| /* SCTP kernel implementation |
| * (C) Copyright IBM Corp. 2001, 2004 |
| * Copyright (c) 1999-2000 Cisco, Inc. |
| * Copyright (c) 1999-2001 Motorola, Inc. |
| * |
| * This file is part of the SCTP kernel implementation |
| * |
| * These functions handle output processing. |
| * |
| * This SCTP implementation is free software; |
| * you can redistribute it and/or modify it under the terms of |
| * the GNU General Public License as published by |
| * the Free Software Foundation; either version 2, or (at your option) |
| * any later version. |
| * |
| * This SCTP implementation is distributed in the hope that it |
| * will be useful, but WITHOUT ANY WARRANTY; without even the implied |
| * ************************ |
| * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
| * See the GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with GNU CC; see the file COPYING. If not, write to |
| * the Free Software Foundation, 59 Temple Place - Suite 330, |
| * Boston, MA 02111-1307, USA. |
| * |
| * Please send any bug reports or fixes you make to the |
| * email address(es): |
| * lksctp developers <lksctp-developers@lists.sourceforge.net> |
| * |
| * Or submit a bug report through the following website: |
| * http://www.sf.net/projects/lksctp |
| * |
| * Written or modified by: |
| * La Monte H.P. Yarroll <piggy@acm.org> |
| * Karl Knutson <karl@athena.chicago.il.us> |
| * Jon Grimm <jgrimm@austin.ibm.com> |
| * Sridhar Samudrala <sri@us.ibm.com> |
| * |
| * Any bugs reported given to us we will try to fix... any fixes shared will |
| * be incorporated into the next SCTP release. |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/types.h> |
| #include <linux/kernel.h> |
| #include <linux/wait.h> |
| #include <linux/time.h> |
| #include <linux/ip.h> |
| #include <linux/ipv6.h> |
| #include <linux/init.h> |
| #include <linux/slab.h> |
| #include <net/inet_ecn.h> |
| #include <net/ip.h> |
| #include <net/icmp.h> |
| #include <net/net_namespace.h> |
| |
| #include <linux/socket.h> /* for sa_family_t */ |
| #include <net/sock.h> |
| |
| #include <net/sctp/sctp.h> |
| #include <net/sctp/sm.h> |
| #include <net/sctp/checksum.h> |
| |
| /* Forward declarations for private helpers. */ |
| static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet, |
| struct sctp_chunk *chunk); |
| static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, |
| struct sctp_chunk *chunk); |
| static void sctp_packet_append_data(struct sctp_packet *packet, |
| struct sctp_chunk *chunk); |
| static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, |
| struct sctp_chunk *chunk, |
| u16 chunk_len); |
| |
| static void sctp_packet_reset(struct sctp_packet *packet) |
| { |
| packet->size = packet->overhead; |
| packet->has_cookie_echo = 0; |
| packet->has_sack = 0; |
| packet->has_data = 0; |
| packet->has_auth = 0; |
| packet->ipfragok = 0; |
| packet->auth = NULL; |
| } |
| |
| /* Config a packet. |
| * This appears to be a followup set of initializations. |
| */ |
| struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, |
| __u32 vtag, int ecn_capable) |
| { |
| struct sctp_chunk *chunk = NULL; |
| |
| SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__, |
| packet, vtag); |
| |
| packet->vtag = vtag; |
| |
| if (ecn_capable && sctp_packet_empty(packet)) { |
| chunk = sctp_get_ecne_prepend(packet->transport->asoc); |
| |
| /* If there a is a prepend chunk stick it on the list before |
| * any other chunks get appended. |
| */ |
| if (chunk) |
| sctp_packet_append_chunk(packet, chunk); |
| } |
| |
| return packet; |
| } |
| |
| /* Initialize the packet structure. */ |
| struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, |
| struct sctp_transport *transport, |
| __u16 sport, __u16 dport) |
| { |
| struct sctp_association *asoc = transport->asoc; |
| size_t overhead; |
| |
| SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__, |
| packet, transport); |
| |
| packet->transport = transport; |
| packet->source_port = sport; |
| packet->destination_port = dport; |
| INIT_LIST_HEAD(&packet->chunk_list); |
| if (asoc) { |
| struct sctp_sock *sp = sctp_sk(asoc->base.sk); |
