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 22static 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 32static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb) 33{ 34 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED); 35 dccp_fin(sk, skb); 36 dccp_set_state(sk, DCCP_CLOSED); 37 sk_wake_async(sk, 1, POLL_HUP); 38} 39 40static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb) 41{ 42 /* 43 * Step 7: Check for unexpected packet types 44 * If (S.is_server and P.type == CloseReq) 45 * Send Sync packet acknowledging P.seqno 46 * Drop packet and return 47 */ 48 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) { 49 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC); 50 return; 51 } 52 53 if (sk->sk_state != DCCP_CLOSING) 54 dccp_set_state(sk, DCCP_CLOSING); 55 dccp_send_close(sk, 0); 56} 57 58static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb) 59{ 60 struct dccp_sock *dp = dccp_sk(sk); 61 62 if (dccp_msk(sk)->dccpms_send_ack_vector) 63 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk, 64 DCCP_SKB_CB(skb)->dccpd_ack_seq); 65} 66 67static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb) 68{ 69 const struct dccp_hdr *dh = dccp_hdr(skb); 70 struct dccp_sock *dp = dccp_sk(sk); 71 u64 lswl, lawl; 72 73 /* 74 * Step 5: Prepare sequence numbers for Sync 75 * If P.type == Sync or P.type == SyncAck, 76 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL, 77 * / * P is valid, so update sequence number variables 78 * accordingly. After this update, P will pass the tests 79 * in Step 6. A SyncAck is generated if necessary in 80 * Step 15 * / 81 * Update S.GSR, S.SWL, S.SWH 82 * Otherwise, 83 * Drop packet and return 84 */ 85 if (dh->dccph_type == DCCP_PKT_SYNC || 86 dh->dccph_type == DCCP_PKT_SYNCACK) { 87 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 88 dp->dccps_awl, dp->dccps_awh) && 89 dccp_delta_seqno(dp->dccps_swl, 90 DCCP_SKB_CB(skb)->dccpd_seq) >= 0) 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 DCCP_WARN("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", dccp_packet_name(dh->dccph_type), 136 (unsigned long long) lswl, 137 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq, 138 (unsigned long long) dp->dccps_swh, 139 (DCCP_SKB_CB(skb)->dccpd_ack_seq == 140 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists", 141 (unsigned long long) lawl, 142 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq, 143 (unsigned long long) dp->dccps_awh); 144 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC); 145 return -1; 146 } 147 148 return 0; 149} 150 151static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 152 const struct dccp_hdr *dh, const unsigned len) 153{ 154 struct dccp_sock *dp = dccp_sk(sk); 155 156 switch (dccp_hdr(skb)->dccph_type) { 157 case DCCP_PKT_DATAACK: 158 case DCCP_PKT_DATA: 159 __skb_pull(skb, dh->dccph_doff * 4); 160 __skb_queue_tail(&sk->sk_receive_queue, skb); 161 skb_set_owner_r(skb, sk); 162 sk->sk_data_ready(sk, 0); 163 return 0; 164 case DCCP_PKT_ACK: 165 goto discard; 166 case DCCP_PKT_RESET: 167 /* 168 * Step 9: Process Reset 169 * If P.type == Reset, 170 * Tear down connection 171 * S.state := TIMEWAIT 172 * Set TIMEWAIT timer 173 * Drop packet and return 174 */ 175 dccp_fin(sk, skb); 176 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 177 return 0; 178 case DCCP_PKT_CLOSEREQ: 179 dccp_rcv_closereq(sk, skb); 180 goto discard; 181 case DCCP_PKT_CLOSE: 182 dccp_rcv_close(sk, skb); 183 return 0; 184 case DCCP_PKT_REQUEST: 185 /* Step 7 186 * or (S.is_server and P.type == Response) 187 * or (S.is_client and P.type == Request) 188 * or (S.state >= OPEN and P.type == Request 189 * and P.seqno >= S.OSR) 190 * or (S.state >= OPEN and P.type == Response 191 * and P.seqno >= S.OSR) 192 * or (S.state == RESPOND and P.type == Data), 193 * Send Sync packet acknowledging P.seqno 194 * Drop packet and return 195 */ 196 if (dp->dccps_role != DCCP_ROLE_LISTEN) 197 goto send_sync; 198 goto check_seq; 199 case DCCP_PKT_RESPONSE: 200 if (dp->dccps_role != DCCP_ROLE_CLIENT) 201 goto send_sync; 202check_seq: 203 if (dccp_delta_seqno(dp->dccps_osr, 204 DCCP_SKB_CB(skb)->dccpd_seq) >= 0) { 205send_sync: 206 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 207 DCCP_PKT_SYNC); 208 } 209 break; 210 case DCCP_PKT_SYNC: 211 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, 212 DCCP_PKT_SYNCACK); 213 /* 214 * From RFC 4340, sec. 5.7 215 * 216 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets 217 * MAY have non-zero-length application data areas, whose 218 * contents receivers MUST ignore. 