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linux/net/sctp/associola.c

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/* SCTP kernel reference Implementation
* (C) Copyright IBM Corp. 2001, 2004
* Copyright (c) 1999-2000 Cisco, Inc.
* Copyright (c) 1999-2001 Motorola, Inc.
* Copyright (c) 2001 Intel Corp.
* Copyright (c) 2001 La Monte H.P. Yarroll
*
* This file is part of the SCTP kernel reference Implementation
*
* This module provides the abstraction for an SCTP association.
*
* 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@us.ibm.com>
* Xingang Guo <xingang.guo@intel.com>
* Hui Huang <hui.huang@nokia.com>
* Sridhar Samudrala <sri@us.ibm.com>
* Daisy Chang <daisyc@us.ibm.com>
* Ryan Layer <rmlayer@us.ibm.com>
* Kevin Gao <kevin.gao@intel.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/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <net/ipv6.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
/* Forward declarations for internal functions. */
static void sctp_assoc_bh_rcv(struct sctp_association *asoc);
/* 1st Level Abstractions. */
/* Initialize a new association from provided memory. */
static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
const struct sctp_endpoint *ep,
const struct sock *sk,
sctp_scope_t scope,
gfp_t gfp)
{
struct sctp_sock *sp;
int i;
/* Retrieve the SCTP per socket area. */
sp = sctp_sk((struct sock *)sk);
/* Init all variables to a known value. */
memset(asoc, 0, sizeof(struct sctp_association));
/* Discarding const is appropriate here. */
asoc->ep = (struct sctp_endpoint *)ep;
sctp_endpoint_hold(asoc->ep);
/* Hold the sock. */
asoc->base.sk = (struct sock *)sk;
sock_hold(asoc->base.sk);
/* Initialize the common base substructure. */
asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
/* Initialize the object handling fields. */
atomic_set(&asoc->base.refcnt, 1);
asoc->base.dead = 0;
asoc->base.malloced = 0;
/* Initialize the bind addr area. */
sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
rwlock_init(&asoc->base.addr_lock);
asoc->state = SCTP_STATE_CLOSED;
/* Set these values from the socket values, a conversion between
* millsecons to seconds/microseconds must also be done.
*/
asoc->cookie_life.tv_sec = sp->assocparams.sasoc_cookie_life / 1000;
asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)
* 1000;
asoc->frag_point = 0;
/* Set the association max_retrans and RTO values from the
* socket values.
*/
asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
asoc->overall_error_count = 0;
/* Initialize the association's heartbeat interval based on the
* sock configured value.
*/
asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
/* Initialize path max retrans value. */
asoc->pathmaxrxt = sp->pathmaxrxt;
/* Initialize default path MTU. */
asoc->pathmtu = sp->pathmtu;
/* Set association default SACK delay */
asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
/* Set the association default flags controlling
* Heartbeat, SACK delay, and Path MTU Discovery.
*/
asoc->param_flags = sp->param_flags;
/* Initialize the maximum mumber of new data packets that can be sent
* in a burst.
*/
asoc->max_burst = sctp_max_burst;
/* initialize association timers */
asoc->timeouts[SCTP_EVENT_TIMEOUT_NONE] = 0;
asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
asoc->timeouts[SCTP_EVENT_TIMEOUT_T3_RTX] = 0;
asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = 0;
/* sctpimpguide Section 2.12.2
* If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
* recommended value of 5 times 'RTO.Max'.
*/
asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
= 5 * asoc->rto_max;
asoc->timeouts[SCTP_EVENT_TIMEOUT_HEARTBEAT] = 0;
asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] =
sp->autoclose * HZ;
/* Initilizes the timers */
for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
init_timer(&asoc->timers[i]);
asoc->timers[i].function = sctp_timer_events[i];
asoc->timers[i].data = (unsigned long) asoc;
}
/* Pull default initialization values from the sock options.
* Note: This assumes that the values have already been
* validated in the sock.
*/
asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
asoc->c.sinit_num_ostreams = sp->initmsg.sinit_num_ostreams;
asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
asoc->max_init_timeo =
msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
/* Allocate storage for the ssnmap after the inbound and outbound
* streams have been negotiated during Init.
*/
asoc->ssnmap = NULL;
/* Set the local window size for receive.
* This is also the rcvbuf space per association.
* RFC 6 - A SCTP receiver MUST be able to receive a minimum of
* 1500 bytes in one SCTP packet.
