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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 45 46 #include <linux/types.h> 47 #include <linux/kernel.h> 48 #include <linux/wait.h> 49 #include <linux/time.h> 50 #include <linux/ip.h> 51 #include <linux/ipv6.h> 52 #include <linux/init.h> 53 #include <linux/slab.h> 54 #include <net/inet_ecn.h> 55 #include <net/ip.h> 56 #include <net/icmp.h> 57 #include <net/net_namespace.h> 58 59 #include <linux/socket.h> /* for sa_family_t */ 60 #include <net/sock.h> 61 62 #include <net/sctp/sctp.h> 63 #include <net/sctp/sm.h> 64 #include <net/sctp/checksum.h> 65 66 /* Forward declarations for private helpers. */ 67 static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 68 struct sctp_chunk *chunk); 69 static void sctp_packet_append_data(struct sctp_packet *packet, 70 struct sctp_chunk *chunk); 71 static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, 72 struct sctp_chunk *chunk, 73 u16 chunk_len); 74 75 static void sctp_packet_reset(struct sctp_packet *packet) 76 { 77 packet->size = packet->overhead; 78 packet->has_cookie_echo = 0; 79 packet->has_sack = 0; 80 packet->has_data = 0; 81 packet->has_auth = 0; 82 packet->ipfragok = 0; 83 packet->auth = NULL; 84 } 85 86 /* Config a packet. 87 * This appears to be a followup set of initializations. 88 */ 89 struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, 90 __u32 vtag, int ecn_capable) 91 { 92 struct sctp_chunk *chunk = NULL; 93 94 SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__, 95 packet, vtag); 96 97 packet->vtag = vtag; 98 99 if (ecn_capable && sctp_packet_empty(packet)) { 100 chunk = sctp_get_ecne_prepend(packet->transport->asoc); 101 102 /* If there a is a prepend chunk stick it on the list before 103 * any other chunks get appended. 104 */ 105 if (chunk) 106 sctp_packet_append_chunk(packet, chunk); 107 } 108 109 return packet; 110 } 111 112 /* Initialize the packet structure. */ 113 struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, 114 struct sctp_transport *transport, 115 __u16 sport, __u16 dport) 116 { 117 struct sctp_association *asoc = transport->asoc; 118 size_t overhead; 119 120 SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__, 121 packet, transport); 122 123 packet->transport = transport; 124 packet->source_port = sport; 125 packet->destination_port = dport; 126 INIT_LIST_HEAD(&packet->chunk_list); 127 if (asoc) { 128 struct sctp_sock *sp = sctp_sk(asoc->base.sk); 129 overhead = sp->pf->af->net_header_len; 130 } else { 131 overhead = sizeof(struct ipv6hdr); 132 } 133 overhead += sizeof(struct sctphdr); 134 packet->overhead = overhead; 135 sctp_packet_reset(packet); 136 packet->vtag = 0; 137 packet->malloced = 0; 138 return packet; 139 } 140 141 /* Free a packet. */ 142 void sctp_packet_free(struct sctp_packet *packet) 143 { 144 struct sctp_chunk *chunk, *tmp; 145 146 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); 147 148 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 149 list_del_init(&chunk->list); 150 sctp_chunk_free(chunk); 151 } 152 153 if (packet->malloced) 154 kfree(packet); 155 } 156 157 /* This routine tries to append the chunk to the offered packet. If adding 158 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk 159 * is not present in the packet, it transmits the input packet. 