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/config.h> 14 #include <linux/dccp.h> 15 #include <linux/kernel.h> 16 #include <linux/skbuff.h> 17 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 inline 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 struct dccp_sock *dp = dccp_sk(sk); 47 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 48 struct dccp_hdr *dh; 49 /* XXX For now we're using only 48 bits sequence numbers */ 50 const int dccp_header_size = sizeof(*dh) + 51 sizeof(struct dccp_hdr_ext) + 52 dccp_packet_hdr_len(dcb->dccpd_type); 53 int err, set_ack = 1; 54 u64 ackno = dp->dccps_gsr; 55 56 dccp_inc_seqno(&dp->dccps_gss); 57 58 switch (dcb->dccpd_type) { 59 case DCCP_PKT_DATA: 60 set_ack = 0; 61 /* fall through */ 62 case DCCP_PKT_DATAACK: 63 break; 64 65 case DCCP_PKT_SYNC: 66 case DCCP_PKT_SYNCACK: 67 ackno = dcb->dccpd_seq; 68 /* fall through */ 69 default: 70 /* 71 * Only data packets should come through with skb->sk 72 * set. 73 */ 74 WARN_ON(skb->sk); 75 skb_set_owner_w(skb, sk); 76 break; 77 } 78 79 dcb->dccpd_seq = dp->dccps_gss; 80 dccp_insert_options(sk, skb); 81 82 skb->h.raw = skb_push(skb, dccp_header_size); 83 dh = dccp_hdr(skb); 84 85 /* Build DCCP header and checksum it. */ 86 memset(dh, 0, dccp_header_size); 87 dh->dccph_type = dcb->dccpd_type; 88 dh->dccph_sport = inet->sport; 89 dh->dccph_dport = inet->dport; 90 dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; 91 dh->dccph_ccval = dcb->dccpd_ccval; 92 /* XXX For now we're using only 48 bits sequence numbers */ 93 dh->dccph_x = 1; 94 95 dp->dccps_awh = dp->dccps_gss; 96 dccp_hdr_set_seq(dh, dp->dccps_gss); 97 if (set_ack) 98 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); 99 100 switch (dcb->dccpd_type) { 101 case DCCP_PKT_REQUEST: 102 dccp_hdr_request(skb)->dccph_req_service = 103 dp->dccps_service; 104 break; 105 case DCCP_PKT_RESET: 106 dccp_hdr_reset(skb)->dccph_reset_code = 107 dcb->dccpd_reset_code; 108 break; 109 } 110 111 dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, 112 inet->daddr); 113 114 if (set_ack) 115 dccp_event_ack_sent(sk); 116 117 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 118 119 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 120 err = ip_queue_xmit(skb, 0); 121 if (err <= 0) 122 return err; 123 124 /* NET_XMIT_CN is special. It does not guarantee, 125 * that this packet is lost. It tells that device 126 * is about to start to drop packets or already 127 * drops some packets of the same priority and 128 * invokes us to send less aggressively. 129 */ 130 return err == NET_XMIT_CN ? 0 : err; 131 } 132 return -ENOBUFS; 133 } 134 135 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) 136 { 137 struct dccp_sock *dp = dccp_sk(sk); 138 int mss_now; 139 140 /* 141 * FIXME: we really should be using the af_specific thing to support 142 * IPv6. 143 * mss_now = pmtu - tp->af_specific->net_header_len - 144 * sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext); 145 */ 146 mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) - 147 sizeof(struct dccp_hdr_ext); 148 149 /* Now subtract optional transport overhead */ 150 mss_now -= dp->dccps_ext_header_len; 151 152 /* 153 * FIXME: this should come from the CCID infrastructure, where, say, 154 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets 155 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED 156 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to 157 * make it a multiple of 4 158 */ 159 160 mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; 161 162 /* And store cached results */ 163 dp->dccps_pmtu_cookie = pmtu; 164 dp->dccps_mss_cache = mss_now; 165 166 return mss_now; 167 } 168 169 void dccp_write_space(struct sock *sk) 170 { 171 read_lock(&sk->sk_callback_lock); 172 173 if (sk->sk_sleep && waitqueue_active(sk->sk_sleep)) 174 wake_up_interruptible(sk->sk_sleep); 175 /* Should agree with poll, otherwise some programs break */ 176 if (sock_writeable(sk)) 177 sk_wake_async(sk, 2, POLL_OUT); 178 179 read_unlock(&sk->sk_callback_lock); 180 } 181 182 /** 183 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet 184 * @sk: socket to wait for 185 * @timeo: for how long 186 */ 187 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb, 188 long *timeo) 189 { 190 struct dccp_sock *dp = dccp_sk(sk); 191 DEFINE_WAIT(wait); 192 long delay; 193 int rc; 194 195 while (1) { 196 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); 197 198 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) 199 goto do_error; 200 if (!