1 /* SCTP kernel implementation 2 * (C) Copyright IBM Corp. 2001, 2004 3 * Copyright (c) 1999-2000 Cisco, Inc. 4 * Copyright (c) 1999-2001 Motorola, Inc. 5 * 6 * This file is part of the SCTP kernel implementation 7 * 8 * These functions handle output processing. 9 * 10 * This SCTP implementation is free software; 11 * you can redistribute it and/or modify it under the terms of 12 * the GNU General Public License as published by 13 * the Free Software Foundation; either version 2, or (at your option) 14 * any later version. 15 * 16 * This SCTP implementation is distributed in the hope that it 17 * will be useful, but WITHOUT ANY WARRANTY; without even the implied 18 * ************************ 19 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 20 * See the GNU General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with GNU CC; see the file COPYING. If not, write to 24 * the Free Software Foundation, 59 Temple Place - Suite 330, 25 * Boston, MA 02111-1307, USA. 26 * 27 * Please send any bug reports or fixes you make to the 28 * email address(es): 29 * lksctp developers <lksctp-developers@lists.sourceforge.net> 30 * 31 * Or submit a bug report through the following website: 32 * http://www.sf.net/projects/lksctp 33 * 34 * Written or modified by: 35 * La Monte H.P. Yarroll <piggy@acm.org> 36 * Karl Knutson <karl@athena.chicago.il.us> 37 * Jon Grimm <jgrimm@austin.ibm.com> 38 * Sridhar Samudrala <sri@us.ibm.com> 39 * 40 * Any bugs reported given to us we will try to fix... any fixes shared will 41 * be incorporated into the next SCTP release. 42 */ 43 44 #include <linux/types.h> 45 #include <linux/kernel.h> 46 #include <linux/wait.h> 47 #include <linux/time.h> 48 #include <linux/ip.h> 49 #include <linux/ipv6.h> 50 #include <linux/init.h> 51 #include <linux/slab.h> 52 #include <net/inet_ecn.h> 53 #include <net/ip.h> 54 #include <net/icmp.h> 55 #include <net/net_namespace.h> 56 57 #include <linux/socket.h> /* for sa_family_t */ 58 #include <net/sock.h> 59 60 #include <net/sctp/sctp.h> 61 #include <net/sctp/sm.h> 62 #include <net/sctp/checksum.h> 63 64 /* Forward declarations for private helpers. */ 65 static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 66 struct sctp_chunk *chunk); 67 static void sctp_packet_append_data(struct sctp_packet *packet, 68 struct sctp_chunk *chunk); 69 static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, 70 struct sctp_chunk *chunk, 71 u16 chunk_len); 72 73 static void sctp_packet_reset(struct sctp_packet *packet) 74 { 75 packet->size = packet->overhead; 76 packet->has_cookie_echo = 0; 77 packet->has_sack = 0; 78 packet->has_data = 0; 79 packet->has_auth = 0; 80 packet->ipfragok = 0; 81 packet->auth = NULL; 82 } 83 84 /* Config a packet. 85 * This appears to be a followup set of initializations. 86 */ 87 struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, 88 __u32 vtag, int ecn_capable) 89 { 90 struct sctp_chunk *chunk = NULL; 91 92 SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__, 93 packet, vtag); 94 95 sctp_packet_reset(packet); 96 packet->vtag = vtag; 97 98 if (ecn_capable && sctp_packet_empty(packet)) { 99 chunk = sctp_get_ecne_prepend(packet->transport->asoc); 100 101 /* If there a is a prepend chunk stick it on the list before 102 * any other chunks get appended. 103 */ 104 if (chunk) 105 sctp_packet_append_chunk(packet, chunk); 106 } 107 108 return packet; 109 } 110 111 /* Initialize the packet structure. */ 112 struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, 113 struct sctp_transport *transport, 114 __u16 sport, __u16 dport) 115 { 116 struct sctp_association *asoc = transport->asoc; 117 size_t overhead; 118 119 SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__, 120 packet, transport); 121 122 packet->transport = transport; 123 packet->source_port = sport; 124 packet->destination_port = dport; 125 INIT_LIST_HEAD(&packet->chunk_list); 126 if (asoc) { 127 struct sctp_sock *sp = sctp_sk(asoc->base.sk); 128 overhead = sp->pf->af->net_header_len; 129 } else { 130 overhead = sizeof(struct ipv6hdr); 131 } 132 overhead += sizeof(struct sctphdr); 133 packet->overhead = overhead; 134 sctp_packet_reset(packet); 135 packet->vtag = 0; 136 packet->malloced = 0; 137 return packet; 138 } 139 140 /* Free a packet. */ 141 void sctp_packet_free(struct sctp_packet *packet) 142 { 143 struct sctp_chunk *chunk, *tmp; 144 145 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); 146 147 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 148 list_del_init(&chunk->list); 149 sctp_chunk_free(chunk); 150 } 151 152 if (packet->malloced) 153 kfree(packet); 154 } 155 156 /* This routine tries to append the chunk to the offered packet. If adding 157 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk 158 * is not present in the packet, it transmits the input packet. 159 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long 160 * as it can fit in the packet, but any more data that does not fit in this 161 * packet can be sent only after receiving the COOKIE_ACK. 162 */ 163 sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, 164 struct sctp_chunk *chunk, 165 int one_packet) 166 { 167 sctp_xmit_t retval; 168 int error = 0; 169 170 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, 171 packet, chunk); 172 173 switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { 174 case SCTP_XMIT_PMTU_FULL: 175 if (!packet->has_cookie_echo) { 176 error = sctp_packet_transmit(packet); 177 if (error < 0) 178 chunk->skb->sk->sk_err = -error; 179 180 /* If we have an empty packet, then we can NOT ever 181 * return PMTU_FULL. 182 */ 183 if (!one_packet) 184 retval = sctp_packet_append_chunk(packet, 185 chunk); 186 } 187 break; 188 189 case SCTP_XMIT_RWND_FULL: 190 case SCTP_XMIT_OK: 191 case SCTP_XMIT_NAGLE_DELAY: 192 break; 193 } 194 195 return retval; 196 } 197 198 /* Try to bundle an auth chunk into the packet. */ 199 static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, 200 struct sctp_chunk *chunk) 201 { 202 struct sctp_association *asoc = pkt->transport->asoc; 203 struct sctp_chunk *auth; 204 sctp_xmit_t retval = SCTP_XMIT_OK; 205 206 /* if we don't have an association, we can't do authentication */ 207 if (!asoc) 208 return retval; 209 210 /* See if this is an auth chunk we are bundling or if 211 * auth is already bundled. 212 */ 213 if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth) 214 return retval; 215 216 /* if the peer did not request this chunk to be authenticated, 217 * don't do it 218 */ 219 if (!chunk->auth) 220 return retval; 221 222 auth = sctp_make_auth(asoc); 223 if (!auth) 224 return retval; 225 226 retval = sctp_packet_append_chunk(pkt, auth); 227 228 return retval; 229 } 230 231 /* Try to bundle a SACK with the packet. */ 232 static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, 233 struct sctp_chunk *chunk) 234 { 235 sctp_xmit_t retval = SCTP_XMIT_OK; 236 237 /* If sending DATA and haven't aleady bundled a SACK, try to 238 * bundle one in to the packet. 239 */ 240 if (sctp_chunk_is_data(chunk) && !pkt->has_sack && 241 !pkt->has_cookie_echo) { 242 struct sctp_association *asoc; 243 struct timer_list *timer; 244 asoc = pkt->transport->asoc; 245 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; 246 247 /* If the SACK timer is running, we have a pending SACK */ 248 if (timer_pending(timer)) { 249 struct sctp_chunk *sack; 250 asoc->a_rwnd = asoc->rwnd; 251 sack = sctp_make_sack(asoc); 252 if (sack) { 253 retval = sctp_packet_append_chunk(pkt, sack); 254 asoc->peer.sack_needed = 0; 255 if (del_timer(timer)) 256 sctp_association_put(asoc); 257 } 258 } 259 } 260 return retval; 261 } 262 263 /* Append a chunk to the offered packet reporting back any inability to do 264 * so. 265 */ 266 sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, 267 struct sctp_chunk *chunk) 268 { 269 sctp_xmit_t retval = SCTP_XMIT_OK; 270 __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); 271 272 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet, 