| overhead = sp->pf->af->net_header_len; |
| } else { |
| overhead = sizeof(struct ipv6hdr); |
| } |
| overhead += sizeof(struct sctphdr); |
| packet->overhead = overhead; |
| sctp_packet_reset(packet); |
| packet->vtag = 0; |
| |
| return packet; |
| } |
| |
| /* Free a packet. */ |
| void sctp_packet_free(struct sctp_packet *packet) |
| { |
| struct sctp_chunk *chunk, *tmp; |
| |
| SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
| |
| list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
| list_del_init(&chunk->list); |
| sctp_chunk_free(chunk); |
| } |
| } |
| |
| /* This routine tries to append the chunk to the offered packet. If adding |
| * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk |
| * is not present in the packet, it transmits the input packet. |
| * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long |
| * as it can fit in the packet, but any more data that does not fit in this |
| * packet can be sent only after receiving the COOKIE_ACK. |
| */ |
| sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, |
| struct sctp_chunk *chunk, |
| int one_packet) |
| { |
| sctp_xmit_t retval; |
| int error = 0; |
| |
| SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, |
| packet, chunk); |
| |
| switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { |
| case SCTP_XMIT_PMTU_FULL: |
| if (!packet->has_cookie_echo) { |
| error = sctp_packet_transmit(packet); |
| if (error < 0) |
| chunk->skb->sk->sk_err = -error; |
| |
| /* If we have an empty packet, then we can NOT ever |
| * return PMTU_FULL. |
| */ |
| if (!one_packet) |
| retval = sctp_packet_append_chunk(packet, |
| chunk); |
| } |
| break; |
| |
| case SCTP_XMIT_RWND_FULL: |
| case SCTP_XMIT_OK: |
| case SCTP_XMIT_NAGLE_DELAY: |
| break; |
| } |
| |
| return retval; |
| } |
| |
| /* Try to bundle an auth chunk into the packet. */ |
| static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, |
| struct sctp_chunk *chunk) |
| { |
| struct sctp_association *asoc = pkt->transport->asoc; |
| struct sctp_chunk *auth; |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| |
| /* if we don't have an association, we can't do authentication */ |
| if (!asoc) |
| return retval; |
| |
| /* See if this is an auth chunk we are bundling or if |
| * auth is already bundled. |
| */ |
| if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth) |
| return retval; |
| |
| /* if the peer did not request this chunk to be authenticated, |
| * don't do it |
| */ |
| if (!chunk->auth) |
| return retval; |
| |
| auth = sctp_make_auth(asoc); |
| if (!auth) |
| return retval; |
| |
| retval = __sctp_packet_append_chunk(pkt, auth); |
| |
| if (retval != SCTP_XMIT_OK) |
| sctp_chunk_free(auth); |
| |
| return retval; |
| } |
| |
| /* Try to bundle a SACK with the packet. */ |
| static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, |
| struct sctp_chunk *chunk) |
| { |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| |
| /* If sending DATA and haven't aleady bundled a SACK, try to |
| * bundle one in to the packet. |
| */ |
| if (sctp_chunk_is_data(chunk) && !pkt->has_sack && |
| !pkt->has_cookie_echo) { |
| struct sctp_association *asoc; |
| struct timer_list *timer; |
| asoc = pkt->transport->asoc; |
| timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; |
| |
| /* If the SACK timer is running, we have a pending SACK */ |
| if (timer_pending(timer)) { |
| struct sctp_chunk *sack; |
| |
| if (pkt->transport->sack_generation != |
| pkt->transport->asoc->peer.sack_generation) |
| return retval; |
| |
| asoc->a_rwnd = asoc->rwnd; |
| sack = sctp_make_sack(asoc); |
| if (sack) { |
| retval = __sctp_packet_append_chunk(pkt, sack); |
| if (retval != SCTP_XMIT_OK) { |
| sctp_chunk_free(sack); |
| goto out; |
| } |
| asoc->peer.sack_needed = 0; |
| if (del_timer(timer)) |
| sctp_association_put(asoc); |
| } |
| } |
| } |
| out: |
| return retval; |
| } |
| |
| |
| /* Append a chunk to the offered packet reporting back any inability to do |
| * so. |
| */ |
| static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet, |
| struct sctp_chunk *chunk) |