*/
if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
else
asoc->rwnd = sk->sk_rcvbuf/2;
asoc->a_rwnd = asoc->rwnd;
asoc->rwnd_over = 0;
/* Use my own max window until I learn something better. */
asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
/* Set the sndbuf size for transmit. */
asoc->sndbuf_used = 0;
/* Initialize the receive memory counter */
atomic_set(&asoc->rmem_alloc, 0);
init_waitqueue_head(&asoc->wait);
asoc->c.my_vtag = sctp_generate_tag(ep);
asoc->peer.i.init_tag = 0; /* INIT needs a vtag of 0. */
asoc->c.peer_vtag = 0;
asoc->c.my_ttag = 0;
asoc->c.peer_ttag = 0;
asoc->c.my_port = ep->base.bind_addr.port;
asoc->c.initial_tsn = sctp_generate_tsn(ep);
asoc->next_tsn = asoc->c.initial_tsn;
asoc->ctsn_ack_point = asoc->next_tsn - 1;
asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
asoc->highest_sacked = asoc->ctsn_ack_point;
asoc->last_cwr_tsn = asoc->ctsn_ack_point;
asoc->unack_data = 0;
/* ADDIP Section 4.1 Asconf Chunk Procedures
*
* When an endpoint has an ASCONF signaled change to be sent to the
* remote endpoint it should do the following:
* ...
* A2) a serial number should be assigned to the chunk. The serial
* number SHOULD be a monotonically increasing number. The serial
* numbers SHOULD be initialized at the start of the
* association to the same value as the initial TSN.
*/
asoc->addip_serial = asoc->c.initial_tsn;
INIT_LIST_HEAD(&asoc->addip_chunk_list);
/* Make an empty list of remote transport addresses. */
INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
asoc->peer.transport_count = 0;
/* RFC 2960 5.1 Normal Establishment of an Association
*
* After the reception of the first data chunk in an
* association the endpoint must immediately respond with a
* sack to acknowledge the data chunk. Subsequent
* acknowledgements should be done as described in Section
* 6.2.
*
* [We implement this by telling a new association that it
* already received one packet.]
*/
asoc->peer.sack_needed = 1;
/* Assume that the peer recongizes ASCONF until reported otherwise
* via an ERROR chunk.
*/
asoc->peer.asconf_capable = 1;
/* Create an input queue. */
sctp_inq_init(&asoc->base.inqueue);
sctp_inq_set_th_handler(&asoc->base.inqueue,
(void (*)(void *))sctp_assoc_bh_rcv,
asoc);
/* Create an output queue. */
sctp_outq_init(asoc, &asoc->outqueue);
if (!sctp_ulpq_init(&asoc->ulpq, asoc))
goto fail_init;
/* Set up the tsn tracking. */
sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE, 0);
asoc->need_ecne = 0;
asoc->assoc_id = 0;
/* Assume that peer would support both address types unless we are
* told otherwise.
*/
asoc->peer.ipv4_address = 1;
asoc->peer.ipv6_address = 1;
INIT_LIST_HEAD(&asoc->asocs);
asoc->autoclose = sp->autoclose;
asoc->default_stream = sp->default_stream;
asoc->default_ppid = sp->default_ppid;
asoc->default_flags = sp->default_flags;
asoc->default_context = sp->default_context;
asoc->default_timetolive = sp->default_timetolive;
return asoc;
fail_init:
sctp_endpoint_put(asoc->ep);
sock_put(asoc->base.sk);
return NULL;
}
/* Allocate and initialize a new association */
struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
const struct sock *sk,
sctp_scope_t scope,
gfp_t gfp)
{
struct sctp_association *asoc;
asoc = t_new(struct sctp_association, gfp);
if (!asoc)
goto fail;
if (!sctp_association_init(asoc, ep, sk, scope, gfp))
goto fail_init;
asoc->base.malloced = 1;
SCTP_DBG_OBJCNT_INC(assoc);
SCTP_DEBUG_PRINTK("Created asoc %p\n", asoc);
return asoc;
fail_init:
kfree(asoc);
fail:
return NULL;
}
/* Free this association if possible. There may still be users, so
* the actual deallocation may be delayed.
*/
void sctp_association_free(struct sctp_association *asoc)
{
struct sock *sk = asoc->base.sk;
struct sctp_transport *transport;
struct list_head *pos, *temp;
int i;
list_del(&asoc->asocs);
/* Decrement the backlog value for a TCP-style listening socket. */
if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
sk->sk_ack_backlog--;
/* Mark as dead, so other users can know this structure is
* going away.
