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 after48(ackno, dp->dccps_gar)) 244 dp->dccps_gar = ackno; 245 } else { 246 unsigned long now = jiffies; 247 /* 248 * Step 6: Check sequence numbers 249 * Otherwise, 250 * If P.type == Reset, 251 * Send Sync packet acknowledging S.GSR 252 * Otherwise, 253 * Send Sync packet acknowledging P.seqno 254 * Drop packet and return 255 * 256 * These Syncs are rate-limited as per RFC 4340, 7.5.4: 257 * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second. 258 */ 259 if (time_before(now, (dp->dccps_rate_last + 260 sysctl_dccp_sync_ratelimit))) 261 return 0; 262 263 DCCP_WARN("Step 6 failed for %s packet, " 264 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and " 265 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), " 266 "sending SYNC...\n", dccp_packet_name(dh->dccph_type), 267 (unsigned long long) lswl, (unsigned long long) seqno, 268 (unsigned long long) dp->dccps_swh, 269 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" 270 : "exists", 271 (unsigned long long) lawl, (unsigned long long) ackno, 272 (unsigned long long) dp->dccps_awh); 273 274 dp->dccps_rate_last = now; 275 276 if (dh->dccph_type == DCCP_PKT_RESET) 277 seqno = dp->dccps_gsr; 278 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC); 279 return -1; 280 } 281 282 return 0; 283 } 284 285 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 286 const struct dccp_hdr *dh, const unsigned len) 287 { 288 struct dccp_sock *dp = dccp_sk(sk); 289 290 switch (dccp_hdr(skb)->dccph_type) { 291 case DCCP_PKT_DATAACK: 292 case DCCP_PKT_DATA: 293 /* 294 * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when 295 * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening" 296 * - sk_receive_queue is full, use Code 2, "Receive Buffer" 297 */ 298 dccp_enqueue_skb(sk, skb); 299 return 0; 300 case DCCP_PKT_ACK: 301 goto discard; 302 case DCCP_PKT_RESET: 303 /* 304 * Step 9: Process Reset 305 * If P.type == Reset, 306 * Tear down connection 307 * S.state := TIMEWAIT 308 * Set TIMEWAIT timer 309 * Drop packet and return 310 */ 311 dccp_rcv_reset(sk, skb); 312 return 0; 313 case DCCP_PKT_CLOSEREQ: 314 if (dccp_rcv_closereq(sk, skb)) 315 return 0; 316 goto discard; 317 case DCCP_PKT_CLOSE: 318 if (dccp_rcv_close(sk, skb)) 319 return 0; 320 goto discard; 321 case DCCP_PKT_REQUEST: 322 /* Step 7 323 * or (S.is_server and P.type == Response) 324 * or (S.is_client and P.type == Request) 325 * or (S.state >= OPEN and P.type == Request 326 * and P.seqno >= S.OSR) 327 * or (S.state >= OPEN and P.type == Response 328 * and P.seqno >= S.OSR) 329 * or (S.state == RESPOND and P.type == Data), 330 * Send Sync packet acknowledging P.seqno 331 * Drop packet and return 332 */ 333 if (dp->dccps_role != DCCP_ROLE_LISTEN) 334 goto send_sync; 335 goto check_seq; 336 case DCCP_PKT_RESPONSE: 337 if (dp->dccps_role != DCCP_ROLE_CLIENT) 338 goto send_sync; 339 check_seq: 340 if (dccp_delta_seqno(dp->dccps_osr, 341 DCCP_SKB_CB(skb)->dccpd_seq) >= 0) { 342 send_sync: 343 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 344 DCCP_PKT_SYNC); 345 } 346 break; 347 case DCCP_PKT_SYNC: 348 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 349 DCCP_PKT_SYNCACK); 350 /* 351 * From RFC 4340, sec. 5.7 352 * 353 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets 354 * MAY have non-zero-length application data areas, whose 355 * contents receivers MUST ignore. 