1 /* 2 * net/dccp/output.c 3 * 4 * An implementation of the DCCP protocol 5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12 13 #include <linux/dccp.h> 14 #include <linux/kernel.h> 15 #include <linux/skbuff.h> 16 17 #include <net/inet_sock.h> 18 #include <net/sock.h> 19 20 #include "ackvec.h" 21 #include "ccid.h" 22 #include "dccp.h" 23 24 static inline void dccp_event_ack_sent(struct sock *sk) 25 { 26 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 27 } 28 29 static void dccp_skb_entail(struct sock *sk, struct sk_buff *skb) 30 { 31 skb_set_owner_w(skb, sk); 32 WARN_ON(sk->sk_send_head); 33 sk->sk_send_head = skb; 34 } 35 36 /* 37 * All SKB's seen here are completely headerless. It is our 38 * job to build the DCCP header, and pass the packet down to 39 * IP so it can do the same plus pass the packet off to the 40 * device. 41 */ 42 static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) 43 { 44 if (likely(skb != NULL)) { 45 const struct inet_sock *inet = inet_sk(sk); 46 const struct inet_connection_sock *icsk = inet_csk(sk); 47 struct dccp_sock *dp = dccp_sk(sk); 48 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 49 struct dccp_hdr *dh; 50 /* XXX For now we're using only 48 bits sequence numbers */ 51 const u32 dccp_header_size = sizeof(*dh) + 52 sizeof(struct dccp_hdr_ext) + 53 dccp_packet_hdr_len(dcb->dccpd_type); 54 int err, set_ack = 1; 55 u64 ackno = dp->dccps_gsr; 56 /* 57 * 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, 0, 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(skb, 0); 139 return net_xmit_eval(err); 140 } 141 return -ENOBUFS; 142 } 143 144 /** 145 * dccp_determine_ccmps - Find out about CCID-specfic 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 read_lock(&sk->sk_callback_lock); 198 199 if (sk_has_sleeper(sk)) 200 wake_up_interruptible(sk->sk_sleep); 201 /* Should agree with poll, otherwise some programs break */ 202 if (sock_writeable(sk)) 203 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); 204 205 read_unlock(&sk->sk_callback_lock); 206 } 207 208 /** 209 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet 210 * @sk: socket to wait for 211 * @skb: current skb to pass on for waiting 212 * @delay: sleep timeout in milliseconds (> 0) 213 * This function is called by default when the socket is closed, and 214 * when a non-zero linger time is set on the socket. For consistency 215 */ 216 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb, int delay) 217 { 218 struct dccp_sock *dp = dccp_sk(sk); 219 DEFINE_WAIT(wait); 220 unsigned long jiffdelay; 221 int rc; 222 223 do { 224 dccp_pr_debug("delayed send by %d msec\n", delay); 225 jiffdelay = msecs_to_jiffies(delay); 226 227 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); 228 229 sk->sk_write_pending++; 230 release_sock(sk); 231 schedule_timeout(jiffdelay); 232 lock_sock(sk); 233 sk->sk_write_pending--; 234 235 if (sk->sk_err) 236 goto do_error; 237 if (signal_pending(current)) 238 goto do_interrupted; 239 240 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); 241 } while ((delay = rc) > 0); 242 out: 243 finish_wait(sk->sk_sleep, &wait); 244 return rc; 245 246 do_error: 247 rc = -EPIPE; 248 goto out; 249 do_interrupted: 250 rc = -EINTR; 251 goto out; 252 } 253 254 void dccp_write_xmit(struct sock *sk, int block) 255 { 256 struct dccp_sock *dp = dccp_sk(sk); 257 struct sk_buff *skb; 258 259 while ((skb = skb_peek(&sk->sk_write_queue))) { 260 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); 261 262 if (err > 0) { 263 if (!block) { 264 sk_reset_timer(sk, &dp->dccps_xmit_timer, 265 msecs_to_jiffies(err)+jiffies); 266 break; 267 } else 268 err = dccp_wait_for_ccid(sk, skb, err); 269 if (err && err != -EINTR) 270 DCCP_BUG("err=%d after dccp_wait_for_ccid", err); 271 } 272 273 skb_dequeue(&sk->sk_write_queue); 274 if (err == 0) { 275 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 276 const int len = skb->len; 277 278 if (sk->sk_state == DCCP_PARTOPEN) { 279 const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD; 280 /* 281 * See 8.1.5 - Handshake Completion. 