*timeo) 201 goto do_nonblock; 202 if (signal_pending(current)) 203 goto do_interrupted; 204 205 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, 206 skb->len); 207 if (rc <= 0) 208 break; 209 delay = msecs_to_jiffies(rc); 210 if (delay > *timeo || delay < 0) 211 goto do_nonblock; 212 213 sk->sk_write_pending++; 214 release_sock(sk); 215 *timeo -= schedule_timeout(delay); 216 lock_sock(sk); 217 sk->sk_write_pending--; 218 } 219 out: 220 finish_wait(sk->sk_sleep, &wait); 221 return rc; 222 223 do_error: 224 rc = -EPIPE; 225 goto out; 226 do_nonblock: 227 rc = -EAGAIN; 228 goto out; 229 do_interrupted: 230 rc = sock_intr_errno(*timeo); 231 goto out; 232 } 233 234 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo) 235 { 236 const struct dccp_sock *dp = dccp_sk(sk); 237 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, 238 skb->len); 239 240 if (err > 0) 241 err = dccp_wait_for_ccid(sk, skb, timeo); 242 243 if (err == 0) { 244 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 245 const int len = skb->len; 246 247 if (sk->sk_state == DCCP_PARTOPEN) { 248 /* See 8.1.5. Handshake Completion */ 249 inet_csk_schedule_ack(sk); 250 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 251 inet_csk(sk)->icsk_rto, 252 DCCP_RTO_MAX); 253 dcb->dccpd_type = DCCP_PKT_DATAACK; 254 } else if (dccp_ack_pending(sk)) 255 dcb->dccpd_type = DCCP_PKT_DATAACK; 256 else 257 dcb->dccpd_type = DCCP_PKT_DATA; 258 259 err = dccp_transmit_skb(sk, skb); 260 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len); 261 } else 262 kfree_skb(skb); 263 264 return err; 265 } 266 267 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 268 { 269 if (inet_sk_rebuild_header(sk) != 0) 270 return -EHOSTUNREACH; /* Routing failure or similar. */ 271 272 return dccp_transmit_skb(sk, (skb_cloned(skb) ? 273 pskb_copy(skb, GFP_ATOMIC): 274 skb_clone(skb, GFP_ATOMIC))); 275 } 276 277 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, 278 struct request_sock *req) 279 { 280 struct dccp_hdr *dh; 281 struct dccp_request_sock *dreq; 282 const int dccp_header_size = sizeof(struct dccp_hdr) + 283 sizeof(struct dccp_hdr_ext) + 284 sizeof(struct dccp_hdr_response); 285 struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN + 286 dccp_header_size, 1, 287 GFP_ATOMIC); 288 if (skb == NULL) 289 return NULL; 290 291 /* Reserve space for headers. */ 292 skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size); 293 294 skb->dst = dst_clone(dst); 295 skb->csum = 0; 296 297 dreq = dccp_rsk(req); 298 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; 299 DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss; 300 dccp_insert_options(sk, skb); 301 302 skb->h.raw = skb_push(skb, dccp_header_size); 303 304 dh = dccp_hdr(skb); 305 memset(dh, 0, 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 dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr, 318 inet_rsk(req)->rmt_addr); 319 320 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 321 return skb; 322 } 323 324 struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst, 325 const enum dccp_reset_codes code) 326 327 { 328 struct dccp_hdr *dh; 329 struct dccp_sock *dp = dccp_sk(sk); 330 const int dccp_header_size = sizeof(struct dccp_hdr) + 331 sizeof(struct dccp_hdr_ext) + 332 sizeof(struct dccp_hdr_reset); 333 struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN + 334 dccp_header_size, 1, 335 GFP_ATOMIC); 336 if (skb == NULL) 337 return NULL; 338 339 /* Reserve space for headers. */ 340 skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size); 341 342 skb->dst = dst_clone(dst); 343 skb->csum = 0; 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 dccp_insert_options(sk, skb); 351 352 skb->h.raw = skb_push(skb, dccp_header_size); 353 354 dh = dccp_hdr(skb); 355 memset(dh, 0, dccp_header_size); 356 357 dh->dccph_sport = inet_sk(sk)->sport; 358 dh->dccph_dport = inet_sk(sk)->dport; 359 dh->dccph_doff = (dccp_header_size + 360 DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; 361 dh->dccph_type = DCCP_PKT_RESET; 362 dh->dccph_x = 1; 363 dccp_hdr_set_seq(dh, dp->dccps_gss); 364 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr); 365 366 dccp_hdr_reset(skb)->dccph_reset_code = code; 367 368 dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr, 369 inet_sk(sk)->daddr); 370 371 DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 372 return skb; 373 } 374 375 /* 376 * Do all connect socket setups that can be done AF independent. 