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 dccp_inc_seqno(&dp->dccps_gss); 58 59 switch (dcb->dccpd_type) { 60 case DCCP_PKT_DATA: 61 set_ack = 0; 62 /* fall through */ 63 case DCCP_PKT_DATAACK: 64 break; 65 66 case DCCP_PKT_REQUEST: 67 set_ack = 0; 68 /* fall through */ 69 70 case DCCP_PKT_SYNC: 71 case DCCP_PKT_SYNCACK: 72 ackno = dcb->dccpd_seq; 73 /* fall through */ 74 default: 75 /* 76 * Only data packets should come through with skb->sk 77 * set. 78 */ 79 WARN_ON(skb->sk); 80 skb_set_owner_w(skb, sk); 81 break; 82 } 83 84 dcb->dccpd_seq = dp->dccps_gss; 85 86 if (dccp_insert_options(sk, skb)) { 87 kfree_skb(skb); 88 return -EPROTO; 89 } 90 91 92 /* Build DCCP header and checksum it. */ 93 dh = dccp_zeroed_hdr(skb, dccp_header_size); 94 dh->dccph_type = dcb->dccpd_type; 95 dh->dccph_sport = inet->sport; 96 dh->dccph_dport = inet->dport; 97 dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; 98 dh->dccph_ccval = dcb->dccpd_ccval; 99 dh->dccph_cscov = dp->dccps_pcslen; 100 /* XXX For now we're using only 48 bits sequence numbers */ 101 dh->dccph_x = 1; 102 103 dp->dccps_awh = dp->dccps_gss; 104 dccp_hdr_set_seq(dh, dp->dccps_gss); 105 if (set_ack) 106 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); 107 108 switch (dcb->dccpd_type) { 109 case DCCP_PKT_REQUEST: 110 dccp_hdr_request(skb)->dccph_req_service = 111 dp->dccps_service; 112 break; 113 case DCCP_PKT_RESET: 114 dccp_hdr_reset(skb)->dccph_reset_code = 115 dcb->dccpd_reset_code; 116 break; 117 } 118 119 icsk->icsk_af_ops->send_check(sk, 0, skb); 120 121 if (set_ack) 122 dccp_event_ack_sent(sk); 123 124 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 125 126 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 127 err = icsk->icsk_af_ops->queue_xmit(skb, 0); 128 return net_xmit_eval(err); 129 } 130 return -ENOBUFS; 131 } 132 133 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) 134 { 135 struct inet_connection_sock *icsk = inet_csk(sk); 136 struct dccp_sock *dp = dccp_sk(sk); 137 int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len - 138 sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext)); 139 140 /* Now subtract optional transport overhead */ 141 mss_now -= icsk->icsk_ext_hdr_len; 142 143 /* 144 * FIXME: this should come from the CCID infrastructure, where, say, 145 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets 146 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED 147 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to 148 * make it a multiple of 4 149 */ 150 151 mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; 152 153 /* And store cached results */ 154 icsk->icsk_pmtu_cookie = pmtu; 155 dp->dccps_mss_cache = mss_now; 156 157 return mss_now; 158 } 159 160 EXPORT_SYMBOL_GPL(dccp_sync_mss); 161 162 void dccp_write_space(struct sock *sk) 163 { 164 read_lock(&sk->sk_callback_lock); 165 166 if (sk->sk_sleep && waitqueue_active(sk->sk_sleep)) 167 wake_up_interruptible(sk->sk_sleep); 168 /* Should agree with poll, otherwise some programs break */ 169 if (sock_writeable(sk)) 170 sk_wake_async(sk, 2, POLL_OUT); 171 172 read_unlock(&sk->sk_callback_lock); 173 } 174 175 /** 176 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet 177 * @sk: socket to wait for 178 */ 179 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb) 180 { 181 struct dccp_sock *dp = dccp_sk(sk); 182 DEFINE_WAIT(wait); 183 unsigned long delay; 184 int rc; 185 186 while (1) { 187 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); 188 189 if (sk->sk_err) 190 goto do_error; 191 if (signal_pending(current)) 192 goto do_interrupted; 193 194 