253                 /*
254                  * See 8.1.5 - Handshake Completion.
255                  *
256                  * For robustness we resend Confirm options until the client has
257                  * entered OPEN. During the initial feature negotiation, the MPS
258                  * is smaller than usual, reduced by the Change/Confirm options.
259                  */
260                 if (!list_empty(&dp->dccps_featneg) && len > cur_mps) {
261                         DCCP_WARN("Payload too large (%d) for featneg.\n", len);
262                         dccp_send_ack(sk);
263                         dccp_feat_list_purge(&dp->dccps_featneg);
264                 }
265 
266                 inet_csk_schedule_ack(sk);
267                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
268                                               inet_csk(sk)->icsk_rto,
269                                               DCCP_RTO_MAX);
270                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK;
271         } else if (dccp_ack_pending(sk)) {
272                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK;
273         } else {
274                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATA;
275         }
276 
277         err = dccp_transmit_skb(sk, skb);
278         if (err)
279                 dccp_pr_debug("transmit_skb() returned err=%d\n", err);
280         /*
281          * Register this one as sent even if an error occurred. To the remote
282          * end a local packet drop is indistinguishable from network loss, i.e.
283          * any local drop will eventually be reported via receiver feedback.
284          */
285         ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len);
286 
287         /*
288          * If the CCID needs to transfer additional header options out-of-band
289          * (e.g. Ack Vectors or feature-negotiation options), it activates this
290          * flag to schedule a Sync. The Sync will automatically incorporate all
291          * currently pending header options, thus clearing the backlog.
292          */
293         if (dp->dccps_sync_scheduled)
294                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
295 }
296 
297 /**
298  * dccp_flush_write_queue  -  Drain queue at end of connection
299  * Since dccp_sendmsg queues packets without waiting for them to be sent, it may
300  * happen that the TX queue is not empty at the end of a connection. We give the
301  * HC-sender CCID a grace period of up to @time_budget jiffies. If this function
302  * returns with a non-empty write queue, it will be purged later.
303  */
304 void dccp_flush_write_queue(struct sock *sk, long *time_budget)
305 {
306         struct dccp_sock *dp = dccp_sk(sk);
307         struct sk_buff *skb;
308         long delay, rc;
309 
310         while (*time_budget > 0 && (skb = skb_peek(&sk->sk_write_queue))) {
311                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
312 
313                 switch (ccid_packet_dequeue_eval(rc)) {
314                 case CCID_PACKET_WILL_DEQUEUE_LATER:
315                         /*
316                          * If the CCID determines when to send, the next sending
317                          * time is unknown or the CCID may not even send again
318                          * (e.g. remote host crashes or lost Ack packets).
319                          */
320                         DCCP_WARN("CCID did not manage to send all packets\n");
321                         return;
322                 case CCID_PACKET_DELAY:
323                         delay = msecs_to_jiffies(rc);
324                         if (delay > *time_budget)
325                                 return;
326                         rc = dccp_wait_for_ccid(sk, delay);
327                         if (rc < 0)
328                                 return;
329                         *time_budget -= (delay - rc);
330                         /* check again if we can send now */
331                         break;
332                 case CCID_PACKET_SEND_AT_ONCE:
333                         dccp_xmit_packet(sk);
334                         break;
335                 case CCID_PACKET_ERR:
336                         skb_dequeue(&sk->sk_write_queue);
337                         kfree_skb(skb);
338                         dccp_pr_debug("packet discarded due to err=%ld\n", rc);
339                 }
340         }
341 }
342 
343 void dccp_write_xmit(struct sock *sk)
344 {
345         struct dccp_sock *dp = dccp_sk(sk);
346         struct sk_buff *skb;
347 
348         while ((skb = dccp_qpolicy_top(sk))) {
349                 int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
350 
351                 switch (ccid_packet_dequeue_eval(rc)) {
352                 case CCID_PACKET_WILL_DEQUEUE_LATER:
353                         return;
354                 case CCID_PACKET_DELAY:
355                         sk_reset_timer(sk, &dp->dccps_xmit_timer,
356                                        jiffies + msecs_to_jiffies(rc));
357                         return;
358                 case CCID_PACKET_SEND_AT_ONCE:
359                         dccp_xmit_packet(sk);
360                         break;
361                 case CCID_PACKET_ERR:
362                         dccp_qpolicy_drop(sk, skb);
363                         dccp_pr_debug("packet discarded due to err=%d\n", rc);
364                 }
365         }
366 }
367 
368 /**
369  * dccp_retransmit_skb  -  Retransmit Request, Close, or CloseReq packets
370  * There are only four retransmittable packet types in DCCP:
371  * - Request  in client-REQUEST  state (sec. 8.1.1),
372  * - CloseReq in server-CLOSEREQ state (sec. 8.3),
373  * - Close    in   node-CLOSING  state (sec. 8.3),
374  * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()).