160 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long 161 * as it can fit in the packet, but any more data that does not fit in this 162 * packet can be sent only after receiving the COOKIE_ACK. 163 */ 164 sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, 165 struct sctp_chunk *chunk, 166 int one_packet) 167 { 168 sctp_xmit_t retval; 169 int error = 0; 170 171 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, 172 packet, chunk); 173 174 switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { 175 case SCTP_XMIT_PMTU_FULL: 176 if (!packet->has_cookie_echo) { 177 error = sctp_packet_transmit(packet); 178 if (error < 0) 179 chunk->skb->sk->sk_err = -error; 180 181 /* If we have an empty packet, then we can NOT ever 182 * return PMTU_FULL. 183 */ 184 if (!one_packet) 185 retval = sctp_packet_append_chunk(packet, 186 chunk); 187 } 188 break; 189 190 case SCTP_XMIT_RWND_FULL: 191 case SCTP_XMIT_OK: 192 case SCTP_XMIT_NAGLE_DELAY: 193 break; 194 } 195 196 return retval; 197 } 198 199 /* Try to bundle an auth chunk into the packet. */ 200 static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, 201 struct sctp_chunk *chunk) 202 { 203 struct sctp_association *asoc = pkt->transport->asoc; 204 struct sctp_chunk *auth; 205 sctp_xmit_t retval = SCTP_XMIT_OK; 206 207 /* if we don't have an association, we can't do authentication */ 208 if (!asoc) 209 return retval; 210 211 /* See if this is an auth chunk we are bundling or if 212 * auth is already bundled. 213 */ 214 if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth) 215 return retval; 216 217 /* if the peer did not request this chunk to be authenticated, 218 * don't do it 219 */ 220 if (!chunk->auth) 221 return retval; 222 223 auth = sctp_make_auth(asoc); 224 if (!auth) 225 return retval; 226 227 retval = sctp_packet_append_chunk(pkt, auth); 228 229 return retval; 230 } 231 232 /* Try to bundle a SACK with the packet. */ 233 static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, 234 struct sctp_chunk *chunk) 235 { 236 sctp_xmit_t retval = SCTP_XMIT_OK; 237 238 /* If sending DATA and haven't aleady bundled a SACK, try to 239 * bundle one in to the packet. 240 */ 241 if (sctp_chunk_is_data(chunk) && !pkt->has_sack && 242 !pkt->has_cookie_echo) { 243 struct sctp_association *asoc; 244 struct timer_list *timer; 245 asoc = pkt->transport->asoc; 246 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; 247 248 /* If the SACK timer is running, we have a pending SACK */ 249 if (timer_pending(timer)) { 250 struct sctp_chunk *sack; 251 asoc->a_rwnd = asoc->rwnd; 252 sack = sctp_make_sack(asoc); 253 if (sack) { 254 retval = sctp_packet_append_chunk(pkt, sack); 255 asoc->peer.sack_needed = 0; 256 if (del_timer(timer)) 257 sctp_association_put(asoc); 258 } 259 } 260 } 261 return retval; 262 } 263 264 /* Append a chunk to the offered packet reporting back any inability to do 265 * so. 266 */ 267 sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, 268 struct sctp_chunk *chunk) 269 { 270 sctp_xmit_t retval = SCTP_XMIT_OK; 271 __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); 272 273 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet, 274 chunk); 275 276 /* Data chunks are special. Before seeing what else we can 277 * bundle into this packet, check to see if we are allowed to 278 * send this DATA. 279 */ 280 if (sctp_chunk_is_data(chunk)) { 281 retval = sctp_packet_can_append_data(packet, chunk); 282 if (retval != SCTP_XMIT_OK) 283 goto finish; 284 } 285 286 /* Try to bundle AUTH chunk */ 287 retval = sctp_packet_bundle_auth(packet, chunk); 288 if (retval != SCTP_XMIT_OK) 289 goto finish; 290 291 /* Try to bundle SACK chunk */ 292 retval = sctp_packet_bundle_sack(packet, chunk); 293 if (retval != SCTP_XMIT_OK) 294 goto finish; 295 296 /* Check to see if this chunk will fit into the packet */ 297 retval = sctp_packet_will_fit(packet, chunk, chunk_len); 298 if (retval != SCTP_XMIT_OK) 299 goto finish; 300 301 /* We believe that this chunk is OK to add to the packet */ 302 switch (chunk->chunk_hdr->type) { 303 case SCTP_CID_DATA: 304 /* Account for the data being in the packet */ 305 