input.c revision a4bf3902427a128455b8de299ff0918072b2e974
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/config.h> 14#include <linux/dccp.h> 15#include <linux/skbuff.h> 16 17#include <net/sock.h> 18 19#include "ackvec.h" 20#include "ccid.h" 21#include "dccp.h" 22 23static void dccp_fin(struct sock *sk, struct sk_buff *skb) 24{ 25 sk->sk_shutdown |= RCV_SHUTDOWN; 26 sock_set_flag(sk, SOCK_DONE); 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 33static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb) 34{ 35 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED); 36 dccp_fin(sk, skb); 37 dccp_set_state(sk, DCCP_CLOSED); 38 sk_wake_async(sk, 1, POLL_HUP); 39} 40 41static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb) 42{ 43 /* 44 * Step 7: Check for unexpected packet types 45 * If (S.is_server and P.type == CloseReq) 46 * Send Sync packet acknowledging P.seqno 47 * Drop packet and return 48 */ 49 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) { 50 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC); 51 return; 52 } 53 54 if (sk->sk_state != DCCP_CLOSING) 55 dccp_set_state(sk, DCCP_CLOSING); 56 dccp_send_close(sk, 0); 57} 58 59static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb) 60{ 61 struct dccp_sock *dp = dccp_sk(sk); 62 63 if (dccp_msk(sk)->dccpms_send_ack_vector) 64 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk, 65 DCCP_SKB_CB(skb)->dccpd_ack_seq); 66} 67 68static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb) 69{ 70 const struct dccp_hdr *dh = dccp_hdr(skb); 71 struct dccp_sock *dp = dccp_sk(sk); 72 u64 lswl, lawl; 73 74 /* 75 * Step 5: Prepare sequence numbers for Sync 76 * If P.type == Sync or P.type == SyncAck, 77 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL, 78 * / * P is valid, so update sequence number variables 79 * accordingly. After this update, P will pass the tests 80 * in Step 6. A SyncAck is generated if necessary in 81 * Step 15 * / 82 * Update S.GSR, S.SWL, S.SWH 83 * Otherwise, 84 * Drop packet and return 85 */ 86 if (dh->dccph_type == DCCP_PKT_SYNC || 87 dh->dccph_type == DCCP_PKT_SYNCACK) { 88 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 89 dp->dccps_awl, dp->dccps_awh) && 90 !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl)) 91 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); 92 else 93 return -1; 94 } 95 96 /* 97 * Step 6: Check sequence numbers 98 * Let LSWL = S.SWL and LAWL = S.AWL 99 * If P.type == CloseReq or P.type == Close or P.type == Reset, 100 * LSWL := S.GSR + 1, LAWL := S.GAR 101 * If LSWL <= P.seqno <= S.SWH 102 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH), 103 * Update S.GSR, S.SWL, S.SWH 104 * If P.type != Sync, 105 * Update S.GAR 106 * Otherwise, 107 * Send Sync packet acknowledging P.seqno 108 * Drop packet and return 109 */ 110 lswl = dp->dccps_swl; 111 lawl = dp->dccps_awl; 112 113 if (dh->dccph_type == DCCP_PKT_CLOSEREQ || 114 dh->dccph_type == DCCP_PKT_CLOSE || 115 dh->dccph_type == DCCP_PKT_RESET) { 116 lswl = dp->dccps_gsr; 117 dccp_inc_seqno(&lswl); 118 lawl = dp->dccps_gar; 119 } 120 121 if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) && 122 (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ || 123 between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 124 lawl, dp->dccps_awh))) { 125 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); 126 127 if (dh->dccph_type != DCCP_PKT_SYNC && 128 (DCCP_SKB_CB(skb)->dccpd_ack_seq != 129 DCCP_PKT_WITHOUT_ACK_SEQ)) 130 dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq; 131 } else { 132 LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed for %s packet, " 133 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and " 134 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), " 135 "sending SYNC...