375  * This function expects sk->sk_send_head to contain the original skb.
376  */
377 int dccp_retransmit_skb(struct sock *sk)
378 {
379         WARN_ON(sk->sk_send_head == NULL);
380 
381         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
382                 return -EHOSTUNREACH; /* Routing failure or similar. */
383 
384         /* this count is used to distinguish original and retransmitted skb */
385         inet_csk(sk)->icsk_retransmits++;
386 
387         return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC));
388 }
389 
390 struct sk_buff *dccp_make_response(const struct sock *sk, struct dst_entry *dst,
391                                    struct request_sock *req)
392 {
393         struct dccp_hdr *dh;
394         struct dccp_request_sock *dreq;
395         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
396                                      sizeof(struct dccp_hdr_ext) +
397                                      sizeof(struct dccp_hdr_response);
398         struct sk_buff *skb;
399 
400         /* sk is marked const to clearly express we dont hold socket lock.
401          * sock_wmalloc() will atomically change sk->sk_wmem_alloc,
402          * it is safe to promote sk to non const.
403          */
404         skb = sock_wmalloc((struct sock *)sk, MAX_DCCP_HEADER, 1,
405                            GFP_ATOMIC);
406         if (!skb)
407                 return NULL;
408 
409         skb_reserve(skb, MAX_DCCP_HEADER);
410 
411         skb_dst_set(skb, dst_clone(dst));
412 
413         dreq = dccp_rsk(req);
414         if (inet_rsk(req)->acked)       /* increase GSS upon retransmission */
415                 dccp_inc_seqno(&dreq->dreq_gss);
416         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
417         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_gss;
418 
419         /* Resolve feature dependencies resulting from choice of CCID */
420         if (dccp_feat_server_ccid_dependencies(dreq))
421                 goto response_failed;
422 
423         if (dccp_insert_options_rsk(dreq, skb))
424                 goto response_failed;
425 
426         /* Build and checksum header */
427         dh = dccp_zeroed_hdr(skb, dccp_header_size);
428 
429         dh->dccph_sport = htons(inet_rsk(req)->ir_num);
430         dh->dccph_dport = inet_rsk(req)->ir_rmt_port;
431         dh->dccph_doff  = (dccp_header_size +
432                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
433         dh->dccph_type  = DCCP_PKT_RESPONSE;
434         dh->dccph_x     = 1;
435         dccp_hdr_set_seq(dh, dreq->dreq_gss);
436         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_gsr);
437         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
438 
439         dccp_csum_outgoing(skb);
440 
441         /* We use `acked' to remember that a Response was already sent. */
442         inet_rsk(req)->acked = 1;
443         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
444         return skb;
445 response_failed:
446         kfree_skb(skb);
447         return NULL;
448 }
449 
450 EXPORT_SYMBOL_GPL(dccp_make_response);
451 
452 /* answer offending packet in @rcv_skb with Reset from control socket @ctl */
453 struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb)
454 {
455         struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh;
456         struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb);
457         const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
458                                        sizeof(struct dccp_hdr_ext) +
459                                        sizeof(struct dccp_hdr_reset);
460         struct dccp_hdr_reset *dhr;
461         struct sk_buff *skb;
462 
463         skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
464         if (skb == NULL)
465                 return NULL;
466 
467         skb_reserve(skb, sk->sk_prot->max_header);
468 
469         /* Swap the send and the receive. */
470         dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
471         dh->dccph_type  = DCCP_PKT_RESET;
472         dh->dccph_sport = rxdh->dccph_dport;
473         dh->dccph_dport = rxdh->dccph_sport;
474         dh->dccph_doff  = dccp_hdr_reset_len / 4;
475         dh->dccph_x     = 1;
476 
477         dhr = dccp_hdr_reset(skb);
478         dhr->dccph_reset_code = dcb->dccpd_reset_code;
479 
480         switch (dcb->dccpd_reset_code) {
481         case DCCP_RESET_CODE_PACKET_ERROR:
482                 dhr->dccph_reset_data[0] = rxdh->dccph_type;
483                 break;
484         case DCCP_RESET_CODE_OPTION_ERROR:      /* fall through */
