socket.c

/*
 * net/tipc/socket.c: TIPC socket API
 *
 * Copyright (c) 2001-2007, 2012-2017, Ericsson AB
 * Copyright (c) 2004-2008, 2010-2013, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/rhashtable.h>
#include <linux/sched/signal.h>

#include "core.h"
#include "name_table.h"
#include "node.h"
#include "link.h"
#include "name_distr.h"
#include "socket.h"
#include "bcast.h"
#include "netlink.h"
#include "group.h"
#include "trace.h"

#define CONN_TIMEOUT_DEFAULT    8000    /* default connect timeout = 8s */
#define CONN_PROBING_INTV	msecs_to_jiffies(3600000)  /* [ms] => 1 h */
#define TIPC_FWD_MSG		1
#define TIPC_MAX_PORT		0xffffffff
#define TIPC_MIN_PORT		1
#define TIPC_ACK_RATE		4       /* ACK at 1/4 of of rcv window size */

enum {
	TIPC_LISTEN = TCP_LISTEN,
	TIPC_ESTABLISHED = TCP_ESTABLISHED,
	TIPC_OPEN = TCP_CLOSE,
	TIPC_DISCONNECTING = TCP_CLOSE_WAIT,
	TIPC_CONNECTING = TCP_SYN_SENT,
};

struct sockaddr_pair {
	struct sockaddr_tipc sock;
	struct sockaddr_tipc member;
};

/**
 * struct tipc_sock - TIPC socket structure
 * @sk: socket - interacts with 'port' and with user via the socket API
 * @conn_type: TIPC type used when connection was established
 * @conn_instance: TIPC instance used when connection was established
 * @published: non-zero if port has one or more associated names
 * @max_pkt: maximum packet size "hint" used when building messages sent by port
 * @portid: unique port identity in TIPC socket hash table
 * @phdr: preformatted message header used when sending messages
 * #cong_links: list of congested links
 * @publications: list of publications for port
 * @blocking_link: address of the congested link we are currently sleeping on
 * @pub_count: total # of publications port has made during its lifetime
 * @conn_timeout: the time we can wait for an unresponded setup request
 * @dupl_rcvcnt: number of bytes counted twice, in both backlog and rcv queue
 * @cong_link_cnt: number of congested links
 * @snt_unacked: # messages sent by socket, and not yet acked by peer
 * @rcv_unacked: # messages read by user, but not yet acked back to peer
 * @peer: 'connected' peer for dgram/rdm
 * @node: hash table node
 * @mc_method: cookie for use between socket and broadcast layer
 * @rcu: rcu struct for tipc_sock
 */
struct tipc_sock {
	struct sock sk;
	u32 conn_type;
	u32 conn_instance;
	int published;
	u32 max_pkt;
	u32 portid;
	struct tipc_msg phdr;
	struct list_head cong_links;
	struct list_head publications;
	u32 pub_count;
	atomic_t dupl_rcvcnt;
	u16 conn_timeout;
	bool probe_unacked;
	u16 cong_link_cnt;
	u16 snt_unacked;
	u16 snd_win;
	u16 peer_caps;
	u16 rcv_unacked;
	u16 rcv_win;
	struct sockaddr_tipc peer;
	struct rhash_head node;
	struct tipc_mc_method mc_method;
	struct rcu_head rcu;
	struct tipc_group *group;
	bool group_is_open;
};

static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
static void tipc_data_ready(struct sock *sk);
static void tipc_write_space(struct sock *sk);
static void tipc_sock_destruct(struct sock *sk);
static int tipc_release(struct socket *sock);
static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags,
		       bool kern);
static void tipc_sk_timeout(struct timer_list *t);
static int tipc_sk_publish(struct tipc_sock *tsk, uint scope,
			   struct tipc_name_seq const *seq);
static int tipc_sk_withdraw(struct tipc_sock *tsk, uint scope,
			    struct tipc_name_seq const *seq);
static int tipc_sk_leave(struct tipc_sock *tsk);
static struct tipc_sock *tipc_sk_lookup(struct net *net, u32 portid);
static int tipc_sk_insert(struct tipc_sock *tsk);
static void tipc_sk_remove(struct tipc_sock *tsk);
static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz);
static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz);

static const struct proto_ops packet_ops;
static const struct proto_ops stream_ops;
static const struct proto_ops msg_ops;
static struct proto tipc_proto;
static const struct rhashtable_params tsk_rht_params;

static u32 tsk_own_node(struct tipc_sock *tsk)
{
	return msg_prevnode(&tsk->phdr);
}

static u32 tsk_peer_node(struct tipc_sock *tsk)
{
	return msg_destnode(&tsk->phdr);
}

