patch-2.4.23 linux-2.4.23/net/sctp/output.c

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diff -urN linux-2.4.22/net/sctp/output.c linux-2.4.23/net/sctp/output.c
@@ -0,0 +1,636 @@
+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 International Business Machines, Corp.
+ *
+ * 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 void sctp_packet_reset(struct sctp_packet *packet);
+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,
+				       sctp_packet_phandler_t *prepend_handler)
+{
+	int packet_empty = (packet->size == SCTP_IP_OVERHEAD);
+
+	packet->vtag = vtag;
+	packet->ecn_capable = ecn_capable;
+	packet->get_prepend_chunk = prepend_handler;
+	packet->has_cookie_echo = 0;
+	packet->has_sack = 0;
+	packet->ipfragok = 0;
+
+	/* We might need to call the prepend_handler right away.  */
+	if (packet_empty)
+		sctp_packet_reset(packet);
+	return packet;
+}
+
+/* Initialize the packet structure. */
+struct sctp_packet *sctp_packet_init(struct sctp_packet *packet,
+				     struct sctp_transport *transport,
+				     __u16 sport, __u16 dport)
+{
+	packet->transport = transport;
+	packet->source_port = sport;
+	packet->destination_port = dport;
+	skb_queue_head_init(&packet->chunks);
+	packet->vtag = 0;
+	packet->ecn_capable = 0;
+	packet->get_prepend_chunk = NULL;
+	packet->has_cookie_echo = 0;
+	packet->has_sack = 0;
+	packet->ipfragok = 0;
+	packet->malloced = 0;
+	sctp_packet_reset(packet);
+	return packet;
+}
+
+/* Free a packet.  */
+void sctp_packet_free(struct sctp_packet *packet)
+{
+	struct sctp_chunk *chunk;
+
+        while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)))
+		sctp_free_chunk(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;
+
+	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->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_MUST_FRAG:
+	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;
+
+	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) {
+		int packet_empty = (packet->size == SCTP_IP_OVERHEAD);
+
+		/* Both control chunks and data chunks with TSNs are
+		 * non-fragmentable.
+		 */
+		int fragmentable = sctp_chunk_is_data(chunk) &&
+			(!chunk->has_tsn);
+		if (packet_empty) {
+			if (fragmentable) {
+				retval = SCTP_XMIT_MUST_FRAG;
+				goto finish;
+			} else {
+				/* The packet is too big but we can
+				 * not fragment it--we have to just
+				 * transmit and rely on IP
+				 * fragmentation.
+				 */
+				packet->ipfragok = 1;
+				goto append;
+			}
+		} else { /* !packet_empty */
+			retval = SCTP_XMIT_PMTU_FULL;
+			goto finish;
+		}
+	} else {
+		/* The chunk fits in the packet.  */
+		goto append;
+	}
+
+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;
+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;
+
+	/* Do NOT generate a chunkless packet... */
+	if (skb_queue_empty(&packet->chunks))
+		return err;
+
+	/* Set up convenience variables... */
+	chunk = (struct sctp_chunk *) (packet->chunks.next);
+	sk = chunk->skb->sk;
+
+	/* Allocate the new skb.  */
+	nskb = dev_alloc_skb(packet->size);
+	if (!nskb) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	/* Make sure the outbound skb has enough header room reserved. */
+	skb_reserve(nskb, SCTP_IP_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))) {
+		chunk->num_times_sent++;
+		chunk->sent_at = jiffies;
+		if (sctp_chunk_is_data(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 ((1 == chunk->num_times_sent) &&
+			    (!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);      
+
+		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, "
+				  "%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,
+				  "num_times_sent", chunk->num_times_sent,
+				  "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_free_chunk(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."
+	 *
+	 * If ECN capable && negotiated && it makes sense for
+	 * this packet to support it (e.g. post ECN negotiation)
+	 * then lets set the ECT bit
+	 *
+	 * FIXME:  Need to do something else for IPv6
+	 */
+	if (packet->ecn_capable) {
+		INET_ECN_xmit(nskb->sk);
+	} else {
+		INET_ECN_dontxmit(nskb->sk);
+	}
+
+	/* Set up the IP options.  */
+	/* BUG: not implemented
+	 * For v4 this all lives somewhere in 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_ESTABLISHED == asoc->state) &&
+		    (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 length %d\n",
+			  nskb->len);
+	(*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok);
+out:
+	packet->size = SCTP_IP_OVERHEAD;
+	return err;
+no_route:
+	kfree_skb(nskb);
+	IP_INC_STATS_BH(IpOutNoRoutes);
+
+	/* 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; */
+	goto out;
+}
+
+/********************************************************************
+ * 2nd Level Abstractions
+ ********************************************************************/
+
+/*
+ * This private function resets the packet to a fresh state.
+ */
+static void sctp_packet_reset(struct sctp_packet *packet)
+{
+	struct sctp_chunk *chunk = NULL;
+
+	packet->size = SCTP_IP_OVERHEAD;
+
+	if (packet->get_prepend_chunk)
+		chunk = packet->get_prepend_chunk(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);
+}
+
+/* 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_opt *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_IP_OVERHEAD == packet->size &&
+	    q->outstanding_bytes && SCTP_STATE_ESTABLISHED == asoc->state) {
+		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 - SCTP_IP_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;
+
+finish:
+	return retval;
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)