1 files changed, 646 insertions, 0 deletions

diff --git a/net/sctp/output.c b/net/sctp/output.c
new file mode 100644
index 000000000000..9013f64f5219
--- /dev/null
+++ b/net/sctp/output.c
@@ -0,0 +1,646 @@
+/* SCTP kernel reference 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 reference Implementation
+ *
+ * These functions handle output processing.
+ *
+ * The SCTP reference 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.
+ *
+ * The SCTP reference implementation is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ *                 ************************
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU CC; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <lksctp-developers@lists.sourceforge.net>
+ *
+ * Or submit a bug report through the following website:
+ *    http://www.sf.net/projects/lksctp
+ *
+ * Written or modified by:
+ *    La Monte H.P. Yarroll <piggy@acm.org>
+ *    Karl Knutson          <karl@athena.chicago.il.us>
+ *    Jon Grimm             <jgrimm@austin.ibm.com>
+ *    Sridhar Samudrala     <sri@us.ibm.com>
+ *
+ * Any bugs reported given to us we will try to fix... any fixes shared will
+ * be incorporated into the next SCTP release.
+ */
+
+#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 <net/inet_ecn.h>
+#include <net/icmp.h>
+
+#ifndef TEST_FRAME
+#include <net/tcp.h>
+#endif /* TEST_FRAME (not defined) */
+
+#include <linux/socket.h> /* for sa_family_t */
+#include <net/sock.h>
+
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+
+/* Forward declarations for private helpers. */
+static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet,
+                                           struct sctp_chunk *chunk);
+
+/* Config a packet.
+ * This appears to be a followup set of initializations.
+ */
+struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
+                                       __u32 vtag, int ecn_capable)
+{
+        struct sctp_chunk *chunk = NULL;
+
+        SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __FUNCTION__,
+                          packet, vtag);
+
+        packet->vtag = vtag;
+        packet->has_cookie_echo = 0;
+        packet->has_sack = 0;
+        packet->ipfragok = 0;
+
+        if (ecn_capable && sctp_packet_empty(packet)) {
+                chunk = sctp_get_ecne_prepend(packet->transport->asoc);
+
+                /* If there a is a prepend chunk stick it on the list before
+                 * any other chunks get appended.
+                 */
+                if (chunk)
+                        sctp_packet_append_chunk(packet, chunk);
+        }
+
+        return packet;
+}
+
+/* Initialize the packet structure. */
+struct sctp_packet *sctp_packet_init(struct sctp_packet *packet,
+                                     struct sctp_transport *transport,
+                                     __u16 sport, __u16 dport)
+{
+        struct sctp_association *asoc = transport->asoc;
+        size_t overhead;
+
+        SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __FUNCTION__,
+                          packet, transport);
+
+        packet->transport = transport;
+        packet->source_port = sport;
+        packet->destination_port = dport;
+        skb_queue_head_init(&packet->chunks);
+        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;
+        packet->size = overhead;
+        packet->vtag = 0;
+        packet->has_cookie_echo = 0;
+        packet->has_sack = 0;
+        packet->ipfragok = 0;
+        packet->malloced = 0;
+        return packet;
+}
+
+/* Free a packet.  */
+void sctp_packet_free(struct sctp_packet *packet)
+{
+        struct sctp_chunk *chunk;
+
+        SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet);
+
+        while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL)
+                sctp_chunk_free(chunk);
+
+        if (packet->malloced)
+                kfree(packet);
+}
+
+/* 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)
+{
+        sctp_xmit_t retval;
+        int error = 0;
+
+        SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __FUNCTION__,
+                          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.
+                         */
+                        retval = sctp_packet_append_chunk(packet, chunk);
+                }
+                break;
+
+        case SCTP_XMIT_RWND_FULL:
+        case SCTP_XMIT_OK:
+        case SCTP_XMIT_NAGLE_DELAY:
+                break;
+        };
+
+        return retval;
+}
+
+/* Try to bundle 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;
+                asoc = pkt->transport->asoc;
+
+                if (asoc->a_rwnd > asoc->rwnd) {
+                        struct sctp_chunk *sack;
+                        asoc->a_rwnd = asoc->rwnd;
+                        sack = sctp_make_sack(asoc);
+                        if (sack) {
+                                struct timer_list *timer;
+                                retval = sctp_packet_append_chunk(pkt, sack);
+                                asoc->peer.sack_needed = 0;
+                                timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
+                                if (timer_pending(timer) && del_timer(timer))
+                                        sctp_association_put(asoc);
+                        }
+                }
+        }
+        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;
+        __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length));
+        size_t psize;
+        size_t pmtu;
+        int too_big;
+
+        SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __FUNCTION__, packet,
+                          chunk);
+
+        retval = sctp_packet_bundle_sack(packet, chunk);
+        psize = packet->size;
+
+        if (retval != SCTP_XMIT_OK)
+                goto finish;
+
+        pmtu  = ((packet->transport->asoc) ?