*/
asoc->base.dead = 1;
/* Dispose of any data lying around in the outqueue. */
sctp_outq_free(&asoc->outqueue);
/* Dispose of any pending messages for the upper layer. */
sctp_ulpq_free(&asoc->ulpq);
/* Dispose of any pending chunks on the inqueue. */
sctp_inq_free(&asoc->base.inqueue);
/* Free ssnmap storage. */
sctp_ssnmap_free(asoc->ssnmap);
/* Clean up the bound address list. */
sctp_bind_addr_free(&asoc->base.bind_addr);
/* Do we need to go through all of our timers and
* delete them? To be safe we will try to delete all, but we
* should be able to go through and make a guess based
* on our state.
*/
for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
if (timer_pending(&asoc->timers[i]) &&
del_timer(&asoc->timers[i]))
sctp_association_put(asoc);
}
/* Free peer's cached cookie. */
kfree(asoc->peer.cookie);
/* Release the transport structures. */
list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
transport = list_entry(pos, struct sctp_transport, transports);
list_del(pos);
sctp_transport_free(transport);
}
asoc->peer.transport_count = 0;
/* Free any cached ASCONF_ACK chunk. */
if (asoc->addip_last_asconf_ack)
sctp_chunk_free(asoc->addip_last_asconf_ack);
/* Free any cached ASCONF chunk. */
if (asoc->addip_last_asconf)
sctp_chunk_free(asoc->addip_last_asconf);
sctp_association_put(asoc);
}
/* Cleanup and free up an association. */
static void sctp_association_destroy(struct sctp_association *asoc)
{
SCTP_ASSERT(asoc->base.dead, "Assoc is not dead", return);
sctp_endpoint_put(asoc->ep);
sock_put(asoc->base.sk);
if (asoc->assoc_id != 0) {
spin_lock_bh(&sctp_assocs_id_lock);
idr_remove(&sctp_assocs_id, asoc->assoc_id);
spin_unlock_bh(&sctp_assocs_id_lock);
}
BUG_TRAP(!atomic_read(&asoc->rmem_alloc));
if (asoc->base.malloced) {
kfree(asoc);
SCTP_DBG_OBJCNT_DEC(assoc);
}
}
/* Change the primary destination address for the peer. */
void sctp_assoc_set_primary(struct sctp_association *asoc,
struct sctp_transport *transport)
{
asoc->peer.primary_path = transport;
/* Set a default msg_name for events. */
memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
sizeof(union sctp_addr));
/* If the primary path is changing, assume that the
* user wants to use this new path.
*/
if ((transport->state == SCTP_ACTIVE) ||
(transport->state == SCTP_UNKNOWN))
asoc->peer.active_path = transport;
/*
* SFR-CACC algorithm:
* Upon the receipt of a request to change the primary
* destination address, on the data structure for the new
* primary destination, the sender MUST do the following:
*
* 1) If CHANGEOVER_ACTIVE is set, then there was a switch
* to this destination address earlier. The sender MUST set
* CYCLING_CHANGEOVER to indicate that this switch is a
* double switch to the same destination address.
*/
if (transport->cacc.changeover_active)
transport->cacc.cycling_changeover = 1;
/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
* a changeover has occurred.
*/
transport->cacc.changeover_active = 1;
/* 3) The sender MUST store the next TSN to be sent in
* next_tsn_at_change.
*/
transport->cacc.next_tsn_at_change = asoc->next_tsn;
}
/* Remove a transport from an association. */
void sctp_assoc_rm_peer(struct sctp_association *asoc,
struct sctp_transport *peer)
{
struct list_head *pos;
struct sctp_transport *transport;
SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_rm_peer:association %p addr: ",
" port: %d\n",
asoc,
(&peer->ipaddr),
peer->ipaddr.v4.sin_port);
/* If we are to remove the current retran_path, update it
* to the next peer before removing this peer from the list.
*/
if (asoc->peer.retran_path == peer)
sctp_assoc_update_retran_path(asoc);
/* Remove this peer from the list. */
list_del(&peer->transports);
/* Get the first transport of asoc. */
pos = asoc->peer.transport_addr_list.next;
transport = list_entry(pos, struct sctp_transport, transports);
/* Update any entries that match the peer to be deleted. */
if (asoc->peer.primary_path == peer)
sctp_assoc_set_primary(asoc, transport);
if (asoc->peer.active_path == peer)
asoc->peer.active_path = transport;
if (asoc->peer.last_data_from == peer)
asoc->peer.last_data_from = transport;
/* If we remove the transport an INIT was last sent to, set it to
* NULL. Combined with the update of the retran path above, this
* will cause the next INIT to be sent to the next available
* transport, maintaining the cycle.