356 */ 357 goto discard; 358 } 359 360 DCCP_INC_STATS_BH(DCCP_MIB_INERRS); 361 discard: 362 __kfree_skb(skb); 363 return 0; 364 } 365 366 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 367 const struct dccp_hdr *dh, const unsigned len) 368 { 369 struct dccp_sock *dp = dccp_sk(sk); 370 371 if (dccp_check_seqno(sk, skb)) 372 goto discard; 373 374 if (dccp_parse_options(sk, NULL, skb)) 375 return 1; 376 377 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 378 dccp_event_ack_recv(sk, skb); 379 380 if (dp->dccps_hc_rx_ackvec != NULL && 381 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 382 DCCP_SKB_CB(skb)->dccpd_seq, 383 DCCP_ACKVEC_STATE_RECEIVED)) 384 goto discard; 385 dccp_deliver_input_to_ccids(sk, skb); 386 387 return __dccp_rcv_established(sk, skb, dh, len); 388 discard: 389 __kfree_skb(skb); 390 return 0; 391 } 392 393 EXPORT_SYMBOL_GPL(dccp_rcv_established); 394 395 static int dccp_rcv_request_sent_state_process(struct sock *sk, 396 struct sk_buff *skb, 397 const struct dccp_hdr *dh, 398 const unsigned len) 399 { 400 /* 401 * Step 4: Prepare sequence numbers in REQUEST 402 * If S.state == REQUEST, 403 * If (P.type == Response or P.type == Reset) 404 * and S.AWL <= P.ackno <= S.AWH, 405 * / * Set sequence number variables corresponding to the 406 * other endpoint, so P will pass the tests in Step 6 * / 407 * Set S.GSR, S.ISR, S.SWL, S.SWH 408 * / * Response processing continues in Step 10; Reset 409 * processing continues in Step 9 * / 410 */ 411 if (dh->dccph_type == DCCP_PKT_RESPONSE) { 412 const struct inet_connection_sock *icsk = inet_csk(sk); 413 struct dccp_sock *dp = dccp_sk(sk); 414 long tstamp = dccp_timestamp(); 415 416 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 417 dp->dccps_awl, dp->dccps_awh)) { 418 dccp_pr_debug("invalid ackno: S.AWL=%llu, " 419 "P.ackno=%llu, S.AWH=%llu\n", 420 (unsigned long long)dp->dccps_awl, 421 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, 422 (unsigned long long)dp->dccps_awh); 423 goto out_invalid_packet; 424 } 425 426 /* 427 * If option processing (Step 8) failed, return 1 here so that 428 * dccp_v4_do_rcv() sends a Reset. The Reset code depends on 429 * the option type and is set in dccp_parse_options(). 430 */ 431 if (dccp_parse_options(sk, NULL, skb)) 432 return 1; 433 434 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ 435 if (likely(dp->dccps_options_received.dccpor_timestamp_echo)) 436 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp - 437 dp->dccps_options_received.dccpor_timestamp_echo)); 438 439 /* Stop the REQUEST timer */ 440 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); 441 WARN_ON(sk->sk_send_head == NULL); 442 kfree_skb(sk->sk_send_head); 443 sk->sk_send_head = NULL; 444 445 /* 446 * Set ISR, GSR from packet. ISS was set in dccp_v{4,6}_connect 447 * and GSS in dccp_transmit_skb(). Setting AWL/AWH and SWL/SWH 448 * is done as part of activating the feature values below, since 449 * these settings depend on the local/remote Sequence Window 450 * features, which were undefined or not confirmed until now. 451 */ 452 dp->dccps_gsr = dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; 453 454 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); 455 456 /* 457 * Step 10: Process REQUEST state (second part) 458 * If S.state == REQUEST, 459 * / * If we get here, P is a valid Response from the 460 * server (see Step 4), and we should move to 461 * PARTOPEN state. PARTOPEN means send an Ack, 462 * don't send Data packets, retransmit Acks 463 * periodically, and always include any Init Cookie 464 * from the Response * / 465 * S.state := PARTOPEN 466 * Set PARTOPEN timer 467 * Continue with S.state == PARTOPEN 468 * / * Step 12 will send the Ack completing the 469 * three-way handshake * / 470 */ 471 dccp_set_state(sk, DCCP_PARTOPEN); 472 473 /* 474 * If feature negotiation was successful, activate features now; 475 * an activation failure means that this host could not activate 476 * one ore more features (e.g. insufficient memory), which would 477 * leave at least one feature in an undefined state. 