sctp_packet_append_data(packet, chunk); 306 /* Disallow SACK bundling after DATA. */ 307 packet->has_sack = 1; 308 /* Disallow AUTH bundling after DATA */ 309 packet->has_auth = 1; 310 /* Let it be knows that packet has DATA in it */ 311 packet->has_data = 1; 312 /* timestamp the chunk for rtx purposes */ 313 chunk->sent_at = jiffies; 314 break; 315 case SCTP_CID_COOKIE_ECHO: 316 packet->has_cookie_echo = 1; 317 break; 318 319 case SCTP_CID_SACK: 320 packet->has_sack = 1; 321 break; 322 323 case SCTP_CID_AUTH: 324 packet->has_auth = 1; 325 packet->auth = chunk; 326 break; 327 } 328 329 /* It is OK to send this chunk. */ 330 list_add_tail(&chunk->list, &packet->chunk_list); 331 packet->size += chunk_len; 332 chunk->transport = packet->transport; 333 finish: 334 return retval; 335 } 336 337 /* All packets are sent to the network through this function from 338 * sctp_outq_tail(). 339 * 340 * The return value is a normal kernel error return value. 341 */ 342 int sctp_packet_transmit(struct sctp_packet *packet) 343 { 344 struct sctp_transport *tp = packet->transport; 345 struct sctp_association *asoc = tp->asoc; 346 struct sctphdr *sh; 347 struct sk_buff *nskb; 348 struct sctp_chunk *chunk, *tmp; 349 struct sock *sk; 350 int err = 0; 351 int padding; /* How much padding do we need? */ 352 __u8 has_data = 0; 353 struct dst_entry *dst = tp->dst; 354 unsigned char *auth = NULL; /* pointer to auth in skb data */ 355 __u32 cksum_buf_len = sizeof(struct sctphdr); 356 357 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); 358 359 /* Do NOT generate a chunkless packet. */ 360 if (list_empty(&packet->chunk_list)) 361 return err; 362 363 /* Set up convenience variables... */ 364 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); 365 sk = chunk->skb->sk; 366 367 /* Allocate the new skb. */ 368 nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); 369 if (!nskb) 370 goto nomem; 371 372 /* Make sure the outbound skb has enough header room reserved. */ 373 skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); 374 375 /* Set the owning socket so that we know where to get the 376 * destination IP address. 377 */ 378 skb_set_owner_w(nskb, sk); 379 380 /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ 381 if (!dst || (dst->obsolete > 1)) { 382 dst_release(dst); 383 sctp_transport_route(tp, NULL, sctp_sk(sk)); 384 if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { 385 sctp_assoc_sync_pmtu(asoc); 386 } 387 } 388 dst = dst_clone(tp->dst); 389 skb_dst_set(nskb, dst); 390 if (!dst) 391 goto no_route; 392 393 /* Build the SCTP header. */ 394 sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); 395 skb_reset_transport_header(nskb); 396 sh->source = htons(packet->source_port); 397 sh->dest = htons(packet->destination_port); 398 399 /* From 6.8 Adler-32 Checksum Calculation: 400 * After the packet is constructed (containing the SCTP common 401 * header and one or more control or DATA chunks), the 402 * transmitter shall: 403 * 404 * 1) Fill in the proper Verification Tag in the SCTP common 405 * header and initialize the checksum field to 0's. 406 */ 407 sh->vtag = htonl(packet->vtag); 408 sh->checksum = 0; 409 410 /** 411 * 6.10 Bundling 412 * 413 * An endpoint bundles chunks by simply including multiple 414 * chunks in one outbound SCTP packet. ... 415 */ 416 417 /** 418 * 3.2 Chunk Field Descriptions 419 * 420 * The total length of a chunk (including Type, Length and 421 * Value fields) MUST be a multiple of 4 bytes. If the length 422 * of the chunk is not a multiple of 4 bytes, the sender MUST 423 * pad the chunk with all zero bytes and this padding is not 424 * included in the chunk length field. The sender should 425 * never pad with more than 3 bytes. 