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 "ccid.h" 20 #include "dccp.h" 21 22 static void dccp_fin(struct sock *sk, struct sk_buff *skb) 23 { 24 sk->sk_shutdown |= RCV_SHUTDOWN; 25 sock_set_flag(sk, SOCK_DONE); 26 __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4); 27 __skb_queue_tail(&sk->sk_receive_queue, skb); 28 skb_set_owner_r(skb, sk); 29 sk->sk_data_ready(sk, 0); 30 } 31 32 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb) 33 { 34 switch (sk->sk_state) { 35 case DCCP_PARTOPEN: 36 case DCCP_OPEN: 37 dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED); 38 dccp_fin(sk, skb); 39 dccp_set_state(sk, DCCP_CLOSED); 40 break; 41 } 42 } 43 44 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb) 45 { 46 /* 47 * Step 7: Check for unexpected packet types 48 * If (S.is_server and P.type == CloseReq) 49 * Send Sync packet acknowledging P.seqno 50 * Drop packet and return 51 */ 52 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) { 53 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq); 54 return; 55 } 56 57 switch (sk->sk_state) { 58 case DCCP_PARTOPEN: 59 case DCCP_OPEN: 60 dccp_set_state(sk, DCCP_CLOSING); 61 dccp_send_close(sk); 62 break; 63 } 64 } 65 66 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb) 67 { 68 struct dccp_sock *dp = dccp_sk(sk); 69 70 if (dp->dccps_options.dccpo_send_ack_vector) 71 dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk, 72 DCCP_SKB_CB(skb)->dccpd_ack_seq); 73 } 74 75 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb) 76 { 77 const struct dccp_hdr *dh = dccp_hdr(skb); 78 struct dccp_sock *dp = dccp_sk(sk); 79 u64 lswl = dp->dccps_swl; 80 u64 lawl = dp->dccps_awl; 81 82 /* 83 * Step 5: Prepare sequence numbers for Sync 84 * If P.type == Sync or P.type == SyncAck, 85 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL, 86 * / * P is valid, so update sequence number variables 87 * accordingly. After this update, P will pass the tests 88 * in Step 6. A SyncAck is generated if necessary in 89 * Step 15 * / 90 * Update S.GSR, S.SWL, S.SWH 91 * Otherwise, 92 * Drop packet and return 93 */ 94 if (dh->dccph_type == DCCP_PKT_SYNC || 95 dh->dccph_type == DCCP_PKT_SYNCACK) { 96 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 97 dp->dccps_awl, dp->dccps_awh) && 98 !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl)) 99 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); 100 else 101 return -1; 102 /* 103 * Step 6: Check sequence numbers 104 * Let LSWL = S.SWL and LAWL = S.AWL 105 * If P.type == CloseReq or P.type == Close or P.type == Reset, 106 * LSWL := S.GSR + 1, LAWL := S.GAR 107 * If LSWL <= P.seqno <= S.SWH 108 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH), 109 * Update S.GSR, S.SWL, S.SWH 110 * If P.type != Sync, 111 * Update S.GAR 112 * Otherwise, 113 * Send Sync packet acknowledging P.seqno 114 * Drop packet and return 115 */ 116 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ || 117 dh->dccph_type == DCCP_PKT_CLOSE || 118 dh->dccph_type == DCCP_PKT_RESET) { 119 lswl = dp->dccps_gsr; 120 dccp_inc_seqno(&lswl); 121 lawl = dp->dccps_gar; 122 } 123 124 if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) && 125 (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ || 126 between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 127 lawl, dp->dccps_awh))) { 128 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); 129 130 if (dh->dccph_type != DCCP_PKT_SYNC && 131 (DCCP_SKB_CB(skb)->dccpd_ack_seq != 132 DCCP_PKT_WITHOUT_ACK_SEQ)) 133 dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq; 134 } else { 135 dccp_pr_debug("Step 6 failed, sending SYNC...