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-rw-r--r--net/sctp/output.c841
1 files changed, 841 insertions, 0 deletions
diff --git a/net/sctp/output.c b/net/sctp/output.c
new file mode 100644
index 000000000..1441eaf46
--- /dev/null
+++ b/net/sctp/output.c
@@ -0,0 +1,841 @@
+// 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_pmtu_check(tp)) {
+ if (asoc->param_flags & SPP_PMTUD_ENABLE)
+ 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) ? tp->dst->dev->gso_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 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);
+
+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;
+ 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_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 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);
+ 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 */
+ 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;
+ 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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 06:42:43 +0000