426 * 427 * [This whole comment explains WORD_ROUND() below.] 428 */ 429 SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); 430 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 431 list_del_init(&chunk->list); 432 if (sctp_chunk_is_data(chunk)) { 433 /* 6.3.1 C4) When data is in flight and when allowed 434 * by rule C5, a new RTT measurement MUST be made each 435 * round trip. Furthermore, new RTT measurements 436 * SHOULD be made no more than once per round-trip 437 * for a given destination transport address. 438 */ 439 440 if (!tp->rto_pending) { 441 chunk->rtt_in_progress = 1; 442 tp->rto_pending = 1; 443 } 444 has_data = 1; 445 } 446 447 padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; 448 if (padding) 449 memset(skb_put(chunk->skb, padding), 0, padding); 450 451 /* if this is the auth chunk that we are adding, 452 * store pointer where it will be added and put 453 * the auth into the packet. 454 */ 455 if (chunk == packet->auth) 456 auth = skb_tail_pointer(nskb); 457 458 cksum_buf_len += chunk->skb->len; 459 memcpy(skb_put(nskb, chunk->skb->len), 460 chunk->skb->data, chunk->skb->len); 461 462 SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", 463 "*** Chunk", chunk, 464 sctp_cname(SCTP_ST_CHUNK( 465 chunk->chunk_hdr->type)), 466 chunk->has_tsn ? "TSN" : "No TSN", 467 chunk->has_tsn ? 468 ntohl(chunk->subh.data_hdr->tsn) : 0, 469 "length", ntohs(chunk->chunk_hdr->length), 470 "chunk->skb->len", chunk->skb->len, 471 "rtt_in_progress", chunk->rtt_in_progress); 472 473 /* 474 * If this is a control chunk, this is our last 475 * reference. Free data chunks after they've been 476 * acknowledged or have failed. 477 */ 478 if (!sctp_chunk_is_data(chunk)) 479 sctp_chunk_free(chunk); 480 } 481 482 /* SCTP-AUTH, Section 6.2 483 * The sender MUST calculate the MAC as described in RFC2104 [2] 484 * using the hash function H as described by the MAC Identifier and 485 * the shared association key K based on the endpoint pair shared key 486 * described by the shared key identifier. The 'data' used for the 487 * computation of the AUTH-chunk is given by the AUTH chunk with its 488 * HMAC field set to zero (as shown in Figure 6) followed by all 489 * chunks that are placed after the AUTH chunk in the SCTP packet. 490 */ 491 if (auth) 492 sctp_auth_calculate_hmac(asoc, nskb, 493 (struct sctp_auth_chunk *)auth, 494 GFP_ATOMIC); 495 496 /* 2) Calculate the Adler-32 checksum of the whole packet, 497 * including the SCTP common header and all the 498 * chunks. 499 * 500 * Note: Adler-32 is no longer applicable, as has been replaced 501 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. 502 */ 503 if (!sctp_checksum_disable && 504 !(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM))) { 505 __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len); 506 507 /* 3) Put the resultant value into the checksum field in the 508 * common header, and leave the rest of the bits unchanged. 509 */ 510 sh->checksum = sctp_end_cksum(crc32); 511 } else { 512 if (dst->dev->features & NETIF_F_SCTP_CSUM) { 513 /* no need to seed psuedo checksum for SCTP */ 514 nskb->ip_summed = CHECKSUM_PARTIAL; 515 nskb->csum_start = (skb_transport_header(nskb) - 516 nskb->head); 517 nskb->csum_offset = offsetof(struct sctphdr, checksum); 518 } else { 519 nskb->ip_summed = CHECKSUM_UNNECESSARY; 520 } 521 } 522 523 /* IP layer ECN support 524 * From RFC 2481 525 * "The ECN-Capable Transport (ECT) bit would be set by the 526 * data sender to indicate that the end-points of the 527 * transport protocol are ECN-capable." 528 * 529 * Now setting the ECT bit all the time, as it should not cause 530 * any problems protocol-wise even if our peer ignores it. 531 * 532 * Note: The works for IPv6 layer checks this bit too later 533 * in transmission. See IP6_ECN_flow_xmit(). 