1 /* 2 * net/dccp/input.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/skbuff.h> 15 #include <linux/slab.h> 16 17 #include <net/sock.h> 18 19 #include "ackvec.h" 20 #include "ccid.h" 21 #include "dccp.h" 22 23 /* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */ 24 int sysctl_dccp_sync_ratelimit __read_mostly = HZ / 8; 25 26 static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb) 27 { 28 __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4); 29 __skb_queue_tail(&sk->sk_receive_queue, skb); 30 skb_set_owner_r(skb, sk); 31 sk->sk_data_ready(sk, 0); 32 } 33 34 static void dccp_fin(struct sock *sk, struct sk_buff *skb) 35 { 36 /* 37 * On receiving Close/CloseReq, both RD/WR shutdown are performed. 38 * RFC 4340, 8.3 says that we MAY send further Data/DataAcks after 39 * receiving the closing segment, but there is no guarantee that such 40 * data will be processed at all. 41 */ 42 sk->sk_shutdown = SHUTDOWN_MASK; 43 sock_set_flag(sk, SOCK_DONE); 44 dccp_enqueue_skb(sk, skb); 45 } 46 47 static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb) 48 { 49 int queued = 0; 50 51 switch (sk->sk_state) { 52 /* 53 * We ignore Close when received in one of the following states: 54 * - CLOSED (may be a late or duplicate packet) 55 * - PASSIVE_CLOSEREQ (the peer has sent a CloseReq earlier) 56 * - RESPOND (already handled by dccp_check_req) 57 */ 58 case DCCP_CLOSING: 59 /* 60 * Simultaneous-close: receiving a Close after sending one. This 61 * can happen if both client and server perform active-close and 62 * will result in an endless ping-pong of crossing and retrans- 63 * mitted Close packets, which only terminates when one of the 64 * nodes times out (min. 64 seconds). Quicker convergence can be 65 * achieved when one of the nodes acts as tie-breaker. 66 * This is ok as both ends are done with data transfer and each 67 * end is just waiting for the other to acknowledge termination. 68 */ 69 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) 70 break; 71 /* fall through */ 72 case DCCP_REQUESTING: 73 case DCCP_ACTIVE_CLOSEREQ: 74 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED); 75 dccp_done(sk); 76 break; 77 case DCCP_OPEN: 78 case DCCP_PARTOPEN: 79 /* Give waiting application a chance to read pending data */ 80 queued = 1; 81 dccp_fin(sk, skb); 82 dccp_set_state(sk, DCCP_PASSIVE_CLOSE); 83 /* fall through */ 84 case DCCP_PASSIVE_CLOSE: 85 /* 86 * Retransmitted Close: we have already enqueued the first one. 87 */ 88 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); 89 } 90 return queued; 91 } 92 93 static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb) 94 { 95 int queued = 0; 96 97 /* 98 * Step 7: Check for unexpected packet types 99 * If (S.is_server and P.type == CloseReq) 100 * Send Sync packet acknowledging P.seqno 101 * Drop packet and return 102 */ 103 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) { 104 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC); 105 return queued; 106 } 107 108 /* Step 13: process relevant Client states < CLOSEREQ */ 109 switch (sk->sk_state) { 110 case DCCP_REQUESTING: 111 dccp_send_close(sk, 0); 112 dccp_set_state(sk, DCCP_CLOSING); 113 break; 114 case DCCP_OPEN: 115 case DCCP_PARTOPEN: 116 /* Give waiting application a chance to read pending data */ 117 queued = 1; 118 dccp_fin(sk, skb); 119 dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ); 120 /* fall through */ 121 case DCCP_PASSIVE_CLOSEREQ: 122 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); 123 } 124 return queued; 125 } 126 127 static u16 dccp_reset_code_convert(const u8 code) 128 { 129 const u16 error_code[] = { 130 [DCCP_RESET_CODE_CLOSED] = 0, /* normal termination */ 131 [DCCP_RESET_CODE_UNSPECIFIED] = 0, /* nothing known */ 132 [DCCP_RESET_CODE_ABORTED] = ECONNRESET, 133 134 [DCCP_RESET_CODE_NO_CONNECTION] = ECONNREFUSED, 135 [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED, 136 [DCCP_RESET_CODE_TOO_BUSY] = EUSERS, 137 [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT, 138 139 [DCCP_RESET_CODE_PACKET_ERROR] = ENOMSG, 140 [DCCP_RESET_CODE_BAD_INIT_COOKIE] = EBADR, 141 [DCCP_RESET_CODE_BAD_SERVICE_CODE] = EBADRQC, 142 [DCCP_RESET_CODE_OPTION_ERROR] = EILSEQ, 143 [DCCP_RESET_CODE_MANDATORY_ERROR] = EOPNOTSUPP, 144 }; 145 146 return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code]; 147 } 148 149 static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb) 150 { 151 u16 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code); 152 153 sk->sk_err = err; 154 155 /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */ 156 dccp_fin(sk, skb); 157 158 if (err && !sock_flag(sk, SOCK_DEAD)) 159 sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR); 160 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 161 } 162 163 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb) 164 { 165 struct dccp_sock *dp = dccp_sk(sk); 166 167 if (dp->dccps_hc_rx_ackvec != NULL) 168 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk, 169 DCCP_SKB_CB(skb)->dccpd_ack_seq); 170 } 171 172 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb) 173 { 174 const struct dccp_sock *dp = dccp_sk(sk); 175 176 /* Don't deliver to RX CCID when node has shut down read end. */ 177 if (!(sk->sk_shutdown & RCV_SHUTDOWN)) 178 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 179 /* 180 * Until the TX queue has been drained, we can not honour SHUT_WR, since 181 * we need received feedback as input to adjust congestion control. 182 */ 183 if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN)) 184 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 185 } 186 187 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb) 188 { 189 const struct dccp_hdr *dh = dccp_hdr(skb); 190 struct dccp_sock *dp = dccp_sk(sk); 191 u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq, 192 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; 193 194 /* 195 * Step 5: Prepare sequence numbers for Sync 196 * If P.type == Sync or P.type == SyncAck, 197 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL, 198 * / * P is valid, so update sequence number variables 199 * accordingly. After this update, P will pass the tests 200 * in Step 6. A SyncAck is generated if necessary in 201 * Step 15 * / 202 * Update S.GSR, S.SWL, S.SWH 203 * Otherwise, 204 * Drop packet and return 205 */ 206 if (dh->dccph_type == DCCP_PKT_SYNC || 207 dh->dccph_type == DCCP_PKT_SYNCACK) { 208 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) && 209 dccp_delta_seqno(dp->dccps_swl, seqno) >= 0) 210 dccp_update_gsr(sk, seqno); 211 else 212 return -1; 213 } 214 215 /* 216 * Step 6: Check sequence numbers 217 * Let LSWL = S.SWL and LAWL = S.AWL 218 * If P.type == CloseReq or P.type == Close or P.type == Reset, 219 * LSWL := S.GSR + 1, LAWL := S.GAR 220 * If LSWL <= P.seqno <= S.SWH 221 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH), 222 * Update S.GSR, S.SWL, S.SWH 223 * If P.type != Sync, 224 * Update S.GAR 225 */ 226 lswl = dp->dccps_swl; 227 lawl = dp->dccps_awl; 228 229 if (dh->dccph_type == DCCP_PKT_CLOSEREQ || 230 dh->dccph_type == DCCP_PKT_CLOSE || 231 dh->dccph_type == DCCP_PKT_RESET) { 232 lswl = ADD48(dp->dccps_gsr, 1); 233 lawl = dp->dccps_gar; 234 } 235 236 if (between48(seqno, lswl, dp->dccps_swh) && 237 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ || 238 between48(ackno, lawl, dp->dccps_awh))) { 239 dccp_update_gsr(sk, seqno); 240 241 if (dh->dccph_type != DCCP_PKT_SYNC && 242 (ackno != DCCP_PKT_WITHOUT_ACK_SEQ)) 243 dp->dccps_gar = ackno; 244 } else { 245 unsigned long now = jiffies; 246 /* 247 * Step 6: Check sequence numbers 248 * Otherwise, 249 * If P.type == Reset, 250 * Send Sync packet acknowledging S.GSR 251 * Otherwise, 252 * Send Sync packet acknowledging P.seqno 253 * Drop packet and return 254 * 255 * These Syncs are rate-limited as per RFC 4340, 7.5.4: 256 * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second. 