377 */ 378 static inline void dccp_connect_init(struct sock *sk) 379 { 380 struct dst_entry *dst = __sk_dst_get(sk); 381 struct inet_connection_sock *icsk = inet_csk(sk); 382 383 sk->sk_err = 0; 384 sock_reset_flag(sk, SOCK_DONE); 385 386 dccp_sync_mss(sk, dst_mtu(dst)); 387 388 /* 389 * FIXME: set dp->{dccps_swh,dccps_swl}, with 390 * something like dccp_inc_seq 391 */ 392 393 icsk->icsk_retransmits = 0; 394 } 395 396 int dccp_connect(struct sock *sk) 397 { 398 struct sk_buff *skb; 399 struct inet_connection_sock *icsk = inet_csk(sk); 400 401 dccp_connect_init(sk); 402 403 skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation); 404 if (unlikely(skb == NULL)) 405 return -ENOBUFS; 406 407 /* Reserve space for headers. */ 408 skb_reserve(skb, MAX_DCCP_HEADER); 409 410 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; 411 skb->csum = 0; 412 413 dccp_skb_entail(sk, skb); 414 dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL)); 415 DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); 416 417 /* Timer for repeating the REQUEST until an answer. */ 418 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 419 icsk->icsk_rto, DCCP_RTO_MAX); 420 return 0; 421 } 422 423 void dccp_send_ack(struct sock *sk) 424 { 425 /* If we have been reset, we may not send again. */ 426 if (sk->sk_state != DCCP_CLOSED) { 427 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC); 428 429 if (skb == NULL) { 430 inet_csk_schedule_ack(sk); 431 inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 432 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 433 TCP_DELACK_MAX, 434 DCCP_RTO_MAX); 435 return; 436 } 437 438 /* Reserve space for headers */ 439 skb_reserve(skb, MAX_DCCP_HEADER); 440 skb->csum = 0; 441 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; 442 dccp_transmit_skb(sk, skb); 443 } 444 } 445 446 EXPORT_SYMBOL_GPL(dccp_send_ack); 447 448 void dccp_send_delayed_ack(struct sock *sk) 449 { 450 struct inet_connection_sock *icsk = inet_csk(sk); 451 /* 452 * FIXME: tune this timer. elapsed time fixes the skew, so no problem 453 * with using 2s, and active senders also piggyback the ACK into a 454 * DATAACK packet, so this is really for quiescent senders. 455 */ 456 unsigned long timeout = jiffies + 2 * HZ; 457 458 /* Use new timeout only if there wasn't a older one earlier. */ 459 if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 460 /* If delack timer was blocked or is about to expire, 461 * send ACK now. 462 * 463 * FIXME: check the "about to expire" part 464 */ 465 if (icsk->icsk_ack.blocked) { 466 dccp_send_ack(sk); 467 return; 468 } 469 470 if (!time_before(timeout, icsk->icsk_ack.timeout)) 471 timeout = icsk->icsk_ack.timeout; 472 } 473 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 474 icsk->icsk_ack.timeout = timeout; 475 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 476 } 477 478 void dccp_send_sync(struct sock *sk, const u64 seq, 479 const enum dccp_pkt_type pkt_type) 480 { 481 /* 482 * We are not putting this on the write queue, so 483 * dccp_transmit_skb() will set the ownership to this 484 * sock. 485 */ 486 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC); 487 488 if (skb == NULL) 489 /* FIXME: how to make sure the sync is sent? */ 490 return; 491 492 /* Reserve space for headers and prepare control bits. */ 493 skb_reserve(skb, MAX_DCCP_HEADER); 494 skb->csum = 0; 495 DCCP_SKB_CB(skb)->dccpd_type = pkt_type; 496 DCCP_SKB_CB(skb)->dccpd_seq = seq; 497 498 dccp_transmit_skb(sk, skb); 499 } 500 501 /* 502 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This 503 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under 504 * any circumstances. 505 */ 506 void dccp_send_close(struct sock *sk, const int active) 507 { 508 struct dccp_sock *dp = dccp_sk(sk); 509 struct sk_buff *skb; 510 const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; 511 512 skb = alloc_skb(sk->sk_prot->max_header, prio); 513 if (skb == NULL) 514 return; 515 516 /* Reserve space for headers and prepare control bits. */ 517 skb_reserve(skb, sk->sk_prot->max_header); 518 skb->csum = 0; 519 DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ? 520 DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ; 521 522 if (active) { 523 dccp_skb_entail(sk, skb); 524 dccp_transmit_skb(sk, skb_clone(skb, prio)); 525 } else 526 dccp_transmit_skb(sk, skb); 527 } 528