282 * 283 * For robustness we resend Confirm options until the client has 284 * entered OPEN. During the initial feature negotiation, the MPS 285 * is smaller than usual, reduced by the Change/Confirm options. 286 */ 287 if (!list_empty(&dp->dccps_featneg) && len > cur_mps) { 288 DCCP_WARN("Payload too large (%d) for featneg.\n", len); 289 dccp_send_ack(sk); 290 dccp_feat_list_purge(&dp->dccps_featneg); 291 } 292 293 inet_csk_schedule_ack(sk); 294 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 295 inet_csk(sk)->icsk_rto, 296 DCCP_RTO_MAX); 297 dcb->dccpd_type = DCCP_PKT_DATAACK; 298 } else if (dccp_ack_pending(sk)) 299 dcb->dccpd_type = DCCP_PKT_DATAACK; 300 else 301 dcb->dccpd_type = DCCP_PKT_DATA; 302 303 err = dccp_transmit_skb(sk, skb); 304 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len); 305 if (err) 306 DCCP_BUG("err=%d after ccid_hc_tx_packet_sent", 307 err); 308 } else { 309 dccp_pr_debug("packet discarded due to err=%d\n", err); 310 kfree_skb(skb); 311 } 312 } 313 } 314 315 /** 316 * dccp_retransmit_skb - Retransmit Request, Close, or CloseReq packets 317 * There are only four retransmittable packet types in DCCP: 318 * - Request in client-REQUEST state (sec. 8.1.1), 319 * - CloseReq in server-CLOSEREQ state (sec. 8.3), 320 * - Close in node-CLOSING state (sec. 8.3), 321 * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()). 322 * This function expects sk->sk_send_head to contain the original skb. 323 */ 324 int dccp_retransmit_skb(struct sock *sk) 325 { 326 WARN_ON(sk->sk_send_head == NULL); 327 328 if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0) 329 return -EHOSTUNREACH; /* Routing failure or similar. */ 330 331 /* this count is used to distinguish original and retransmitted skb */ 332 inet_csk(sk)->icsk_retransmits++; 333 334 return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC)); 335 } 336 337 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, 338 struct request_sock *req) 339 { 340 struct dccp_hdr *dh; 341 struct dccp_request_sock *dreq; 342 const u32 dccp_header_size = sizeof(struct dccp_hdr) + 343 sizeof(struct dccp_hdr_ext) + 344 sizeof(struct dccp_hdr_response); 345 struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 346 GFP_ATOMIC); 347 if (skb == NULL) 348 return NULL; 349 350 /* Reserve space for headers. */ 351 skb_reserve(skb, sk->sk_prot->max_header); 352 353 skb_dst_set(skb, dst_clone(dst)); 354 355 dreq = dccp_rsk(req); 356 if (inet_rsk(req)->acked) /* increase ISS upon retransmission */ 357 dccp_inc_seqno(&dreq->dreq_iss); 358 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; 359 DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss; 360 361 /* Resolve feature dependencies resulting from choice of CCID */ 362 if (dccp_feat_server_ccid_dependencies(dreq)) 363 goto response_failed; 364 365 if (dccp_insert_options_rsk(dreq, skb)) 366 goto response_failed; 367 368 /* Build and checksum header */ 369 dh = dccp_zeroed_hdr(skb, dccp_header_size); 370 371 dh->dccph_sport = inet_rsk(req)->loc_port; 372 dh->dccph_dport = inet_rsk(req)->rmt_port; 373 dh->dccph_doff = (dccp_header_size + 374 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 375 dh->dccph_type = DCCP_PKT_RESPONSE; 376 dh->dccph_x = 1; 377 dccp_hdr_set_seq(dh, dreq->dreq_iss); 378 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr); 379 dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service; 380 381 dccp_csum_outgoing(skb); 382 383 /* We use `acked' to remember that a Response was already sent. */ 384 inet_rsk(req)->acked = 1; 385 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 386 return skb; 387 response_failed: 388 kfree_skb(skb); 389 return NULL; 390 } 391 392 EXPORT_SYMBOL_GPL(dccp_make_response); 393 394 /* answer offending packet in @rcv_skb with Reset from control socket @ctl */ 395 struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb) 396 { 397 struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh; 398 struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb); 399 const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) + 400 sizeof(struct dccp_hdr_ext) + 401 sizeof(struct dccp_hdr_reset); 402 struct dccp_hdr_reset *dhr; 403 struct sk_buff *skb; 404 405 skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 406 if (skb == NULL) 407 return NULL; 408 409 skb_reserve(skb, sk->sk_prot->max_header); 410 411 /* Swap the send and the receive. */ 412 dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len); 413 dh->dccph_type = DCCP_PKT_RESET; 414 dh->dccph_sport = rxdh->dccph_dport; 415 dh->dccph_dport = rxdh->dccph_sport; 416 dh->dccph_doff = dccp_hdr_reset_len / 4; 417 dh->dccph_x = 1; 418 419 dhr = dccp_hdr_reset(skb); 420 dhr->dccph_reset_code = dcb->dccpd_reset_code; 421 422 switch (dcb->dccpd_reset_code) { 423 case DCCP_RESET_CODE_PACKET_ERROR: 424 dhr->dccph_reset_data[0] = rxdh->dccph_type; 425 break; 426 case DCCP_RESET_CODE_OPTION_ERROR: /* fall through */ 427 case DCCP_RESET_CODE_MANDATORY_ERROR: 428 memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3); 429 break; 430 } 431 /* 432 * From RFC 4340, 8.3.1: 433 * If P.ackno exists, set R.seqno := P.ackno + 1. 434 * Else set R.seqno := 0. 435 */ 436 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 437 dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1)); 438 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq); 439 440 dccp_csum_outgoing(skb); 441 return skb; 442 } 443 444 EXPORT_SYMBOL_GPL(dccp_ctl_make_reset); 445 446 /* send Reset on established socket, to close or abort the connection */ 447 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code) 448 { 449 struct sk_buff *skb; 450 /* 451 * FIXME: what if rebuild_header fails? 452 * Should we be doing a rebuild_header here? 453 */ 454 int err = inet_csk(sk)->icsk_af_ops->rebuild_header(sk); 455 456 if (err != 0) 457 return err; 458 459 skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC); 460 if (skb == NULL) 461 return -ENOBUFS; 462 463 /* Reserve space for headers and prepare control bits. */ 464 skb_reserve(skb, sk->sk_prot->max_header); 465 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; 466 DCCP_SKB_CB(skb)->dccpd_reset_code = code; 467 468 return dccp_transmit_skb(sk, skb); 469 } 470 471 /* 472 * Do all connect socket setups that can be done AF independent. 473 */ 474 static inline void dccp_connect_init(struct sock *sk) 475 { 476 struct dccp_sock *dp = dccp_sk(sk); 477 struct dst_entry *dst = __sk_dst_get(sk); 478 struct inet_connection_sock *icsk = inet_csk(sk); 479 480 sk->sk_err = 0; 481 sock_reset_flag(sk, SOCK_DONE); 482 483 dccp_sync_mss(sk, dst_mtu(dst)); 484 485 /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */ 486 dp->dccps_gar = dp->dccps_iss; 487 488 icsk->icsk_retransmits = 0; 489 } 490 491 int dccp_connect(struct sock *sk) 492 { 493 struct sk_buff *skb; 494 struct inet_connection_sock *icsk = inet_csk(sk); 495 496 /* do not connect if feature negotiation setup fails */ 497 if (dccp_feat_finalise_settings(dccp_sk(sk))) 498 return -EPROTO; 499 500 dccp_connect_init(sk); 501 502 skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation); 503 if (unlikely(skb == NULL)) 504 return -ENOBUFS; 505 506 /* Reserve space for headers. */ 507 skb_reserve(skb, sk->sk_prot->max_header); 508 509 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; 510 511 dccp_skb_entail(sk, skb); 512 dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL)); 513 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); 514 515 /* Timer for repeating the REQUEST until an answer. */ 516 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 517 icsk->icsk_rto, DCCP_RTO_MAX); 518 return 0; 519 } 520 521 EXPORT_SYMBOL_GPL(dccp_connect); 522 523 void dccp_send_ack(struct sock *sk) 524 { 525 /* If we have been reset, we may not send again. */ 