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); 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 static 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_handle_ackvec_processing(struct sock *sk, struct sk_buff *skb) 164 { 165 struct dccp_ackvec *av = dccp_sk(sk)->dccps_hc_rx_ackvec; 166 167 if (av == NULL) 168 return; 169 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 170 dccp_ackvec_clear_state(av, DCCP_SKB_CB(skb)->dccpd_ack_seq); 171 dccp_ackvec_input(av, skb); 172 } 173 174 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb) 175 { 176 const struct dccp_sock *dp = dccp_sk(sk); 177 178 /* Don't deliver to RX CCID when node has shut down read end. */ 179 if (!(sk->sk_shutdown & RCV_SHUTDOWN)) 180 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 181 /* 182 * Until the TX queue has been drained, we can not honour SHUT_WR, since 183 * we need received feedback as input to adjust congestion control. 184 */ 185 if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN)) 186 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 187 } 188 189 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb) 190 { 191 const struct dccp_hdr *dh = dccp_hdr(skb); 192 struct dccp_sock *dp = dccp_sk(sk); 193 u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq, 194 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; 195 196 /* 197 * Step 5: Prepare sequence numbers for Sync 198 * If P.type == Sync or P.type == SyncAck, 199 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL, 200 * / * P is valid, so update sequence number variables 201 * accordingly. After this update, P will pass the tests 202 * in Step 6. A SyncAck is generated if necessary in 203 * Step 15 * / 204 * Update S.GSR, S.SWL, S.SWH 205 * Otherwise, 206 * Drop packet and return 207 */ 208 if (dh->dccph_type == DCCP_PKT_SYNC || 209 dh->dccph_type == DCCP_PKT_SYNCACK) { 210 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) && 211 dccp_delta_seqno(dp->dccps_swl, seqno) >= 0) 212 dccp_update_gsr(sk, seqno); 213 else 214 return -1; 215 } 216 217 /* 218 * Step 6: Check sequence numbers 219 * Let LSWL = S.SWL and LAWL = S.AWL 220 * If P.type == CloseReq or P.type == Close or P.type == Reset, 221 * LSWL := S.GSR + 1, LAWL := S.GAR 222 * If LSWL <= P.seqno <= S.SWH 223 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH), 224 * Update S.GSR, S.SWL, S.SWH 225 * If P.type != Sync, 226 * Update S.GAR 227 */ 228 lswl = dp->dccps_swl; 229 lawl = dp->dccps_awl; 230 231 if (dh->dccph_type == DCCP_PKT_CLOSEREQ || 232 dh->dccph_type == DCCP_PKT_CLOSE || 233 dh->dccph_type == DCCP_PKT_RESET) { 234 lswl = ADD48(dp->dccps_gsr, 1); 235 lawl = dp->dccps_gar; 236 } 237 238 if (between48(seqno, lswl, dp->dccps_swh) && 239 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ || 240 between48(ackno, lawl, dp->dccps_awh))) { 241 dccp_update_gsr(sk, seqno); 242 243 if (dh->dccph_type != DCCP_PKT_SYNC && 244 ackno != DCCP_PKT_WITHOUT_ACK_SEQ && 245 after48(ackno, dp->dccps_gar)) 246 dp->dccps_gar = ackno; 247 } else { 248 unsigned long now = jiffies; 249 /* 250 * Step 6: Check sequence numbers 251 * Otherwise, 252 * If P.type == Reset, 253 * Send Sync packet acknowledging S.GSR 254 * Otherwise, 255 * Send Sync packet acknowledging P.seqno 256 * Drop packet and return 257 * 258 * These Syncs are rate-limited as per RFC 4340, 7.5.4: 259 * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second. 260 */ 261 if (time_before(now, (dp->dccps_rate_last + 262 sysctl_dccp_sync_ratelimit))) 263 return -1; 264 265 DCCP_WARN("Step 6 failed for %s packet, " 266 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and " 267 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), " 268 "sending SYNC...