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 /* enqueue @skb on sk_send_head for retransmission, return clone to send now */ 31 static struct sk_buff *dccp_skb_entail(struct sock *sk, struct sk_buff *skb) 32 { 33 skb_set_owner_w(skb, sk); 34 WARN_ON(sk->sk_send_head); 35 sk->sk_send_head = skb; 36 return skb_clone(sk->sk_send_head, gfp_any()); 37 } 38 39 /* 40 * All SKB's seen here are completely headerless. It is our 41 * job to build the DCCP header, and pass the packet down to 42 * IP so it can do the same plus pass the packet off to the 43 * device. 44 */ 45 static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) 46 { 47 if (likely(skb != NULL)) { 48 struct inet_sock *inet = inet_sk(sk); 49 const struct inet_connection_sock *icsk = inet_csk(sk); 50 struct dccp_sock *dp = dccp_sk(sk); 51 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 52 struct dccp_hdr *dh; 53 /* XXX For now we're using only 48 bits sequence numbers */ 54 const u32 dccp_header_size = sizeof(*dh) + 55 sizeof(struct dccp_hdr_ext) + 56 dccp_packet_hdr_len(dcb->dccpd_type); 57 int err, set_ack = 1; 58 u64 ackno = dp->dccps_gsr; 59 /* 60 * Increment GSS here already in case the option code needs it. 61 * Update GSS for real only if option processing below succeeds. 62 */ 63 dcb->dccpd_seq = ADD48(dp->dccps_gss, 1); 64 65 switch (dcb->dccpd_type) { 66 case DCCP_PKT_DATA: 67 set_ack = 0; 68 /* fall through */ 69 case DCCP_PKT_DATAACK: 70 case DCCP_PKT_RESET: 71 break; 72 73 case DCCP_PKT_REQUEST: 74 set_ack = 0; 75 /* Use ISS on the first (non-retransmitted) Request. */ 76 if (icsk->icsk_retransmits == 0) 77 dcb->dccpd_seq = dp->dccps_iss; 78 /* fall through */ 79 80 case DCCP_PKT_SYNC: 81 case DCCP_PKT_SYNCACK: 82 ackno = dcb->dccpd_ack_seq; 83 /* fall through */ 84 default: 85 /* 86 * Set owner/destructor: some skbs are allocated via 87 * alloc_skb (e.g. when retransmission may happen). 88 * Only Data, DataAck, and Reset packets should come 89 * through here with skb->sk set. 90 */ 91 WARN_ON(skb->sk); 92 skb_set_owner_w(skb, sk); 93 break; 94 } 95 96 if (dccp_insert_options(sk, skb)) { 97 kfree_skb(skb); 98 return -EPROTO; 99 } 100 101 102 /* Build DCCP header and checksum it. */ 103 dh = dccp_zeroed_hdr(skb, dccp_header_size); 104 dh->dccph_type = dcb->dccpd_type; 105 dh->dccph_sport = inet->inet_sport; 106 dh->dccph_dport = inet->inet_dport; 107 dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; 108 dh->dccph_ccval = dcb->dccpd_ccval; 109 dh->dccph_cscov = dp->dccps_pcslen; 110 /* XXX For now we're using only 48 bits sequence numbers */ 111 dh->dccph_x = 1; 112 113 dccp_update_gss(sk, dcb->dccpd_seq); 114 dccp_hdr_set_seq(dh, dp->dccps_gss); 115 if (set_ack) 116 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); 117 118 switch (dcb->dccpd_type) { 119 case DCCP_PKT_REQUEST: 120 dccp_hdr_request(skb)->dccph_req_service = 121 dp->dccps_service; 122 /* 123 * Limit Ack window to ISS <= P.ackno <= GSS, so that 124 * only Responses to Requests we sent are considered. 125 */ 126 dp->dccps_awl = dp->dccps_iss; 127 break; 128 case DCCP_PKT_RESET: 129 dccp_hdr_reset(skb)->dccph_reset_code = 130 dcb->dccpd_reset_code; 131 break; 132 } 133 134 icsk->icsk_af_ops->send_check(sk, skb); 135 136 if (set_ack) 137 dccp_event_ack_sent(sk); 138 139 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 140 141 err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); 142 return net_xmit_eval(err); 143 } 144 return -ENOBUFS; 145 } 146 147 /** 148 * dccp_determine_ccmps - Find out about CCID-specific packet-size limits 149 * We only consider the HC-sender CCID for setting the CCMPS (RFC 4340, 14.), 150 * since the RX CCID is restricted to feedback packets (Acks), which are small 151 * in comparison with the data traffic. A value of 0 means "no current CCMPS". 