526 if (sk->sk_state != DCCP_CLOSED) { 527 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, 528 GFP_ATOMIC); 529 530 if (skb == NULL) { 531 inet_csk_schedule_ack(sk); 532 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 533 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 534 TCP_DELACK_MAX, 535 DCCP_RTO_MAX); 536 return; 537 } 538 539 /* Reserve space for headers */ 540 skb_reserve(skb, sk->sk_prot->max_header); 541 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; 542 dccp_transmit_skb(sk, skb); 543 } 544 } 545 546 EXPORT_SYMBOL_GPL(dccp_send_ack); 547 548 #if 0 549 /* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */ 550 void dccp_send_delayed_ack(struct sock *sk) 551 { 552 struct inet_connection_sock *icsk = inet_csk(sk); 553 /* 554 * FIXME: tune this timer. elapsed time fixes the skew, so no problem 555 * with using 2s, and active senders also piggyback the ACK into a 556 * DATAACK packet, so this is really for quiescent senders. 557 */ 558 unsigned long timeout = jiffies + 2 * HZ; 559 560 /* Use new timeout only if there wasn't a older one earlier. */ 561 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 562 /* If delack timer was blocked or is about to expire, 563 * send ACK now. 564 * 565 * FIXME: check the "about to expire" part 566 */ 567 if (icsk->icsk_ack.blocked) { 568 dccp_send_ack(sk); 569 return; 570 } 571 572 if (!time_before(timeout, icsk->icsk_ack.timeout)) 573 timeout = icsk->icsk_ack.timeout; 574 } 575 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 576 icsk->icsk_ack.timeout = timeout; 577 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 578 } 579 #endif 580 581 void dccp_send_sync(struct sock *sk, const u64 ackno, 582 const enum dccp_pkt_type pkt_type) 583 { 584 /* 585 * We are not putting this on the write queue, so 586 * dccp_transmit_skb() will set the ownership to this 587 * sock. 588 */ 589 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 590 591 if (skb == NULL) { 592 /* FIXME: how to make sure the sync is sent? */ 593 DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type)); 594 return; 595 } 596 597 /* Reserve space for headers and prepare control bits. */ 598 skb_reserve(skb, sk->sk_prot->max_header); 599 DCCP_SKB_CB(skb)->dccpd_type = pkt_type; 600 DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno; 601 602 dccp_transmit_skb(sk, skb); 603 } 604 605 EXPORT_SYMBOL_GPL(dccp_send_sync); 606 607 /* 608 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This 609 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under 610 * any circumstances. 611 */ 612 void dccp_send_close(struct sock *sk, const int active) 613 { 614 struct dccp_sock *dp = dccp_sk(sk); 615 struct sk_buff *skb; 616 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; 617 618 skb = alloc_skb(sk->sk_prot->max_header, prio); 619 if (skb == NULL) 620 return; 621 622 /* Reserve space for headers and prepare control bits. */ 623 skb_reserve(skb, sk->sk_prot->max_header); 624 if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait) 625 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ; 626 else 627 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE; 628 629 if (active) { 630 dccp_write_xmit(sk, 1); 631 dccp_skb_entail(sk, skb); 632 dccp_transmit_skb(sk, skb_clone(skb, prio)); 633 /* 634 * Retransmission timer for active-close: RFC 4340, 8.3 requires 635 * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ 636 * state can be left. The initial timeout is 2 RTTs. 637 * Since RTT measurement is done by the CCIDs, there is no easy 638 * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4 639 * is too low (200ms); we use a high value to avoid unnecessary 640 * retransmissions when the link RTT is > 0.2 seconds. 641 * FIXME: Let main module sample RTTs and use that instead. 642 */ 643 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 644 DCCP_TIMEOUT_INIT, DCCP_RTO_MAX); 645 } else 646 dccp_transmit_skb(sk, skb); 647 } 648