+                 (packet->transport->asoc->pmtu) :
+                 (packet->transport->pmtu));
+
+        too_big = (psize + chunk_len > pmtu);
+
+        /* Decide if we need to fragment or resubmit later. */
+        if (too_big) {
+                /* Both control chunks and data chunks with TSNs are
+                 * non-fragmentable.
+                 */
+                if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk)) {
+                        /* We no longer do re-fragmentation.
+                         * Just fragment at the IP layer, if we
+                         * actually hit this condition
+                         */
+                        packet->ipfragok = 1;
+                        goto append;
+
+                } else {
+                        retval = SCTP_XMIT_PMTU_FULL;
+                        goto finish;
+                }
+        }
+
+append:
+        /* We believe that this chunk is OK to add to the packet (as
+         * long as we have the cwnd for it).
+         */
+
+        /* DATA is a special case since we must examine both rwnd and cwnd
+         * before we send DATA.
+         */
+        if (sctp_chunk_is_data(chunk)) {
+                retval = sctp_packet_append_data(packet, chunk);
+                /* Disallow SACK bundling after DATA. */
+                packet->has_sack = 1;
+                if (SCTP_XMIT_OK != retval)
+                        goto finish;
+        } else if (SCTP_CID_COOKIE_ECHO == chunk->chunk_hdr->type)
+                packet->has_cookie_echo = 1;
+        else if (SCTP_CID_SACK == chunk->chunk_hdr->type)
+                packet->has_sack = 1;
+
+        /* It is OK to send this chunk.  */
+        __skb_queue_tail(&packet->chunks, (struct sk_buff *)chunk);
+        packet->size += chunk_len;
+        chunk->transport = packet->transport;
+finish:
+        return retval;
+}
+
+/* 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;
+        __u32 crc32;
+        struct sk_buff *nskb;
+        struct sctp_chunk *chunk;
+        struct sock *sk;
+        int err = 0;
+        int padding;            /* How much padding do we need?  */
+        __u8 has_data = 0;
+        struct dst_entry *dst;
+
+        SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet);
+
+        /* Do NOT generate a chunkless packet. */
+        chunk = (struct sctp_chunk *)skb_peek(&packet->chunks);
+        if (unlikely(!chunk))
+                return err;
+
+        /* Set up convenience variables... */
+        sk = chunk->skb->sk;
+
+        /* Allocate the new skb.  */
+        nskb = dev_alloc_skb(packet->size);
+        if (!nskb)
+                goto nomem;
+
+        /* Make sure the outbound skb has enough header room reserved. */
+        skb_reserve(nskb, packet->overhead);
+
+        /* Set the owning socket so that we know where to get the
+         * destination IP address.
+         */
+        skb_set_owner_w(nskb, sk);
+
+        /* Build the SCTP header.  */
+        sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
+        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;
+
+        /* 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>.
+         */
+        crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr));
+
+        /**
+         * 6.10 Bundling
+         *
+         *    An endpoint bundles chunks by simply including multiple
+         *    chunks in one outbound SCTP packet.  ...
+         */
+
+        /**
+         * 3.2  Chunk Field Descriptions
+         *
+         * The total length of a chunk (including Type, Length and
+         * Value fields) MUST be a multiple of 4 bytes.  If the length
+         * of the chunk is not a multiple of 4 bytes, the sender MUST
+         * pad the chunk with all zero bytes and this padding is not
+         * included in the chunk length field.  The sender should
+         * never pad with more than 3 bytes.
+         *
+         * [This whole comment explains WORD_ROUND() below.]
+         */
+        SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n");
+        while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) {
+                if (sctp_chunk_is_data(chunk)) {
+
+                        if (!chunk->has_tsn) {
+                                sctp_chunk_assign_ssn(chunk);
+                                sctp_chunk_assign_tsn(chunk);
+
+                        /* 6.3.1 C4) When data is in flight and when allowed
+                         * by rule C5, a new RTT measurement MUST be made each
+                         * round trip.  Furthermore, new RTT measurements
+                         * SHOULD be made no more than once per round-trip
+                         * for a given destination transport address.
+                         */
+
+                                if (!tp->rto_pending) {
+                                        chunk->rtt_in_progress = 1;
+                                        tp->rto_pending = 1;
+                                }
+                        } else
+                                chunk->resent = 1;
+
+                        chunk->sent_at = jiffies;
+                        has_data = 1;
+                }
+
+                padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
+                if (padding)
+                        memset(skb_put(chunk->skb, padding), 0, padding);
+
+                crc32 = sctp_update_copy_cksum(skb_put(nskb, chunk->skb->len),
+                                               chunk->skb->data,
+                                               chunk->skb->len, crc32);
+
+                SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
+                                  "*** Chunk", chunk,
+                                  sctp_cname(SCTP_ST_CHUNK(
+                                          chunk->chunk_hdr->type)),
+                                  chunk->has_tsn ? "TSN" : "No TSN",
+                                  chunk->has_tsn ?
