--- /dev/null
+/* 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.
+ */
+struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
+ __u32 vtag, int ecn_capable)
+{
+ struct sctp_chunk *chunk = NULL;
+
+ pr_debug("%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;
+
+ 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;
+
+ return packet;
+}
+
+/* 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)
+{
+ sctp_xmit_t retval;
+ int error = 0;
+
+ pr_debug("%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_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;
+
+ 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);
+}
+
+/* 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;
+ unsigned char *auth = NULL; /* pointer to auth in skb data */
+
+ pr_debug("%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 + MAX_HEADER, GFP_ATOMIC);
+ if (!nskb)
+ goto nomem;
+
+ /* Make sure the outbound skb has enough header room reserved. */
+ skb_reserve(nskb, packet->overhead + 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);
+ if (!dst)
+ goto no_route;
+ skb_dst_set(nskb, dst);
+
+ /* 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.]
+ */
+
+ pr_debug("***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 (!chunk->resent && !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);
+
+ 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);
+
+ /*
+ * 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) {
+ sh->checksum = sctp_compute_cksum(nskb, 0);
+ } 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->timeouts[SCTP_EVENT_TIMEOUT_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);
+ }
+ }
+
+ pr_debug("***sctp_transmit_packet*** skb->len:%d\n", nskb->len);
+
+ nskb->ignore_df = packet->ipfragok;
+ tp->af_specific->sctp_xmit(nskb, tp);
+
+out:
+ sctp_packet_reset(packet);
+ return err;
+no_route:
+ kfree_skb(nskb);
+
+ if (asoc)
+ IP_INC_STATS(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)
+{
+ 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)
+ /* 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;
+ /* 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;
+}
Code Review / kvmfornfv.git / blobdiff