152 */ 153 static u32 dccp_determine_ccmps(const struct dccp_sock *dp) 154 { 155 const struct ccid *tx_ccid = dp->dccps_hc_tx_ccid; 156 157 if (tx_ccid == NULL || tx_ccid->ccid_ops == NULL) 158 return 0; 159 return tx_ccid->ccid_ops->ccid_ccmps; 160 } 161 162 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) 163 { 164 struct inet_connection_sock *icsk = inet_csk(sk); 165 struct dccp_sock *dp = dccp_sk(sk); 166 u32 ccmps = dccp_determine_ccmps(dp); 167 u32 cur_mps = ccmps ? min(pmtu, ccmps) : pmtu; 168 169 /* Account for header lengths and IPv4/v6 option overhead */ 170 cur_mps -= (icsk->icsk_af_ops->net_header_len + icsk->icsk_ext_hdr_len + 171 sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext)); 172 173 /* 174 * Leave enough headroom for common DCCP header options. 175 * This only considers options which may appear on DCCP-Data packets, as 176 * per table 3 in RFC 4340, 5.8. When running out of space for other 177 * options (eg. Ack Vector which can take up to 255 bytes), it is better 178 * to schedule a separate Ack. Thus we leave headroom for the following: 179 * - 1 byte for Slow Receiver (11.6) 180 * - 6 bytes for Timestamp (13.1) 181 * - 10 bytes for Timestamp Echo (13.3) 182 * - 8 bytes for NDP count (7.7, when activated) 183 * - 6 bytes for Data Checksum (9.3) 184 * - %DCCPAV_MIN_OPTLEN bytes for Ack Vector size (11.4, when enabled) 185 */ 186 cur_mps -= roundup(1 + 6 + 10 + dp->dccps_send_ndp_count * 8 + 6 + 187 (dp->dccps_hc_rx_ackvec ? DCCPAV_MIN_OPTLEN : 0), 4); 188 189 /* And store cached results */ 190 icsk->icsk_pmtu_cookie = pmtu; 191 dp->dccps_mss_cache = cur_mps; 192 193 return cur_mps; 194 } 195 196 EXPORT_SYMBOL_GPL(dccp_sync_mss); 197 198 void dccp_write_space(struct sock *sk) 199 { 200 struct socket_wq *wq; 201 202 rcu_read_lock(); 203 wq = rcu_dereference(sk->sk_wq); 204 if (wq_has_sleeper(wq)) 205 wake_up_interruptible(&wq->wait); 206 /* Should agree with poll, otherwise some programs break */ 207 if (sock_writeable(sk)) 208 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); 209 210 rcu_read_unlock(); 211 } 212 213 /** 214 * dccp_wait_for_ccid - Await CCID send permission 215 * @sk: socket to wait for 216 * @delay: timeout in jiffies 217 * 218 * This is used by CCIDs which need to delay the send time in process context. 219 */ 220 static int dccp_wait_for_ccid(struct sock *sk, unsigned long delay) 221 { 222 DEFINE_WAIT(wait); 223 long remaining; 224 225 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); 226 sk->sk_write_pending++; 227 release_sock(sk); 228 229 remaining = schedule_timeout(delay); 230 231 lock_sock(sk); 232 sk->sk_write_pending--; 233 finish_wait(sk_sleep(sk), &wait); 234 235 if (signal_pending(current) || sk->sk_err) 236 return -1; 237 return remaining; 238 } 239 240 /** 241 * dccp_xmit_packet - Send data packet under control of CCID 242 * Transmits next-queued payload and informs CCID to account for the packet. 243 */ 244 static void dccp_xmit_packet(struct sock *sk) 245 { 246 int err, len; 247 struct dccp_sock *dp = dccp_sk(sk); 248 struct sk_buff *skb = dccp_qpolicy_pop(sk); 249 250 if (unlikely(skb == NULL)) 251 return; 252 len = skb->len; 253 254 if (sk->sk_state == DCCP_PARTOPEN) { 255 const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD; 256 /* 257 * See 8.1.5 - Handshake Completion. 