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 #include <linux/slab.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 * Increment GSS here already in case the option code needs it. 59 * Update GSS for real only if option processing below succeeds. 60 */ 61 dcb->dccpd_seq = ADD48(dp->dccps_gss, 1); 62 63 switch (dcb->dccpd_type) { 64 case DCCP_PKT_DATA: 65 set_ack = 0; 66 /* fall through */ 67 case DCCP_PKT_DATAACK: 68 case DCCP_PKT_RESET: 69 break; 70 71 case DCCP_PKT_REQUEST: 72 set_ack = 0; 73 /* Use ISS on the first (non-retransmitted) Request. */ 74 if (icsk->icsk_retransmits == 0) 75 dcb->dccpd_seq = dp->dccps_iss; 76 /* fall through */ 77 78 case DCCP_PKT_SYNC: 79 case DCCP_PKT_SYNCACK: 80 ackno = dcb->dccpd_ack_seq; 81 /* fall through */ 82 default: 83 /* 84 * Set owner/destructor: some skbs are allocated via 85 * alloc_skb (e.g. when retransmission may happen). 86 * Only Data, DataAck, and Reset packets should come 87 * through here with skb->sk set. 88 */ 89 WARN_ON(skb->sk); 90 skb_set_owner_w(skb, sk); 91 break; 92 } 93 94 if (dccp_insert_options(sk, skb)) { 95 kfree_skb(skb); 96 return -EPROTO; 97 } 98 99 100 /* Build DCCP header and checksum it. */ 101 dh = dccp_zeroed_hdr(skb, dccp_header_size); 102 dh->dccph_type = dcb->dccpd_type; 103 dh->dccph_sport = inet->inet_sport; 104 dh->dccph_dport = inet->inet_dport; 105 dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; 106 dh->dccph_ccval = dcb->dccpd_ccval; 107 dh->dccph_cscov = dp->dccps_pcslen; 108 /* XXX For now we're using only 48 bits sequence numbers */ 109 dh->dccph_x = 1; 110 111 dccp_update_gss(sk, dcb->dccpd_seq); 112 dccp_hdr_set_seq(dh, dp->dccps_gss); 113 if (set_ack) 114 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); 115 116 switch (dcb->dccpd_type) { 117 case DCCP_PKT_REQUEST: 118 dccp_hdr_request(skb)->dccph_req_service = 119 dp->dccps_service; 120 /* 121 * Limit Ack window to ISS <= P.ackno <= GSS, so that 122 * only Responses to Requests we sent are considered. 123 */ 124 dp->dccps_awl = dp->dccps_iss; 125 break; 126 case DCCP_PKT_RESET: 127 dccp_hdr_reset(skb)->dccph_reset_code = 128 dcb->dccpd_reset_code; 129 break; 130 } 131 132 icsk->icsk_af_ops->send_check(sk, skb); 133 134 if (set_ack) 135 dccp_event_ack_sent(sk); 136 137 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 138 139 err = icsk->icsk_af_ops->queue_xmit(skb); 140 return net_xmit_eval(err); 141 } 142 return -ENOBUFS; 143 } 144 145 /** 146 * dccp_determine_ccmps - Find out about CCID-specfic packet-size limits 147 * We only consider the HC-sender CCID for setting the CCMPS (RFC 4340, 14.), 148 * since the RX CCID is restricted to feedback packets (Acks), which are small 149 * in comparison with the data traffic. A value of 0 means "no current CCMPS". 150 */ 151 static u32 dccp_determine_ccmps(const struct dccp_sock *dp) 152 { 153 const struct ccid *tx_ccid = dp->dccps_hc_tx_ccid; 154 155 if (tx_ccid == NULL || tx_ccid->ccid_ops == NULL) 156 return 0; 157 return tx_ccid->ccid_ops->ccid_ccmps; 158 } 159 160 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) 161 { 162 struct inet_connection_sock *icsk = inet_csk(sk); 163 struct dccp_sock *dp = dccp_sk(sk); 164 u32 ccmps = dccp_determine_ccmps(dp); 165 u32 cur_mps = ccmps ? min(pmtu, ccmps) : pmtu; 166 167 /* Account for header lengths and IPv4/v6 option overhead */ 168 cur_mps -= (icsk->icsk_af_ops->net_header_len + icsk->icsk_ext_hdr_len + 169 sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext)); 170 171 /* 172 * Leave enough headroom for common DCCP header options. 