static u32 tsk_peer_port(struct tipc_sock *tsk)
{
	return msg_destport(&tsk->phdr);
}

static  bool tsk_unreliable(struct tipc_sock *tsk)
{
	return msg_src_droppable(&tsk->phdr) != 0;
}

static void tsk_set_unreliable(struct tipc_sock *tsk, bool unreliable)
{
	msg_set_src_droppable(&tsk->phdr, unreliable ? 1 : 0);
}

static bool tsk_unreturnable(struct tipc_sock *tsk)
{
	return msg_dest_droppable(&tsk->phdr) != 0;
}

static void tsk_set_unreturnable(struct tipc_sock *tsk, bool unreturnable)
{
	msg_set_dest_droppable(&tsk->phdr, unreturnable ? 1 : 0);
}

static int tsk_importance(struct tipc_sock *tsk)
{
	return msg_importance(&tsk->phdr);
}

static int tsk_set_importance(struct tipc_sock *tsk, int imp)
{
	if (imp > TIPC_CRITICAL_IMPORTANCE)
		return -EINVAL;
	msg_set_importance(&tsk->phdr, (u32)imp);
	return 0;
}

static struct tipc_sock *tipc_sk(const struct sock *sk)
{
	return container_of(sk, struct tipc_sock, sk);
}

static bool tsk_conn_cong(struct tipc_sock *tsk)
{
	return tsk->snt_unacked > tsk->snd_win;
}

static u16 tsk_blocks(int len)
{
	return ((len / FLOWCTL_BLK_SZ) + 1);
}

/* tsk_blocks(): translate a buffer size in bytes to number of
 * advertisable blocks, taking into account the ratio truesize(len)/len
 * We can trust that this ratio is always < 4 for len >= FLOWCTL_BLK_SZ
 */
static u16 tsk_adv_blocks(int len)
{
	return len / FLOWCTL_BLK_SZ / 4;
}

/* tsk_inc(): increment counter for sent or received data
 * - If block based flow control is not supported by peer we
 *   fall back to message based ditto, incrementing the counter
 */
static u16 tsk_inc(struct tipc_sock *tsk, int msglen)
{
	if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
		return ((msglen / FLOWCTL_BLK_SZ) + 1);
	return 1;
}

/**
 * tsk_advance_rx_queue - discard first buffer in socket receive queue
 *
 * Caller must hold socket lock
 */
static void tsk_advance_rx_queue(struct sock *sk)
{
	trace_tipc_sk_advance_rx(sk, NULL, TIPC_DUMP_SK_RCVQ, " ");
	kfree_skb(__skb_dequeue(&sk->sk_receive_queue));
}

/* tipc_sk_respond() : send response message back to sender
 */
static void tipc_sk_respond(struct sock *sk, struct sk_buff *skb, int err)
{
	u32 selector;
	u32 dnode;
	u32 onode = tipc_own_addr(sock_net(sk));

	if (!tipc_msg_reverse(onode, &skb, err))
		return;

	trace_tipc_sk_rej_msg(sk, skb, TIPC_DUMP_NONE, "@sk_respond!");
	dnode = msg_destnode(buf_msg(skb));
	selector = msg_origport(buf_msg(skb));
	tipc_node_xmit_skb(sock_net(sk), skb, dnode, selector);
}

/**
 * tsk_rej_rx_queue - reject all buffers in socket receive queue
 *
 * Caller must hold socket lock
 */
static void tsk_rej_rx_queue(struct sock *sk)
{
	struct sk_buff *skb;

	while ((skb = __skb_dequeue(&sk->sk_receive_queue)))
		tipc_sk_respond(sk, skb, TIPC_ERR_NO_PORT);
}

static bool tipc_sk_connected(struct sock *sk)
{
	return sk->sk_state == TIPC_ESTABLISHED;
}

/* tipc_sk_type_connectionless - check if the socket is datagram socket
 * @sk: socket
 *
 * Returns true if connection less, false otherwise
 */
static bool tipc_sk_type_connectionless(struct sock *sk)
{
	return sk->sk_type == SOCK_RDM || sk->sk_type == SOCK_DGRAM;
}