| { |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); |
| |
| /* Check to see if this chunk will fit into the packet */ |
| retval = sctp_packet_will_fit(packet, chunk, chunk_len); |
| if (retval != SCTP_XMIT_OK) |
| goto finish; |
| |
| /* We believe that this chunk is OK to add to the packet */ |
| switch (chunk->chunk_hdr->type) { |
| case SCTP_CID_DATA: |
| /* Account for the data being in the packet */ |
| sctp_packet_append_data(packet, chunk); |
| /* Disallow SACK bundling after DATA. */ |
| packet->has_sack = 1; |
| /* Disallow AUTH bundling after DATA */ |
| packet->has_auth = 1; |
| /* Let it be knows that packet has DATA in it */ |
| packet->has_data = 1; |
| /* timestamp the chunk for rtx purposes */ |
| chunk->sent_at = jiffies; |
| break; |
| case SCTP_CID_COOKIE_ECHO: |
| packet->has_cookie_echo = 1; |
| break; |
| |
| case SCTP_CID_SACK: |
| packet->has_sack = 1; |
| if (chunk->asoc) |
| chunk->asoc->stats.osacks++; |
| break; |
| |
| case SCTP_CID_AUTH: |
| packet->has_auth = 1; |
| packet->auth = chunk; |
| break; |
| } |
| |
| /* It is OK to send this chunk. */ |
| list_add_tail(&chunk->list, &packet->chunk_list); |
| packet->size += chunk_len; |
| chunk->transport = packet->transport; |
| finish: |
| return retval; |
| } |
| |
| /* Append a chunk to the offered packet reporting back any inability to do |
| * so. |
| */ |
| sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, |
| struct sctp_chunk *chunk) |
| { |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| |
| SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet, |
| chunk); |
| |
| /* Data chunks are special. Before seeing what else we can |
| * bundle into this packet, check to see if we are allowed to |
| * send this DATA. |
| */ |
| if (sctp_chunk_is_data(chunk)) { |
| retval = sctp_packet_can_append_data(packet, chunk); |
| if (retval != SCTP_XMIT_OK) |
| goto finish; |
| } |
| |
| /* Try to bundle AUTH chunk */ |
| retval = sctp_packet_bundle_auth(packet, chunk); |
| if (retval != SCTP_XMIT_OK) |
| goto finish; |
| |
| /* Try to bundle SACK chunk */ |
| retval = sctp_packet_bundle_sack(packet, chunk); |
| if (retval != SCTP_XMIT_OK) |
| goto finish; |
| |
| retval = __sctp_packet_append_chunk(packet, chunk); |
| |
| finish: |
| return retval; |
| } |
| |
| static void sctp_packet_release_owner(struct sk_buff *skb) |
| { |
| sk_free(skb->sk); |
| } |
| |
| static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk) |
| { |
| skb_orphan(skb); |
| skb->sk = sk; |
| skb->destructor = sctp_packet_release_owner; |
| |
| /* |
| * The data chunks have already been accounted for in sctp_sendmsg(), |
| * therefore only reserve a single byte to keep socket around until |
| * the packet has been transmitted. |
| */ |
| atomic_inc(&sk->sk_wmem_alloc); |
| } |
| |
| /* All packets are sent to the network through this function from |
| * sctp_outq_tail(). |
| * |
| * The return value is a normal kernel error return value. |
| */ |
| int sctp_packet_transmit(struct sctp_packet *packet) |
| { |
| struct sctp_transport *tp = packet->transport; |
| struct sctp_association *asoc = tp->asoc; |
| struct sctphdr *sh; |
| struct sk_buff *nskb; |
| struct sctp_chunk *chunk, *tmp; |
| struct sock *sk; |
| int err = 0; |
| int padding; /* How much padding do we need? */ |
| __u8 has_data = 0; |
| struct dst_entry *dst = tp->dst; |
| unsigned char *auth = NULL; /* pointer to auth in skb data */ |
| __u32 cksum_buf_len = sizeof(struct sctphdr); |
| |
| SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
| |
| /* Do NOT generate a chunkless packet. */ |
| if (list_empty(&packet->chunk_list)) |
| return err; |
| |
| /* Set up convenience variables... */ |
| chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); |
| sk = chunk->skb->sk; |
| |
| /* Allocate the new skb. */ |
| nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); |
| if (!nskb) |
| goto nomem; |
| |
| /* Make sure the outbound skb has enough header room reserved. */ |
| skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); |
| |
| /* Set the owning socket so that we know where to get the |
| * destination IP address. |
| */ |