273 chunk); 274 275 /* Data chunks are special. Before seeing what else we can 276 * bundle into this packet, check to see if we are allowed to 277 * send this DATA. 278 */ 279 if (sctp_chunk_is_data(chunk)) { 280 retval = sctp_packet_can_append_data(packet, chunk); 281 if (retval != SCTP_XMIT_OK) 282 goto finish; 283 } 284 285 /* Try to bundle AUTH chunk */ 286 retval = sctp_packet_bundle_auth(packet, chunk); 287 if (retval != SCTP_XMIT_OK) 288 goto finish; 289 290 /* Try to bundle SACK chunk */ 291 retval = sctp_packet_bundle_sack(packet, chunk); 292 if (retval != SCTP_XMIT_OK) 293 goto finish; 294 295 /* Check to see if this chunk will fit into the packet */ 296 retval = sctp_packet_will_fit(packet, chunk, chunk_len); 297 if (retval != SCTP_XMIT_OK) 298 goto finish; 299 300 /* We believe that this chunk is OK to add to the packet */ 301 switch (chunk->chunk_hdr->type) { 302 case SCTP_CID_DATA: 303 /* Account for the data being in the packet */ 304 sctp_packet_append_data(packet, chunk); 305 /* Disallow SACK bundling after DATA. */ 306 packet->has_sack = 1; 307 /* Disallow AUTH bundling after DATA */ 308 packet->has_auth = 1; 309 /* Let it be knows that packet has DATA in it */ 310 packet->has_data = 1; 311 /* timestamp the chunk for rtx purposes */ 312 chunk->sent_at = jiffies; 313 break; 314 case SCTP_CID_COOKIE_ECHO: 315 packet->has_cookie_echo = 1; 316 break; 317 318 case SCTP_CID_SACK: 319 packet->has_sack = 1; 320 break; 321 322 case SCTP_CID_AUTH: 323 packet->has_auth = 1; 324 packet->auth = chunk; 325 break; 326 } 327 328 /* It is OK to send this chunk. */ 329 list_add_tail(&chunk->list, &packet->chunk_list); 330 packet->size += chunk_len; 331 chunk->transport = packet->transport; 332 finish: 333 return retval; 334 } 335 336 /* All packets are sent to the network through this function from 337 * sctp_outq_tail(). 338 * 339 * The return value is a normal kernel error return value. 340 */ 341 int sctp_packet_transmit(struct sctp_packet *packet) 342 { 343 struct sctp_transport *tp = packet->transport; 344 struct sctp_association *asoc = tp->asoc; 345 struct sctphdr *sh; 346 struct sk_buff *nskb; 347 struct sctp_chunk *chunk, *tmp; 348 struct sock *sk; 349 int err = 0; 350 int padding; /* How much padding do we need? */ 351 __u8 has_data = 0; 352 struct dst_entry *dst = tp->dst; 353 unsigned char *auth = NULL; /* pointer to auth in skb data */ 354 __u32 cksum_buf_len = sizeof(struct sctphdr); 355 356 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); 357 358 /* Do NOT generate a chunkless packet. */ 359 if (list_empty(&packet->chunk_list)) 360 return err; 361 362 /* Set up convenience variables... */ 363 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); 364 sk = chunk->skb->sk; 365 366 /* Allocate the new skb. */ 367 nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); 368 if (!nskb) 369 goto nomem; 370 371 /* Make sure the outbound skb has enough header room reserved. */ 372 skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); 373 374 /* Set the owning socket so that we know where to get the 375 * destination IP address. 376 */ 377 skb_set_owner_w(nskb, sk); 378 379 /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ 380 if (!dst || (dst->obsolete > 1)) { 381 dst_release(dst); 382 sctp_transport_route(tp, NULL, sctp_sk(sk)); 383 if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { 384 sctp_assoc_sync_pmtu(asoc); 385 } 386 } 387 dst = dst_clone(tp->dst); 388 skb_dst_set(nskb, dst); 389 if (!dst) 390 goto no_route; 391 392 /* Build the SCTP header. */ 393 sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); 394 skb_reset_transport_header(nskb); 395 sh->source = htons(packet->source_port); 396 sh->dest = htons(packet->destination_port); 397 398 /* From 6.8 Adler-32 Checksum Calculation: 399 * After the packet is constructed (containing the SCTP common 400 * header and one or more control or DATA chunks), the 401 * transmitter shall: 402 * 403 * 1) Fill in the proper Verification Tag in the SCTP common 404 * header and initialize the checksum field to 0's. 405 */ 406 sh->vtag = htonl(packet->vtag); 407 sh->checksum = 0; 408 409 /** 410 * 6.10 Bundling 411 * 412 * An endpoint bundles chunks by simply including multiple 413 * chunks in one outbound SCTP packet. ... 414 */ 415 416 /** 417 * 3.2 Chunk Field Descriptions 418 * 419 * The total length of a chunk (including Type, Length and 420 * Value fields) MUST be a multiple of 4 bytes. If the length 421 * of the chunk is not a multiple of 4 bytes, the sender MUST 422 * pad the chunk with all zero bytes and this padding is not 423 * included in the chunk length field. The sender should 424 * never pad with more than 3 bytes. 425 * 426 * [This whole comment explains WORD_ROUND() below.] 427 */ 428 SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); 429 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 430 list_del_init(&chunk->list); 431 if (sctp_chunk_is_data(chunk)) { 432 /* 6.3.1 C4) When data is in flight and when allowed 433 * by rule C5, a new RTT measurement MUST be made each 434 * round trip. Furthermore, new RTT measurements 435 * SHOULD be made no more than once per round-trip 436 * for a given destination transport address. 437 */ 438 439 if (!tp->rto_pending) { 440 chunk->rtt_in_progress = 1; 441 tp->rto_pending = 1; 442 } 443 has_data = 1; 444 } 445 446 padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; 447 if (padding) 448 memset(skb_put(chunk->skb, padding), 0, padding); 449 450 /* if this is the auth chunk that we are adding, 451 * store pointer where it will be added and put 452 * the auth into the packet. 453 */ 454 if (chunk == packet->auth) 455 auth = skb_tail_pointer(nskb); 456 457 cksum_buf_len += chunk->skb->len; 458 memcpy(skb_put(nskb, chunk->skb->len), 459 chunk->skb->data, chunk->skb->len); 460 461 SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", 462 "*** Chunk", chunk, 463 sctp_cname(SCTP_ST_CHUNK( 464 chunk->chunk_hdr->type)), 465 chunk->has_tsn ? "TSN" : "No TSN", 466 chunk->has_tsn ? 467 ntohl(chunk->subh.data_hdr->tsn) : 0, 468 "length", ntohs(chunk->chunk_hdr->length), 469 "chunk->skb->len", chunk->skb->len, 470 "rtt_in_progress", chunk->rtt_in_progress); 471 472 /* 473 * If this is a control chunk, this is our last 474 * reference. Free data chunks after they've been 475 * acknowledged or have failed. 476 */ 477 if (!sctp_chunk_is_data(chunk)) 478 sctp_chunk_free(chunk); 479 } 480 481 /* SCTP-AUTH, Section 6.2 482 * The sender MUST calculate the MAC as described in RFC2104 [2] 483 * using the hash function H as described by the MAC Identifier and 484 * the shared association key K based on the endpoint pair shared key 485 * described by the shared key identifier. The 'data' used for the 486 * computation of the AUTH-chunk is given by the AUTH chunk with its 487 * HMAC field set to zero (as shown in Figure 6) followed by all 488 * chunks that are placed after the AUTH chunk in the SCTP packet. 489 */ 490 if (auth) 491 sctp_auth_calculate_hmac(asoc, nskb, 492 (struct sctp_auth_chunk *)auth, 493 GFP_ATOMIC); 494 495 /* 2) Calculate the Adler-32 checksum of the whole packet, 496 * including the SCTP common header and all the 497 * chunks. 498 * 499 * Note: Adler-32 is no longer applicable, as has been replaced 500 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. 501 */ 502 if (!sctp_checksum_disable && 503 !(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM))) { 504 __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len); 505 506 /* 3) Put the resultant value into the checksum field in the 507 * common header, and leave the rest of the bits unchanged. 508 */ 509 sh->checksum = sctp_end_cksum(crc32); 510 } else { 511 if (dst->dev->features & NETIF_F_SCTP_CSUM) { 512 /* no need to seed psuedo checksum for SCTP */ 513 nskb->ip_summed = CHECKSUM_PARTIAL; 514 nskb->csum_start = (skb_transport_header(nskb) - 515 nskb->head); 516 nskb->csum_offset = offsetof(struct sctphdr, checksum); 517 } else { 518 nskb->ip_summed = CHECKSUM_UNNECESSARY; 519 } 520 } 521 522 /* IP layer ECN support 523 * From RFC 2481 524 * "The ECN-Capable Transport (ECT) bit would be set by the 525 * data sender to indicate that the end-points of the 526 * transport protocol are ECN-capable." 527 * 528 * Now setting the ECT bit all the time, as it should not cause 529 * any problems protocol-wise even if our peer ignores it. 530 * 531 * Note: The works for IPv6 layer checks this bit too later 532 * in transmission. See IP6_ECN_flow_xmit(). 533 */ 534 (*tp->af_specific->ecn_capable)(nskb->sk); 535 536 /* Set up the IP options. */ 537 /* BUG: not implemented 538 * For v4 this all lives somewhere in sk->sk_opt... 539 */ 540 541 /* Dump that on IP! */ 542 if (asoc && asoc->peer.last_sent_to != tp) { 543 /* Considering the multiple CPU scenario, this is a 544 * "correcter" place for last_sent_to. --xguo 545 */ 546 asoc->peer.last_sent_to = tp; 547 } 548 549 if (has_data) { 550 struct timer_list *timer; 551 unsigned long timeout; 552 553 /* Restart the AUTOCLOSE timer when sending data. */ 554 if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { 555 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 556 timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 557 558 if (!mod_timer(timer, jiffies + timeout)) 559 sctp_association_hold(asoc); 560 } 561 } 562 563 SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", 564 nskb->len); 565 566 nskb->local_df = packet->ipfragok; 567 (*tp->af_specific->sctp_xmit)(nskb, tp); 568 569 out: 570 sctp_packet_reset(packet); 571 return err; 572 no_route: 573 kfree_skb(nskb); 574 IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES); 575 576 /* FIXME: Returning the 'err' will effect all the associations 577 * associated with a socket, although only one of the paths of the 578 * association is unreachable. 579 * The real failure of a transport or association can be passed on 580 * to the user via notifications. So setting this error may not be 581 * required. 582 */ 583 /* err = -EHOSTUNREACH; */ 584 err: 585 /* Control chunks are unreliable so just drop them. DATA chunks 586 * will get resent or dropped later. 587 */ 588 589 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 590 list_del_init(&chunk->list); 591 if (!sctp_chunk_is_data(chunk)) 592 sctp_chunk_free(chunk); 593 } 594 goto out; 595 nomem: 596 err = -ENOMEM; 597 goto err; 598 } 599 600 /******************************************************************** 601 * 2nd Level Abstractions 602 ********************************************************************/ 603 604 /* This private function check to see if a chunk can be added */ 605 static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 606 struct sctp_chunk *chunk) 607 { 608 sctp_xmit_t retval = SCTP_XMIT_OK; 609 size_t datasize, rwnd, inflight, flight_size; 610 struct sctp_transport *transport = packet->transport; 611 struct sctp_association *asoc = transport->asoc; 612 struct sctp_outq *q = &asoc->outqueue; 613 614 /* RFC 2960 6.1 Transmission of DATA Chunks 615 * 616 * A) At any given time, the data sender MUST NOT transmit new data to 617 * any destination transport address if its peer's rwnd indicates 618 * that the peer has no buffer space (i.e. rwnd is 0, see Section 619 * 6.2.1). However, regardless of the value of rwnd (including if it 620 * is 0), the data sender can always have one DATA chunk in flight to 621 * the receiver if allowed by cwnd (see rule B below). This rule 622 * allows the sender to probe for a change in rwnd that the sender 623 * missed due to the SACK having been lost in transit from the data 624 * receiver to the data sender. 625 */ 626 627 rwnd = asoc->peer.rwnd; 628 inflight = q->outstanding_bytes; 629 flight_size = transport->flight_size; 630 631 datasize = sctp_data_size(chunk); 632 633 if (datasize > rwnd) { 634 if (inflight > 0) { 635 /* We have (at least) one data chunk in flight, 636 * so we can't fall back to rule 6.1 B). 637 */ 638 retval = SCTP_XMIT_RWND_FULL; 639 goto finish; 640 } 641 } 642 643 /* RFC 2960 6.1 Transmission of DATA Chunks 644 * 645 * B) At any given time, the sender MUST NOT transmit new data 646 * to a given transport address if it has cwnd or more bytes 647 * of data outstanding to that transport address. 648 */ 649 /* RFC 7.2.4 & the Implementers Guide 2.8. 650 * 651 * 3) ... 652 * When a Fast Retransmit is being performed the sender SHOULD 653 * ignore the value of cwnd and SHOULD NOT delay retransmission. 654 */ 655 if (chunk->fast_retransmit != SCTP_NEED_FRTX) 656 if (flight_size >= transport->cwnd) { 657 retval = SCTP_XMIT_RWND_FULL; 658 goto finish; 659 } 660 661 /* Nagle's algorithm to solve small-packet problem: 662 * Inhibit the sending of new chunks when new outgoing data arrives 663 * if any previously transmitted data on the connection remains 664 * unacknowledged. 665 */ 666 if (!sctp_sk(asoc->base.sk)->nodelay && sctp_packet_empty(packet) && 667 inflight && sctp_state(asoc, ESTABLISHED)) { 668 unsigned max = transport->pathmtu - packet->overhead; 669 unsigned len = chunk->skb->len + q->out_qlen; 670 671 /* Check whether this chunk and all the rest of pending 672 * data will fit or delay in hopes of bundling a full 673 * sized packet. 674 * Don't delay large message writes that may have been 675 * fragmeneted into small peices. 676 */ 677 if ((len < max) && chunk->msg->can_delay) { 678 retval = SCTP_XMIT_NAGLE_DELAY; 679 goto finish; 680 } 681 } 682 683 finish: 684 return retval; 685 } 686 687 /* This private function does management things when adding DATA chunk */ 688 static void sctp_packet_append_data(struct sctp_packet *packet, 689 struct sctp_chunk *chunk) 690 { 691 struct sctp_transport *transport = packet->transport; 692 size_t datasize = sctp_data_size(chunk); 693 struct sctp_association *asoc = transport->asoc; 694 u32 rwnd = asoc->peer.rwnd; 695 696 /* Keep track of how many bytes are in flight over this transport. */ 697 transport->flight_size += datasize; 698 699 /* Keep track of how many bytes are in flight to the receiver. */ 700 asoc->outqueue.outstanding_bytes += datasize; 701 702 /* Update our view of the receiver's rwnd. Include sk_buff overhead 703 * while updating peer.rwnd so that it reduces the chances of a 704 * receiver running out of receive buffer space even when receive 705 * window is still open. This can happen when a sender is sending 706 * sending small messages. 707 */ 708 datasize += sizeof(struct sk_buff); 709 if (datasize < rwnd) 710 rwnd -= datasize; 711 else 712 rwnd = 0; 713 714 asoc->peer.rwnd = rwnd; 715 /* Has been accepted for transmission. */ 716 if (!asoc->peer.prsctp_capable) 717 chunk->msg->can_abandon = 0; 718 sctp_chunk_assign_tsn(chunk); 719 sctp_chunk_assign_ssn(chunk); 720 } 721 722 static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, 723 struct sctp_chunk *chunk, 724 u16 chunk_len) 725 { 726 size_t psize; 727 size_t pmtu; 728 int too_big; 729 sctp_xmit_t retval = SCTP_XMIT_OK; 730 731 psize = packet->size; 732 pmtu = ((packet->transport->asoc) ? 733 (packet->transport->asoc->pathmtu) : 734 (packet->transport->pathmtu)); 735 736 too_big = (psize + chunk_len > pmtu); 737 738 /* Decide if we need to fragment or resubmit later. */ 739 if (too_big) { 740 /* It's OK to fragmet at IP level if any one of the following 741 * is true: 742 * 1. The packet is empty (meaning this chunk is greater 743 * the MTU) 744 * 2. The chunk we are adding is a control chunk 745 * 3. The packet doesn't have any data in it yet and data 746 * requires authentication. 747 */ 748 if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) || 749 (!packet->has_data && chunk->auth)) { 750 /* We no longer do re-fragmentation. 751 * Just fragment at the IP layer, if we 752 * actually hit this condition 753 */ 754 packet->ipfragok = 1; 755 } else { 756 retval = SCTP_XMIT_PMTU_FULL; 757 } 758 } 759 760 return retval; 761 } 762