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); 195 if (rc <= 0) 196 break; 197 dccp_pr_debug("delayed send by %d msec\n", rc); 198 delay = msecs_to_jiffies(rc); 199 sk->sk_write_pending++; 200 release_sock(sk); 201 schedule_timeout(delay); 202 lock_sock(sk); 203 sk->sk_write_pending--; 204 } 205 out: 206 finish_wait(sk->sk_sleep, &wait); 207 return rc; 208 209 do_error: 210 rc = -EPIPE; 211 goto out; 212 do_interrupted: 213 rc = -EINTR; 214 goto out; 215 } 216 217 void dccp_write_xmit(struct sock *sk, int block) 218 { 219 struct dccp_sock *dp = dccp_sk(sk); 220 struct sk_buff *skb; 221 222 while ((skb = skb_peek(&sk->sk_write_queue))) { 223 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); 224 225 if (err > 0) { 226 if (!block) { 227 sk_reset_timer(sk, &dp->dccps_xmit_timer, 228 msecs_to_jiffies(err)+jiffies); 229 break; 230 } else 231 err = dccp_wait_for_ccid(sk, skb); 232 if (err && err != -EINTR) 233 DCCP_BUG("err=%d after dccp_wait_for_ccid", err); 234 } 235 236 skb_dequeue(&sk->sk_write_queue); 237 if (err == 0) { 238 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 239 const int len = skb->len; 240 241 if (sk->sk_state == DCCP_PARTOPEN) { 242 /* See 8.1.5. Handshake Completion */ 243 inet_csk_schedule_ack(sk); 244 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 245 inet_csk(sk)->icsk_rto, 246 DCCP_RTO_MAX); 247 dcb->dccpd_type = DCCP_PKT_DATAACK; 248 } else if (dccp_ack_pending(sk)) 249 dcb->dccpd_type = DCCP_PKT_DATAACK; 250 else 251 dcb->dccpd_type = DCCP_PKT_DATA; 252 253 err = dccp_transmit_skb(sk, skb); 254 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len); 255 if (err) 256 DCCP_BUG("err=%d after ccid_hc_tx_packet_sent", 257 err); 258 } else { 259 dccp_pr_debug("packet discarded due to err=%d\n", err); 260 kfree_skb(skb); 261 } 262 } 263 } 264 265 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 266 { 267 if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0) 268 return -EHOSTUNREACH; /* Routing failure or similar. */ 269 270 return dccp_transmit_skb(sk, (skb_cloned(skb) ? 271 pskb_copy(skb, GFP_ATOMIC): 272 skb_clone(skb, GFP_ATOMIC))); 273 } 274 275 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, 276 struct request_sock *req) 277 { 278 struct dccp_hdr *dh; 279 struct dccp_request_sock *dreq; 280 const u32 dccp_header_size = sizeof(struct dccp_hdr) + 281 sizeof(struct dccp_hdr_ext) + 282 sizeof(struct dccp_hdr_response); 283 struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 284 GFP_ATOMIC); 285 if (skb == NULL) 286 return NULL; 287 288 /* Reserve space for headers. */ 289 skb_reserve(skb, sk->sk_prot->max_header); 290 291 skb->dst = dst_clone(dst); 292 293 dreq = dccp_rsk(req); 294 if (inet_rsk(req)->acked) /* increase ISS upon retransmission */ 295 dccp_inc_seqno(&dreq->dreq_iss); 296 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; 297 DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss; 298 299 if (dccp_insert_options(sk, skb)) { 300 kfree_skb(skb); 301 return NULL; 302 } 303 304 /* Build and checksum header */ 305 dh = dccp_zeroed_hdr(skb, dccp_header_size); 306 307 dh->dccph_sport = inet_sk(sk)->sport; 308 dh->dccph_dport = inet_rsk(req)->rmt_port; 309 dh->dccph_doff = (dccp_header_size + 310 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 311 dh->dccph_type = DCCP_PKT_RESPONSE; 312 dh->dccph_x = 1; 313 dccp_hdr_set_seq(dh, dreq->dreq_iss); 314 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr); 315 dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service; 316 317 dccp_csum_outgoing(skb); 318 319 /* We use `acked' to remember that a Response was