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 skb->h.raw = skb_push(skb, dccp_header_size); 92 dh = dccp_hdr(skb); 93 94 /* Build DCCP header and checksum it. */ 95 memset(dh, 0, dccp_header_size); 96 dh->dccph_type = dcb->dccpd_type; 97 dh->dccph_sport = inet->sport; 98 dh->dccph_dport = inet->dport; 99 dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; 100 dh->dccph_ccval = dcb->dccpd_ccval; 101 /* XXX For now we're using only 48 bits sequence numbers */ 102 dh->dccph_x = 1; 103 104 dp->dccps_awh = dp->dccps_gss; 105 dccp_hdr_set_seq(dh, dp->dccps_gss); 106 if (set_ack) 107 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); 108 109 switch (dcb->dccpd_type) { 110 case DCCP_PKT_REQUEST: 111 dccp_hdr_request(skb)->dccph_req_service = 112 dp->dccps_service; 113 break; 114 case DCCP_PKT_RESET: 115 dccp_hdr_reset(skb)->dccph_reset_code = 116 dcb->dccpd_reset_code; 117 break; 118 } 119 120 icsk->icsk_af_ops->send_check(sk, skb->len, skb); 121 122 if (set_ack) 123 dccp_event_ack_sent(sk); 124 125 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 126 127 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 128 err = icsk->icsk_af_ops->queue_xmit(skb, 0); 129 if (err <= 0) 130 return err; 131 132 /* NET_XMIT_CN is special. It does not guarantee, 133 * that this packet is lost. It tells that device 134 * is about to start to drop packets or already 135 * drops some packets of the same priority and 136 * invokes us to send less aggressively. 137 */ 138 return err == NET_XMIT_CN ? 0 : err; 139 } 140 return -ENOBUFS; 141 } 142 143 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) 144 { 145 struct inet_connection_sock *icsk = inet_csk(sk); 146 struct dccp_sock *dp = dccp_sk(sk); 147 int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len - 148 sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext)); 149 150 /* Now subtract optional transport overhead */ 151 mss_now -= icsk->icsk_ext_hdr_len; 152 153 /* 154 * FIXME: this should come from the CCID infrastructure, where, say, 155 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets 156 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED 157 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to 158 * make it a multiple of 4 159 */ 160 161 mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; 162 163 /* And store cached results */ 164 icsk->icsk_pmtu_cookie = pmtu; 165 dp->dccps_mss_cache = mss_now; 166 167 return mss_now; 168 } 169 170 EXPORT_SYMBOL_GPL(dccp_sync_mss); 171 172 void dccp_write_space(struct sock *sk) 173 { 174 read_lock(&sk->sk_callback_lock); 175 176 if (sk->sk_sleep && waitqueue_active(sk->sk_sleep)) 177 wake_up_interruptible(sk->sk_sleep); 178 /* Should agree with poll, otherwise some programs break */ 179 if (sock_writeable(sk)) 180 sk_wake_async(sk, 2, POLL_OUT); 181 182 read_unlock(&sk->sk_callback_lock); 183 } 184 185 /** 186 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet 187 * @sk: socket to wait for 188 * @timeo: for how long 189 */ 190 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb, 191 long *timeo) 192 { 193 struct dccp_sock *dp = dccp_sk(sk); 194 DEFINE_WAIT(wait); 195 long delay; 196 int rc; 197 198 while (1) { 199 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); 200 201 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) 202 goto do_error; 203 if (!*timeo) 204 goto do_nonblock; 205 if (signal_pending(current)) 206 goto do_interrupted; 207 208 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, 209 skb->len); 210 if (rc <= 0) 211 break; 212 delay = msecs_to_jiffies(rc); 213 if (delay > *timeo || delay < 0) 214 goto do_nonblock; 215 216 sk->sk_write_pending++; 217 release_sock(sk); 218 *timeo -= schedule_timeout(delay); 219 lock_sock(sk); 220 sk->sk_write_pending--; 221 } 222 out: 223 finish_wait(sk->sk_sleep, &wait); 224 return rc; 225 226 do_error: 227 rc = -EPIPE; 228 goto out; 229 do_nonblock: 230 rc = -EAGAIN; 231 goto out; 232 do_interrupted: 233 rc = sock_intr_errno(*timeo); 234 goto out; 235 } 236 237 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo) 238 { 239 const struct dccp_sock *dp = dccp_sk(sk); 240 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, 241 skb->len); 242 243 if (err > 0) 244 err = dccp_wait_for_ccid(sk, skb, timeo); 245 246 if (err == 0) { 247 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 248 const int len = skb->len; 249 250 if (sk->sk_state == DCCP_PARTOPEN) { 251 /* See 8.1.5. Handshake Completion */ 252 inet_csk_schedule_ack(sk); 253 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 254 inet_csk(sk)->icsk_rto, 255 DCCP_RTO_MAX); 256 dcb->dccpd_type = DCCP_PKT_DATAACK; 257 } else if (dccp_ack_pending(sk)) 258 dcb->dccpd_type = DCCP_PKT_DATAACK; 259 else 260 dcb->dccpd_type = DCCP_PKT_DATA; 261 262 err = dccp_transmit_skb(sk, skb); 263 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len); 264 } else 265 kfree_skb(skb); 266 267 return err; 268 } 269 270 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 271 { 272 if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0) 273 return -EHOSTUNREACH; /* Routing failure or similar. */ 274 275 return dccp_transmit_skb(sk, (skb_cloned(skb) ? 