*/
if (asoc->init_last_sent_to == peer)
asoc->init_last_sent_to = NULL;
asoc->peer.transport_count--;
sctp_transport_free(peer);
}
/* Add a transport address to an association. */
struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
const union sctp_addr *addr,
const gfp_t gfp,
const int peer_state)
{
struct sctp_transport *peer;
struct sctp_sock *sp;
unsigned short port;
sp = sctp_sk(asoc->base.sk);
/* AF_INET and AF_INET6 share common port field. */
port = addr->v4.sin_port;
SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_add_peer:association %p addr: ",
" port: %d state:%d\n",
asoc,
addr,
addr->v4.sin_port,
peer_state);
/* Set the port if it has not been set yet. */
if (0 == asoc->peer.port)
asoc->peer.port = port;
/* Check to see if this is a duplicate. */
peer = sctp_assoc_lookup_paddr(asoc, addr);
if (peer) {
if (peer->state == SCTP_UNKNOWN) {
if (peer_state == SCTP_ACTIVE)
peer->state = SCTP_ACTIVE;
if (peer_state == SCTP_UNCONFIRMED)
peer->state = SCTP_UNCONFIRMED;
}
return peer;
}
peer = sctp_transport_new(addr, gfp);
if (!peer)
return NULL;
sctp_transport_set_owner(peer, asoc);
/* Initialize the peer's heartbeat interval based on the
* association configured value.
*/
peer->hbinterval = asoc->hbinterval;
/* Set the path max_retrans. */
peer->pathmaxrxt = asoc->pathmaxrxt;
/* Initialize the peer's SACK delay timeout based on the
* association configured value.
*/
peer->sackdelay = asoc->sackdelay;
/* Enable/disable heartbeat, SACK delay, and path MTU discovery
* based on association setting.
*/
peer->param_flags = asoc->param_flags;
/* Initialize the pmtu of the transport. */
if (peer->param_flags & SPP_PMTUD_ENABLE)
sctp_transport_pmtu(peer);
else if (asoc->pathmtu)
peer->pathmtu = asoc->pathmtu;
else
peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
/* If this is the first transport addr on this association,
* initialize the association PMTU to the peer's PMTU.
* If not and the current association PMTU is higher than the new
* peer's PMTU, reset the association PMTU to the new peer's PMTU.
*/
if (asoc->pathmtu)
asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
else
asoc->pathmtu = peer->pathmtu;
SCTP_DEBUG_PRINTK("sctp_assoc_add_peer:association %p PMTU set to "
"%d\n", asoc, asoc->pathmtu);
asoc->frag_point = sctp_frag_point(sp, asoc->pathmtu);
/* The asoc->peer.port might not be meaningful yet, but
* initialize the packet structure anyway.
*/
sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
asoc->peer.port);
/* 7.2.1 Slow-Start
*
* o The initial cwnd before DATA transmission or after a sufficiently
* long idle period MUST be set to
* min(4*MTU, max(2*MTU, 4380 bytes))
*
* o The initial value of ssthresh MAY be arbitrarily high
* (for example, implementations MAY use the size of the
* receiver advertised window).
*/
peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
/* At this point, we may not have the receiver's advertised window,
* so initialize ssthresh to the default value and it will be set
* later when we process the INIT.
*/
peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
peer->partial_bytes_acked = 0;
peer->flight_size = 0;
/* Set the transport's RTO.initial value */
peer->rto = asoc->rto_initial;
/* Set the peer's active state. */
peer->state = peer_state;
/* Attach the remote transport to our asoc. */
list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);
asoc->peer.transport_count++;
/* If we do not yet have a primary path, set one. */
if (!asoc->peer.primary_path) {
sctp_assoc_set_primary(asoc, peer);
asoc->peer.retran_path = peer;
}
if (asoc->peer.active_path == asoc->peer.retran_path) {
asoc->peer.retran_path = peer;
}
return peer;
}
/* Delete a transport address from an association. */
void sctp_assoc_del_peer(struct sctp_association *asoc,
const union sctp_addr *addr)
{
struct list_head *pos;
struct list_head *temp;
struct sctp_transport *transport;
list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
transport = list_entry(pos, struct sctp_transport, transports);
if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
/* Do book keeping for removing the peer and free it. */
sctp_assoc_rm_peer(asoc, transport);
break;
}
}
}
/* Lookup a transport by address. */
struct sctp_transport *sctp_assoc_lookup_paddr(
const struct sctp_association *asoc,
const union sctp_addr *address)
{
struct sctp_transport *t;
struct list_head *pos;
/* Cycle through all transports searching for a peer address. */
list_for_each(pos, &asoc->peer.transport_addr_list) {
t = list_entry(pos, struct sctp_transport, transports);
if (sctp_cmp_addr_exact(address, &t->ipaddr))
return t;
}
return NULL;
}
/* Engage in transport control operations.