\n", dccp_packet_name(dh->dccph_type), 269 (unsigned long long) lswl, (unsigned long long) seqno, 270 (unsigned long long) dp->dccps_swh, 271 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" 272 : "exists", 273 (unsigned long long) lawl, (unsigned long long) ackno, 274 (unsigned long long) dp->dccps_awh); 275 276 dp->dccps_rate_last = now; 277 278 if (dh->dccph_type == DCCP_PKT_RESET) 279 seqno = dp->dccps_gsr; 280 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC); 281 return -1; 282 } 283 284 return 0; 285 } 286 287 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 288 const struct dccp_hdr *dh, const unsigned int len) 289 { 290 struct dccp_sock *dp = dccp_sk(sk); 291 292 switch (dccp_hdr(skb)->dccph_type) { 293 case DCCP_PKT_DATAACK: 294 case DCCP_PKT_DATA: 295 /* 296 * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when 297 * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening" 298 * - sk_receive_queue is full, use Code 2, "Receive Buffer" 299 */ 300 dccp_enqueue_skb(sk, skb); 301 return 0; 302 case DCCP_PKT_ACK: 303 goto discard; 304 case DCCP_PKT_RESET: 305 /* 306 * Step 9: Process Reset 307 * If P.type == Reset, 308 * Tear down connection 309 * S.state := TIMEWAIT 310 * Set TIMEWAIT timer 311 * Drop packet and return 312 */ 313 dccp_rcv_reset(sk, skb); 314 return 0; 315 case DCCP_PKT_CLOSEREQ: 316 if (dccp_rcv_closereq(sk, skb)) 317 return 0; 318 goto discard; 319 case DCCP_PKT_CLOSE: 320 if (dccp_rcv_close(sk, skb)) 321 return 0; 322 goto discard; 323 case DCCP_PKT_REQUEST: 324 /* Step 7 325 * or (S.is_server and P.type == Response) 326 * or (S.is_client and P.type == Request) 327 * or (S.state >= OPEN and P.type == Request 328 * and P.seqno >= S.OSR) 329 * or (S.state >= OPEN and P.type == Response 330 * and P.seqno >= S.OSR) 331 * or (S.state == RESPOND and P.type == Data), 332 * Send Sync packet acknowledging P.seqno 333 * Drop packet and return 334 */ 335 if (dp->dccps_role != DCCP_ROLE_LISTEN) 336 goto send_sync; 337 goto check_seq; 338 case DCCP_PKT_RESPONSE: 339 if (dp->dccps_role != DCCP_ROLE_CLIENT) 340 goto send_sync; 341 check_seq: 342 if (dccp_delta_seqno(dp->dccps_osr, 343 DCCP_SKB_CB(skb)->dccpd_seq) >= 0) { 344 send_sync: 345 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 346 DCCP_PKT_SYNC); 347 } 348 break; 349 case DCCP_PKT_SYNC: 350 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 351 DCCP_PKT_SYNCACK); 352 /* 353 * From RFC 4340, sec. 5.7 354 * 355 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets 356 * MAY have non-zero-length application data areas, whose 357 * contents receivers MUST ignore. 358 */ 359 goto discard; 360 } 361 362 DCCP_INC_STATS(DCCP_MIB_INERRS); 363 discard: 364 __kfree_skb(skb); 365 return 0; 366 } 367 368 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 369 const struct dccp_hdr *dh, const unsigned int len) 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 dccp_handle_ackvec_processing(sk, skb); 378 dccp_deliver_input_to_ccids(sk, skb); 379 380 return __dccp_rcv_established(sk, skb, dh, len); 381 discard: 382 __kfree_skb(skb); 383 return 0; 384 } 385 386 EXPORT_SYMBOL_GPL(dccp_rcv_established); 387 388 static int dccp_rcv_request_sent_state_process(struct sock *sk, 389 struct sk_buff *skb, 390 const struct dccp_hdr *dh, 391 const unsigned int len) 392 { 393 /* 394 * Step 4: Prepare sequence numbers in REQUEST 395 * If S.state == REQUEST, 396 * If (P.type == Response or P.type == Reset) 397 * and S.AWL <= P.ackno <= S.AWH, 398 * / * Set sequence number variables corresponding to the 399 * other endpoint, so P will pass the tests in Step 6 * / 400 * Set S.GSR, S.ISR, S.SWL, S.SWH 401 * / * Response processing continues in Step 10; Reset 402 * processing continues in Step 9 * / 403 */ 404 if (dh->dccph_type == DCCP_PKT_RESPONSE) { 405 const struct inet_connection_sock *icsk = inet_csk(sk); 406 struct dccp_sock *dp = dccp_sk(sk); 407 long tstamp = dccp_timestamp(); 408 409 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 410 dp->dccps_awl, dp->dccps_awh)) { 411 dccp_pr_debug("invalid ackno: S.AWL=%llu, " 412 "P.ackno=%llu, S.AWH=%llu\n", 413 (unsigned long long)dp->dccps_awl, 414 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, 415 (unsigned long long)dp->dccps_awh); 416 goto out_invalid_packet; 417 } 418 419 /* 420 * If option processing (Step 8) failed, return 1 here so that 421 * dccp_v4_do_rcv() sends a Reset. The Reset code depends on 422 * the option type and is set in dccp_parse_options(). 423 */ 424 if (dccp_parse_options(sk, NULL, skb)) 425 return 1; 426 427 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ 428 if (likely(dp->dccps_options_received.dccpor_timestamp_echo)) 429 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp - 430 dp->dccps_options_received.dccpor_timestamp_echo)); 431 432 /* Stop the REQUEST timer */ 433 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); 434 WARN_ON(sk->sk_send_head == NULL); 435 kfree_skb(sk->sk_send_head); 436 sk->sk_send_head = NULL; 437 438 /* 439 * Set ISR, GSR from packet. ISS was set in dccp_v{4,6}_connect 440 * and GSS in dccp_transmit_skb(). Setting AWL/AWH and SWL/SWH 441 * is done as part of activating the feature values below, since 442 * these settings depend on the local/remote Sequence Window 443 * features, which were undefined or not confirmed until now. 444 */ 445 dp->dccps_gsr = dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; 446 447 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); 448 449 /* 450 * Step 10: Process REQUEST state (second part) 451 * If S.state == REQUEST, 452 * / * If we get here, P is a valid Response from the 453 * server (see Step 4), and we should move to 454 * PARTOPEN state. PARTOPEN means send an Ack, 455 * don't send Data packets, retransmit Acks 456 * periodically, and always include any Init Cookie 457 * from the Response * / 458 * S.state := PARTOPEN 459 * Set PARTOPEN timer 460 * Continue with S.state == PARTOPEN 461 * / * Step 12 will send the Ack completing the 462 * three-way handshake * / 463 */ 464 dccp_set_state(sk, DCCP_PARTOPEN); 465 466 /* 467 * If feature negotiation was successful, activate features now; 468 * an activation failure means that this host could not activate 469 * one ore more features (e.g. insufficient memory), which would 470 * leave at least one feature in an undefined state. 471 */ 472 if (dccp_feat_activate_values(sk, &dp->dccps_featneg)) 473 goto unable_to_proceed; 474 475 /* Make sure socket is routed, for correct metrics. */ 476 icsk->icsk_af_ops->rebuild_header(sk); 477 478 if (!sock_flag(sk, SOCK_DEAD)) { 479 sk->sk_state_change(sk); 480 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); 481 } 482 483 if (sk->sk_write_pending || inet_csk_in_pingpong_mode(sk) || 484 icsk->icsk_accept_queue.rskq_defer_accept) { 485 /* Save one ACK. Data will be ready after 486 * several ticks, if write_pending is set. 487 * 488 * It may be deleted, but with this feature tcpdumps 489 * look so _wonderfully_ clever, that I was not able 490 * to stand against the temptation 8) --ANK 491 */ 492 /* 493 * OK, in DCCP we can as well do a similar trick, its 494 * even in the draft, but there is no need for us to 495 * schedule an ack here, as dccp_sendmsg does this for 496 * us, also stated in the draft. -acme 497 */ 498 __kfree_skb(skb); 499 return 0; 500 } 501 dccp_send_ack(sk); 502 return -1; 503 } 504 505 out_invalid_packet: 506 /* dccp_v4_do_rcv will send a reset */ 507 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 508 return 1; 509 510 unable_to_proceed: 511 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED; 512 /* 513 * We mark this socket as no longer usable, so that the loop in 514 * dccp_sendmsg() terminates and the application gets notified. 