| sctp_packet_set_owner_w(nskb, sk); |
| |
| if (!sctp_transport_dst_check(tp)) { |
| sctp_transport_route(tp, NULL, sctp_sk(sk)); |
| if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { |
| sctp_assoc_sync_pmtu(sk, asoc); |
| } |
| } |
| dst = dst_clone(tp->dst); |
| skb_dst_set(nskb, dst); |
| if (!dst) |
| goto no_route; |
| |
| /* Build the SCTP header. */ |
| sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); |
| skb_reset_transport_header(nskb); |
| sh->source = htons(packet->source_port); |
| sh->dest = htons(packet->destination_port); |
| |
| /* From 6.8 Adler-32 Checksum Calculation: |
| * After the packet is constructed (containing the SCTP common |
| * header and one or more control or DATA chunks), the |
| * transmitter shall: |
| * |
| * 1) Fill in the proper Verification Tag in the SCTP common |
| * header and initialize the checksum field to 0's. |
| */ |
| sh->vtag = htonl(packet->vtag); |
| sh->checksum = 0; |
| |
| /** |
| * 6.10 Bundling |
| * |
| * An endpoint bundles chunks by simply including multiple |
| * chunks in one outbound SCTP packet. ... |
| */ |
| |
| /** |
| * 3.2 Chunk Field Descriptions |
| * |
| * The total length of a chunk (including Type, Length and |
| * Value fields) MUST be a multiple of 4 bytes. If the length |
| * of the chunk is not a multiple of 4 bytes, the sender MUST |
| * pad the chunk with all zero bytes and this padding is not |
| * included in the chunk length field. The sender should |
| * never pad with more than 3 bytes. |
| * |
| * [This whole comment explains WORD_ROUND() below.] |
| */ |
| SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); |
| list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
| list_del_init(&chunk->list); |
| if (sctp_chunk_is_data(chunk)) { |
| /* 6.3.1 C4) When data is in flight and when allowed |
| * by rule C5, a new RTT measurement MUST be made each |
| * round trip. Furthermore, new RTT measurements |
| * SHOULD be made no more than once per round-trip |
| * for a given destination transport address. |
| */ |
| |
| if (!tp->rto_pending) { |
| chunk->rtt_in_progress = 1; |
| tp->rto_pending = 1; |
| } |
| has_data = 1; |
| } |
| |
| padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; |
| if (padding) |
| memset(skb_put(chunk->skb, padding), 0, padding); |
| |
| /* if this is the auth chunk that we are adding, |
| * store pointer where it will be added and put |
| * the auth into the packet. |
| */ |
| if (chunk == packet->auth) |
| auth = skb_tail_pointer(nskb); |
| |
| cksum_buf_len += chunk->skb->len; |
| memcpy(skb_put(nskb, chunk->skb->len), |
| chunk->skb->data, chunk->skb->len); |
| |
| SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", |
| "*** Chunk", chunk, |
| sctp_cname(SCTP_ST_CHUNK( |
| chunk->chunk_hdr->type)), |
| chunk->has_tsn ? "TSN" : "No TSN", |
| chunk->has_tsn ? |
| ntohl(chunk->subh.data_hdr->tsn) : 0, |
| "length", ntohs(chunk->chunk_hdr->length), |
| "chunk->skb->len", chunk->skb->len, |
| "rtt_in_progress", chunk->rtt_in_progress); |
| |
| /* |
| * If this is a control chunk, this is our last |
| * reference. Free data chunks after they've been |
| * acknowledged or have failed. |
| */ |
| if (!sctp_chunk_is_data(chunk)) |
| sctp_chunk_free(chunk); |
| } |
| |
| /* SCTP-AUTH, Section 6.2 |
| * The sender MUST calculate the MAC as described in RFC2104 [2] |
| * using the hash function H as described by the MAC Identifier and |
| * the shared association key K based on the endpoint pair shared key |
| * described by the shared key identifier. The 'data' used for the |
| * computation of the AUTH-chunk is given by the AUTH chunk with its |
| * HMAC field set to zero (as shown in Figure 6) followed by all |
| * chunks that are placed after the AUTH chunk in the SCTP packet. |
| */ |
| if (auth) |
| sctp_auth_calculate_hmac(asoc, nskb, |
| (struct sctp_auth_chunk *)auth, |
| GFP_ATOMIC); |
| |
| /* 2) Calculate the Adler-32 checksum of the whole packet, |
| * including the SCTP common header and all the |
| * chunks. |
| * |
| * Note: Adler-32 is no longer applicable, as has been replaced |
| * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. |