258 * 259 * For robustness we resend Confirm options until the client has 260 * entered OPEN. During the initial feature negotiation, the MPS 261 * is smaller than usual, reduced by the Change/Confirm options. 262 */ 263 if (!list_empty(&dp->dccps_featneg) && len > cur_mps) { 264 DCCP_WARN("Payload too large (%d) for featneg.\n", len); 265 dccp_send_ack(sk); 266 dccp_feat_list_purge(&dp->dccps_featneg); 267 } 268 269 inet_csk_schedule_ack(sk); 270 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 271 inet_csk(sk)->icsk_rto, 272 DCCP_RTO_MAX); 273 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK; 274 } else if (dccp_ack_pending(sk)) { 275 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK; 276 } else { 277 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATA; 278 } 279 280 err = dccp_transmit_skb(sk, skb); 281 if (err) 282 dccp_pr_debug("transmit_skb() returned err=%d\n", err); 283 /* 284 * Register this one as sent even if an error occurred. To the remote 285 * end a local packet drop is indistinguishable from network loss, i.e. 286 * any local drop will eventually be reported via receiver feedback. 287 */ 288 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len); 289 290 /* 291 * If the CCID needs to transfer additional header options out-of-band 292 * (e.g. Ack Vectors or feature-negotiation options), it activates this 293 * flag to schedule a Sync. The Sync will automatically incorporate all 294 * currently pending header options, thus clearing the backlog. 295 */ 296 if (dp->dccps_sync_scheduled) 297 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 298 } 299 300 /** 301 * dccp_flush_write_queue - Drain queue at end of connection 302 * Since dccp_sendmsg queues packets without waiting for them to be sent, it may 303 * happen that the TX queue is not empty at the end of a connection. We give the 304 * HC-sender CCID a grace period of up to @time_budget jiffies. If this function 305 * returns with a non-empty write queue, it will be purged later. 306 */ 307 void dccp_flush_write_queue(struct sock *sk, long *time_budget) 308 { 309 struct dccp_sock *dp = dccp_sk(sk); 310 struct sk_buff *skb; 311 long delay, rc; 312 313 while (*time_budget > 0 && (skb = skb_peek(&sk->sk_write_queue))) { 314 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); 315 316 switch (ccid_packet_dequeue_eval(rc)) { 317 case CCID_PACKET_WILL_DEQUEUE_LATER: 318 /* 319 * If the CCID determines when to send, the next sending 320 * time is unknown or the CCID may not even send again 321 * (e.g. remote host crashes or lost Ack packets). 322 */ 323 DCCP_WARN("CCID did not manage to send all packets\n"); 324 return; 325 case CCID_PACKET_DELAY: 326 delay = msecs_to_jiffies(rc); 327 if (delay > *time_budget) 328 return; 329 rc = dccp_wait_for_ccid(sk, delay); 330 if (rc < 0) 331 return; 332 *time_budget -= (delay - rc); 333 /* check again if we can send now */ 334 break; 335 case CCID_PACKET_SEND_AT_ONCE: 336 dccp_xmit_packet(sk); 337 break; 338 case CCID_PACKET_ERR: 339 skb_dequeue(&sk->sk_write_queue); 340 kfree_skb(skb); 341 dccp_pr_debug("packet discarded due to err=%ld\n", rc); 342 } 343 } 344 } 345 346 void dccp_write_xmit(struct sock *sk) 347 { 348 struct dccp_sock *dp = dccp_sk(sk); 349 struct sk_buff *skb; 350 351 while ((skb = dccp_qpolicy_top(sk))) { 352 int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); 353 354 switch (ccid_packet_dequeue_eval(rc)) { 355 case CCID_PACKET_WILL_DEQUEUE_LATER: 356 return; 357 case CCID_PACKET_DELAY: 358 sk_reset_timer(sk, &dp->dccps_xmit_timer, 359 jiffies + msecs_to_jiffies(rc)); 360 return; 361 case CCID_PACKET_SEND_AT_ONCE: 362 dccp_xmit_packet(sk); 363 break; 364 case CCID_PACKET_ERR: 365 dccp_qpolicy_drop(sk, skb); 366 dccp_pr_debug("packet discarded due to err=%d\n", rc); 367 } 368 } 369 } 370 371 /** 372 * dccp_retransmit_skb - Retransmit Request, Close, or CloseReq packets 373 * There are only four retransmittable packet types in DCCP: 374 * - Request in client-REQUEST state (sec. 8.1.1), 375 * - CloseReq in server-CLOSEREQ state (sec. 8.3), 376 * - Close in node-CLOSING state (sec. 8.3), 377 * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()). 