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