| */ |
| if (!sctp_checksum_disable) { |
| if (!(dst->dev->features & NETIF_F_SCTP_CSUM) || |
| (dst_xfrm(dst) != NULL) || packet->ipfragok) { |
| __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len); |
| |
| /* 3) Put the resultant value into the checksum field in the |
| * common header, and leave the rest of the bits unchanged. |
| */ |
| sh->checksum = sctp_end_cksum(crc32); |
| } else { |
| /* no need to seed pseudo checksum for SCTP */ |
| nskb->ip_summed = CHECKSUM_PARTIAL; |
| nskb->csum_start = (skb_transport_header(nskb) - |
| nskb->head); |
| nskb->csum_offset = offsetof(struct sctphdr, checksum); |
| } |
| } |
| |
| /* IP layer ECN support |
| * From RFC 2481 |
| * "The ECN-Capable Transport (ECT) bit would be set by the |
| * data sender to indicate that the end-points of the |
| * transport protocol are ECN-capable." |
| * |
| * Now setting the ECT bit all the time, as it should not cause |
| * any problems protocol-wise even if our peer ignores it. |
| * |
| * Note: The works for IPv6 layer checks this bit too later |
| * in transmission. See IP6_ECN_flow_xmit(). |
| */ |
| (*tp->af_specific->ecn_capable)(nskb->sk); |
| |
| /* Set up the IP options. */ |
| /* BUG: not implemented |
| * For v4 this all lives somewhere in sk->sk_opt... |
| */ |
| |
| /* Dump that on IP! */ |
| if (asoc) { |
| asoc->stats.opackets++; |
| if (asoc->peer.last_sent_to != tp) |
| /* Considering the multiple CPU scenario, this is a |
| * "correcter" place for last_sent_to. --xguo |
| */ |
| asoc->peer.last_sent_to = tp; |
| } |
| |
| if (has_data) { |
| struct timer_list *timer; |
| unsigned long timeout; |
| |
| /* Restart the AUTOCLOSE timer when sending data. */ |
| if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { |
| timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; |
| timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; |
| |
| if (!mod_timer(timer, jiffies + timeout)) |
| sctp_association_hold(asoc); |
| } |
| } |
| |
| SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", |
| nskb->len); |
| |
| nskb->local_df = packet->ipfragok; |
| (*tp->af_specific->sctp_xmit)(nskb, tp); |
| |
| out: |
| sctp_packet_reset(packet); |
| return err; |
| no_route: |
| kfree_skb(nskb); |
| IP_INC_STATS_BH(sock_net(asoc->base.sk), IPSTATS_MIB_OUTNOROUTES); |
| |
| /* FIXME: Returning the 'err' will effect all the associations |
| * associated with a socket, although only one of the paths of the |
| * association is unreachable. |
| * The real failure of a transport or association can be passed on |
| * to the user via notifications. So setting this error may not be |
| * required. |
| */ |
| /* err = -EHOSTUNREACH; */ |
| err: |
| /* Control chunks are unreliable so just drop them. DATA chunks |
| * will get resent or dropped later. |
| */ |
| |
| list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
| list_del_init(&chunk->list); |
| if (!sctp_chunk_is_data(chunk)) |
| sctp_chunk_free(chunk); |
| } |
| goto out; |
| nomem: |
| err = -ENOMEM; |
| goto err; |
| } |
| |
| /******************************************************************** |
| * 2nd Level Abstractions |
| ********************************************************************/ |
| |
| /* This private function check to see if a chunk can be added */ |
| static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, |
| struct sctp_chunk *chunk) |
| { |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| size_t datasize, rwnd, inflight, flight_size; |
| struct sctp_transport *transport = packet->transport; |
| struct sctp_association *asoc = transport->asoc; |
| struct sctp_outq *q = &asoc->outqueue; |
| |
| /* RFC 2960 6.1 Transmission of DATA Chunks |
| * |
| * A) At any given time, the data sender MUST NOT transmit new data to |
| * any destination transport address if its peer's rwnd indicates |
| * that the peer has no buffer space (i.e. rwnd is 0, see Section |
| * 6.2.1). However, regardless of the value of rwnd (including if it |
| * is 0), the data sender can always have one DATA chunk in flight to |
| * the receiver if allowed by cwnd (see rule B below). This rule |