* Mark the transport up or down and send a notification to the user.
* Select and update the new active and retran paths.
*/
void sctp_assoc_control_transport(struct sctp_association *asoc,
struct sctp_transport *transport,
sctp_transport_cmd_t command,
sctp_sn_error_t error)
{
struct sctp_transport *t = NULL;
struct sctp_transport *first;
struct sctp_transport *second;
struct sctp_ulpevent *event;
struct list_head *pos;
int spc_state = 0;
/* Record the transition on the transport. */
switch (command) {
case SCTP_TRANSPORT_UP:
transport->state = SCTP_ACTIVE;
spc_state = SCTP_ADDR_AVAILABLE;
break;
case SCTP_TRANSPORT_DOWN:
transport->state = SCTP_INACTIVE;
spc_state = SCTP_ADDR_UNREACHABLE;
break;
default:
return;
};
/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
* user.
*/
event = sctp_ulpevent_make_peer_addr_change(asoc,
(struct sockaddr_storage *) &transport->ipaddr,
0, spc_state, error, GFP_ATOMIC);
if (event)
sctp_ulpq_tail_event(&asoc->ulpq, event);
/* Select new active and retran paths. */
/* Look for the two most recently used active transports.
*
* This code produces the wrong ordering whenever jiffies
* rolls over, but we still get usable transports, so we don't
* worry about it.
*/
first = NULL; second = NULL;
list_for_each(pos, &asoc->peer.transport_addr_list) {
t = list_entry(pos, struct sctp_transport, transports);
if ((t->state == SCTP_INACTIVE) ||
(t->state == SCTP_UNCONFIRMED))
continue;
if (!first || t->last_time_heard > first->last_time_heard) {
second = first;
first = t;
}
if (!second || t->last_time_heard > second->last_time_heard)
second = t;
}
/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
*
* By default, an endpoint should always transmit to the
* primary path, unless the SCTP user explicitly specifies the
* destination transport address (and possibly source
* transport address) to use.
*
* [If the primary is active but not most recent, bump the most
* recently used transport.]
*/
if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
(asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&
first != asoc->peer.primary_path) {
second = first;
first = asoc->peer.primary_path;
}
/* If we failed to find a usable transport, just camp on the
* primary, even if it is inactive.
*/
if (!first) {
first = asoc->peer.primary_path;
second = asoc->peer.primary_path;
}
/* Set the active and retran transports. */
asoc->peer.active_path = first;
asoc->peer.retran_path = second;
}
/* Hold a reference to an association. */
void sctp_association_hold(struct sctp_association *asoc)
{
atomic_inc(&asoc->base.refcnt);
}
/* Release a reference to an association and cleanup
* if there are no more references.
*/
void sctp_association_put(struct sctp_association *asoc)
{
if (atomic_dec_and_test(&asoc->base.refcnt))
sctp_association_destroy(asoc);
}
/* Allocate the next TSN, Transmission Sequence Number, for the given
* association.
*/
__u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
{
/* From Section 1.6 Serial Number Arithmetic:
* Transmission Sequence Numbers wrap around when they reach
* 2**32 - 1. That is, the next TSN a DATA chunk MUST use
* after transmitting TSN = 2*32 - 1 is TSN = 0.
*/
__u32 retval = asoc->next_tsn;
asoc->next_tsn++;
asoc->unack_data++;
return retval;
}
/* Compare two addresses to see if they match. Wildcard addresses
* only match themselves.
*/
int sctp_cmp_addr_exact(const union sctp_addr *ss1,
const union sctp_addr *ss2)
{
struct sctp_af *af;
af = sctp_get_af_specific(ss1->sa.sa_family);
if (unlikely(!af))
return 0;
return af->cmp_addr(ss1, ss2);
}
/* Return an ecne chunk to get prepended to a packet.
* Note: We are sly and return a shared, prealloced chunk. FIXME:
* No we don't, but we could/should.
*/
struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
{
struct sctp_chunk *chunk;
/* Send ECNE if needed.
* Not being able to allocate a chunk here is not deadly.
*/
if (asoc->need_ecne)
chunk = sctp_make_ecne(asoc, asoc->last_ecne_tsn);
else
chunk = NULL;
return chunk;
}
/*
* Find which transport this TSN was sent on.