378 * This function expects sk->sk_send_head to contain the original skb. 379 */ 380 int dccp_retransmit_skb(struct sock *sk) 381 { 382 WARN_ON(sk->sk_send_head == NULL); 383 384 if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0) 385 return -EHOSTUNREACH; /* Routing failure or similar. */ 386 387 /* this count is used to distinguish original and retransmitted skb */ 388 inet_csk(sk)->icsk_retransmits++; 389 390 return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC)); 391 } 392 393 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, 394 struct request_sock *req) 395 { 396 struct dccp_hdr *dh; 397 struct dccp_request_sock *dreq; 398 const u32 dccp_header_size = sizeof(struct dccp_hdr) + 399 sizeof(struct dccp_hdr_ext) + 400 sizeof(struct dccp_hdr_response); 401 struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 402 GFP_ATOMIC); 403 if (skb == NULL) 404 return NULL; 405 406 /* Reserve space for headers. */ 407 skb_reserve(skb, sk->sk_prot->max_header); 408 409 skb_dst_set(skb, dst_clone(dst)); 410 411 dreq = dccp_rsk(req); 412 if (inet_rsk(req)->acked) /* increase GSS upon retransmission */ 413 dccp_inc_seqno(&dreq->dreq_gss); 414 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; 415 DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_gss; 416 417 /* Resolve feature dependencies resulting from choice of CCID */ 418 if (dccp_feat_server_ccid_dependencies(dreq)) 419 goto response_failed; 420 421 if (dccp_insert_options_rsk(dreq, skb)) 422 goto response_failed; 423 424 /* Build and checksum header */ 425 dh = dccp_zeroed_hdr(skb, dccp_header_size); 426 427 dh->dccph_sport = htons(inet_rsk(req)->ir_num); 428 dh->dccph_dport = inet_rsk(req)->ir_rmt_port; 429 dh->dccph_doff = (dccp_header_size + 430 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 431 dh->dccph_type = DCCP_PKT_RESPONSE; 432 dh->dccph_x = 1; 433 dccp_hdr_set_seq(dh, dreq->dreq_gss); 434 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_gsr); 435 dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service; 436 437 dccp_csum_outgoing(skb); 438 439 /* We use `acked' to remember that a Response was already sent. */ 440 inet_rsk(req)->acked = 1; 441 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 442 return skb; 443 response_failed: 444 kfree_skb(skb); 445 return NULL; 446 } 447 448 EXPORT_SYMBOL_GPL(dccp_make_response); 449 450 /* answer offending packet in @rcv_skb with Reset from control socket @ctl */ 451 struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb) 452 { 453 struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh; 454 struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb); 455 const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) + 456 sizeof(struct dccp_hdr_ext) + 457 sizeof(struct dccp_hdr_reset); 458 struct dccp_hdr_reset *dhr; 459 struct sk_buff *skb; 460 461 skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 462 if (skb == NULL) 463 return NULL; 464 465 skb_reserve(skb, sk->sk_prot->max_header); 466 467 /* Swap the send and the receive. */ 468 dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len); 