257 */ 258 if (time_before(now, (dp->dccps_rate_last + 259 sysctl_dccp_sync_ratelimit))) 260 return 0; 261 262 DCCP_WARN("DCCP: Step 6 failed for %s packet, " 263 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and " 264 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), " 265 "sending SYNC...\n", dccp_packet_name(dh->dccph_type), 266 (unsigned long long) lswl, (unsigned long long) seqno, 267 (unsigned long long) dp->dccps_swh, 268 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" 269 : "exists", 270 (unsigned long long) lawl, (unsigned long long) ackno, 271 (unsigned long long) dp->dccps_awh); 272 273 dp->dccps_rate_last = now; 274 275 if (dh->dccph_type == DCCP_PKT_RESET) 276 seqno = dp->dccps_gsr; 277 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC); 278 return -1; 279 } 280 281 return 0; 282 } 283 284 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 285 const struct dccp_hdr *dh, const unsigned len) 286 { 287 struct dccp_sock *dp = dccp_sk(sk); 288 289 switch (dccp_hdr(skb)->dccph_type) { 290 case DCCP_PKT_DATAACK: 291 case DCCP_PKT_DATA: 292 /* 293 * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when 294 * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening" 295 * - sk_receive_queue is full, use Code 2, "Receive Buffer" 296 */ 297 dccp_enqueue_skb(sk, skb); 298 return 0; 299 case DCCP_PKT_ACK: 300 goto discard; 301 case DCCP_PKT_RESET: 302 /* 303 * Step 9: Process Reset 304 * If P.type == Reset, 305 * Tear down connection 306 * S.state := TIMEWAIT 307 * Set TIMEWAIT timer 308 * Drop packet and return 309 */ 310 dccp_rcv_reset(sk, skb); 311 return 0; 312 case DCCP_PKT_CLOSEREQ: 313 if (dccp_rcv_closereq(sk, skb)) 314 return 0; 315 goto discard; 316 case DCCP_PKT_CLOSE: 317 if (dccp_rcv_close(sk, skb)) 318 return 0; 319 goto discard; 320 case DCCP_PKT_REQUEST: 321 /* Step 7 322 * or (S.is_server and P.type == Response) 323 * or (S.is_client and P.type == Request) 324 * or (S.state >= OPEN and P.type == Request 325 * and P.seqno >= S.OSR) 326 * or (S.state >= OPEN and P.type == Response 327 * and P.seqno >= S.OSR) 328 * or (S.state == RESPOND and P.type == Data), 329 * Send Sync packet acknowledging P.seqno 330 * Drop packet and return 331 */ 332 if (dp->dccps_role != DCCP_ROLE_LISTEN) 333 goto send_sync; 334 goto check_seq; 335 case DCCP_PKT_RESPONSE: 336 if (dp->dccps_role != DCCP_ROLE_CLIENT) 337 goto send_sync; 338 check_seq: 339 if (dccp_delta_seqno(dp->dccps_osr, 340 DCCP_SKB_CB(skb)->dccpd_seq) >= 0) { 341 send_sync: 342 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 343 DCCP_PKT_SYNC); 344 } 345 break; 346 case DCCP_PKT_SYNC: 347 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 348 DCCP_PKT_SYNCACK); 349 /* 350 * From RFC 4340, sec. 5.7 351 * 352 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets 353 * MAY have non-zero-length application data areas, whose 354 * contents receivers MUST ignore. 355 */ 356 goto discard; 357 } 358 359 DCCP_INC_STATS_BH(DCCP_MIB_INERRS); 360 discard: 361 __kfree_skb(skb); 362 return 0; 363 } 364 365 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 366 const struct dccp_hdr *dh, const unsigned len) 367 { 368 struct dccp_sock *dp = dccp_sk(sk); 369 370 if (dccp_check_seqno(sk, skb)) 371 goto discard; 372 373 if (dccp_parse_options(sk, NULL, skb)) 374 return 1; 375 376 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 377 dccp_event_ack_recv(sk, skb); 378 379 if (dp->dccps_hc_rx_ackvec != NULL && 380 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 381 DCCP_SKB_CB(skb)->dccpd_seq, 382 DCCP_ACKVEC_STATE_RECEIVED)) 383 goto discard; 384 dccp_deliver_input_to_ccids(sk, skb); 385 386 return __dccp_rcv_established(sk, skb, dh, len); 387 discard: 388 __kfree_skb(skb); 389 return 0; 390 } 391 392 EXPORT_SYMBOL_GPL(dccp_rcv_established); 393 394 static int dccp_rcv_request_sent_state_process(struct sock *sk, 395 struct sk_buff *skb, 396 const struct dccp_hdr *dh, 397 const unsigned len) 398 { 399 /* 400 * Step 4: Prepare sequence numbers in REQUEST 401 * If S.state == REQUEST, 402 * If (P.type == Response or P.type == Reset) 403 * and S.AWL <= P.ackno <= S.AWH, 404 * / * Set sequence number variables corresponding to the 405 * other endpoint, so P will pass the tests in Step 6 * / 406 * Set S.GSR, S.ISR, S.SWL, S.SWH 407 * / * Response processing continues in Step 10; Reset 408 * processing continues in Step 9 * / 409 */ 410 if (dh->dccph_type == DCCP_PKT_RESPONSE) { 411 const struct inet_connection_sock *icsk = inet_csk(sk); 412 struct dccp_sock *dp = dccp_sk(sk); 413 long tstamp = dccp_timestamp(); 414 415 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 416 dp->dccps_awl, dp->dccps_awh)) { 417 dccp_pr_debug("invalid ackno: S.AWL=%llu, " 418 "P.ackno=%llu, S.AWH=%llu\n", 419 (unsigned long long)dp->dccps_awl, 420 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, 421 (unsigned long long)dp->dccps_awh); 422 goto out_invalid_packet; 423 } 424 425 /* 426 * If option processing (Step 8) failed, return 1 here so that 427 * dccp_v4_do_rcv() sends a Reset. The Reset code depends on 428 * the option type and is set in dccp_parse_options(). 429 */ 430 if (dccp_parse_options(sk, NULL, skb)) 431 return 1; 432 433 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ 434 if (likely(dp->dccps_options_received.dccpor_timestamp_echo)) 435 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp - 436 dp->dccps_options_received.dccpor_timestamp_echo)); 437 438 /* Stop the REQUEST timer */ 439 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); 440 WARN_ON(sk->sk_send_head == NULL); 441 kfree_skb(sk->sk_send_head); 442 sk->sk_send_head = NULL; 443 444 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; 445 dccp_update_gsr(sk, dp->dccps_isr); 446 /* 447 * SWL and AWL are initially adjusted so that they are not less than 448 * the initial Sequence Numbers received and sent, respectively: 449 * SWL := max(GSR + 1 - floor(W/4), ISR), 450 * AWL := max(GSS - W' + 1, ISS). 451 * These adjustments MUST be applied only at the beginning of the 452 * connection. 453 * 454 * AWL was adjusted in dccp_v4_connect -acme 455 */ 456 dccp_set_seqno(&dp->dccps_swl, 457 max48(dp->dccps_swl, dp->dccps_isr)); 458 459 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); 460 461 /* 462 * Step 10: Process REQUEST state (second part) 463 * If S.state == REQUEST, 464 * / * If we get here, P is a valid Response from the 465 * server (see Step 4), and we should move to 466 * PARTOPEN state. PARTOPEN means send an Ack, 467 * don't send Data packets, retransmit Acks 468 * periodically, and always include any Init Cookie 469 * from the Response * / 470 * S.state := PARTOPEN 471 * Set PARTOPEN timer 472 * Continue with S.state == PARTOPEN 473 * / * Step 12 will send the Ack completing the 474 * three-way handshake * / 475 */ 476 dccp_set_state(sk, DCCP_PARTOPEN); 477 478 /* 479 * If feature negotiation was successful, activate features now; 480 * an activation failure means that this host could not activate 481 * one ore more features (e.g. insufficient memory), which would 482 * leave at least one feature in an undefined state. 