already sent. */ 320 inet_rsk(req)->acked = 1; 321 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 322 return skb; 323 } 324 325 EXPORT_SYMBOL_GPL(dccp_make_response); 326 327 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst, 328 const enum dccp_reset_codes code) 329 { 330 struct dccp_hdr *dh; 331 struct dccp_sock *dp = dccp_sk(sk); 332 const u32 dccp_header_size = sizeof(struct dccp_hdr) + 333 sizeof(struct dccp_hdr_ext) + 334 sizeof(struct dccp_hdr_reset); 335 struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 336 GFP_ATOMIC); 337 if (skb == NULL) 338 return NULL; 339 340 /* Reserve space for headers. */ 341 skb_reserve(skb, sk->sk_prot->max_header); 342 343 skb->dst = dst_clone(dst); 344 345 dccp_inc_seqno(&dp->dccps_gss); 346 347 DCCP_SKB_CB(skb)->dccpd_reset_code = code; 348 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; 349 DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss; 350 351 if (dccp_insert_options(sk, skb)) { 352 kfree_skb(skb); 353 return NULL; 354 } 355 356 dh = dccp_zeroed_hdr(skb, dccp_header_size); 357 358 dh->dccph_sport = inet_sk(sk)->sport; 359 dh->dccph_dport = inet_sk(sk)->dport; 360 dh->dccph_doff = (dccp_header_size + 361 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 362 dh->dccph_type = DCCP_PKT_RESET; 363 dh->dccph_x = 1; 364 dccp_hdr_set_seq(dh, dp->dccps_gss); 365 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr); 366 367 dccp_hdr_reset(skb)->dccph_reset_code = code; 368 inet_csk(sk)->icsk_af_ops->send_check(sk, 0, skb); 369 370 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 371 return skb; 372 } 373 374 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code) 375 { 376 /* 377 * FIXME: what if rebuild_header fails? 378 * Should we be doing a rebuild_header here? 379 */ 380 int err = inet_sk_rebuild_header(sk); 381 382 if (err == 0) { 383 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache, 384 code); 385 if (skb != NULL) { 386 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 387 err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, 0); 388 return net_xmit_eval(err); 389 } 390 } 391 392 return err; 393 } 394 395 /* 396 * Do all connect socket setups that can be done AF independent. 397 */ 398 static inline void dccp_connect_init(struct sock *sk) 399 { 400 struct dccp_sock *dp = dccp_sk(sk); 401 struct dst_entry *dst = __sk_dst_get(sk); 402 struct inet_connection_sock *icsk = inet_csk(sk); 403 404 sk->sk_err = 0; 405 sock_reset_flag(sk, SOCK_DONE); 406 407 dccp_sync_mss(sk, dst_mtu(dst)); 408 409 /* 410 * SWL and AWL are initially adjusted so that they are not less than 411 * the initial Sequence Numbers received and sent, respectively: 412 * SWL := max(GSR + 1 - floor(W/4), ISR), 413 * AWL := max(GSS - W' + 1, ISS). 414 * These adjustments MUST be applied only at the beginning of the 415 * connection. 416 */ 417 dccp_update_gss(sk, dp->dccps_iss); 418 dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss)); 419 420 /* S.GAR - greatest valid acknowledgement number received on a non-Sync; 421 * initialized to S.ISS (sec. 8.5) */ 422 dp->dccps_gar = dp->dccps_iss; 423 424 icsk->icsk_retransmits = 0; 425 } 426 427 int dccp_connect(struct sock *sk) 428 { 429 struct sk_buff *skb; 430 struct inet_connection_sock *icsk = inet_csk(sk); 431 432 dccp_connect_init(sk); 433 434 skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation); 435 if (unlikely(skb == NULL)) 436 return -ENOBUFS; 437 438 /* Reserve space for headers. */ 439 skb_reserve(skb, sk->sk_prot->max_header); 440 441 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; 442 443 