469 dh->dccph_type = DCCP_PKT_RESET; 470 dh->dccph_sport = rxdh->dccph_dport; 471 dh->dccph_dport = rxdh->dccph_sport; 472 dh->dccph_doff = dccp_hdr_reset_len / 4; 473 dh->dccph_x = 1; 474 475 dhr = dccp_hdr_reset(skb); 476 dhr->dccph_reset_code = dcb->dccpd_reset_code; 477 478 switch (dcb->dccpd_reset_code) { 479 case DCCP_RESET_CODE_PACKET_ERROR: 480 dhr->dccph_reset_data[0] = rxdh->dccph_type; 481 break; 482 case DCCP_RESET_CODE_OPTION_ERROR: /* fall through */ 483 case DCCP_RESET_CODE_MANDATORY_ERROR: 484 memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3); 485 break; 486 } 487 /* 488 * From RFC 4340, 8.3.1: 489 * If P.ackno exists, set R.seqno := P.ackno + 1. 490 * Else set R.seqno := 0. 491 */ 492 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 493 dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1)); 494 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq); 495 496 dccp_csum_outgoing(skb); 497 return skb; 498 } 499 500 EXPORT_SYMBOL_GPL(dccp_ctl_make_reset); 501 502 /* send Reset on established socket, to close or abort the connection */ 503 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code) 504 { 505 struct sk_buff *skb; 506 /* 507 * FIXME: what if rebuild_header fails? 508 * Should we be doing a rebuild_header here? 509 */ 510 int err = inet_csk(sk)->icsk_af_ops->rebuild_header(sk); 511 512 if (err != 0) 513 return err; 514 515 skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC); 516 if (skb == NULL) 517 return -ENOBUFS; 518 519 /* Reserve space for headers and prepare control bits. */ 520 skb_reserve(skb, sk->sk_prot->max_header); 521 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; 522 DCCP_SKB_CB(skb)->dccpd_reset_code = code; 523 524 return dccp_transmit_skb(sk, skb); 525 } 526 527 /* 528 * Do all connect socket setups that can be done AF independent. 529 */ 530 int dccp_connect(struct sock *sk) 531 { 532 struct sk_buff *skb; 533 struct dccp_sock *dp = dccp_sk(sk); 534 struct dst_entry *dst = __sk_dst_get(sk); 535 struct inet_connection_sock *icsk = inet_csk(sk); 536 537 sk->sk_err = 0; 538 sock_reset_flag(sk, SOCK_DONE); 539 540 dccp_sync_mss(sk, dst_mtu(dst)); 541 542 /* do not connect if feature negotiation setup fails */ 543 if (dccp_feat_finalise_settings(dccp_sk(sk))) 544 return -EPROTO; 545 546 /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */ 547 dp->dccps_gar = dp->dccps_iss; 548 549 skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation); 550 if (unlikely(skb == NULL)) 551 return -ENOBUFS; 552 553 /* Reserve space for headers. */ 554 skb_reserve(skb, sk->sk_prot->max_header); 555 556 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; 557 558 dccp_transmit_skb(sk, dccp_skb_entail(sk, skb)); 559 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); 560 561 /* Timer for repeating the REQUEST until an answer. */ 562 icsk->icsk_retransmits = 0; 563 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 564 icsk->icsk_rto, DCCP_RTO_MAX); 565 return 0; 566 } 567 568 EXPORT_SYMBOL_GPL(dccp_connect); 569 570 void dccp_send_ack(struct sock *sk) 571 { 572 /* If we have been reset, we may not send again. */ 573 if (sk->sk_state != DCCP_CLOSED) { 574 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, 575 GFP_ATOMIC); 576 577 if (skb == NULL) { 578 inet_csk_schedule_ack(sk); 579 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 580 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 581 TCP_DELACK_MAX, 582 DCCP_RTO_MAX); 583 return; 584 } 585 586 /* Reserve space for headers */ 587 skb_reserve(skb, sk->sk_prot->max_header); 588 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; 589 dccp_transmit_skb(sk, skb); 590 } 591 } 592 593 EXPORT_SYMBOL_GPL(dccp_send_ack); 594 595 #if 0 596 /* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */ 597 void dccp_send_delayed_ack(struct sock *sk) 598 { 599 struct inet_connection_sock *icsk = inet_csk(sk); 600 /* 601 * FIXME: tune this timer. elapsed time fixes the skew, so no problem 602 * with using 2s, and active senders also piggyback the ACK into a 603 * DATAACK packet, so this is really for quiescent senders. 