219 */ 220 goto discard; 221 } 222 223 DCCP_INC_STATS_BH(DCCP_MIB_INERRS); 224discard: 225 __kfree_skb(skb); 226 return 0; 227} 228 229int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, 230 const struct dccp_hdr *dh, const unsigned len) 231{ 232 struct dccp_sock *dp = dccp_sk(sk); 233 234 if (dccp_check_seqno(sk, skb)) 235 goto discard; 236 237 if (dccp_parse_options(sk, skb)) 238 goto discard; 239 240 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 241 dccp_event_ack_recv(sk, skb); 242 243 if (dccp_msk(sk)->dccpms_send_ack_vector && 244 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 245 DCCP_SKB_CB(skb)->dccpd_seq, 246 DCCP_ACKVEC_STATE_RECEIVED)) 247 goto discard; 248 249 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 250 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 251 252 return __dccp_rcv_established(sk, skb, dh, len); 253discard: 254 __kfree_skb(skb); 255 return 0; 256} 257 258EXPORT_SYMBOL_GPL(dccp_rcv_established); 259 260static int dccp_rcv_request_sent_state_process(struct sock *sk, 261 struct sk_buff *skb, 262 const struct dccp_hdr *dh, 263 const unsigned len) 264{ 265 /* 266 * Step 4: Prepare sequence numbers in REQUEST 267 * If S.state == REQUEST, 268 * If (P.type == Response or P.type == Reset) 269 * and S.AWL <= P.ackno <= S.AWH, 270 * / * Set sequence number variables corresponding to the 271 * other endpoint, so P will pass the tests in Step 6 * / 272 * Set S.GSR, S.ISR, S.SWL, S.SWH 273 * / * Response processing continues in Step 10; Reset 274 * processing continues in Step 9 * / 275 */ 276 if (dh->dccph_type == DCCP_PKT_RESPONSE) { 277 const struct inet_connection_sock *icsk = inet_csk(sk); 278 struct dccp_sock *dp = dccp_sk(sk); 279 280 /* Stop the REQUEST timer */ 281 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); 282 BUG_TRAP(sk->sk_send_head != NULL); 283 __kfree_skb(sk->sk_send_head); 284 sk->sk_send_head = NULL; 285 286 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 287 dp->dccps_awl, dp->dccps_awh)) { 288 dccp_pr_debug("invalid ackno: S.AWL=%llu, " 289 "P.ackno=%llu, S.AWH=%llu \n", 290 (unsigned long long)dp->dccps_awl, 291 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, 292 (unsigned long long)dp->dccps_awh); 293 goto out_invalid_packet; 294 } 295 296 if (dccp_parse_options(sk, skb)) 297 goto out_invalid_packet; 298 299 /* Obtain RTT sample from SYN exchange (used by CCID 3) */ 300 if (dp->dccps_options_received.dccpor_timestamp_echo) { 301 struct timeval now; 302 303 dccp_timestamp(sk, &now); 304 dp->dccps_syn_rtt = dccp_sample_rtt(sk, &now, NULL); 305 } 306 307 if (dccp_msk(sk)->dccpms_send_ack_vector && 308 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 309 DCCP_SKB_CB(skb)->dccpd_seq, 310 DCCP_ACKVEC_STATE_RECEIVED)) 311 goto out_invalid_packet; 312 313 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; 314 dccp_update_gsr(sk, dp->dccps_isr); 315 /* 316 * SWL and AWL are initially adjusted so that they are not less than 317 * the initial Sequence Numbers received and sent, respectively: 318 * SWL := max(GSR + 1 - floor(W/4), ISR), 319 * AWL := max(GSS - W' + 1, ISS). 320 * These adjustments MUST be applied only at the beginning of the 321 * connection. 