diff options
Diffstat (limited to 'net/sctp/output.c')
| -rw-r--r-- | net/sctp/output.c | 865 |
1 files changed, 865 insertions, 0 deletions
diff --git a/net/sctp/output.c b/net/sctp/output.c new file mode 100644 index 0000000000..a63df055ac --- /dev/null +++ b/net/sctp/output.c @@ -0,0 +1,865 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* 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. + * + * 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 enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet, + struct sctp_chunk *chunk); +static enum sctp_xmit 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 enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet, + struct sctp_chunk *chunk, + u16 chunk_len); + +static void sctp_packet_reset(struct sctp_packet *packet) +{ + /* sctp_packet_transmit() relies on this to reset size to the + * current overhead after sending packets. + */ + 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; + struct sctp_sock *sp = NULL; + struct sock *sk; + + pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag); + packet->vtag = vtag; + + /* do the following jobs only once for a flush schedule */ + if (!sctp_packet_empty(packet)) + return; + + /* set packet max_size with pathmtu, then calculate overhead */ + packet->max_size = tp->pathmtu; + + if (asoc) { + sk = asoc->base.sk; + sp = sctp_sk(sk); + } + packet->overhead = sctp_mtu_payload(sp, 0, 0); + packet->size = packet->overhead; + + if (!asoc) + return; + + /* update dst or transport pathmtu if in need */ + if (!sctp_transport_dst_check(tp)) { + sctp_transport_route(tp, NULL, sp); + if (asoc->param_flags & SPP_PMTUD_ENABLE) + sctp_assoc_sync_pmtu(asoc); + } else if (!sctp_transport_pl_enabled(tp) && + asoc->param_flags & SPP_PMTUD_ENABLE) { + if (!sctp_transport_pmtu_check(tp)) + sctp_assoc_sync_pmtu(asoc); + } + + if (asoc->pmtu_pending) { + if (asoc->param_flags & SPP_PMTUD_ENABLE) + sctp_assoc_sync_pmtu(asoc); + asoc->pmtu_pending = 0; + } + + /* If there a is a prepend chunk stick it on the list before + * any other chunks get appended. + */ + if (ecn_capable) { + struct sctp_chunk *chunk = sctp_get_ecne_prepend(asoc); + + if (chunk) + sctp_packet_append_chunk(packet, chunk); + } + + if (!tp->dst) + return; + + /* set packet max_size with gso_max_size if gso is enabled*/ + rcu_read_lock(); + if (__sk_dst_get(sk) != tp->dst) { + dst_hold(tp->dst); + sk_setup_caps(sk, tp->dst); + } + packet->max_size = sk_can_gso(sk) ? min(READ_ONCE(tp->dst->dev->gso_max_size), + GSO_LEGACY_MAX_SIZE) + : asoc->pathmtu; + rcu_read_unlock(); +} + +/* Initialize the packet structure. */ +void sctp_packet_init(struct sctp_packet *packet, + struct sctp_transport *transport, + __u16 sport, __u16 dport) +{ + 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); + /* The overhead will be calculated by sctp_packet_config() */ + packet->overhead = 0; + 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. + */ +enum sctp_xmit sctp_packet_transmit_chunk(struct sctp_packet *packet, + struct sctp_chunk *chunk, + int one_packet, gfp_t gfp) +{ + enum sctp_xmit 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 a pad chunk into a packet with a heartbeat chunk for PLPMTUTD probe */ +static enum sctp_xmit sctp_packet_bundle_pad(struct sctp_packet *pkt, struct sctp_chunk *chunk) +{ + struct sctp_transport *t = pkt->transport; + struct sctp_chunk *pad; + int overhead = 0; + + if (!chunk->pmtu_probe) + return SCTP_XMIT_OK; + + /* calculate the Padding Data size for the pad chunk */ + overhead += sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr); + overhead += sizeof(struct sctp_sender_hb_info) + sizeof(struct sctp_pad_chunk); + pad = sctp_make_pad(t->asoc, t->pl.probe_size - overhead); + if (!pad) + return SCTP_XMIT_DELAY; + + list_add_tail(&pad->list, &pkt->chunk_list); + pkt->size += SCTP_PAD4(ntohs(pad->chunk_hdr->length)); + chunk->transport = t; + + return SCTP_XMIT_OK; +} + +/* Try to bundle an auth chunk into the packet. */ +static enum sctp_xmit sctp_packet_bundle_auth(struct sctp_packet *pkt, + struct sctp_chunk *chunk) +{ + struct sctp_association *asoc = pkt->transport->asoc; + enum sctp_xmit retval = SCTP_XMIT_OK; + struct sctp_chunk *auth; + + /* 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, chunk->shkey->key_id); + if (!auth) + return retval; + + auth->shkey = chunk->shkey; + sctp_auth_shkey_hold(auth->shkey); + + 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 enum sctp_xmit sctp_packet_bundle_sack(struct sctp_packet *pkt, + struct sctp_chunk *chunk) +{ + enum sctp_xmit 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; + } + SCTP_INC_STATS(asoc->base.net, + SCTP_MIB_OUTCTRLCHUNKS); + asoc->stats.octrlchunks++; + 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 enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet, + struct sctp_chunk *chunk) +{ + __u16 chunk_len = SCTP_PAD4(ntohs(chunk->chunk_hdr->length)); + enum sctp_xmit retval = SCTP_XMIT_OK; + + /* 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: + case SCTP_CID_I_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. + */ +enum sctp_xmit sctp_packet_append_chunk(struct sctp_packet *packet, + struct sctp_chunk *chunk) +{ + enum sctp_xmit 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); + if (retval != SCTP_XMIT_OK) + goto finish; + + retval = sctp_packet_bundle_pad(packet, chunk); + +finish: + return retval; +} + +static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb) +{ + if (SCTP_OUTPUT_CB(head)->last == head) + skb_shinfo(head)->frag_list = skb; + else + SCTP_OUTPUT_CB(head)->last->next = skb; + SCTP_OUTPUT_CB(head)->last = skb; + + head->truesize += skb->truesize; + head->data_len += skb->len; + head->len += skb->len; + refcount_add(skb->truesize, &head->sk->sk_wmem_alloc); + + __skb_header_release(skb); +} + +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; + SCTP_OUTPUT_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) + skb_put_zero(chunk->skb, padding); + + if (chunk == packet->auth) + auth = (struct sctp_auth_chunk *) + skb_tail_pointer(nskb); + + skb_put_data(nskb, 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, + packet->auth->shkey, 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) + sctp_packet_gso_append(head, nskb); + + 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; + goto chksum; + } + + if (sctp_checksum_disable) + return 1; + + if (!(tp->dst->dev->features & NETIF_F_SCTP_CRC) || + dst_xfrm(tp->dst) || packet->ipfragok || tp->encap_port) { + 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_not_inet = 1; + 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 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; + + if (packet->size > tp->pathmtu && !packet->ipfragok && !chunk->pmtu_probe) { + if (tp->pl.state == SCTP_PL_ERROR) { /* do IP fragmentation if in Error state */ + packet->ipfragok = 1; + } else { + if (!sk_can_gso(sk)) { /* check gso */ + 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); + skb_set_owner_w(head, sk); + + /* set sctp header */ + sh = 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; + + /* drop packet if no dst */ + if (!tp->dst) { + IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); + kfree_skb(head); + goto out; + } + + /* 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; + if (tp->dst_pending_confirm) + skb_set_dst_pending_confirm(head, 1); + /* neighbour should be confirmed on successful transmission or + * positive error + */ + if (tp->af_specific->sctp_xmit(head, tp) >= 0 && + tp->dst_pending_confirm) + tp->dst_pending_confirm = 0; + +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 enum sctp_xmit 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 || inflight == 0) && + !asoc->force_delay) + /* Nothing unacked */ + return SCTP_XMIT_OK; + + if (!sctp_packet_empty(packet)) + /* Append to packet */ + 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 - sctp_datachk_len(&chunk->asoc->stream) - 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); + asoc->stream.si->assign_number(chunk); +} + +static enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet, + struct sctp_chunk *chunk, + u16 chunk_len) +{ + enum sctp_xmit retval = SCTP_XMIT_OK; + size_t psize, pmtu, maxsize; + + /* Don't bundle in this packet if this chunk's auth key doesn't + * match other chunks already enqueued on this packet. Also, + * don't bundle the chunk with auth key if other chunks in this + * packet don't have auth key. + */ + if ((packet->auth && chunk->shkey != packet->auth->shkey) || + (!packet->auth && chunk->shkey && + chunk->chunk_hdr->type != SCTP_CID_AUTH)) + return SCTP_XMIT_PMTU_FULL; + + 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; +} |