/* tsk_peer_msg - verify if message was sent by connected port's peer
 *
 * Handles cases where the node's network address has changed from
 * the default of <0.0.0> to its configured setting.
 */
static bool tsk_peer_msg(struct tipc_sock *tsk, struct tipc_msg *msg)
{
	struct sock *sk = &tsk->sk;
	u32 self = tipc_own_addr(sock_net(sk));
	u32 peer_port = tsk_peer_port(tsk);
	u32 orig_node, peer_node;

	if (unlikely(!tipc_sk_connected(sk)))
		return false;

	if (unlikely(msg_origport(msg) != peer_port))
		return false;

	orig_node = msg_orignode(msg);
	peer_node = tsk_peer_node(tsk);

	if (likely(orig_node == peer_node))
		return true;

	if (!orig_node && peer_node == self)
		return true;

	if (!peer_node && orig_node == self)
		return true;

	return false;
}

/* tipc_set_sk_state - set the sk_state of the socket
 * @sk: socket
 *
 * Caller must hold socket lock
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_set_sk_state(struct sock *sk, int state)
{
	int oldsk_state = sk->sk_state;
	int res = -EINVAL;

	switch (state) {
	case TIPC_OPEN:
		res = 0;
		break;
	case TIPC_LISTEN:
	case TIPC_CONNECTING:
		if (oldsk_state == TIPC_OPEN)
			res = 0;
		break;
	case TIPC_ESTABLISHED:
		if (oldsk_state == TIPC_CONNECTING ||
		    oldsk_state == TIPC_OPEN)
			res = 0;
		break;
	case TIPC_DISCONNECTING:
		if (oldsk_state == TIPC_CONNECTING ||
		    oldsk_state == TIPC_ESTABLISHED)
			res = 0;
		break;
	}

	if (!res)
		sk->sk_state = state;

	return res;
}

static int tipc_sk_sock_err(struct socket *sock, long *timeout)
{
	struct sock *sk = sock->sk;
	int err = sock_error(sk);
	int typ = sock->type;

	if (err)
		return err;
	if (typ == SOCK_STREAM || typ == SOCK_SEQPACKET) {
		if (sk->sk_state == TIPC_DISCONNECTING)
			return -EPIPE;
		else if (!tipc_sk_connected(sk))
			return -ENOTCONN;
	}
	if (!*timeout)
		return -EAGAIN;
	if (signal_pending(current))
		return sock_intr_errno(*timeout);

	return 0;
}

#define tipc_wait_for_cond(sock_, timeo_, condition_)			       \
({                                                                             \
	DEFINE_WAIT_FUNC(wait_, woken_wake_function);                          \
	struct sock *sk_;						       \
	int rc_;							       \
									       \
	while ((rc_ = !(condition_))) {					       \
		/* coupled with smp_wmb() in tipc_sk_proto_rcv() */            \
		smp_rmb();                                                     \
		sk_ = (sock_)->sk;					       \
		rc_ = tipc_sk_sock_err((sock_), timeo_);		       \
		if (rc_)						       \
			break;						       \
		add_wait_queue(sk_sleep(sk_), &wait_);                         \
		release_sock(sk_);					       \
		*(timeo_) = wait_woken(&wait_, TASK_INTERRUPTIBLE, *(timeo_)); \
		sched_annotate_sleep();				               \
		lock_sock(sk_);						       \
		remove_wait_queue(sk_sleep(sk_), &wait_);		       \
	}								       \
	rc_;								       \
})

/**
 * tipc_sk_create - create a TIPC socket
 * @net: network namespace (must be default network)
 * @sock: pre-allocated socket structure
 * @protocol: protocol indicator (must be 0)
 * @kern: caused by kernel or by userspace?
 *
 * This routine creates additional data structures used by the TIPC socket,
 * initializes them, and links them together.
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_sk_create(struct net *net, struct socket *sock,
			  int protocol, int kern)
{
	const struct proto_ops *ops;
	struct sock *sk;
	struct tipc_sock *tsk;
	struct tipc_msg *msg;

	/* Validate arguments */
	if (unlikely(protocol != 0))
		return -EPROTONOSUPPORT;

	switch (sock->type) {
	case SOCK_STREAM:
		ops = &stream_ops;
		break;
	case SOCK_SEQPACKET:
		ops = &packet_ops;
		break;
	case SOCK_DGRAM:
	case SOCK_RDM:
		ops = &msg_ops;
		break;
	default:
		return -EPROTOTYPE;
	}

	/* Allocate socket's protocol area */
	sk = sk_alloc(net, AF_TIPC, GFP_KERNEL, &tipc_proto, kern);
	if (sk == NULL)
		return -ENOMEM;

	tsk = tipc_sk(sk);
	tsk->max_pkt = MAX_PKT_DEFAULT;
	INIT_LIST_HEAD(&tsk->publications);
	INIT_LIST_HEAD(&tsk->cong_links);
	msg = &tsk->phdr;

	/* Finish initializing socket data structures */
	sock->ops = ops;
	sock_init_data(sock, sk);
	tipc_set_sk_state(sk, TIPC_OPEN);
	if (tipc_sk_insert(tsk)) {
		pr_warn("Socket create failed; port number exhausted\n");
		return -EINVAL;
	}