\n"); 136 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq); 137 return -1; 138 } 139 140 return 0; 141 } 142 143 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 144 const struct dccp_hdr *dh, const unsigned len) 145 { 146 struct dccp_sock *dp = dccp_sk(sk); 147 148 if (dccp_check_seqno(sk, skb)) 149 goto discard; 150 151 if (dccp_parse_options(sk, skb)) 152 goto discard; 153 154 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 155 dccp_event_ack_recv(sk, skb); 156 157 /* 158 * FIXME: check ECN to see if we should use 159 * DCCP_ACKPKTS_STATE_ECN_MARKED 160 */ 161 if (dp->dccps_options.dccpo_send_ack_vector) { 162 struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts; 163 164 if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts, 165 DCCP_SKB_CB(skb)->dccpd_seq, 166 DCCP_ACKPKTS_STATE_RECEIVED)) { 167 LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable " 168 "packets buffer full!\n"); 169 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1; 170 inet_csk_schedule_ack(sk); 171 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 172 TCP_DELACK_MIN, 173 DCCP_RTO_MAX); 174 goto discard; 175 } 176 177 /* 178 * FIXME: this activation is probably wrong, have to study more 179 * TCP delack machinery and how it fits into DCCP draft, but 180 * for now it kinda "works" 8) 181 */ 182 if (!inet_csk_ack_scheduled(sk)) { 183 inet_csk_schedule_ack(sk); 184 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ, 185 DCCP_RTO_MAX); 186 } 187 } 188 189 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 190 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 191 192 switch (dccp_hdr(skb)->dccph_type) { 193 case DCCP_PKT_DATAACK: 194 case DCCP_PKT_DATA: 195 /* 196 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED 197 * option if it is. 198 */ 199 __skb_pull(skb, dh->dccph_doff * 4); 200 __skb_queue_tail(&sk->sk_receive_queue, skb); 201 skb_set_owner_r(skb, sk); 202 sk->sk_data_ready(sk, 0); 203 return 0; 204 case DCCP_PKT_ACK: 205 goto discard; 206 case DCCP_PKT_RESET: 207 /* 208 * Step 9: Process Reset 209 * If P.type == Reset, 210 * Tear down connection 211 * S.state := TIMEWAIT 212 * Set TIMEWAIT timer 213 * Drop packet and return 214 */ 215 dccp_fin(sk, skb); 216 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 217 return 0; 218 case DCCP_PKT_CLOSEREQ: 219 dccp_rcv_closereq(sk, skb); 220 goto discard; 221 case DCCP_PKT_CLOSE: 222 dccp_rcv_close(sk, skb); 223 return 0; 224 case DCCP_PKT_REQUEST: 225 /* Step 7 226 * or (S.is_server and P.type == Response) 227 * or (S.is_client and P.type == Request) 228 * or (S.state >= OPEN and P.type == Request 229 * and P.seqno >= S.OSR) 230 * or (S.state >= OPEN and P.type == Response 231 * and P.seqno >= S.OSR) 232 * or (S.state == RESPOND and P.type == Data), 233 * Send Sync packet acknowledging P.seqno 234 * Drop packet and return 235 */ 236 if (dp->dccps_role != DCCP_ROLE_LISTEN) 237 goto send_sync; 238 goto check_seq; 239 case DCCP_PKT_RESPONSE: 240 if (dp->dccps_role != DCCP_ROLE_CLIENT) 241 goto send_sync; 242 check_seq: 243 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) { 244 send_sync: 245 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq); 246 } 247 break; 248 } 249 250 DCCP_INC_STATS_BH(DCCP_MIB_INERRS); 251 discard: 252 __kfree_skb(skb); 253 return 0; 254 } 255 256 static int dccp_rcv_request_sent_state_process(struct sock *sk, 257 struct sk_buff *skb, 258 const struct dccp_hdr *dh, 259 const unsigned len) 260 { 261 /* 262 * Step 4: Prepare sequence numbers in REQUEST 263 * If S.state == REQUEST, 264 * If (P.type == Response or P.type == Reset) 265 * and S.AWL <= P.ackno <= S.AWH, 266 * / * Set sequence number variables corresponding to the 267 * other endpoint, so P will pass the tests in Step 6 * / 268 * Set S.GSR, S.ISR, S.SWL, S.SWH 269 * / * Response processing continues in Step 10; Reset 270 * processing continues in Step 9 * / 271 */ 272 if (dh->dccph_type == DCCP_PKT_RESPONSE) { 273 const struct inet_connection_sock *icsk = inet_csk(sk); 274 struct dccp_sock *dp = dccp_sk(sk); 275 276 /* Stop the REQUEST timer */ 277 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); 278 BUG_TRAP(sk->sk_send_head != NULL); 279 __kfree_skb(sk->sk_send_head); 280 sk->sk_send_head = NULL; 281 282 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 283 dp->dccps_awl, dp->dccps_awh)) { 284 dccp_pr_debug("invalid ackno: S.AWL=%llu, " 285 "P.ackno=%llu, S.AWH=%llu \n", 286 (unsigned long long)dp->dccps_awl, 287 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, 288 (unsigned long long)dp->dccps_awh); 289 goto out_invalid_packet; 290 } 291 292 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; 293 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); 294 295 if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 || 296 ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) { 297 ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk); 298 ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk); 299 /* FIXME: send appropriate RESET code */ 300 goto out_invalid_packet; 301 } 302 303 dccp_sync_mss(sk, dp->dccps_pmtu_cookie); 304 305 /* 306 * Step 10: Process REQUEST state (second part) 307 * If S.state == REQUEST, 308 * / * If we get here, P is a valid Response from the 309 * server (see Step 4), and we should move to 310 * PARTOPEN state. PARTOPEN means send an Ack, 311 * don't send Data packets, retransmit Acks 312 * periodically, and always include any Init Cookie 313 * from the Response * / 314 * S.state := PARTOPEN 315 * Set PARTOPEN timer 316 * Continue with S.state == PARTOPEN 317 * / * Step 12 will send the Ack completing the 318 * three-way handshake * / 319 */ 320 dccp_set_state(sk, DCCP_PARTOPEN); 321 322 /* Make sure socket is routed, for correct metrics. */ 323 inet_sk_rebuild_header(sk); 324 325 if (!sock_flag(sk, SOCK_DEAD)) { 326 sk->sk_state_change(sk); 327 sk_wake_async(sk, 0, POLL_OUT); 328 } 329 330 if (sk->sk_write_pending || icsk->icsk_ack.pingpong || 331 icsk->icsk_accept_queue.rskq_defer_accept) { 332 /* Save one ACK. Data will be ready after 333 * several ticks, if write_pending is set. 334 * 335 * It may be deleted, but with this feature tcpdumps 336 * look so _wonderfully_ clever, that I was not able 337 * to stand against the temptation 8) --ANK 338 */ 339 /* 340 * OK, in DCCP we can as well do a similar trick, its 341 * even in the draft, but there is no need for us to 342 * schedule an ack here, as dccp_sendmsg does this for 343 * us, also stated in the draft. -acme 344 */ 345 __kfree_skb(skb); 346 return 0; 347 } 348 dccp_send_ack(sk); 349 return -1; 350 } 351 352 out_invalid_packet: 353 return 1; /* dccp_v4_do_rcv will send a reset, but... 354 FIXME: the reset code should be 355 DCCP_RESET_CODE_PACKET_ERROR */ 356 } 357 358 static int dccp_rcv_respond_partopen_state_process(struct sock *sk, 359 struct sk_buff *skb, 360 const struct dccp_hdr *dh, 361 const unsigned len) 362 { 363 int queued = 0; 364 365 switch (dh->dccph_type) { 366 case DCCP_PKT_RESET: 367 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 368 break; 369 case DCCP_PKT_DATAACK: 370 case DCCP_PKT_ACK: 371 /* 372 * FIXME: we should be reseting the PARTOPEN (DELACK) timer 373 * here but only if we haven't used the DELACK timer for 374 * something else, like sending a delayed ack for a TIMESTAMP 375 * echo, etc, for now were not clearing it, sending an extra 376 * ACK when there is nothing else to do in DELACK is not a big 377 * deal after all. 378 */ 379 380 /* Stop the PARTOPEN timer */ 381 if (sk->sk_state == DCCP_PARTOPEN) 382 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 383 384 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; 385 dccp_set_state(sk, DCCP_OPEN); 386 387 if (dh->dccph_type == DCCP_PKT_DATAACK) { 388 dccp_rcv_established(sk, skb, dh, len); 389 queued = 1; /* packet was