483 */ 484 if (dccp_feat_activate_values(sk, &dp->dccps_featneg)) 485 goto unable_to_proceed; 486 487 /* Make sure socket is routed, for correct metrics. */ 488 icsk->icsk_af_ops->rebuild_header(sk); 489 490 if (!sock_flag(sk, SOCK_DEAD)) { 491 sk->sk_state_change(sk); 492 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); 493 } 494 495 if (sk->sk_write_pending || icsk->icsk_ack.pingpong || 496 icsk->icsk_accept_queue.rskq_defer_accept) { 497 /* Save one ACK. Data will be ready after 498 * several ticks, if write_pending is set. 499 * 500 * It may be deleted, but with this feature tcpdumps 501 * look so _wonderfully_ clever, that I was not able 502 * to stand against the temptation 8) --ANK 503 */ 504 /* 505 * OK, in DCCP we can as well do a similar trick, its 506 * even in the draft, but there is no need for us to 507 * schedule an ack here, as dccp_sendmsg does this for 508 * us, also stated in the draft. -acme 509 */ 510 __kfree_skb(skb); 511 return 0; 512 } 513 dccp_send_ack(sk); 514 return -1; 515 } 516 517 out_invalid_packet: 518 /* dccp_v4_do_rcv will send a reset */ 519 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 520 return 1; 521 522 unable_to_proceed: 523 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED; 524 /* 525 * We mark this socket as no longer usable, so that the loop in 526 * dccp_sendmsg() terminates and the application gets notified. 527 */ 528 dccp_set_state(sk, DCCP_CLOSED); 529 sk->sk_err = ECOMM; 530 return 1; 531 } 532 533 static int dccp_rcv_respond_partopen_state_process(struct sock *sk, 534 struct sk_buff *skb, 535 const struct dccp_hdr *dh, 536 const unsigned len) 537 { 538 struct dccp_sock *dp = dccp_sk(sk); 539 u32 sample = dp->dccps_options_received.dccpor_timestamp_echo; 540 int queued = 0; 541 542 switch (dh->dccph_type) { 543 case DCCP_PKT_RESET: 544 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 545 break; 546 case DCCP_PKT_DATA: 547 if (sk->sk_state == DCCP_RESPOND) 548 break; 549 case DCCP_PKT_DATAACK: 550 case DCCP_PKT_ACK: 551 /* 552 * FIXME: we should be reseting the PARTOPEN (DELACK) timer 553 * here but only if we haven't used the DELACK timer for 554 * something else, like sending a delayed ack for a TIMESTAMP 555 * echo, etc, for now were not clearing it, sending an extra 556 * ACK when there is nothing else to do in DELACK is not a big 557 * deal after all. 558 */ 559 560 /* Stop the PARTOPEN timer */ 561 if (sk->sk_state == DCCP_PARTOPEN) 562 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 563 564 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ 565 if (likely(sample)) { 566 long delta = dccp_timestamp() - sample; 567 568 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta); 569 } 570 571 dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; 572 dccp_set_state(sk, DCCP_OPEN); 573 574 if (dh->dccph_type == DCCP_PKT_DATAACK || 575 dh->dccph_type == DCCP_PKT_DATA) { 576 __dccp_rcv_established(sk, skb, dh, len); 577 queued = 1; /* packet was queued 578 (by __dccp_rcv_established) */ 579 } 580 break; 581 } 582 583 return queued; 584 } 585 586 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 587 struct dccp_hdr *dh, unsigned len) 588 { 589 struct dccp_sock *dp = dccp_sk(sk); 590 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 591 const int old_state = sk->sk_state; 592 int queued = 0; 593 594 /* 595 * Step 3: Process LISTEN state 596 * 597 * If S.state == LISTEN, 598 * If P.type == Request or P contains a valid Init Cookie option, 599 * (* Must scan the packet's options to check for Init 600 * Cookies. Only Init Cookies are processed here, 601 * however; other options are processed in Step 8. This 602 * scan need only be performed if the endpoint uses Init 603 * Cookies *) 604 * (* Generate a new socket and switch to that socket *) 605 * Set S := new socket for this port pair 606 * S.state = RESPOND 607 * Choose S.ISS (initial seqno) or set from Init Cookies 608 * Initialize S.GAR := S.ISS 609 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init 610 * Cookies Continue with S.state == RESPOND 611 * (* A Response packet will be generated in Step 11 *) 612 * Otherwise, 613 * Generate Reset(No Connection) unless P.type == Reset 614 * Drop packet and return 615 */ 616 if (sk->sk_state == DCCP_LISTEN) { 617 if (dh->dccph_type == DCCP_PKT_REQUEST) { 618 if (inet_csk(sk)->icsk_af_ops->conn_request(sk, 619 skb) < 0) 620 return 1; 621 goto discard; 622 } 623 if (dh->dccph_type == DCCP_PKT_RESET) 624 goto discard; 625 626 /* Caller (dccp_v4_do_rcv) will send Reset */ 627 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 628 return 1; 629 } 630 631 if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) { 632 if (dccp_check_seqno(sk, skb)) 633 goto discard; 634 635 /* 636 * Step 8: Process options and mark acknowledgeable 637 */ 638 if (dccp_parse_options(sk, NULL, skb)) 639 return 1; 640 641 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 642 dccp_event_ack_recv(sk, skb); 643 644 if (dp->dccps_hc_rx_ackvec != NULL && 645 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 646 DCCP_SKB_CB(skb)->dccpd_seq, 647 DCCP_ACKVEC_STATE_RECEIVED)) 648 goto discard; 649 650 dccp_deliver_input_to_ccids(sk, skb); 651 } 652 653 /* 654 * Step 9: Process Reset 655 * If P.type == Reset, 656 * Tear down connection 657 * S.state := TIMEWAIT 658 * Set TIMEWAIT timer 659 * Drop packet and return 660 */ 661 if (dh->dccph_type == DCCP_PKT_RESET) { 662 dccp_rcv_reset(sk, skb); 663 return 0; 664 /* 665 * Step 7: Check for unexpected packet types 666 * If (S.is_server and P.type == Response) 667 * or (S.is_client and P.type == Request) 668 * or (S.state == RESPOND and P.type == Data), 669 * Send Sync packet acknowledging P.seqno 670 * Drop packet and return 671 */ 672 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && 673 dh->dccph_type == DCCP_PKT_RESPONSE) || 674 (dp->dccps_role == DCCP_ROLE_CLIENT && 675 dh->dccph_type == DCCP_PKT_REQUEST) || 676 (sk->sk_state == DCCP_RESPOND && 677 dh->dccph_type == DCCP_PKT_DATA)) { 678 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC); 679 goto discard; 680 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { 681 if (dccp_rcv_closereq(sk, skb)) 682 return 0; 683 goto discard; 684 } else if (dh->dccph_type == DCCP_PKT_CLOSE) { 685 if (dccp_rcv_close(sk, skb)) 686 return 0; 687 goto discard; 688 } 689 690 switch (sk->sk_state) { 691 case DCCP_CLOSED: 692 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 693 return 1; 694 695 case DCCP_REQUESTING: 696 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); 697 if (queued >= 0) 698 return queued; 699 700 __kfree_skb(skb); 701 return 0; 702 703 case DCCP_RESPOND: 704 case DCCP_PARTOPEN: 705 queued = dccp_rcv_respond_partopen_state_process(sk, skb, 706 dh, len); 707 break; 708 } 709 710 if (dh->dccph_type == DCCP_PKT_ACK || 711 dh->dccph_type == DCCP_PKT_DATAACK) { 712 switch (old_state) { 713 case DCCP_PARTOPEN: 714 sk->sk_state_change(sk); 715 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); 716 break; 717 } 718 } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) { 719 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK); 720 goto discard; 721 } 722 723 if (!queued) { 724 discard: 725 __kfree_skb(skb); 726 } 727 return 0; 728 } 729 730 EXPORT_SYMBOL_GPL(dccp_rcv_state_process); 731 732 /** 733 * dccp_sample_rtt - Validate and finalise computation of RTT sample 734 * @delta: number of microseconds between packet and acknowledgment 735 * The routine is kept generic to work in different contexts. It should be 736 * called immediately when the ACK used for the RTT sample arrives. 737 */ 738 u32 dccp_sample_rtt(struct sock *sk, long delta) 739 { 740 /* dccpor_elapsed_time is either zeroed out or set and > 0 */ 741 delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10; 742 743 if (unlikely(delta <= 0)) { 744 DCCP_WARN("unusable RTT sample %ld, using min\n", delta); 745 return DCCP_SANE_RTT_MIN; 746 } 747 if (unlikely(delta > DCCP_SANE_RTT_MAX)) { 748 DCCP_WARN("RTT sample %ld too large, using max\n", delta); 749 return DCCP_SANE_RTT_MAX; 750 } 751 752 return delta; 753 } 754