322 * 323 * AWL was adjusted in dccp_v4_connect -acme 324 */ 325 dccp_set_seqno(&dp->dccps_swl, 326 max48(dp->dccps_swl, dp->dccps_isr)); 327 328 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); 329 330 /* 331 * Step 10: Process REQUEST state (second part) 332 * If S.state == REQUEST, 333 * / * If we get here, P is a valid Response from the 334 * server (see Step 4), and we should move to 335 * PARTOPEN state. PARTOPEN means send an Ack, 336 * don't send Data packets, retransmit Acks 337 * periodically, and always include any Init Cookie 338 * from the Response * / 339 * S.state := PARTOPEN 340 * Set PARTOPEN timer 341 * Continue with S.state == PARTOPEN 342 * / * Step 12 will send the Ack completing the 343 * three-way handshake * / 344 */ 345 dccp_set_state(sk, DCCP_PARTOPEN); 346 347 /* Make sure socket is routed, for correct metrics. */ 348 icsk->icsk_af_ops->rebuild_header(sk); 349 350 if (!sock_flag(sk, SOCK_DEAD)) { 351 sk->sk_state_change(sk); 352 sk_wake_async(sk, 0, POLL_OUT); 353 } 354 355 if (sk->sk_write_pending || icsk->icsk_ack.pingpong || 356 icsk->icsk_accept_queue.rskq_defer_accept) { 357 /* Save one ACK. Data will be ready after 358 * several ticks, if write_pending is set. 359 * 360 * It may be deleted, but with this feature tcpdumps 361 * look so _wonderfully_ clever, that I was not able 362 * to stand against the temptation 8) --ANK 363 */ 364 /* 365 * OK, in DCCP we can as well do a similar trick, its 366 * even in the draft, but there is no need for us to 367 * schedule an ack here, as dccp_sendmsg does this for 368 * us, also stated in the draft. -acme 369 */ 370 __kfree_skb(skb); 371 return 0; 372 } 373 dccp_send_ack(sk); 374 return -1; 375 } 376 377out_invalid_packet: 378 /* dccp_v4_do_rcv will send a reset */ 379 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 380 return 1; 381} 382 383static int dccp_rcv_respond_partopen_state_process(struct sock *sk, 384 struct sk_buff *skb, 385 const struct dccp_hdr *dh, 386 const unsigned len) 387{ 388 int queued = 0; 389 390 switch (dh->dccph_type) { 391 case DCCP_PKT_RESET: 392 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 393 break; 394 case DCCP_PKT_DATA: 395 if (sk->sk_state == DCCP_RESPOND) 396 break; 397 case DCCP_PKT_DATAACK: 398 case DCCP_PKT_ACK: 399 400 /* Stop the PARTOPEN timer */ 401 if (sk->sk_state == DCCP_PARTOPEN) 402 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 403 404 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; 405 dccp_set_state(sk, DCCP_OPEN); 406 407 if (dh->dccph_type == DCCP_PKT_DATAACK || 408 dh->dccph_type == DCCP_PKT_DATA) { 409 __dccp_rcv_established(sk, skb, dh, len); 410 queued = 1; /* packet was queued 411 (by __dccp_rcv_established) */ 412 } 413 break; 414 } 415 416 return queued; 417} 418 419int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 420 struct dccp_hdr *dh, unsigned len) 421{ 422 struct dccp_sock *dp = dccp_sk(sk); 423 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 424 const int old_state = sk->sk_state; 425 int queued = 0; 426 427 /* 428 * Step 3: Process LISTEN state 429 * 430 * If S.state == LISTEN, 431 * If P.type == Request or P contains a valid Init Cookie option, 432 * (* Must scan the packet's options to check for Init 433 * Cookies. Only Init Cookies are processed here, 434 * however; other options are processed in Step 8. This 435 * scan need only be performed if the endpoint uses Init 436 * Cookies *) 437 * (* Generate a new socket and switch to that socket *) 438 * Set S := new socket for this port pair 439 * S.state = RESPOND 440 * Choose S.ISS (initial seqno) or set from Init Cookies 441 * Initialize S.GAR := S.ISS 442 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init 443 * Cookies Continue with S.state == RESPOND 444 * (* A Response packet will be generated in Step 11 *) 445 * Otherwise, 446 * Generate Reset(No Connection) unless P.type == Reset 447 * Drop packet and return 448 */ 449 if (sk->sk_state == DCCP_LISTEN) { 450 if (dh->dccph_type == DCCP_PKT_REQUEST) { 451 if (inet_csk(sk)->icsk_af_ops->conn_request(sk, 452 skb) < 0) 453 return 1; 454 455 goto discard; 456 } 457 if (dh->dccph_type == DCCP_PKT_RESET) 458 goto discard; 459 460 /* Caller (dccp_v4_do_rcv) will send Reset */ 461 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 462 return 1; 463 } 464 465 if (sk->sk_state != DCCP_REQUESTING) { 466 if (dccp_check_seqno(sk, skb)) 