515 */ 516 dccp_set_state(sk, DCCP_CLOSED); 517 sk->sk_err = ECOMM; 518 return 1; 519 } 520 521 static int dccp_rcv_respond_partopen_state_process(struct sock *sk, 522 struct sk_buff *skb, 523 const struct dccp_hdr *dh, 524 const unsigned int len) 525 { 526 struct dccp_sock *dp = dccp_sk(sk); 527 u32 sample = dp->dccps_options_received.dccpor_timestamp_echo; 528 int queued = 0; 529 530 switch (dh->dccph_type) { 531 case DCCP_PKT_RESET: 532 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 533 break; 534 case DCCP_PKT_DATA: 535 if (sk->sk_state == DCCP_RESPOND) 536 break; 537 /* fall through */ 538 case DCCP_PKT_DATAACK: 539 case DCCP_PKT_ACK: 540 /* 541 * FIXME: we should be resetting the PARTOPEN (DELACK) timer 542 * here but only if we haven't used the DELACK timer for 543 * something else, like sending a delayed ack for a TIMESTAMP 544 * echo, etc, for now were not clearing it, sending an extra 545 * ACK when there is nothing else to do in DELACK is not a big 546 * deal after all. 547 */ 548 549 /* Stop the PARTOPEN timer */ 550 if (sk->sk_state == DCCP_PARTOPEN) 551 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 552 553 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ 554 if (likely(sample)) { 555 long delta = dccp_timestamp() - sample; 556 557 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta); 558 } 559 560 dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; 561 dccp_set_state(sk, DCCP_OPEN); 562 563 if (dh->dccph_type == DCCP_PKT_DATAACK || 564 dh->dccph_type == DCCP_PKT_DATA) { 565 __dccp_rcv_established(sk, skb, dh, len); 566 queued = 1; /* packet was queued 567 (by __dccp_rcv_established) */ 568 } 569 break; 570 } 571 572 return queued; 573 } 574 575 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 576 struct dccp_hdr *dh, unsigned int len) 577 { 578 struct dccp_sock *dp = dccp_sk(sk); 579 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 580 const int old_state = sk->sk_state; 581 bool acceptable; 582 int queued = 0; 583 584 /* 585 * Step 3: Process LISTEN state 586 * 587 * If S.state == LISTEN, 588 * If P.type == Request or P contains a valid Init Cookie option, 589 * (* Must scan the packet's options to check for Init 590 * Cookies. Only Init Cookies are processed here, 591 * however; other options are processed in Step 8. This 592 * scan need only be performed if the endpoint uses Init 593 * Cookies *) 594 * (* Generate a new socket and switch to that socket *) 595 * Set S := new socket for this port pair 596 * S.state = RESPOND 597 * Choose S.ISS (initial seqno) or set from Init Cookies 598 * Initialize S.GAR := S.ISS 599 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init 600 * Cookies Continue with S.state == RESPOND 601 * (* A Response packet will be generated in Step 11 *) 602 * Otherwise, 603 * Generate Reset(No Connection) unless P.type == Reset 604 * Drop packet and return 605 */ 606 if (sk->sk_state == DCCP_LISTEN) { 607 if (dh->dccph_type == DCCP_PKT_REQUEST) { 608 /* It is possible that we process SYN packets from backlog, 609 * so we need to make sure to disable BH and RCU right there. 