queued 390 (by dccp_rcv_established) */ 391 } 392 break; 393 } 394 395 return queued; 396 } 397 398 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 399 struct dccp_hdr *dh, unsigned len) 400 { 401 struct dccp_sock *dp = dccp_sk(sk); 402 const int old_state = sk->sk_state; 403 int queued = 0; 404 405 if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING) { 406 if (dccp_check_seqno(sk, skb)) 407 goto discard; 408 409 /* 410 * Step 8: Process options and mark acknowledgeable 411 */ 412 if (dccp_parse_options(sk, skb)) 413 goto discard; 414 415 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != 416 DCCP_PKT_WITHOUT_ACK_SEQ) 417 dccp_event_ack_recv(sk, skb); 418 419 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 420 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 421 422 /* 423 * FIXME: check ECN to see if we should use 424 * DCCP_ACKPKTS_STATE_ECN_MARKED 425 */ 426 if (dp->dccps_options.dccpo_send_ack_vector) { 427 if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts, 428 DCCP_SKB_CB(skb)->dccpd_seq, 429 DCCP_ACKPKTS_STATE_RECEIVED)) 430 goto discard; 431 /* 432 * FIXME: this activation is probably wrong, have to 433 * study more TCP delack machinery and how it fits into 434 * DCCP draft, but for now it kinda "works" 8) 435 */ 436 if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno == 437 DCCP_MAX_SEQNO + 1) && 438 !inet_csk_ack_scheduled(sk)) { 439 inet_csk_schedule_ack(sk); 440 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 441 TCP_DELACK_MIN, 442 DCCP_RTO_MAX); 443 } 444 } 445 } 446 447 /* 448 * Step 9: Process Reset 449 * If P.type == Reset, 450 * Tear down connection 451 * S.state := TIMEWAIT 452 * Set TIMEWAIT timer 453 * Drop packet and return 454 */ 455 if (dh->dccph_type == DCCP_PKT_RESET) { 456 /* 457 * Queue the equivalent of TCP fin so that dccp_recvmsg 458 * exits the loop 459 */ 460 dccp_fin(sk, skb); 461 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 462 return 0; 463 /* 464 * Step 7: Check for unexpected packet types 465 * If (S.is_server and P.type == CloseReq) 466 * or (S.is_server and P.type == Response) 467 * or (S.is_client and P.type == Request) 468 * or (S.state == RESPOND and P.type == Data), 469 * Send Sync packet acknowledging P.seqno 470 * Drop packet and return 471 */ 472 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && 473 (dh->dccph_type == DCCP_PKT_RESPONSE || 474 dh->dccph_type == DCCP_PKT_CLOSEREQ)) || 475 (dp->dccps_role == DCCP_ROLE_CLIENT && 476 dh->dccph_type == DCCP_PKT_REQUEST) || 477 (sk->sk_state == DCCP_RESPOND && 478 dh->dccph_type == DCCP_PKT_DATA)) { 479 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq); 480 goto discard; 481 } 482 483 switch (sk->sk_state) { 484 case DCCP_CLOSED: 485 return 1; 486 487 case DCCP_LISTEN: 488 if (dh->dccph_type == DCCP_PKT_ACK || 489 dh->dccph_type == DCCP_PKT_DATAACK) 490 return 1; 491 492 if (dh->dccph_type == DCCP_PKT_RESET) 493 goto discard; 494 495 if (dh->dccph_type == DCCP_PKT_REQUEST) { 496 if (dccp_v4_conn_request(sk, skb) < 0) 497 return 1; 498 499 /* FIXME: do congestion control initialization */ 500 goto discard; 501 } 502 goto discard; 503 504 case DCCP_REQUESTING: 505 /* FIXME: do congestion control initialization */ 506 507 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); 508 if (queued >= 0) 509 return queued; 510 511 __kfree_skb(skb); 512 return 0; 513 514 case DCCP_RESPOND: 515 case DCCP_PARTOPEN: 516 queued = dccp_rcv_respond_partopen_state_process(sk, skb, 517 dh, len); 518 break; 519 } 520 521 if (dh->dccph_type == DCCP_PKT_ACK || 522 dh->dccph_type == DCCP_PKT_DATAACK) { 523 switch (old_state) { 524 case DCCP_PARTOPEN: 525 sk->sk_state_change(sk); 526 sk_wake_async(sk, 0, POLL_OUT); 527 break; 528 } 529 } 530 531 if (!queued) { 532 discard: 533 __kfree_skb(skb); 534 } 535 return 0; 536 } 537