478 */ 479 if (dccp_feat_activate_values(sk, &dp->dccps_featneg)) 480 goto unable_to_proceed; 481 482 /* Make sure socket is routed, for correct metrics. */ 483 icsk->icsk_af_ops->rebuild_header(sk); 484 485 if (!sock_flag(sk, SOCK_DEAD)) { 486 sk->sk_state_change(sk); 487 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); 488 } 489 490 if (sk->sk_write_pending || icsk->icsk_ack.pingpong || 491 icsk->icsk_accept_queue.rskq_defer_accept) { 492 /* Save one ACK. Data will be ready after 493 * several ticks, if write_pending is set. 494 * 495 * It may be deleted, but with this feature tcpdumps 496 * look so _wonderfully_ clever, that I was not able 497 * to stand against the temptation 8) --ANK 498 */ 499 /* 500 * OK, in DCCP we can as well do a similar trick, its 501 * even in the draft, but there is no need for us to 502 * schedule an ack here, as dccp_sendmsg does this for 503 * us, also stated in the draft. -acme 504 */ 505 __kfree_skb(skb); 506 return 0; 507 } 508 dccp_send_ack(sk); 509 return -1; 510 } 511 512 out_invalid_packet: 513 /* dccp_v4_do_rcv will send a reset */ 514 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 515 return 1; 516 517 unable_to_proceed: 518 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED; 519 /* 520 * We mark this socket as no longer usable, so that the loop in 521 * dccp_sendmsg() terminates and the application gets notified. 522 */ 523 dccp_set_state(sk, DCCP_CLOSED); 524 sk->sk_err = ECOMM; 525 return 1; 526 } 527 528 static int dccp_rcv_respond_partopen_state_process(struct sock *sk, 529 struct sk_buff *skb, 530 const struct dccp_hdr *dh, 531 const unsigned len) 532 { 533 struct dccp_sock *dp = dccp_sk(sk); 534 u32 sample = dp->dccps_options_received.dccpor_timestamp_echo; 535 int queued = 0; 536 537 switch (dh->dccph_type) { 538 case DCCP_PKT_RESET: 539 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 540 break; 541 case DCCP_PKT_DATA: 542 if (sk->sk_state == DCCP_RESPOND) 543 break; 544 case DCCP_PKT_DATAACK: 545 case DCCP_PKT_ACK: 546 /* 547 * FIXME: we should be reseting the PARTOPEN (DELACK) timer 548 * here but only if we haven't used the DELACK timer for 549 * something else, like sending a delayed ack for a TIMESTAMP 550 * echo, etc, for now were not clearing it, sending an extra 551 * ACK when there is nothing else to do in DELACK is not a big 552 * deal after all. 553 */ 554 555 /* Stop the PARTOPEN timer */ 556 if (sk->sk_state == DCCP_PARTOPEN) 557 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 558 559 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ 560 if (likely(sample)) { 561 long delta = dccp_timestamp() - sample; 562 563 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta); 564 } 565 566 dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; 567 dccp_set_state(sk, DCCP_OPEN); 568 569 if (dh->dccph_type == DCCP_PKT_DATAACK || 570 dh->dccph_type == DCCP_PKT_DATA) { 571 __dccp_rcv_established(sk, skb, dh, len); 572 queued = 1; /* packet was queued 573 (by __dccp_rcv_established) */ 574 } 575 break; 576 } 577 578 return queued; 579 } 580 581 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 582 struct dccp_hdr *dh, unsigned len) 583 { 584 struct dccp_sock *dp = dccp_sk(sk); 585 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 586 const int old_state = sk->sk_state; 587 int queued = 0; 588 589 /* 590 * Step 3: Process LISTEN state 591 * 592 * If S.state == LISTEN, 593 * If P.type == Request or P contains a valid Init Cookie option, 594 * (* Must scan the packet's options to check for Init 595 * Cookies. Only Init Cookies are processed here, 596 * however; other options are processed in Step 8. This 597 * scan need only be performed if the endpoint uses Init 598 * Cookies *) 599 * (* Generate a new socket and switch to that socket *) 600 * Set S := new socket for this port pair 601 * S.state = RESPOND 602 * Choose S.ISS (initial seqno) or set from Init Cookies 603 * Initialize S.GAR := S.ISS 604 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init 605 * Cookies Continue with S.state == RESPOND 606 * (* A Response packet will be generated in Step 11 *) 607 * Otherwise, 608 * Generate Reset(No Connection) unless P.type == Reset 609 * Drop