*/
struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
__u32 tsn)
{
struct sctp_transport *active;
struct sctp_transport *match;
struct list_head *entry, *pos;
struct sctp_transport *transport;
struct sctp_chunk *chunk;
__u32 key = htonl(tsn);
match = NULL;
/*
* FIXME: In general, find a more efficient data structure for
* searching.
*/
/*
* The general strategy is to search each transport's transmitted
* list. Return which transport this TSN lives on.
*
* Let's be hopeful and check the active_path first.
* Another optimization would be to know if there is only one
* outbound path and not have to look for the TSN at all.
*
*/
active = asoc->peer.active_path;
list_for_each(entry, &active->transmitted) {
chunk = list_entry(entry, struct sctp_chunk, transmitted_list);
if (key == chunk->subh.data_hdr->tsn) {
match = active;
goto out;
}
}
/* If not found, go search all the other transports. */
list_for_each(pos, &asoc->peer.transport_addr_list) {
transport = list_entry(pos, struct sctp_transport, transports);
if (transport == active)
break;
list_for_each(entry, &transport->transmitted) {
chunk = list_entry(entry, struct sctp_chunk,
transmitted_list);
if (key == chunk->subh.data_hdr->tsn) {
match = transport;
goto out;
}
}
}
out:
return match;
}
/* Is this the association we are looking for? */
struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
const union sctp_addr *laddr,
const union sctp_addr *paddr)
{
struct sctp_transport *transport;
sctp_read_lock(&asoc->base.addr_lock);
if ((asoc->base.bind_addr.port == laddr->v4.sin_port) &&
(asoc->peer.port == paddr->v4.sin_port)) {
transport = sctp_assoc_lookup_paddr(asoc, paddr);
if (!transport)
goto out;
if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
sctp_sk(asoc->base.sk)))
goto out;
}
transport = NULL;
out:
sctp_read_unlock(&asoc->base.addr_lock);
return transport;
}
/* Do delayed input processing. This is scheduled by sctp_rcv(). */
static void sctp_assoc_bh_rcv(struct sctp_association *asoc)
{
struct sctp_endpoint *ep;
struct sctp_chunk *chunk;
struct sock *sk;
struct sctp_inq *inqueue;
int state;
sctp_subtype_t subtype;
int error = 0;
/* The association should be held so we should be safe. */
ep = asoc->ep;
sk = asoc->base.sk;
inqueue = &asoc->base.inqueue;
sctp_association_hold(asoc);
while (NULL != (chunk = sctp_inq_pop(inqueue))) {
state = asoc->state;
subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
/* Remember where the last DATA chunk came from so we
* know where to send the SACK.
*/
if (sctp_chunk_is_data(chunk))
asoc->peer.last_data_from = chunk->transport;
else
SCTP_INC_STATS(SCTP_MIB_INCTRLCHUNKS);
if (chunk->transport)
chunk->transport->last_time_heard = jiffies;
/* Run through the state machine. */
error = sctp_do_sm(SCTP_EVENT_T_CHUNK, subtype,
state, ep, asoc, chunk, GFP_ATOMIC);
/* Check to see if the association is freed in response to
* the incoming chunk. If so, get out of the while loop.
*/
if (asoc->base.dead)
break;
/* If there is an error on chunk, discard this packet. */
if (error && chunk)
chunk->pdiscard = 1;
}
sctp_association_put(asoc);
}
/* This routine moves an association from its old sk to a new sk. */
void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
{
struct sctp_sock *newsp = sctp_sk(newsk);
struct sock *oldsk = assoc->base.sk;
/* Delete the association from the old endpoint's list of
* associations.
*/
list_del_init(&assoc->asocs);
/* Decrement the backlog value for a TCP-style socket. */
if (sctp_style(oldsk, TCP))
oldsk->sk_ack_backlog--;
/* Release references to the old endpoint and the sock. */
sctp_endpoint_put(assoc->ep);
sock_put(assoc->base.sk);
/* Get a reference to the new endpoint. */
assoc->ep = newsp->ep;
sctp_endpoint_hold(assoc->ep);
/* Get a reference to the new sock. */
assoc->base.sk = newsk;
sock_hold(assoc->base.sk);
/* Add the association to the new endpoint's list of associations. */
sctp_endpoint_add_asoc(newsp->ep, assoc);
}
/* Update an association (possibly from unexpected COOKIE-ECHO processing). */
void sctp_assoc_update(struct sctp_association *asoc,
struct sctp_association *new)
{
struct sctp_transport *trans;
struct list_head *pos, *temp;
/* Copy in new parameters of peer. */
asoc->c = new->c;
asoc->peer.rwnd = new->peer.rwnd;
asoc->peer.sack_needed = new->peer.sack_needed;
asoc->peer.i = new->peer.i;
sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE,
asoc->peer.i.initial_tsn);
/* Remove any peer addresses not present in the new association. */
list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
trans = list_entry(pos, struct sctp_transport, transports);
if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr))
sctp_assoc_del_peer(asoc, &trans->ipaddr);
}
/* If the case is A (association restart), use
* initial_tsn as next_tsn. If the case is B, use
* current next_tsn in case data sent to peer
* has been discarded and needs retransmission.
