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