604 */ 605 unsigned long timeout = jiffies + 2 * HZ; 606 607 /* Use new timeout only if there wasn't a older one earlier. */ 608 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 609 /* If delack timer was blocked or is about to expire, 610 * send ACK now. 611 * 612 * FIXME: check the "about to expire" part 613 */ 614 if (icsk->icsk_ack.blocked) { 615 dccp_send_ack(sk); 616 return; 617 } 618 619 if (!time_before(timeout, icsk->icsk_ack.timeout)) 620 timeout = icsk->icsk_ack.timeout; 621 } 622 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 623 icsk->icsk_ack.timeout = timeout; 624 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 625 } 626 #endif 627 628 void dccp_send_sync(struct sock *sk, const u64 ackno, 629 const enum dccp_pkt_type pkt_type) 630 { 631 /* 632 * We are not putting this on the write queue, so 633 * dccp_transmit_skb() will set the ownership to this 634 * sock. 635 */ 636 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 637 638 if (skb == NULL) { 639 /* FIXME: how to make sure the sync is sent? */ 640 DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type)); 641 return; 642 } 643 644 /* Reserve space for headers and prepare control bits. */ 645 skb_reserve(skb, sk->sk_prot->max_header); 646 DCCP_SKB_CB(skb)->dccpd_type = pkt_type; 647 DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno; 648 649 /* 650 * Clear the flag in case the Sync was scheduled for out-of-band data, 651 * such as carrying a long Ack Vector. 652 */ 653 dccp_sk(sk)->dccps_sync_scheduled = 0; 654 655 dccp_transmit_skb(sk, skb); 656 } 657 658 EXPORT_SYMBOL_GPL(dccp_send_sync); 659 660 /* 661 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This 662 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under 663 * any circumstances. 664 */ 665 void dccp_send_close(struct sock *sk, const int active) 666 { 667 struct dccp_sock *dp = dccp_sk(sk); 668 struct sk_buff *skb; 669 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; 670 671 skb = alloc_skb(sk->sk_prot->max_header, prio); 672 if (skb == NULL) 673 return; 674 675 /* Reserve space for headers and prepare control bits. */ 676 skb_reserve(skb, sk->sk_prot->max_header); 677 if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait) 678 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ; 679 else 680 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE; 681 682 if (active) { 683 skb = dccp_skb_entail(sk, skb); 684 /* 685 * Retransmission timer for active-close: RFC 4340, 8.3 requires 686 * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ 687 * state can be left. The initial timeout is 2 RTTs. 688 * Since RTT measurement is done by the CCIDs, there is no easy 689 * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4 690 * is too low (200ms); we use a high value to avoid unnecessary 691 * retransmissions when the link RTT is > 0.2 seconds. 692 * FIXME: Let main module sample RTTs and use that instead. 693 */ 694 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 695 DCCP_TIMEOUT_INIT, DCCP_RTO_MAX); 696 } 697 dccp_transmit_skb(sk, skb); 698 } 699