485         case DCCP_RESET_CODE_MANDATORY_ERROR:
486                 memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3);
487                 break;
488         }
489         /*
490          * From RFC 4340, 8.3.1:
491          *   If P.ackno exists, set R.seqno := P.ackno + 1.
492          *   Else set R.seqno := 0.
493          */
494         if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
495                 dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1));
496         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq);
497 
498         dccp_csum_outgoing(skb);
499         return skb;
500 }
501 
502 EXPORT_SYMBOL_GPL(dccp_ctl_make_reset);
503 
504 /* send Reset on established socket, to close or abort the connection */
505 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
506 {
507         struct sk_buff *skb;
508         /*
509          * FIXME: what if rebuild_header fails?
510          * Should we be doing a rebuild_header here?
511          */
512         int err = inet_csk(sk)->icsk_af_ops->rebuild_header(sk);
513 
514         if (err != 0)
515                 return err;
516 
517         skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC);
518         if (skb == NULL)
519                 return -ENOBUFS;
520 
521         /* Reserve space for headers and prepare control bits. */
522         skb_reserve(skb, sk->sk_prot->max_header);
523         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
524         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
525 
526         return dccp_transmit_skb(sk, skb);
527 }
528 
529 /*
530  * Do all connect socket setups that can be done AF independent.
531  */
532 int dccp_connect(struct sock *sk)
533 {
534         struct sk_buff *skb;
535         struct dccp_sock *dp = dccp_sk(sk);
536         struct dst_entry *dst = __sk_dst_get(sk);
537         struct inet_connection_sock *icsk = inet_csk(sk);
538 
539         sk->sk_err = 0;
540         sock_reset_flag(sk, SOCK_DONE);
541 
542         dccp_sync_mss(sk, dst_mtu(dst));
543 
544         /* do not connect if feature negotiation setup fails */
545         if (dccp_feat_finalise_settings(dccp_sk(sk)))
546                 return -EPROTO;
547 
548         /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */
549         dp->dccps_gar = dp->dccps_iss;
550 
551         skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
552         if (unlikely(skb == NULL))
553                 return -ENOBUFS;
554 
555         /* Reserve space for headers. */
556         skb_reserve(skb, sk->sk_prot->max_header);
557 
558         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
559 
560         dccp_transmit_skb(sk, dccp_skb_entail(sk, skb));
561         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
562 
563         /* Timer for repeating the REQUEST until an answer. */
564         icsk->icsk_retransmits = 0;
565         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
566                                   icsk->icsk_rto, DCCP_RTO_MAX);
567         return 0;
568 }
569 
570 EXPORT_SYMBOL_GPL(dccp_connect);
571 
572 void dccp_send_ack(struct sock *sk)
573 {
574         /* If we have been reset, we may not send again. */
575         if (sk->sk_state != DCCP_CLOSED) {
576                 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header,
577                                                 GFP_ATOMIC);
578 
579                 if (skb == NULL) {
580                         inet_csk_schedule_ack(sk);
581                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
582                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
583                                                   TCP_DELACK_MAX,
584                                                   DCCP_RTO_MAX);
585                         return;
586                 }
587 
588                 /* Reserve space for headers */
589                 skb_reserve(skb, sk->sk_prot->max_header);
590                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
591                 dccp_transmit_skb(sk, skb);
592         }
593 }
594 
595 EXPORT_SYMBOL_GPL(dccp_send_ack);
596 
597 #if 0
598 /* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */
599 void dccp_send_delayed_ack(struct sock *sk)
600 {
601         struct inet_connection_sock *icsk = inet_csk(sk);
602         /*
603          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
604          * with using 2s, and active senders also piggyback the ACK into a
605          * DATAACK packet, so this is really for quiescent senders.