*/
if (asoc->state >= SCTP_STATE_ESTABLISHED) {
asoc->next_tsn = new->next_tsn;
asoc->ctsn_ack_point = new->ctsn_ack_point;
asoc->adv_peer_ack_point = new->adv_peer_ack_point;
/* Reinitialize SSN for both local streams
* and peer's streams.
*/
sctp_ssnmap_clear(asoc->ssnmap);
} else {
/* Add any peer addresses from the new association. */
list_for_each(pos, &new->peer.transport_addr_list) {
trans = list_entry(pos, struct sctp_transport,
transports);
if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
sctp_assoc_add_peer(asoc, &trans->ipaddr,
GFP_ATOMIC, trans->state);
}
asoc->ctsn_ack_point = asoc->next_tsn - 1;
asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
if (!asoc->ssnmap) {
/* Move the ssnmap. */
asoc->ssnmap = new->ssnmap;
new->ssnmap = NULL;
}
}
}
/* Update the retran path for sending a retransmitted packet.
* Round-robin through the active transports, else round-robin
* through the inactive transports as this is the next best thing
* we can try.
*/
void sctp_assoc_update_retran_path(struct sctp_association *asoc)
{
struct sctp_transport *t, *next;
struct list_head *head = &asoc->peer.transport_addr_list;
struct list_head *pos;
/* Find the next transport in a round-robin fashion. */
t = asoc->peer.retran_path;
pos = &t->transports;
next = NULL;
while (1) {
/* Skip the head. */
if (pos->next == head)
pos = head->next;
else
pos = pos->next;
t = list_entry(pos, struct sctp_transport, transports);
/* Try to find an active transport. */
if ((t->state == SCTP_ACTIVE) ||
(t->state == SCTP_UNKNOWN)) {
break;
} else {
/* Keep track of the next transport in case
* we don't find any active transport.
*/
if (!next)
next = t;
}
/* We have exhausted the list, but didn't find any
* other active transports. If so, use the next
* transport.
*/
if (t == asoc->peer.retran_path) {
t = next;
break;
}
}
asoc->peer.retran_path = t;
SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
" %p addr: ",
" port: %d\n",
asoc,
(&t->ipaddr),
t->ipaddr.v4.sin_port);
}
/* Choose the transport for sending a INIT packet. */
struct sctp_transport *sctp_assoc_choose_init_transport(
struct sctp_association *asoc)
{
struct sctp_transport *t;
/* Use the retran path. If the last INIT was sent over the
* retran path, update the retran path and use it.
*/
if (!asoc->init_last_sent_to) {
t = asoc->peer.active_path;
} else {
if (asoc->init_last_sent_to == asoc->peer.retran_path)
sctp_assoc_update_retran_path(asoc);
t = asoc->peer.retran_path;
}
SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
" %p addr: ",
" port: %d\n",
asoc,
(&t->ipaddr),
t->ipaddr.v4.sin_port);
return t;
}
/* Choose the transport for sending a SHUTDOWN packet. */
struct sctp_transport *sctp_assoc_choose_shutdown_transport(
struct sctp_association *asoc)
{
/* If this is the first time SHUTDOWN is sent, use the active path,
* else use the retran path. If the last SHUTDOWN was sent over the
* retran path, update the retran path and use it.
*/
if (!asoc->shutdown_last_sent_to)
return asoc->peer.active_path;
else {
if (asoc->shutdown_last_sent_to == asoc->peer.retran_path)
sctp_assoc_update_retran_path(asoc);
return asoc->peer.retran_path;
}
}
/* Update the association's pmtu and frag_point by going through all the
* transports. This routine is called when a transport's PMTU has changed.