534 */ 535 (*tp->af_specific->ecn_capable)(nskb->sk); 536 537 /* Set up the IP options. */ 538 /* BUG: not implemented 539 * For v4 this all lives somewhere in sk->sk_opt... 540 */ 541 542 /* Dump that on IP! */ 543 if (asoc && asoc->peer.last_sent_to != tp) { 544 /* Considering the multiple CPU scenario, this is a 545 * "correcter" place for last_sent_to. --xguo 546 */ 547 asoc->peer.last_sent_to = tp; 548 } 549 550 if (has_data) { 551 struct timer_list *timer; 552 unsigned long timeout; 553 554 /* Restart the AUTOCLOSE timer when sending data. */ 555 if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { 556 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 557 timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 558 559 if (!mod_timer(timer, jiffies + timeout)) 560 sctp_association_hold(asoc); 561 } 562 } 563 564 SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", 565 nskb->len); 566 567 nskb->local_df = packet->ipfragok; 568 (*tp->af_specific->sctp_xmit)(nskb, tp); 569 570 out: 571 sctp_packet_reset(packet); 572 return err; 573 no_route: 574 kfree_skb(nskb); 575 IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES); 576 577 /* FIXME: Returning the 'err' will effect all the associations 578 * associated with a socket, although only one of the paths of the 579 * association is unreachable. 580 * The real failure of a transport or association can be passed on 581 * to the user via notifications. So setting this error may not be 582 * required. 583 */ 584 /* err = -EHOSTUNREACH; */ 585 err: 586 /* Control chunks are unreliable so just drop them. DATA chunks 587 * will get resent or dropped later. 588 */ 589 590 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 591 list_del_init(&chunk->list); 592 if (!sctp_chunk_is_data(chunk)) 593 sctp_chunk_free(chunk); 594 } 595 goto out; 596 nomem: 597 err = -ENOMEM; 598 goto err; 599 } 600 601 /******************************************************************** 602 * 2nd Level Abstractions 603 ********************************************************************/ 604 605 /* This private function check to see if a chunk can be added */ 606 static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 607 struct sctp_chunk *chunk) 608 { 609 sctp_xmit_t retval = SCTP_XMIT_OK; 610 size_t datasize, rwnd, inflight, flight_size; 611 struct sctp_transport *transport = packet->transport; 612 struct sctp_association *asoc = transport->asoc; 613 struct sctp_outq *q = &asoc->outqueue; 614 615 /* RFC 2960 6.1 Transmission of DATA Chunks 616 * 617 * A) At any given time, the data sender MUST NOT transmit new data to 618 * any destination transport address if its peer's rwnd indicates 619 * that the peer has no buffer space (i.e. rwnd is 0, see Section 620 * 6.2.1). However, regardless of the value of rwnd (including if it 621 * is 0), the data sender can always have one DATA chunk in flight to 622 * the receiver if allowed by cwnd (see rule B below). This rule 623 * allows the sender to probe for a change in rwnd that the sender 624 * missed due to the SACK having been lost in transit from the data 625 * receiver to the data sender. 626 */ 627 628 rwnd = asoc->peer.rwnd; 629 inflight = q->outstanding_bytes; 630 flight_size = transport->flight_size; 631 632 datasize = sctp_data_size(chunk); 633 634 if (datasize > rwnd) { 635 if (inflight > 0) { 636 /* We have (at least) one data chunk in flight, 637 * so we can't fall back to rule 6.1 B). 638 */ 639 retval = SCTP_XMIT_RWND_FULL; 640 goto finish; 641 } 642 } 643 644 /* RFC 2960 6.1 Transmission of DATA Chunks 645 * 646 * B) At any given time, the sender MUST NOT transmit new data 647 * to a given transport address if it has cwnd or more bytes 648 * of data outstanding to that transport address. 