dccp_skb_entail(sk, skb); 444 dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL)); 445 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); 446 447 /* Timer for repeating the REQUEST until an answer. */ 448 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 449 icsk->icsk_rto, DCCP_RTO_MAX); 450 return 0; 451 } 452 453 EXPORT_SYMBOL_GPL(dccp_connect); 454 455 void dccp_send_ack(struct sock *sk) 456 { 457 /* If we have been reset, we may not send again. */ 458 if (sk->sk_state != DCCP_CLOSED) { 459 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, 460 GFP_ATOMIC); 461 462 if (skb == NULL) { 463 inet_csk_schedule_ack(sk); 464 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 465 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 466 TCP_DELACK_MAX, 467 DCCP_RTO_MAX); 468 return; 469 } 470 471 /* Reserve space for headers */ 472 skb_reserve(skb, sk->sk_prot->max_header); 473 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; 474 dccp_transmit_skb(sk, skb); 475 } 476 } 477 478 EXPORT_SYMBOL_GPL(dccp_send_ack); 479 480 void dccp_send_delayed_ack(struct sock *sk) 481 { 482 struct inet_connection_sock *icsk = inet_csk(sk); 483 /* 484 * FIXME: tune this timer. elapsed time fixes the skew, so no problem 485 * with using 2s, and active senders also piggyback the ACK into a 486 * DATAACK packet, so this is really for quiescent senders. 487 */ 488 unsigned long timeout = jiffies + 2 * HZ; 489 490 /* Use new timeout only if there wasn't a older one earlier. */ 491 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 492 /* If delack timer was blocked or is about to expire, 493 * send ACK now. 494 * 495 * FIXME: check the "about to expire" part 496 */ 497 if (icsk->icsk_ack.blocked) { 498 dccp_send_ack(sk); 499 return; 500 } 501 502 if (!time_before(timeout, icsk->icsk_ack.timeout)) 503 timeout = icsk->icsk_ack.timeout; 504 } 505 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 506 icsk->icsk_ack.timeout = timeout; 507 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 508 } 509 510 void dccp_send_sync(struct sock *sk, const u64 seq, 511 const enum dccp_pkt_type pkt_type) 512 { 513 /* 514 * We are not putting this on the write queue, so 515 * dccp_transmit_skb() will set the ownership to this 516 * sock. 517 */ 518 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 519 520 if (skb == NULL) 521 /* FIXME: how to make sure the sync is sent? */ 522 return; 523 524 /* Reserve space for headers and prepare control bits. */ 525 skb_reserve(skb, sk->sk_prot->max_header); 526 DCCP_SKB_CB(skb)->dccpd_type = pkt_type; 527 DCCP_SKB_CB(skb)->dccpd_seq = seq; 528 529 dccp_transmit_skb(sk, skb); 530 } 531 532 EXPORT_SYMBOL_GPL(dccp_send_sync); 533 534 /* 535 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This 536 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under 537 * any circumstances. 538 */ 539 void dccp_send_close(struct sock *sk, const int active) 540 { 541 struct dccp_sock *dp = dccp_sk(sk); 542 struct sk_buff *skb; 543 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; 544 545 skb = alloc_skb(sk->sk_prot->max_header, prio); 546 if (skb == NULL) 547 return; 548 549 /* Reserve space for headers and prepare control bits. */ 550 skb_reserve(skb, sk->sk_prot->max_header); 551 DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ? 552 DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ; 553 554 if (active) { 555 dccp_write_xmit(sk, 1); 556 dccp_skb_entail(sk, skb); 557 dccp_transmit_skb(sk, skb_clone(skb, prio)); 558 /* FIXME do we need a retransmit timer here? */ 559 } else 560 dccp_transmit_skb(sk, skb); 561 } 562