| /* 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, see |
| * <http://www.gnu.org/licenses/>. |
| * |
| * Please send any bug reports or fixes you make to the |
| * email address(es): |
| * lksctp developers <linux-sctp@vger.kernel.org> |
| * |
| * 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> |
| */ |
| |
| #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. |
| */ |
| void sctp_packet_config(struct sctp_packet *packet, __u32 vtag, |
| int ecn_capable) |
| { |
| struct sctp_transport *tp = packet->transport; |
| struct sctp_association *asoc = tp->asoc; |
| |
| pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag); |
| |
| packet->vtag = vtag; |
| |
| if (asoc && tp->dst) { |
| struct sock *sk = asoc->base.sk; |
| |
| rcu_read_lock(); |
| if (__sk_dst_get(sk) != tp->dst) { |
| dst_hold(tp->dst); |
| sk_setup_caps(sk, tp->dst); |
| } |
| |
| if (sk_can_gso(sk)) { |
| struct net_device *dev = tp->dst->dev; |
| |
| packet->max_size = dev->gso_max_size; |
| } else { |
| packet->max_size = asoc->pathmtu; |
| } |
| rcu_read_unlock(); |
| |
| } else { |
| packet->max_size = tp->pathmtu; |
| } |
| |
| if (ecn_capable && sctp_packet_empty(packet)) { |
| struct sctp_chunk *chunk; |
| |
| /* If there a is a prepend chunk stick it on the list before |
| * any other chunks get appended. |
| */ |
| chunk = sctp_get_ecne_prepend(asoc); |
| if (chunk) |
| sctp_packet_append_chunk(packet, chunk); |
| } |
| } |
| |
| /* Initialize the packet structure. */ |
| void sctp_packet_init(struct sctp_packet *packet, |
| struct sctp_transport *transport, |
| __u16 sport, __u16 dport) |
| { |
| struct sctp_association *asoc = transport->asoc; |
| size_t overhead; |
| |
| pr_debug("%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; |
| } |
| |
| /* Free a packet. */ |
| void sctp_packet_free(struct sctp_packet *packet) |
| { |
| struct sctp_chunk *chunk, *tmp; |
| |
| pr_debug("%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, gfp_t gfp) |
| { |
| sctp_xmit_t retval; |
| |
| pr_debug("%s: packet:%p size:%Zu chunk:%p size:%d\n", __func__, |
| packet, packet->size, chunk, chunk->skb ? chunk->skb->len : -1); |
| |
| switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { |
| case SCTP_XMIT_PMTU_FULL: |
| if (!packet->has_cookie_echo) { |
| int error = 0; |
| |
| error = sctp_packet_transmit(packet, gfp); |
| 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_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 = SCTP_PAD4(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; |
| /* Mainly used for prsctp RTX policy */ |
| chunk->sent_count++; |
| 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; |
| |
| pr_debug("%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); |
| } |
| |
| static int sctp_packet_pack(struct sctp_packet *packet, |
| struct sk_buff *head, int gso, gfp_t gfp) |
| { |
| struct sctp_transport *tp = packet->transport; |
| struct sctp_auth_chunk *auth = NULL; |
| struct sctp_chunk *chunk, *tmp; |
| int pkt_count = 0, pkt_size; |
| struct sock *sk = head->sk; |
| struct sk_buff *nskb; |
| int auth_len = 0; |
| |
| if (gso) { |
| skb_shinfo(head)->gso_type = sk->sk_gso_type; |
| NAPI_GRO_CB(head)->last = head; |
| } else { |
| nskb = head; |
| pkt_size = packet->size; |
| goto merge; |
| } |
| |
| do { |
| /* calculate the pkt_size and alloc nskb */ |
| pkt_size = packet->overhead; |
| list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, |
| list) { |
| int padded = SCTP_PAD4(chunk->skb->len); |
| |
| if (chunk == packet->auth) |
| auth_len = padded; |
| else if (auth_len + padded + packet->overhead > |
| tp->pathmtu) |
| return 0; |
| else if (pkt_size + padded > tp->pathmtu) |
| break; |
| pkt_size += padded; |
| } |
| nskb = alloc_skb(pkt_size + MAX_HEADER, gfp); |
| if (!nskb) |
| return 0; |
| skb_reserve(nskb, packet->overhead + MAX_HEADER); |
| |
| merge: |
| /* merge chunks into nskb and append nskb into head list */ |
| pkt_size -= packet->overhead; |
| list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
| int padding; |
| |
| list_del_init(&chunk->list); |
| if (sctp_chunk_is_data(chunk)) { |
| if (!sctp_chunk_retransmitted(chunk) && |
| !tp->rto_pending) { |
| chunk->rtt_in_progress = 1; |