649 */ 650 /* RFC 7.2.4 & the Implementers Guide 2.8. 651 * 652 * 3) ... 653 * When a Fast Retransmit is being performed the sender SHOULD 654 * ignore the value of cwnd and SHOULD NOT delay retransmission. 655 */ 656 if (chunk->fast_retransmit != SCTP_NEED_FRTX) 657 if (flight_size >= transport->cwnd) { 658 retval = SCTP_XMIT_RWND_FULL; 659 goto finish; 660 } 661 662 /* Nagle's algorithm to solve small-packet problem: 663 * Inhibit the sending of new chunks when new outgoing data arrives 664 * if any previously transmitted data on the connection remains 665 * unacknowledged. 666 */ 667 if (!sctp_sk(asoc->base.sk)->nodelay && sctp_packet_empty(packet) && 668 inflight && sctp_state(asoc, ESTABLISHED)) { 669 unsigned max = transport->pathmtu - packet->overhead; 670 unsigned len = chunk->skb->len + q->out_qlen; 671 672 /* Check whether this chunk and all the rest of pending 673 * data will fit or delay in hopes of bundling a full 674 * sized packet. 675 * Don't delay large message writes that may have been 676 * fragmeneted into small peices. 677 */ 678 if ((len < max) && chunk->msg->can_delay) { 679 retval = SCTP_XMIT_NAGLE_DELAY; 680 goto finish; 681 } 682 } 683 684 finish: 685 return retval; 686 } 687 688 /* This private function does management things when adding DATA chunk */ 689 static void sctp_packet_append_data(struct sctp_packet *packet, 690 struct sctp_chunk *chunk) 691 { 692 struct sctp_transport *transport = packet->transport; 693 size_t datasize = sctp_data_size(chunk); 694 struct sctp_association *asoc = transport->asoc; 695 u32 rwnd = asoc->peer.rwnd; 696 697 /* Keep track of how many bytes are in flight over this transport. */ 698 transport->flight_size += datasize; 699 700 /* Keep track of how many bytes are in flight to the receiver. */ 701 asoc->outqueue.outstanding_bytes += datasize; 702 703 /* Update our view of the receiver's rwnd. Include sk_buff overhead 704 * while updating peer.rwnd so that it reduces the chances of a 705 * receiver running out of receive buffer space even when receive 706 * window is still open. This can happen when a sender is sending 707 * sending small messages. 708 */ 709 datasize += sizeof(struct sk_buff); 710 if (datasize < rwnd) 711 rwnd -= datasize; 712 else 713 rwnd = 0; 714 715 asoc->peer.rwnd = rwnd; 716 /* Has been accepted for transmission. */ 717 if (!asoc->peer.prsctp_capable) 718 chunk->msg->can_abandon = 0; 719 sctp_chunk_assign_tsn(chunk); 720 sctp_chunk_assign_ssn(chunk); 721 } 722 723 static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, 724 struct sctp_chunk *chunk, 725 u16 chunk_len) 726 { 727 size_t psize; 728 size_t pmtu; 729 int too_big; 730 sctp_xmit_t retval = SCTP_XMIT_OK; 731 732 psize = packet->size; 733 pmtu = ((packet->transport->asoc) ? 734 (packet->transport->asoc->pathmtu) : 735 (packet->transport->pathmtu)); 736 737 too_big = (psize + chunk_len > pmtu); 738 739 /* Decide if we need to fragment or resubmit later. */ 740 if (too_big) { 741 /* It's OK to fragmet at IP level if any one of the following 742 * is true: 743 * 1. The packet is empty (meaning this chunk is greater 744 * the MTU) 745 * 2. The chunk we are adding is a control chunk 746 * 3. The packet doesn't have any data in it yet and data 747 * requires authentication. 748 */ 749 if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) || 750 (!packet->has_data && chunk->auth)) { 751 /* We no longer do re-fragmentation. 752 * Just fragment at the IP layer, if we 753 * actually hit this condition 754 */ 755 packet->ipfragok = 1; 756 } else { 757 retval = SCTP_XMIT_PMTU_FULL; 758 } 759 } 760 761 return retval; 762 } 763