path: root/net/sctp/output.c

/* 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.
 */
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 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 */
	packet->max_size = tp->pathmtu;
	if (!asoc)
		return;

	/* update dst or transport pathmtu if in need */
	sk = asoc->base.sk;
	if (!sctp_transport_dst_check(tp)) {
		sctp_transport_route(tp, NULL, sctp_sk(sk));
		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 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)
{
	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;
}

/* 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, gfp_t gfp)
{
	sctp_xmit_t 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