276 pskb_copy(skb, GFP_ATOMIC): 277 skb_clone(skb, GFP_ATOMIC))); 278 } 279 280 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, 281 struct request_sock *req) 282 { 283 struct dccp_hdr *dh; 284 struct dccp_request_sock *dreq; 285 const u32 dccp_header_size = sizeof(struct dccp_hdr) + 286 sizeof(struct dccp_hdr_ext) + 287 sizeof(struct dccp_hdr_response); 288 struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 289 GFP_ATOMIC); 290 if (skb == NULL) 291 return NULL; 292 293 /* Reserve space for headers. */ 294 skb_reserve(skb, sk->sk_prot->max_header); 295 296 skb->dst = dst_clone(dst); 297 skb->csum = 0; 298 299 dreq = dccp_rsk(req); 300 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; 301 DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss; 302 303 if (dccp_insert_options(sk, skb)) { 304 kfree_skb(skb); 305 return NULL; 306 } 307 308 skb->h.raw = skb_push(skb, dccp_header_size); 309 310 dh = dccp_hdr(skb); 311 memset(dh, 0, dccp_header_size); 312 313 dh->dccph_sport = inet_sk(sk)->sport; 314 dh->dccph_dport = inet_rsk(req)->rmt_port; 315 dh->dccph_doff = (dccp_header_size + 316 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 317 dh->dccph_type = DCCP_PKT_RESPONSE; 318 dh->dccph_x = 1; 319 dccp_hdr_set_seq(dh, dreq->dreq_iss); 320 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr); 321 dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service; 322 323 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 324 return skb; 325 } 326 327 EXPORT_SYMBOL_GPL(dccp_make_response); 328 329 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst, 330 const enum dccp_reset_codes code) 331 332 { 333 struct dccp_hdr *dh; 334 struct dccp_sock *dp = dccp_sk(sk); 335 const u32 dccp_header_size = sizeof(struct dccp_hdr) + 336 sizeof(struct dccp_hdr_ext) + 337 sizeof(struct dccp_hdr_reset); 338 struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, 339 GFP_ATOMIC); 340 if (skb == NULL) 341 return NULL; 342 343 /* Reserve space for headers. */ 344 skb_reserve(skb, sk->sk_prot->max_header); 345 346 skb->dst = dst_clone(dst); 347 skb->csum = 0; 348 349 dccp_inc_seqno(&dp->dccps_gss); 350 351 DCCP_SKB_CB(skb)->dccpd_reset_code = code; 352 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; 353 DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss; 354 355 if (dccp_insert_options(sk, skb)) { 356 kfree_skb(skb); 357 return NULL; 358 } 359 360 skb->h.raw = skb_push(skb, dccp_header_size); 361 362 dh = dccp_hdr(skb); 363 memset(dh, 0, dccp_header_size); 364 365 dh->dccph_sport = inet_sk(sk)->sport; 366 dh->dccph_dport = inet_sk(sk)->dport; 367 dh->dccph_doff = (dccp_header_size + 368 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 369 dh->dccph_type = DCCP_PKT_RESET; 370 dh->dccph_x = 1; 371 dccp_hdr_set_seq(dh, dp->dccps_gss); 372 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr); 373 374 dccp_hdr_reset(skb)->dccph_reset_code = code; 375 inet_csk(sk)->icsk_af_ops->send_check(sk, skb->len, skb); 376 377 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 378 return skb; 379 } 380 381 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code) 382 { 383 /* 384 * FIXME: what if rebuild_header fails? 385 * Should we be doing a rebuild_header here? 386 */ 387 int err = inet_sk_rebuild_header(sk); 388 389 if (err == 0) { 390 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache, 391 code); 392 if (skb != NULL) { 393 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 394 err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, 0); 395 if (err == NET_XMIT_CN) 396 err = 0; 397 } 398 } 399 400 return err; 401 } 402 403 /* 404 * Do all connect socket setups that can be done AF independent. 