173 * This only considers options which may appear on DCCP-Data packets, as 174 * per table 3 in RFC 4340, 5.8. When running out of space for other 175 * options (eg. Ack Vector which can take up to 255 bytes), it is better 176 * to schedule a separate Ack. Thus we leave headroom for the following: 177 * - 1 byte for Slow Receiver (11.6) 178 * - 6 bytes for Timestamp (13.1) 179 * - 10 bytes for Timestamp Echo (13.3) 180 * - 8 bytes for NDP count (7.7, when activated) 181 * - 6 bytes for Data Checksum (9.3) 182 * - %DCCPAV_MIN_OPTLEN bytes for Ack Vector size (11.4, when enabled) 183 */ 184 cur_mps -= roundup(1 + 6 + 10 + dp->dccps_send_ndp_count * 8 + 6 + 185 (dp->dccps_hc_rx_ackvec ? DCCPAV_MIN_OPTLEN : 0), 4); 186 187 /* And store cached results */ 188 icsk->icsk_pmtu_cookie = pmtu; 189 dp->dccps_mss_cache = cur_mps; 190 191 return cur_mps; 192 } 193 194 EXPORT_SYMBOL_GPL(dccp_sync_mss); 195 196 void dccp_write_space(struct sock *sk) 197 { 198 struct socket_wq *wq; 199 200 rcu_read_lock(); 201 wq = rcu_dereference(sk->sk_wq); 202 if (wq_has_sleeper(wq)) 203 wake_up_interruptible(&wq->wait); 204 /* Should agree with poll, otherwise some programs break */ 205 if (sock_writeable(sk)) 206 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); 207 208 rcu_read_unlock(); 209 } 210 211 /** 212 * dccp_wait_for_ccid - Await CCID send permission 213 * @sk: socket to wait for 214 * @delay: timeout in jiffies 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(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 = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 399 GFP_ATOMIC); 400 if (skb == NULL) 401 return NULL; 402 403 /* Reserve space for headers. */ 404 skb_reserve(skb, sk->sk_prot->max_header); 405 406 skb_dst_set(skb, dst_clone(dst)); 407 408 dreq = dccp_rsk(req); 409 if (inet_rsk(req)->acked) /* increase ISS upon retransmission */ 410 dccp_inc_seqno(&dreq->dreq_iss); 411 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; 412 DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss; 413 414 /* Resolve feature dependencies resulting from choice of CCID */ 415 if (dccp_feat_server_ccid_dependencies(dreq)) 416 goto response_failed; 417 418 if (dccp_insert_options_rsk(dreq, skb)) 419 goto response_failed; 420 421 /* Build and checksum header */ 422 dh = dccp_zeroed_hdr(skb, dccp_header_size); 423 424 dh->dccph_sport = inet_rsk(req)->loc_port; 425 dh->dccph_dport = inet_rsk(req)->rmt_port; 426 dh->dccph_doff = (dccp_header_size + 427 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 428 dh->dccph_type = DCCP_PKT_RESPONSE; 429 dh->dccph_x = 1; 430 dccp_hdr_set_seq(dh, dreq->dreq_iss); 431 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr); 432 dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service; 433 434 dccp_csum_outgoing(skb); 435 436 /* We use `acked' to remember that a Response was already sent. */ 437 inet_rsk(req)->acked = 1; 438 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 439 return skb; 440 response_failed: 441 kfree_skb(skb); 442 return NULL; 443 } 444 445 EXPORT_SYMBOL_GPL(dccp_make_response); 446 447 /* answer offending packet in @rcv_skb with Reset from control socket @ctl */ 448 struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb) 449 { 450 struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh; 451 struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb); 452 const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) + 453 sizeof(struct dccp_hdr_ext) + 454 sizeof(struct dccp_hdr_reset); 455 struct dccp_hdr_reset *dhr; 456 struct sk_buff *skb; 457 458 skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 459 if (skb == NULL) 460 return NULL; 461 462 skb_reserve(skb, sk->sk_prot->max_header); 463 464 /* Swap the send and the receive. */ 465 dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len); 466 dh->dccph_type = DCCP_PKT_RESET; 467 dh->dccph_sport = rxdh->dccph_dport; 468 dh->dccph_dport = rxdh->dccph_sport; 469 dh->dccph_doff = dccp_hdr_reset_len / 4; 470 dh->dccph_x = 1; 471 472 dhr = dccp_hdr_reset(skb); 473 dhr->dccph_reset_code = dcb->dccpd_reset_code; 474 475 switch (dcb->dccpd_reset_code) { 476 case DCCP_RESET_CODE_PACKET_ERROR: 477 dhr->dccph_reset_data[0] = rxdh->dccph_type; 478 break; 479 case DCCP_RESET_CODE_OPTION_ERROR: /* fall through */ 480 case DCCP_RESET_CODE_MANDATORY_ERROR: 481 memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3); 482 break; 483 } 484 /* 485 * From RFC 4340, 8.3.1: 486 * If P.ackno exists, set R.seqno := P.ackno + 1. 487 * Else set R.seqno := 0. 488 */ 489 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 490 dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1)); 491 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq); 492 493 dccp_csum_outgoing(skb); 494 return skb; 495 } 496 497 EXPORT_SYMBOL_GPL(dccp_ctl_make_reset); 498 499 /* send Reset on established socket, to close or abort the connection */ 500 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code) 501 { 502 struct sk_buff *skb; 503 /* 504 * FIXME: what if rebuild_header fails? 505 * Should we be doing a rebuild_header here? 506 */ 507 int err = inet_csk(sk)->icsk_af_ops->rebuild_header(sk); 508 509 if (err != 0) 510 return err; 511 512 skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC); 513 if (skb == NULL) 514 return -ENOBUFS; 515 516 /* Reserve space for headers and prepare control bits. */ 517 skb_reserve(skb, sk->sk_prot->max_header); 518 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; 519 DCCP_SKB_CB(skb)->dccpd_reset_code = code; 520 521 return dccp_transmit_skb(sk, skb); 522 } 523 524 /* 525 * Do all connect socket setups that can be done AF independent. 526 */ 527 int dccp_connect(struct sock *sk) 528 { 529 struct sk_buff *skb; 530 struct dccp_sock *dp = dccp_sk(sk); 531 struct dst_entry *dst = __sk_dst_get(sk); 532 struct inet_connection_sock *icsk = inet_csk(sk); 533 534 sk->sk_err = 0; 535 sock_reset_flag(sk, SOCK_DONE); 536 537 dccp_sync_mss(sk, dst_mtu(dst)); 538 539 /* do not connect if feature negotiation setup fails */ 540 if (dccp_feat_finalise_settings(dccp_sk(sk))) 541 return -EPROTO; 542 543 /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */ 544 dp->dccps_gar = dp->dccps_iss; 545 546 skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation); 547 if (unlikely(skb == NULL)) 548 return -ENOBUFS; 549 550 /* Reserve space for headers. */ 551 skb_reserve(skb, sk->sk_prot->max_header); 552 553 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; 554 555 dccp_skb_entail(sk, skb); 556 dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL)); 557 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); 558 559 /* Timer for repeating the REQUEST until an answer. */ 560 icsk->icsk_retransmits = 0; 561 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 562 icsk->icsk_rto, DCCP_RTO_MAX); 563 return 0; 564 } 565 566 EXPORT_SYMBOL_GPL(dccp_connect); 567 568 void dccp_send_ack(struct sock *sk) 569 { 570 /* If we have been reset, we may not send again. */ 571 if (sk->sk_state != DCCP_CLOSED) { 572 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, 573 GFP_ATOMIC); 574 575 if (skb == NULL) { 576 inet_csk_schedule_ack(sk); 577 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 578 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 579 TCP_DELACK_MAX, 580 DCCP_RTO_MAX); 581 return; 582 } 583 584 /* Reserve space for headers */ 585 skb_reserve(skb, sk->sk_prot->max_header); 586 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; 587 dccp_transmit_skb(sk, skb); 588 } 589 } 590 591 EXPORT_SYMBOL_GPL(dccp_send_ack); 592 593 #if 0 594 /* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */ 595 void dccp_send_delayed_ack(struct sock *sk) 596 { 597 struct inet_connection_sock *icsk = inet_csk(sk); 598 /* 599 * FIXME: tune this timer. elapsed time fixes the skew, so no problem 600 * with using 2s, and active senders also piggyback the ACK into a 601 * DATAACK packet, so this is really for quiescent senders. 