packet and return 610 */ 611 if (sk->sk_state == DCCP_LISTEN) { 612 if (dh->dccph_type == DCCP_PKT_REQUEST) { 613 if (inet_csk(sk)->icsk_af_ops->conn_request(sk, 614 skb) < 0) 615 return 1; 616 goto discard; 617 } 618 if (dh->dccph_type == DCCP_PKT_RESET) 619 goto discard; 620 621 /* Caller (dccp_v4_do_rcv) will send Reset */ 622 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 623 return 1; 624 } 625 626 if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) { 627 if (dccp_check_seqno(sk, skb)) 628 goto discard; 629 630 /* 631 * Step 8: Process options and mark acknowledgeable 632 */ 633 if (dccp_parse_options(sk, NULL, skb)) 634 return 1; 635 636 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 637 dccp_event_ack_recv(sk, skb); 638 639 if (dp->dccps_hc_rx_ackvec != NULL && 640 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 641 DCCP_SKB_CB(skb)->dccpd_seq, 642 DCCP_ACKVEC_STATE_RECEIVED)) 643 goto discard; 644 645 dccp_deliver_input_to_ccids(sk, skb); 646 } 647 648 /* 649 * Step 9: Process Reset 650 * If P.type == Reset, 651 * Tear down connection 652 * S.state := TIMEWAIT 653 * Set TIMEWAIT timer 654 * Drop packet and return 655 */ 656 if (dh->dccph_type == DCCP_PKT_RESET) { 657 dccp_rcv_reset(sk, skb); 658 return 0; 659 /* 660 * Step 7: Check for unexpected packet types 661 * If (S.is_server and P.type == Response) 662 * or (S.is_client and P.type == Request) 663 * or (S.state == RESPOND and P.type == Data), 664 * Send Sync packet acknowledging P.seqno 665 * Drop packet and return 666 */ 667 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && 668 dh->dccph_type == DCCP_PKT_RESPONSE) || 669 (dp->dccps_role == DCCP_ROLE_CLIENT && 670 dh->dccph_type == DCCP_PKT_REQUEST) || 671 (sk->sk_state == DCCP_RESPOND && 672 dh->dccph_type == DCCP_PKT_DATA)) { 673 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC); 674 goto discard; 675 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { 676 if (dccp_rcv_closereq(sk, skb)) 677 return 0; 678 goto discard; 679 } else if (dh->dccph_type == DCCP_PKT_CLOSE) { 680 if (dccp_rcv_close(sk, skb)) 681 return 0; 682 goto discard; 683 } 684 685 switch (sk->sk_state) { 686 case DCCP_CLOSED: 687 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 688 return 1; 689 690 case DCCP_REQUESTING: 691 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); 692 if (queued >= 0) 693 return queued; 694 695 __kfree_skb(skb); 696 return 0; 697 698 case DCCP_RESPOND: 699 case DCCP_PARTOPEN: 700 queued = dccp_rcv_respond_partopen_state_process(sk, skb, 701 dh, len); 702 break; 703 } 704 705 if (dh->dccph_type == DCCP_PKT_ACK || 706 dh->dccph_type == DCCP_PKT_DATAACK) { 707 switch (old_state) { 708 case DCCP_PARTOPEN: 709 sk->sk_state_change(sk); 710 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); 711 break; 712 } 713 } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) { 714 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK); 715 goto discard; 716 } 717 718 if (!queued) { 719 discard: 720 __kfree_skb(skb); 721 } 722 return 0; 723 } 724 725 EXPORT_SYMBOL_GPL(dccp_rcv_state_process); 726 727 /** 728 * dccp_sample_rtt - Validate and finalise computation of RTT sample 729 * @delta: number of microseconds between packet and acknowledgment 730 * The routine is kept generic to work in different contexts. It should be 731 * called immediately when the ACK used for the RTT sample arrives. 732 */ 733 u32 dccp_sample_rtt(struct sock *sk, long delta) 734 { 735 /* dccpor_elapsed_time is either zeroed out or set and > 0 */ 736 delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10; 737 738 if (unlikely(delta <= 0)) { 739 DCCP_WARN("unusable RTT sample %ld, using min\n", delta); 740 return DCCP_SANE_RTT_MIN; 741 } 742 if (unlikely(delta > DCCP_SANE_RTT_MAX)) { 743 DCCP_WARN("RTT sample %ld too large, using max\n", delta); 744 return DCCP_SANE_RTT_MAX; 745 } 746 747 return delta; 748 } 749