| tp->rto_pending = 1; |
| } |
| } |
| |
| padding = SCTP_PAD4(chunk->skb->len) - chunk->skb->len; |
| if (padding) |
| memset(skb_put(chunk->skb, padding), 0, padding); |
| |
| if (chunk == packet->auth) |
| auth = (struct sctp_auth_chunk *) |
| skb_tail_pointer(nskb); |
| |
| memcpy(skb_put(nskb, chunk->skb->len), chunk->skb->data, |
| chunk->skb->len); |
| |
| pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n", |
| 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, |
| ntohs(chunk->chunk_hdr->length), chunk->skb->len, |
| chunk->rtt_in_progress); |
| |
| pkt_size -= SCTP_PAD4(chunk->skb->len); |
| |
| if (!sctp_chunk_is_data(chunk) && chunk != packet->auth) |
| sctp_chunk_free(chunk); |
| |
| if (!pkt_size) |
| break; |
| } |
| |
| if (auth) { |
| sctp_auth_calculate_hmac(tp->asoc, nskb, auth, gfp); |
| /* free auth if no more chunks, or add it back */ |
| if (list_empty(&packet->chunk_list)) |
| sctp_chunk_free(packet->auth); |
| else |
| list_add(&packet->auth->list, |
| &packet->chunk_list); |
| } |
| |
| if (gso) { |
| if (skb_gro_receive(&head, nskb)) { |
| kfree_skb(nskb); |
| return 0; |
| } |
| if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >= |
| sk->sk_gso_max_segs)) |
| return 0; |
| } |
| |
| pkt_count++; |
| } while (!list_empty(&packet->chunk_list)); |
| |
| if (gso) { |
| memset(head->cb, 0, max(sizeof(struct inet_skb_parm), |
| sizeof(struct inet6_skb_parm))); |
| skb_shinfo(head)->gso_segs = pkt_count; |
| skb_shinfo(head)->gso_size = GSO_BY_FRAGS; |
| rcu_read_lock(); |
| if (skb_dst(head) != tp->dst) { |
| dst_hold(tp->dst); |
| sk_setup_caps(sk, tp->dst); |
| } |
| rcu_read_unlock(); |
| goto chksum; |
| } |
| |
| if (sctp_checksum_disable) |
| return 1; |
| |
| if (!(skb_dst(head)->dev->features & NETIF_F_SCTP_CRC) || |
| dst_xfrm(skb_dst(head)) || packet->ipfragok) { |
| struct sctphdr *sh = |
| (struct sctphdr *)skb_transport_header(head); |
| |
| sh->checksum = sctp_compute_cksum(head, 0); |
| } else { |
| chksum: |
| head->ip_summed = CHECKSUM_PARTIAL; |
| head->csum_start = skb_transport_header(head) - head->head; |
| head->csum_offset = offsetof(struct sctphdr, checksum); |
| } |
| |
| return pkt_count; |
| } |
| |
| /* All packets are sent to the network through this function from |
| * sctp_outq_tail(). |
| * |
| * The return value is always 0 for now. |
| */ |
| int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp) |
| { |
| struct sctp_transport *tp = packet->transport; |
| struct sctp_association *asoc = tp->asoc; |
| struct sctp_chunk *chunk, *tmp; |
| int pkt_count, gso = 0; |
| struct dst_entry *dst; |
| struct sk_buff *head; |
| struct sctphdr *sh; |
| struct sock *sk; |
| |
| pr_debug("%s: packet:%p\n", __func__, packet); |
| if (list_empty(&packet->chunk_list)) |
| return 0; |
| chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); |
| sk = chunk->skb->sk; |
| |
| /* check gso */ |
| if (packet->size > tp->pathmtu && !packet->ipfragok) { |
| if (!sk_can_gso(sk)) { |
| pr_err_once("Trying to GSO but underlying device doesn't support it."); |
| goto out; |
| } |
| gso = 1; |
| } |
| |
| /* alloc head skb */ |
| head = alloc_skb((gso ? packet->overhead : packet->size) + |
| MAX_HEADER, gfp); |
| if (!head) |
| goto out; |
| skb_reserve(head, packet->overhead + MAX_HEADER); |
| sctp_packet_set_owner_w(head, sk); |
| |
| /* set sctp header */ |
| sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr)); |
| skb_reset_transport_header(head); |
| sh->source = htons(packet->source_port); |
| sh->dest = htons(packet->destination_port); |
| sh->vtag = htonl(packet->vtag); |
| sh->checksum = 0; |
| |
| /* update dst if in need */ |
| 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); |
| if (!dst) { |
| IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); |
| kfree_skb(head); |
| goto out; |
| } |
| skb_dst_set(head, dst); |
| |
| /* pack up chunks */ |
| pkt_count = sctp_packet_pack(packet, head, gso, gfp); |
| if (!pkt_count) { |
| kfree_skb(head); |
| goto out; |
| } |
| pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len); |
| |
| /* start autoclose timer */ |
| if (packet->has_data && sctp_state(asoc, ESTABLISHED) && |
| asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) { |