606          */
607         unsigned long timeout = jiffies + 2 * HZ;
608 
609         /* Use new timeout only if there wasn't a older one earlier. */
610         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
611                 /* If delack timer was blocked or is about to expire,
612                  * send ACK now.
613                  *
614                  * FIXME: check the "about to expire" part
615                  */
616                 if (icsk->icsk_ack.blocked) {
617                         dccp_send_ack(sk);
618                         return;
619                 }
620 
621                 if (!time_before(timeout, icsk->icsk_ack.timeout))
622                         timeout = icsk->icsk_ack.timeout;
623         }
624         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
625         icsk->icsk_ack.timeout = timeout;
626         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
627 }
628 #endif
629 
630 void dccp_send_sync(struct sock *sk, const u64 ackno,
631                     const enum dccp_pkt_type pkt_type)
632 {
633         /*
634          * We are not putting this on the write queue, so
635          * dccp_transmit_skb() will set the ownership to this
636          * sock.
637          */
638         struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
639 
640         if (skb == NULL) {
641                 /* FIXME: how to make sure the sync is sent? */
642                 DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type));
643                 return;
644         }
645 
646         /* Reserve space for headers and prepare control bits. */
647         skb_reserve(skb, sk->sk_prot->max_header);
648         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
649         DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno;
650 
651         /*
652          * Clear the flag in case the Sync was scheduled for out-of-band data,
653          * such as carrying a long Ack Vector.
654          */
655         dccp_sk(sk)->dccps_sync_scheduled = 0;
656 
657         dccp_transmit_skb(sk, skb);
658 }
659 
660 EXPORT_SYMBOL_GPL(dccp_send_sync);
661 
662 /*
663  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
664  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
665  * any circumstances.
666  */
667 void dccp_send_close(struct sock *sk, const int active)
668 {
669         struct dccp_sock *dp = dccp_sk(sk);
670         struct sk_buff *skb;
671         const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
672 
673         skb = alloc_skb(sk->sk_prot->max_header, prio);
674         if (skb == NULL)
675                 return;
676 
677         /* Reserve space for headers and prepare control bits. */
678         skb_reserve(skb, sk->sk_prot->max_header);
679         if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait)
680                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ;
681         else
682                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE;
683 
684         if (active) {
685                 skb = dccp_skb_entail(sk, skb);
686                 /*
687                  * Retransmission timer for active-close: RFC 4340, 8.3 requires
688                  * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ
689                  * state can be left. The initial timeout is 2 RTTs.
690                  * Since RTT measurement is done by the CCIDs, there is no easy
691                  * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4
692                  * is too low (200ms); we use a high value to avoid unnecessary
693                  * retransmissions when the link RTT is > 0.2 seconds.
694                  * FIXME: Let main module sample RTTs and use that instead.
695                  */
696                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
697                                           DCCP_TIMEOUT_INIT, DCCP_RTO_MAX);
698         }
699         dccp_transmit_skb(sk, skb);
700 }
701 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp