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