| struct timer_list *timer = |
| &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; |
| unsigned long timeout = |
| asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; |
| |
| if (!mod_timer(timer, jiffies + timeout)) |
| sctp_association_hold(asoc); |
| } |
| |
| /* sctp xmit */ |
| tp->af_specific->ecn_capable(sk); |
| if (asoc) { |
| asoc->stats.opackets += pkt_count; |
| if (asoc->peer.last_sent_to != tp) |
| asoc->peer.last_sent_to = tp; |
| } |
| head->ignore_df = packet->ipfragok; |
| tp->af_specific->sctp_xmit(head, tp); |
| |
| out: |
| 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); |
| } |
| sctp_packet_reset(packet); |
| return 0; |
| } |
| |
| /******************************************************************** |
| * 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) |
| { |
| 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 && inflight > 0) |
| /* We have (at least) one data chunk in flight, |
| * so we can't fall back to rule 6.1 B). |
| */ |
| return SCTP_XMIT_RWND_FULL; |
| |
| /* 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 && |
| flight_size >= transport->cwnd) |
| return SCTP_XMIT_RWND_FULL; |
| |
| /* 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) |
| /* Nagle disabled */ |
| return SCTP_XMIT_OK; |
| |
| if (!sctp_packet_empty(packet)) |
| /* Append to packet */ |
| return SCTP_XMIT_OK; |
| |
| if (inflight == 0) |
| /* Nothing unacked */ |
| return SCTP_XMIT_OK; |
| |
| if (!sctp_state(asoc, ESTABLISHED)) |
| return SCTP_XMIT_OK; |
| |
| /* Check whether this chunk and all the rest of pending data will fit |
| * or delay in hopes of bundling a full sized packet. |
| */ |
| if (chunk->skb->len + q->out_qlen > |
| transport->pathmtu - packet->overhead - sizeof(sctp_data_chunk_t) - 4) |
| /* Enough data queued to fill a packet */ |
| return SCTP_XMIT_OK; |
| |
| /* Don't delay large message writes that may have been fragmented */ |
| if (!chunk->msg->can_delay) |
| return SCTP_XMIT_OK; |
| |
| /* Defer until all data acked or packet full */ |
| return SCTP_XMIT_DELAY; |
| } |
| |
| /* 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; |
| 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, pmtu, maxsize; |
| sctp_xmit_t retval = SCTP_XMIT_OK; |
| |
| psize = packet->size; |
| if (packet->transport->asoc) |
| pmtu = packet->transport->asoc->pathmtu; |
| else |
| pmtu = packet->transport->pathmtu; |
| |
| /* Decide if we need to fragment or resubmit later. */ |
| if (psize + chunk_len > pmtu) { |
| /* It's OK to fragment 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 packet doesn't have any data in it yet and data |
| * requires authentication. |
| */ |
| if (sctp_packet_empty(packet) || |
| (!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; |
| goto out; |
| } |
| |
| /* Similarly, if this chunk was built before a PMTU |
| * reduction, we have to fragment it at IP level now. So |
| * if the packet already contains something, we need to |
| * flush. |
| */ |
| maxsize = pmtu - packet->overhead; |
| if (packet->auth) |
| maxsize -= SCTP_PAD4(packet->auth->skb->len); |
| if (chunk_len > maxsize) |
| retval = SCTP_XMIT_PMTU_FULL; |
| |
| /* It is also okay to fragment if the chunk we are |
| * adding is a control chunk, but only if current packet |
| * is not a GSO one otherwise it causes fragmentation of |
| * a large frame. So in this case we allow the |
| * fragmentation by forcing it to be in a new packet. |
| */ |
| if (!sctp_chunk_is_data(chunk) && packet->has_data) |
| retval = SCTP_XMIT_PMTU_FULL; |
| |
| if (psize + chunk_len > packet->max_size) |
| /* Hit GSO/PMTU limit, gotta flush */ |
| retval = SCTP_XMIT_PMTU_FULL; |
| |
| if (!packet->transport->burst_limited && |
| psize + chunk_len > (packet->transport->cwnd >> 1)) |
| /* Do not allow a single GSO packet to use more |
| * than half of cwnd. |
| */ |
| retval = SCTP_XMIT_PMTU_FULL; |
| |
| if (packet->transport->burst_limited && |
| psize + chunk_len > (packet->transport->burst_limited >> 1)) |
| /* Do not allow a single GSO packet to use more |
| * than half of original cwnd. |
| */ |
| retval = SCTP_XMIT_PMTU_FULL; |
| /* Otherwise it will fit in the GSO packet */ |
| } |
| |
| out: |
| return retval; |
| } |