405 */ 406 static inline void dccp_connect_init(struct sock *sk) 407 { 408 struct dccp_sock *dp = dccp_sk(sk); 409 struct dst_entry *dst = __sk_dst_get(sk); 410 struct inet_connection_sock *icsk = inet_csk(sk); 411 412 sk->sk_err = 0; 413 sock_reset_flag(sk, SOCK_DONE); 414 415 dccp_sync_mss(sk, dst_mtu(dst)); 416 417 dccp_update_gss(sk, dp->dccps_iss); 418 /* 419 * SWL and AWL are initially adjusted so that they are not less than 420 * the initial Sequence Numbers received and sent, respectively: 421 * SWL := max(GSR + 1 - floor(W/4), ISR), 422 * AWL := max(GSS - W' + 1, ISS). 423 * These adjustments MUST be applied only at the beginning of the 424 * connection. 425 */ 426 dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss)); 427 428 icsk->icsk_retransmits = 0; 429 } 430 431 int dccp_connect(struct sock *sk) 432 { 433 struct sk_buff *skb; 434 struct inet_connection_sock *icsk = inet_csk(sk); 435 436 dccp_connect_init(sk); 437 438 skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation); 439 if (unlikely(skb == NULL)) 440 return -ENOBUFS; 441 442 /* Reserve space for headers. */ 443 skb_reserve(skb, sk->sk_prot->max_header); 444 445 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; 446 skb->csum = 0; 447 448 dccp_skb_entail(sk, skb); 449 dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL)); 450 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); 451 452 /* Timer for repeating the REQUEST until an answer. */ 453 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 454 icsk->icsk_rto, DCCP_RTO_MAX); 455 return 0; 456 } 457 458 EXPORT_SYMBOL_GPL(dccp_connect); 459 460 void dccp_send_ack(struct sock *sk) 461 { 462 /* If we have been reset, we may not send again. */ 463 if (sk->sk_state != DCCP_CLOSED) { 464 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, 465 GFP_ATOMIC); 466 467 if (skb == NULL) { 468 inet_csk_schedule_ack(sk); 469 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 470 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 471 TCP_DELACK_MAX, 472 DCCP_RTO_MAX); 473 return; 474 } 475 476 /* Reserve space for headers */ 477 skb_reserve(skb, sk->sk_prot->max_header); 478 skb->csum = 0; 479 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; 480 dccp_transmit_skb(sk, skb); 481 } 482 } 483 484 EXPORT_SYMBOL_GPL(dccp_send_ack); 485 486 void dccp_send_delayed_ack(struct sock *sk) 487 { 488 struct inet_connection_sock *icsk = inet_csk(sk); 489 /* 490 * FIXME: tune this timer. elapsed time fixes the skew, so no problem 491 * with using 2s, and active senders also piggyback the ACK into a 492 * DATAACK packet, so this is really for quiescent senders. 493 */ 494 unsigned long timeout = jiffies + 2 * HZ; 495 496 /* Use new timeout only if there wasn't a older one earlier. */ 497 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 498 /* If delack timer was blocked or is about to expire, 499 * send ACK now. 500 * 501 * FIXME: check the "about to expire" part 502 */ 503 if (icsk->icsk_ack.blocked) { 504 dccp_send_ack(sk); 505 return; 506 } 507 508 if (!time_before(timeout, icsk->icsk_ack.timeout)) 509 timeout = icsk->icsk_ack.timeout; 510 } 511 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 512 icsk->icsk_ack.timeout = timeout; 513 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 514 } 515 516 void dccp_send_sync(struct sock *sk, const u64 seq, 517 const enum dccp_pkt_type pkt_type) 518 { 519 /* 520 * We are not putting this on the write queue, so 521 * dccp_transmit_skb() will set the ownership to this 522 * sock. 523 */ 524 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); 525 526 if (skb == NULL) 527 /* FIXME: how to make sure the sync is sent? */ 528 return; 529 530 /* Reserve space for headers and prepare control bits. */ 531 skb_reserve(skb, sk->sk_prot->max_header); 532 skb->csum = 0; 533 DCCP_SKB_CB(skb)->dccpd_type = pkt_type; 534 DCCP_SKB_CB(skb)->dccpd_seq = seq; 535 536 dccp_transmit_skb(sk, skb); 537 } 538 539 EXPORT_SYMBOL_GPL(dccp_send_sync); 540 541 /* 542 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This 543 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under 544 * any circumstances. 545 */ 546 void dccp_send_close(struct sock *sk, const int active) 547 { 548 struct dccp_sock *dp = dccp_sk(sk); 549 struct sk_buff *skb; 550 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; 551 552 skb = alloc_skb(sk->sk_prot->max_header, prio); 553 if (skb == NULL) 554 return; 555 556 /* Reserve space for headers and prepare control bits. */ 557 skb_reserve(skb, sk->sk_prot->max_header); 558 skb->csum = 0; 559 DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ? 560 DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ; 561 562 if (active) { 563 dccp_skb_entail(sk, skb); 564 dccp_transmit_skb(sk, skb_clone(skb, prio)); 565 } else 566 dccp_transmit_skb(sk, skb); 567 } 568