610 */ 611 rcu_read_lock(); 612 local_bh_disable(); 613 acceptable = inet_csk(sk)->icsk_af_ops->conn_request(sk, skb) >= 0; 614 local_bh_enable(); 615 rcu_read_unlock(); 616 if (!acceptable) 617 return 1; 618 consume_skb(skb); 619 return 0; 620 } 621 if (dh->dccph_type == DCCP_PKT_RESET) 622 goto discard; 623 624 /* Caller (dccp_v4_do_rcv) will send Reset */ 625 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 626 return 1; 627 } else if (sk->sk_state == DCCP_CLOSED) { 628 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 629 return 1; 630 } 631 632 /* Step 6: Check sequence numbers (omitted in LISTEN/REQUEST state) */ 633 if (sk->sk_state != DCCP_REQUESTING && dccp_check_seqno(sk, skb)) 634 goto discard; 635 636 /* 637 * Step 7: Check for unexpected packet types 638 * If (S.is_server and P.type == Response) 639 * or (S.is_client and P.type == Request) 640 * or (S.state == RESPOND and P.type == Data), 641 * Send Sync packet acknowledging P.seqno 642 * Drop packet and return 643 */ 644 if ((dp->dccps_role != DCCP_ROLE_CLIENT && 645 dh->dccph_type == DCCP_PKT_RESPONSE) || 646 (dp->dccps_role == DCCP_ROLE_CLIENT && 647 dh->dccph_type == DCCP_PKT_REQUEST) || 648 (sk->sk_state == DCCP_RESPOND && dh->dccph_type == DCCP_PKT_DATA)) { 649 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC); 650 goto discard; 651 } 652 653 /* Step 8: Process options */ 654 if (dccp_parse_options(sk, NULL, skb)) 655 return 1; 656 657 /* 658 * Step 9: Process Reset 659 * If P.type == Reset, 660 * Tear down connection 661 * S.state := TIMEWAIT 662 * Set TIMEWAIT timer 663 * Drop packet and return 664 */ 665 if (dh->dccph_type == DCCP_PKT_RESET) { 666 dccp_rcv_reset(sk, skb); 667 return 0; 668 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { /* Step 13 */ 669 if (dccp_rcv_closereq(sk, skb)) 670 return 0; 671 goto discard; 672 } else if (dh->dccph_type == DCCP_PKT_CLOSE) { /* Step 14 */ 673 if (dccp_rcv_close(sk, skb)) 674 return 0; 675 goto discard; 676 } 677 678 switch (sk->sk_state) { 679 case DCCP_REQUESTING: 680 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); 681 if (queued >= 0) 682 return queued; 683 684 __kfree_skb(skb); 685 return 0; 686 687 case DCCP_PARTOPEN: 688 /* Step 8: if using Ack Vectors, mark packet acknowledgeable */ 689 dccp_handle_ackvec_processing(sk, skb); 690 dccp_deliver_input_to_ccids(sk, skb); 691 /* fall through */ 692 case DCCP_RESPOND: 693 queued = dccp_rcv_respond_partopen_state_process(sk, skb, 694 dh, len); 695 break; 696 } 697 698 if (dh->dccph_type == DCCP_PKT_ACK || 699 dh->dccph_type == DCCP_PKT_DATAACK) { 700 switch (old_state) { 701 case DCCP_PARTOPEN: 702 sk->sk_state_change(sk); 703 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); 704 break; 705 } 706 } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) { 707 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK); 708 goto discard; 709 } 710 711 if (!queued) { 712 discard: 713 __kfree_skb(skb); 714 } 715 return 0; 716 } 717 718 EXPORT_SYMBOL_GPL(dccp_rcv_state_process); 719 720 /** 721 * dccp_sample_rtt - Validate and finalise computation of RTT sample 722 * @delta: number of microseconds between packet and acknowledgment 723 * 724 * The routine is kept generic to work in different contexts. It should be 725 * called immediately when the ACK used for the RTT sample arrives. 726 */ 727 u32 dccp_sample_rtt(struct sock *sk, long delta) 728 { 729 /* dccpor_elapsed_time is either zeroed out or set and > 0 */ 730 delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10; 731 732 if (unlikely(delta <= 0)) { 733 DCCP_WARN("unusable RTT sample %ld, using min\n", delta); 734 return DCCP_SANE_RTT_MIN; 735 } 736 if (unlikely(delta > DCCP_SANE_RTT_MAX)) { 737 DCCP_WARN("RTT sample %ld too large, using max\n", delta); 738 return DCCP_SANE_RTT_MAX; 739 } 740 741 return delta; 742 } 743