+                                  ntohl(chunk->subh.data_hdr->tsn) : 0,
+                                  "length", ntohs(chunk->chunk_hdr->length),
+                                  "chunk->skb->len", chunk->skb->len,
+                                  "rtt_in_progress", chunk->rtt_in_progress);
+
+                /*
+                 * If this is a control chunk, this is our last
+                 * reference. Free data chunks after they've been
+                 * acknowledged or have failed.
+                 */
+                if (!sctp_chunk_is_data(chunk))
+                        sctp_chunk_free(chunk);
+        }
+
+        /* Perform final transformation on checksum. */
+        crc32 = sctp_end_cksum(crc32);
+
+        /* 3) Put the resultant value into the checksum field in the
+         *    common header, and leave the rest of the bits unchanged.
+         */
+        sh->checksum = htonl(crc32);
+
+        /* 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().
+         */
+        INET_ECN_xmit(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->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;
+
+                tp->last_time_used = jiffies;
+
+                /* Restart the AUTOCLOSE timer when sending data. */
+                if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) {
+                        timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
+                        timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
+
+                        if (!mod_timer(timer, jiffies + timeout))
+                                sctp_association_hold(asoc);
+                }
+        }
+
+        dst = tp->dst;
+        /* The 'obsolete' field of dst is set to 2 when a dst is freed. */
+        if (!dst || (dst->obsolete > 1)) {
+                dst_release(dst);
+                sctp_transport_route(tp, NULL, sctp_sk(sk));
+                sctp_assoc_sync_pmtu(asoc);
+        }
+
+        nskb->dst = dst_clone(tp->dst);
+        if (!nskb->dst)
+                goto no_route;
+
+        SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
+                          nskb->len);
+
+        (*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok);
+
+out:
+        packet->size = packet->overhead;
+        return err;
+no_route:
+        kfree_skb(nskb);
+        IP_INC_STATS_BH(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.
+         */
+
+        while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) {
+                if (!sctp_chunk_is_data(chunk))
+                        sctp_chunk_free(chunk);
+        }
+        goto out;
+nomem:
+        err = -ENOMEM;
+        goto err;
+}
+
+/********************************************************************
+ * 2nd Level Abstractions
+ ********************************************************************/
+
+/* This private function handles the specifics of appending DATA chunks.  */
+static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet,
+                                           struct sctp_chunk *chunk)
+{
+        sctp_xmit_t retval = SCTP_XMIT_OK;
+        size_t datasize, rwnd, inflight;
+        struct sctp_transport *transport = packet->transport;
+        __u32 max_burst_bytes;
+        struct sctp_association *asoc = transport->asoc;
+        struct sctp_sock *sp = sctp_sk(asoc->base.sk);
+        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 = asoc->outqueue.outstanding_bytes;
+
+        datasize = sctp_data_size(chunk);
+
+        if (datasize > rwnd) {
+                if (inflight > 0) {
+                        /* We have (at least) one data chunk in flight,
+                         * so we can't fall back to rule 6.1 B).
+                         */
+                        retval = SCTP_XMIT_RWND_FULL;
+                        goto finish;
+                }
+        }
+
+        /* sctpimpguide-05 2.14.2
+         * D) When the time comes for the sender to
+         * transmit new DATA chunks, the protocol parameter Max.Burst MUST
+         * first be applied to limit how many new DATA chunks may be sent.
+         * The limit is applied by adjusting cwnd as follows:
+         *      if ((flightsize + Max.Burst * MTU) < cwnd)
+         *              cwnd = flightsize + Max.Burst * MTU
+         */
+        max_burst_bytes = asoc->max_burst * asoc->pmtu;
+        if ((transport->flight_size + max_burst_bytes) < transport->cwnd) {
+                transport->cwnd = transport->flight_size + max_burst_bytes;
+                SCTP_DEBUG_PRINTK("%s: cwnd limited by max_burst: "
+                                  "transport: %p, cwnd: %d, "
+                                  "ssthresh: %d, flight_size: %d, "
+                                  "pba: %d\n",
+                                  __FUNCTION__, transport,
+                                  transport->cwnd,
+                                  transport->ssthresh,
+                                  transport->flight_size,
+                                  transport->partial_bytes_acked);
+        }
+
+        /* 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)
+                if (transport->flight_size >= transport->cwnd) {
+                        retval = SCTP_XMIT_RWND_FULL;
+                        goto finish;
+                }
+
+        /* Nagle's algorithm to solve small-packet problem:
+         * Inhibit the sending of new chunks when new outgoing data arrives
+         * if any previously transmitted data on the connection remains
+         * unacknowledged.
+         */
+        if (!sp->nodelay && sctp_packet_empty(packet) &&
+            q->outstanding_bytes && sctp_state(asoc, ESTABLISHED)) {
+                unsigned len = datasize + q->out_qlen;
+
+                /* Check whether this chunk and all the rest of pending
+                 * data will fit or delay in hopes of bundling a full
+                 * sized packet.
+                 */
+                if (len < asoc->pmtu - packet->overhead) {
+                        retval = SCTP_XMIT_NAGLE_DELAY;
+                        goto finish;
+                }
+        }
+
+        /* 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;
+
+finish:
+        return retval;
+}