| * allows the sender to probe for a change in rwnd that the sender |
| * missed due to the SACK having been lost in transit from the data |
| * receiver to the data sender. |
| */ |
| |
| rwnd = asoc->peer.rwnd; |
| inflight = q->outstanding_bytes; |
| flight_size = transport->flight_size; |
| |
| datasize = sctp_data_size(chunk); |
| |
| if (datasize > rwnd) { |
| if (inflight > 0) { |
| /* We have (at least) one data chunk in flight, |
| * so we can't fall back to rule 6.1 B). |
| */ |
| retval = SCTP_XMIT_RWND_FULL; |
| goto finish; |
| } |
| } |
| |
| /* RFC 2960 6.1 Transmission of DATA Chunks |
| * |
| * B) At any given time, the sender MUST NOT transmit new data |
| * to a given transport address if it has cwnd or more bytes |
| * of data outstanding to that transport address. |
| */ |
| /* RFC 7.2.4 & the Implementers Guide 2.8. |
| * |
| * 3) ... |
| * When a Fast Retransmit is being performed the sender SHOULD |
| * ignore the value of cwnd and SHOULD NOT delay retransmission. |
| */ |
| if (chunk->fast_retransmit != SCTP_NEED_FRTX) |
| if (flight_size >= transport->cwnd) { |
| retval = SCTP_XMIT_RWND_FULL; |
| goto finish; |
| } |
| |
| /* Nagle's algorithm to solve small-packet problem: |
| * Inhibit the sending of new chunks when new outgoing data arrives |
| * if any previously transmitted data on the connection remains |
| * unacknowledged. |
| */ |
| if (!sctp_sk(asoc->base.sk)->nodelay && sctp_packet_empty(packet) && |
| inflight && sctp_state(asoc, ESTABLISHED)) { |
| unsigned int max = transport->pathmtu - packet->overhead; |
| unsigned int len = chunk->skb->len + q->out_qlen; |
| |
| /* Check whether this chunk and all the rest of pending |
| * data will fit or delay in hopes of bundling a full |
| * sized packet. |
| * Don't delay large message writes that may have been |
| * fragmeneted into small peices. |
| */ |
| if ((len < max) && chunk->msg->can_delay) { |
| retval = SCTP_XMIT_NAGLE_DELAY; |
| goto finish; |
| } |
| } |
| |
| finish: |
| return retval; |
| } |
| |
| /* This private function does management things when adding DATA chunk */ |
| static void sctp_packet_append_data(struct sctp_packet *packet, |
| struct sctp_chunk *chunk) |
| { |
| struct sctp_transport *transport = packet->transport; |
| size_t datasize = sctp_data_size(chunk); |
| struct sctp_association *asoc = transport->asoc; |
| u32 rwnd = asoc->peer.rwnd; |
| |
| /* Keep track of how many bytes are in flight over this transport. */ |
| transport->flight_size += datasize; |
| |
| /* Keep track of how many bytes are in flight to the receiver. */ |
| asoc->outqueue.outstanding_bytes += datasize; |
| |
| /* Update our view of the receiver's rwnd. */ |
| if (datasize < rwnd) |
| rwnd -= datasize; |
| else |
| rwnd = 0; |
| |
| asoc->peer.rwnd = rwnd; |
| /* Has been accepted for transmission. */ |
| if (!asoc->peer.prsctp_capable) |
| chunk->msg->can_abandon = 0; |
| sctp_chunk_assign_tsn(chunk); |
| sctp_chunk_assign_ssn(chunk); |
| } |
| |
| static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, |
| struct sctp_chunk *chunk, |
| u16 chunk_len) |
| { |
| size_t psize; |
| size_t pmtu; |
| int too_big; |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| |
| psize = packet->size; |
| pmtu = ((packet->transport->asoc) ? |
| (packet->transport->asoc->pathmtu) : |
| (packet->transport->pathmtu)); |
| |
| too_big = (psize + chunk_len > pmtu); |
| |
| /* Decide if we need to fragment or resubmit later. */ |
| if (too_big) { |
| /* It's OK to fragmet at IP level if any one of the following |
| * is true: |
| * 1. The packet is empty (meaning this chunk is greater |
| * the MTU) |
| * 2. The chunk we are adding is a control chunk |
| * 3. The packet doesn't have any data in it yet and data |
| * requires authentication. |
| */ |
| if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) || |
| (!packet->has_data && chunk->auth)) { |
| /* We no longer do re-fragmentation. |
| * Just fragment at the IP layer, if we |
| * actually hit this condition |
| */ |
| packet->ipfragok = 1; |
| } else { |
| retval = SCTP_XMIT_PMTU_FULL; |
| } |
| } |
| |
| return retval; |
| } |