*/
void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
{
struct sctp_transport *t;
struct list_head *pos;
__u32 pmtu = 0;
if (!asoc)
return;
/* Get the lowest pmtu of all the transports. */
list_for_each(pos, &asoc->peer.transport_addr_list) {
t = list_entry(pos, struct sctp_transport, transports);
if (!pmtu || (t->pathmtu < pmtu))
pmtu = t->pathmtu;
}
if (pmtu) {
struct sctp_sock *sp = sctp_sk(asoc->base.sk);
asoc->pathmtu = pmtu;
asoc->frag_point = sctp_frag_point(sp, pmtu);
}
SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d\n",
__FUNCTION__, asoc, asoc->pathmtu, asoc->frag_point);
}
/* Should we send a SACK to update our peer? */
static inline int sctp_peer_needs_update(struct sctp_association *asoc)
{
switch (asoc->state) {
case SCTP_STATE_ESTABLISHED:
case SCTP_STATE_SHUTDOWN_PENDING:
case SCTP_STATE_SHUTDOWN_RECEIVED:
case SCTP_STATE_SHUTDOWN_SENT:
if ((asoc->rwnd > asoc->a_rwnd) &&
((asoc->rwnd - asoc->a_rwnd) >=
min_t(__u32, (asoc->base.sk->sk_rcvbuf >> 1), asoc->pathmtu)))
return 1;
break;
default:
break;
}
return 0;
}
/* Increase asoc's rwnd by len and send any window update SACK if needed. */
void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
{
struct sctp_chunk *sack;
struct timer_list *timer;
if (asoc->rwnd_over) {
if (asoc->rwnd_over >= len) {
asoc->rwnd_over -= len;
} else {
asoc->rwnd += (len - asoc->rwnd_over);
asoc->rwnd_over = 0;
}
} else {
asoc->rwnd += len;
}
SCTP_DEBUG_PRINTK("%s: asoc %p rwnd increased by %d to (%u, %u) "
"- %u\n", __FUNCTION__, asoc, len, asoc->rwnd,
asoc->rwnd_over, asoc->a_rwnd);
/* Send a window update SACK if the rwnd has increased by at least the
* minimum of the association's PMTU and half of the receive buffer.
* The algorithm used is similar to the one described in
* Section 4.2.3.3 of RFC 1122.
*/
if (sctp_peer_needs_update(asoc)) {
asoc->a_rwnd = asoc->rwnd;
SCTP_DEBUG_PRINTK("%s: Sending window update SACK- asoc: %p "
"rwnd: %u a_rwnd: %u\n", __FUNCTION__,
asoc, asoc->rwnd, asoc->a_rwnd);
sack = sctp_make_sack(asoc);
if (!sack)
return;
asoc->peer.sack_needed = 0;
sctp_outq_tail(&asoc->outqueue, sack);
/* Stop the SACK timer. */
timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
if (timer_pending(timer) && del_timer(timer))
sctp_association_put(asoc);
}
}
/* Decrease asoc's rwnd by len. */
void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned len)
{
SCTP_ASSERT(asoc->rwnd, "rwnd zero", return);
SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return);
if (asoc->rwnd >= len) {
asoc->rwnd -= len;
} else {
asoc->rwnd_over = len - asoc->rwnd;
asoc->rwnd = 0;
}
SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u)\n",
__FUNCTION__, asoc, len, asoc->rwnd,
asoc->rwnd_over);
}
/* Build the bind address list for the association based on info from the
* local endpoint and the remote peer.
*/
int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
gfp_t gfp)
{
sctp_scope_t scope;
int flags;
/* Use scoping rules to determine the subset of addresses from
* the endpoint.
*/
scope = sctp_scope(&asoc->peer.active_path->ipaddr);
flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
if (asoc->peer.ipv4_address)
flags |= SCTP_ADDR4_PEERSUPP;
if (asoc->peer.ipv6_address)
flags |= SCTP_ADDR6_PEERSUPP;
return sctp_bind_addr_copy(&asoc->base.bind_addr,
&asoc->ep->base.bind_addr,
scope, gfp, flags);
}
/* Build the association's bind address list from the cookie. */
int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
struct sctp_cookie *cookie,
gfp_t gfp)
{
int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
int var_size3 = cookie->raw_addr_list_len;
__u8 *raw = (__u8 *)cookie->peer_init + var_size2;
return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
asoc->ep->base.bind_addr.port, gfp);
}
/* Lookup laddr in the bind address list of an association. */
int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
const union sctp_addr *laddr)
{
int found;
sctp_read_lock(&asoc->base.addr_lock);
if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
sctp_sk(asoc->base.sk))) {
found = 1;
goto out;
}
found = 0;
out:
sctp_read_unlock(&asoc->base.addr_lock);
return found;
}
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