602 */ 603 unsigned long timeout = jiffies + 2 * HZ; 604 605 /* Use new timeout only if there wasn't a older one earlier. */ 606 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 607 /* If delack timer was blocked or is about to expire, 608 * send ACK now. 609 * 610 * FIXME: check the "about to expire" part 611 */ 612 if (icsk->icsk_ack.blocked) { 613 dccp_send_ack(sk); 614 return; 615 } 616 617 if (!time_before(timeout, icsk->icsk_ack.timeout)) 618 timeout = icsk->icsk_ack.timeout; 619 } 620 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 621 icsk->icsk_ack.timeout = timeout; 622 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 623 } 624 #endif 625 626 void dccp_send_sync(struct sock *sk, const u64 ackno, 627 const enum dccp_pkt_type pkt_type) 628 { 629 /* 630 * We are not putting this on the write queue, so 631 * dccp_transmit_skb() will set the ownership to this 632 * sock. 633 */ 634 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 635 636 if (skb == NULL) { 637 /* FIXME: how to make sure the sync is sent? */ 638 DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type)); 639 return; 640 } 641 642 /* Reserve space for headers and prepare control bits. */ 643 skb_reserve(skb, sk->sk_prot->max_header); 644 DCCP_SKB_CB(skb)->dccpd_type = pkt_type; 645 DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno; 646 647 /* 648 * Clear the flag in case the Sync was scheduled for out-of-band data, 649 * such as carrying a long Ack Vector. 650 */ 651 dccp_sk(sk)->dccps_sync_scheduled = 0; 652 653 dccp_transmit_skb(sk, skb); 654 } 655 656 EXPORT_SYMBOL_GPL(dccp_send_sync); 657 658 /* 659 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This 660 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under 661 * any circumstances. 662 */ 663 void dccp_send_close(struct sock *sk, const int active) 664 { 665 struct dccp_sock *dp = dccp_sk(sk); 666 struct sk_buff *skb; 667 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; 668 669 skb = alloc_skb(sk->sk_prot->max_header, prio); 670 if (skb == NULL) 671 return; 672 673 /* Reserve space for headers and prepare control bits. */ 674 skb_reserve(skb, sk->sk_prot->max_header); 675 if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait) 676 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ; 677 else 678 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE; 679 680 if (active) { 681 dccp_skb_entail(sk, skb); 682 dccp_transmit_skb(sk, skb_clone(skb, prio)); 683 /* 684 * Retransmission timer for active-close: RFC 4340, 8.3 requires 685 * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ 686 * state can be left. The initial timeout is 2 RTTs. 687 * Since RTT measurement is done by the CCIDs, there is no easy 688 * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4 689 * is too low (200ms); we use a high value to avoid unnecessary 690 * retransmissions when the link RTT is > 0.2 seconds. 691 * FIXME: Let main module sample RTTs and use that instead. 692 */ 693 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 694 DCCP_TIMEOUT_INIT, DCCP_RTO_MAX); 695 } else 696 dccp_transmit_skb(sk, skb); 697 } 698