467 goto discard; 468 469 /* 470 * Step 8: Process options and mark acknowledgeable 471 */ 472 if (dccp_parse_options(sk, skb)) 473 goto discard; 474 475 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) 476 dccp_event_ack_recv(sk, skb); 477 478 if (dccp_msk(sk)->dccpms_send_ack_vector && 479 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, 480 DCCP_SKB_CB(skb)->dccpd_seq, 481 DCCP_ACKVEC_STATE_RECEIVED)) 482 goto discard; 483 484 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); 485 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); 486 } 487 488 /* 489 * Step 9: Process Reset 490 * If P.type == Reset, 491 * Tear down connection 492 * S.state := TIMEWAIT 493 * Set TIMEWAIT timer 494 * Drop packet and return 495 */ 496 if (dh->dccph_type == DCCP_PKT_RESET) { 497 /* 498 * Queue the equivalent of TCP fin so that dccp_recvmsg 499 * exits the loop 500 */ 501 dccp_fin(sk, skb); 502 dccp_time_wait(sk, DCCP_TIME_WAIT, 0); 503 return 0; 504 /* 505 * Step 7: Check for unexpected packet types 506 * If (S.is_server and P.type == CloseReq) 507 * or (S.is_server and P.type == Response) 508 * or (S.is_client and P.type == Request) 509 * or (S.state == RESPOND and P.type == Data), 510 * Send Sync packet acknowledging P.seqno 511 * Drop packet and return 512 */ 513 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && 514 (dh->dccph_type == DCCP_PKT_RESPONSE || 515 dh->dccph_type == DCCP_PKT_CLOSEREQ)) || 516 (dp->dccps_role == DCCP_ROLE_CLIENT && 517 dh->dccph_type == DCCP_PKT_REQUEST) || 518 (sk->sk_state == DCCP_RESPOND && 519 dh->dccph_type == DCCP_PKT_DATA)) { 520 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC); 521 goto discard; 522 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { 523 dccp_rcv_closereq(sk, skb); 524 goto discard; 525 } else if (dh->dccph_type == DCCP_PKT_CLOSE) { 526 dccp_rcv_close(sk, skb); 527 return 0; 528 } 529 530 if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) { 531 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK); 532 goto discard; 533 } 534 535 switch (sk->sk_state) { 536 case DCCP_CLOSED: 537 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; 538 return 1; 539 540 case DCCP_REQUESTING: 541 542 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); 543 if (queued >= 0) 544 return queued; 545 546 __kfree_skb(skb); 547 return 0; 548 549 case DCCP_RESPOND: 550 case DCCP_PARTOPEN: 551 queued = dccp_rcv_respond_partopen_state_process(sk, skb, 552 dh, len); 553 break; 554 } 555 556 if (dh->dccph_type == DCCP_PKT_ACK || 557 dh->dccph_type == DCCP_PKT_DATAACK) { 558 switch (old_state) { 559 case DCCP_PARTOPEN: 560 sk->sk_state_change(sk); 561 sk_wake_async(sk, 0, POLL_OUT); 562 break; 563 } 564 } 565 566 if (!queued) { 567discard: 568 __kfree_skb(skb); 569 } 570 return 0; 571} 572 573EXPORT_SYMBOL_GPL(dccp_rcv_state_process); 574 575/** 576 * dccp_sample_rtt - Sample RTT from packet exchange 577 * 578 * @sk: connected dccp_sock 579 * @t_recv: receive timestamp of packet with timestamp echo 580 * @t_hist: packet history timestamp or NULL 581 */ 582u32 dccp_sample_rtt(struct sock *sk, struct timeval *t_recv, 583 struct timeval *t_hist) 584{ 585 struct dccp_sock *dp = dccp_sk(sk); 586 struct dccp_options_received *or = &dp->dccps_options_received; 587 suseconds_t delta; 588 589 if (t_hist == NULL) { 590 if (!or->dccpor_timestamp_echo) { 591 DCCP_WARN("packet without timestamp echo\n"); 592 return DCCP_SANE_RTT_MAX; 593 } 594 timeval_sub_usecs(t_recv, or->dccpor_timestamp_echo * 10); 595 delta = timeval_usecs(t_recv); 596 } else 597 delta = timeval_delta(t_recv, t_hist); 598 599 delta -= or->dccpor_elapsed_time * 10; /* either set or 0 */ 600 601 if (unlikely(delta <= 0)) { 602 DCCP_WARN("unusable RTT sample %ld, using min\n", (long)delta); 603 return DCCP_SANE_RTT_MIN; 604 } 605 if (unlikely(delta - (suseconds_t)DCCP_SANE_RTT_MAX > 0)) { 606 DCCP_WARN("RTT sample %ld too large, using max\n", (long)delta); 607 return DCCP_SANE_RTT_MAX; 608 } 609 610 return delta; 611} 612 613EXPORT_SYMBOL_GPL(dccp_sample_rtt); 614