\n", 136 dccp_packet_name(dh->dccph_type), 137 (unsigned long long) lswl, 138 (unsigned long long) 139 DCCP_SKB_CB(skb)->dccpd_seq, 140 (unsigned long long) dp->dccps_swh, 141 (DCCP_SKB_CB(skb)->dccpd_ack_seq == 142 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists", 143 (unsigned long long) lawl, 144 (unsigned long long) 145 DCCP_SKB_CB(skb)->dccpd_ack_seq, 146 (unsigned long long) dp->dccps_awh); 147 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC); 148 return -1; 149 } 150 151 return 0; 152} 153 154static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 155 const struct dccp_hdr *dh, const unsigned len) 156{ 157 struct dccp_sock *dp = dccp_sk(sk); 158 159 switch (dccp_hdr(skb)->dccph_type) { 160 case DCCP_PKT_DATAACK: 161 case DCCP_PKT_DATA: 162 /* 163 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED 164 * option if it is. 165 */ 166 __skb_pull(skb, dh->dccph_doff * 4); 167 __skb_queue_tail(&sk->sk_receive_queue, skb); 168 skb_set_owner_r(skb, sk); 169 sk->sk_data_ready(sk, 0); 170 return 0; 171 case DCCP_PKT_ACK: 172 goto discard; 173 case DCCP_PKT_RESET: 174 /* 175 * Step 9: Process Reset 176 * If P.type == Reset, 177 * Tear down connection 178 * S.state := TIMEWAIT 179 * Set TIMEWAIT timer 180 * Drop packet and return 181 */ 182 dccp_fin(sk, skb); 183 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 184 return 0; 185 case DCCP_PKT_CLOSEREQ: 186 dccp_rcv_closereq(sk, skb); 187 goto discard; 188 case DCCP_PKT_CLOSE: 189 dccp_rcv_close(sk, skb); 190 return 0; 191 case DCCP_PKT_REQUEST: 192 /* Step 7 193 * or (S.is_server and P.type == Response) 194 * or (S.is_client and P.type == Request) 195 * or (S.state >= OPEN and P.type == Request 196 * and P.seqno >= S.OSR) 197 * or (S.state >= OPEN and P.type == Response 198 * and P.seqno >= S.OSR) 199 * or (S.state == RESPOND and P.type == Data), 200 * Send Sync packet acknowledging P.seqno 201 * Drop packet and return 202 */ 203 if (dp->dccps_role != DCCP_ROLE_LISTEN) 204 goto send_sync; 205 goto check_seq; 206 case DCCP_PKT_RESPONSE: 207 if (dp->dccps_role != DCCP_ROLE_CLIENT) 208 goto send_sync; 209check_seq: 210 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) { 211send_sync: 212 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 213 DCCP_PKT_SYNC); 214 } 215 break; 216 case DCCP_PKT_SYNC: 217 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 218 DCCP_PKT_SYNCACK); 219 /* 220 * From the draft: 221 * 222 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets 223 * MAY have non-zero-length application data areas, whose 224 * contents * receivers MUST ignore. 225 */ 226 goto discard; 227 } 228 229 DCCP_INC_STATS_BH(DCCP_MIB_INERRS); 230discard: 231 __kfree_skb(skb); 232 return 0; 233} 234 235int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 236 const struct dccp_hdr *dh, const unsigned len) 237{ 238 struct dccp_sock *dp = dccp_sk(sk); 239 240 if (dccp_check_seqno(sk, skb)) 241 goto discard; 242 243 if (dccp_parse_options(sk, skb)) 244 goto discard; 245 246 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 247 dccp_event_ack_recv(sk, skb); 248 249 if (dccp_msk(sk)->dccpms_send_ack_vector && 250 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 251 DCCP_SKB_CB(skb)->dccpd_seq, 252 DCCP_ACKVEC_STATE_RECEIVED)) 253 goto discard; 254 255 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 256 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 257 258 return __dccp_rcv_established(sk, skb, dh, len); 259discard: 260 __kfree_skb(skb); 261 return 0; 262} 263 264EXPORT_SYMBOL_GPL(dccp_rcv_established); 265 266static int dccp_rcv_request_sent_state_process(struct sock *sk, 267 struct sk_buff *skb, 268 const struct dccp_hdr *dh, 269 const unsigned len) 270{ 271 /* 272 * Step 4: Prepare sequence numbers in REQUEST 273 * If S.state == REQUEST, 274 * If (P.type == Response or P.type == Reset) 275 * and S.AWL <= P.ackno <= S.AWH, 276 * / * Set sequence number variables corresponding to the 277 * other endpoint, so P will pass the tests in Step 6 * / 278 * Set S.GSR, S.ISR, S.SWL, S.SWH 279 * / * Response processing continues in Step 10; Reset 280 * processing continues in Step 9 * / 281 */ 282 if (dh->dccph_type == DCCP_PKT_RESPONSE) { 283 const struct inet_connection_sock *icsk = inet_csk(sk); 284 struct dccp_sock *dp = dccp_sk(sk); 285 286 /* Stop the REQUEST timer */ 287 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); 288 BUG_TRAP(sk->sk_send_head != NULL); 289 __kfree_skb(sk->sk_send_head); 290 sk->sk_send_head = NULL; 291 292 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 293 dp->dccps_awl, dp->dccps_awh)) { 294 dccp_pr_debug("invalid ackno: S.AWL=%llu, " 295 "P.ackno=%llu, S.AWH=%llu \n", 296 (unsigned long long)dp->dccps_awl, 297 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, 298 (unsigned long long)dp->dccps_awh); 299 goto out_invalid_packet; 300 } 301 302 if (dccp_parse_options(sk, skb)) 303 goto out_invalid_packet; 304 305 if (dccp_msk(sk)->dccpms_send_ack_vector && 306 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 307 DCCP_SKB_CB(skb)->dccpd_seq, 308 DCCP_ACKVEC_STATE_RECEIVED)) 309 goto out_invalid_packet; /* FIXME: change error code */ 310 311 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; 312 dccp_update_gsr(sk, dp->dccps_isr); 313 /* 314 * SWL and AWL are initially adjusted so that they are not less than 315 * the initial Sequence Numbers received and sent, respectively: 316 * SWL := max(GSR + 1 - floor(W/4), ISR), 317 * AWL := max(GSS - W' + 1, ISS). 318 * These adjustments MUST be applied only at the beginning of the 319 * connection. 320 * 321 * AWL was adjusted in dccp_v4_connect -acme 322 */ 323 dccp_set_seqno(&dp->dccps_swl, 324 max48(dp->dccps_swl, dp->dccps_isr)); 325 326 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); 327 328 /* 329 * Step 10: Process REQUEST state (second part) 330 * If S.state == REQUEST, 331 * / * If we get here, P is a valid Response from the 332 * server (see Step 4), and we should move to 333 * PARTOPEN state. PARTOPEN means send an Ack, 334 * don't send Data packets, retransmit Acks 335 * periodically, and always include any Init Cookie 336 * from the Response * / 337 * S.state := PARTOPEN 338 * Set PARTOPEN timer 339 * Continue with S.state == PARTOPEN 340 * / * Step 12 will send the Ack completing the 341 * three-way handshake * / 342 */ 343 dccp_set_state(sk, DCCP_PARTOPEN); 344 345 /* Make sure socket is routed, for correct metrics. */ 346 icsk->icsk_af_ops->rebuild_header(sk); 347 348 if (!sock_flag(sk, SOCK_DEAD)) { 349 sk->sk_state_change(sk); 350 sk_wake_async(sk, 0, POLL_OUT); 351 } 352 353 if (sk->sk_write_pending || icsk->icsk_ack.pingpong || 354 icsk->icsk_accept_queue.rskq_defer_accept) { 355 /* Save one ACK. Data will be ready after 356 * several ticks, if write_pending is set. 357 * 358 * It may be deleted, but with this feature tcpdumps 359 * look so _wonderfully_ clever, that I was not able 360 * to stand against the temptation 8) --ANK 361 */ 362 /* 363 * OK, in DCCP we can as well do a similar trick, its 364 * even in the draft, but there is no need for us to 365 * schedule an ack here, as dccp_sendmsg does this for 366 * us, also stated in the draft. -acme 367 */ 368 __kfree_skb(skb); 369 return 0; 370 } 371 dccp_send_ack(sk); 372 return -1; 373 } 374 375out_invalid_packet: 376 /* dccp_v4_do_rcv will send a reset */ 377 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 378 return 1; 379} 380 381static int dccp_rcv_respond_partopen_state_process(struct sock *sk, 382 struct sk_buff *skb, 383 const struct dccp_hdr *dh, 384 const unsigned len) 385{ 386 int queued = 0; 387 388 switch (dh->dccph_type) { 389 case DCCP_PKT_RESET: 390 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 391 break; 392 case DCCP_PKT_DATA: 393 if (sk->sk_state == DCCP_RESPOND) 394 break; 395 case DCCP_PKT_DATAACK: 396 case DCCP_PKT_ACK: 397 /* 398 * FIXME: we should be reseting the PARTOPEN (DELACK) timer 399 * here but only if we haven't used the DELACK timer for 400 * something else, like sending a delayed ack for a TIMESTAMP 401 * echo, etc, for now were not clearing it, sending an extra 402 * ACK when there is nothing else to do in DELACK is not a big 403 * deal after all. 404 */ 405 406 /* Stop the PARTOPEN timer */ 407 if (sk->sk_state == DCCP_PARTOPEN) 408 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 409 410 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; 411 dccp_set_state(sk, DCCP_OPEN); 412 413 if (dh->dccph_type == DCCP_PKT_DATAACK || 414 dh->dccph_type == DCCP_PKT_DATA) { 415 __dccp_rcv_established(sk, skb, dh, len); 416 queued = 1; /* packet was queued 417 (by __dccp_rcv_established) */ 418 } 419 break; 420 } 421 422 return queued; 423} 424 425int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 426 struct dccp_hdr *dh, unsigned len) 427{ 428 struct dccp_sock *dp = dccp_sk(sk); 429 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 430 const int old_state = sk->sk_state; 431 int queued = 0; 432 433 /* 434 * Step 3: Process LISTEN state 435 * (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv) 436 * 437 * If S.state == LISTEN, 438 * If P.type == Request or P contains a valid Init Cookie 439 * option, 440 * * Must scan the packet's options to check for an Init 441 * Cookie. Only the Init Cookie is processed here, 442 * however; other options are processed in Step 8. This 443 * scan need only be performed if the endpoint uses Init 444 * Cookies * 445 * * Generate a new socket and switch to that socket * 446 * Set S := new socket for this port pair 447 * S.state = RESPOND 448 * Choose S.ISS (initial seqno) or set from Init Cookie 449 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 450 * Continue with S.state == RESPOND 451 * * A Response packet will be generated in Step 11 * 452 * Otherwise, 453 * Generate Reset(No Connection) unless P.type == Reset 454 * Drop packet and return 455 * 456 * NOTE: the check for the packet types is done in 457 * dccp_rcv_state_process 458 */ 459 if (sk->sk_state == DCCP_LISTEN) { 460 if (dh->dccph_type == DCCP_PKT_REQUEST) { 461 if (inet_csk(sk)->icsk_af_ops->conn_request(sk, 462 skb) < 0) 463 return 1; 464 465 /* FIXME: do congestion control initialization */ 466 goto discard; 467 } 468 if (dh->dccph_type == DCCP_PKT_RESET) 469 goto discard; 470 471 /* Caller (dccp_v4_do_rcv) will send Reset */ 472 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 473 return 1; 474 } 475 476 if (sk->sk_state != DCCP_REQUESTING) { 477 if (dccp_check_seqno(sk, skb)) 478 goto discard; 479 480 /* 481 * Step 8: Process options and mark acknowledgeable 482 */ 483 if (dccp_parse_options(sk, skb)) 484 goto discard; 485 486 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 487 dccp_event_ack_recv(sk, skb); 488 489 if (dccp_msk(sk)->dccpms_send_ack_vector && 490 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 491 DCCP_SKB_CB(skb)->dccpd_seq, 492 DCCP_ACKVEC_STATE_RECEIVED)) 493 goto discard; 494 495 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 496 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 497 } 498 499 /* 500 * Step 9: Process Reset 501 * If P.type == Reset, 502 * Tear down connection 503 * S.state := TIMEWAIT 504 * Set TIMEWAIT timer 505 * Drop packet and return 506 */ 507 if (dh->dccph_type == DCCP_PKT_RESET) { 508 /* 509 * Queue the equivalent of TCP fin so that dccp_recvmsg 510 * exits the loop 511 */ 512 dccp_fin(sk, skb); 513 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 514 return 0; 515 /* 516 * Step 7: Check for unexpected packet types 517 * If (S.is_server and P.type == CloseReq) 518 * or (S.is_server and P.type == Response) 519 * or (S.is_client and P.type == Request) 520 * or (S.state == RESPOND and P.type == Data), 521 * Send Sync packet acknowledging P.seqno 522 * Drop packet and return 523 */ 524 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && 525 (dh->dccph_type == DCCP_PKT_RESPONSE || 526 dh->dccph_type == DCCP_PKT_CLOSEREQ)) || 527 (dp->dccps_role == DCCP_ROLE_CLIENT && 528 dh->dccph_type == DCCP_PKT_REQUEST) || 529 (sk->sk_state == DCCP_RESPOND && 530 dh->dccph_type == DCCP_PKT_DATA)) { 531 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC); 532 goto discard; 533 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { 534 dccp_rcv_closereq(sk, skb); 535 goto discard; 536 } else if (dh->dccph_type == DCCP_PKT_CLOSE) { 537 dccp_rcv_close(sk, skb); 538 return 0; 539 } 540 541 if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) { 542 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK); 543 goto discard; 544 } 545 546 switch (sk->sk_state) { 547 case DCCP_CLOSED: 548 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 549 return 1; 550 551 case DCCP_REQUESTING: 552 /* FIXME: do congestion control initialization */ 553 554 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); 555 if (queued >= 0) 556 return queued; 557 558 __kfree_skb(skb); 559 return 0; 560 561 case DCCP_RESPOND: 562 case DCCP_PARTOPEN: 563 queued = dccp_rcv_respond_partopen_state_process(sk, skb, 564 dh, len); 565 break; 566 } 567 568 if (dh->dccph_type == DCCP_PKT_ACK || 569 dh->dccph_type == DCCP_PKT_DATAACK) { 570 switch (old_state) { 571 case DCCP_PARTOPEN: 572 sk->sk_state_change(sk); 573 sk_wake_async(sk, 0, POLL_OUT); 574 break; 575 } 576 } 577 578 if (!queued) { 579discard: 580 __kfree_skb(skb); 581 } 582 return 0; 583} 584 585EXPORT_SYMBOL_GPL(dccp_rcv_state_process); 586