	/* Ensure tsk is visible before we read own_addr. */
	smp_mb();

	tipc_msg_init(tipc_own_addr(net), msg, TIPC_LOW_IMPORTANCE,
		      TIPC_NAMED_MSG, NAMED_H_SIZE, 0);

	msg_set_origport(msg, tsk->portid);
	timer_setup(&sk->sk_timer, tipc_sk_timeout, 0);
	sk->sk_shutdown = 0;
	sk->sk_backlog_rcv = tipc_sk_backlog_rcv;
	sk->sk_rcvbuf = sysctl_tipc_rmem[1];
	sk->sk_data_ready = tipc_data_ready;
	sk->sk_write_space = tipc_write_space;
	sk->sk_destruct = tipc_sock_destruct;
	tsk->conn_timeout = CONN_TIMEOUT_DEFAULT;
	tsk->group_is_open = true;
	atomic_set(&tsk->dupl_rcvcnt, 0);

	/* Start out with safe limits until we receive an advertised window */
	tsk->snd_win = tsk_adv_blocks(RCVBUF_MIN);
	tsk->rcv_win = tsk->snd_win;

	if (tipc_sk_type_connectionless(sk)) {
		tsk_set_unreturnable(tsk, true);
		if (sock->type == SOCK_DGRAM)
			tsk_set_unreliable(tsk, true);
	}
	__skb_queue_head_init(&tsk->mc_method.deferredq);
	trace_tipc_sk_create(sk, NULL, TIPC_DUMP_NONE, " ");
	return 0;
}

static void tipc_sk_callback(struct rcu_head *head)
{
	struct tipc_sock *tsk = container_of(head, struct tipc_sock, rcu);

	sock_put(&tsk->sk);
}

/* Caller should hold socket lock for the socket. */
static void __tipc_shutdown(struct socket *sock, int error)
{
	struct sock *sk = sock->sk;
	struct tipc_sock *tsk = tipc_sk(sk);
	struct net *net = sock_net(sk);
	long timeout = CONN_TIMEOUT_DEFAULT;
	u32 dnode = tsk_peer_node(tsk);
	struct sk_buff *skb;

	/* Avoid that hi-prio shutdown msgs bypass msgs in link wakeup queue */
	tipc_wait_for_cond(sock, &timeout, (!tsk->cong_link_cnt &&
					    !tsk_conn_cong(tsk)));

	/* Remove any pending SYN message */
	__skb_queue_purge(&sk->sk_write_queue);

	/* Reject all unreceived messages, except on an active connection
	 * (which disconnects locally & sends a 'FIN+' to peer).
	 */
	while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
		if (TIPC_SKB_CB(skb)->bytes_read) {
			kfree_skb(skb);
			continue;
		}
		if (!tipc_sk_type_connectionless(sk) &&
		    sk->sk_state != TIPC_DISCONNECTING) {
			tipc_set_sk_state(sk, TIPC_DISCONNECTING);
			tipc_node_remove_conn(net, dnode, tsk->portid);
		}
		tipc_sk_respond(sk, skb, error);
	}

	if (tipc_sk_type_connectionless(sk))
		return;

	if (sk->sk_state != TIPC_DISCONNECTING) {
		skb = tipc_msg_create(TIPC_CRITICAL_IMPORTANCE,
				      TIPC_CONN_MSG, SHORT_H_SIZE, 0, dnode,
				      tsk_own_node(tsk), tsk_peer_port(tsk),
				      tsk->portid, error);
		if (skb)
			tipc_node_xmit_skb(net, skb, dnode, tsk->portid);
		tipc_node_remove_conn(net, dnode, tsk->portid);
		tipc_set_sk_state(sk, TIPC_DISCONNECTING);
	}
}

/**
 * tipc_release - destroy a TIPC socket
 * @sock: socket to destroy
 *
 * This routine cleans up any messages that are still queued on the socket.
 * For DGRAM and RDM socket types, all queued messages are rejected.
 * For SEQPACKET and STREAM socket types, the first message is rejected
 * and any others are discarded.  (If the first message on a STREAM socket
 * is partially-read, it is discarded and the next one is rejected instead.)
 *
 * NOTE: Rejected messages are not necessarily returned to the sender!  They
 * are returned or discarded according to the "destination droppable" setting
 * specified for the message by the sender.
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct tipc_sock *tsk;

	/*
	 * Exit if socket isn't fully initialized (occurs when a failed accept()
	 * releases a pre-allocated child socket that was never used)
	 */
	if (sk == NULL)
		return 0;

	tsk = tipc_sk(sk);
	lock_sock(sk);

	trace_tipc_sk_release(sk, NULL, TIPC_DUMP_ALL, " ");
	__tipc_shutdown(sock, TIPC_ERR_NO_PORT);
	sk->sk_shutdown = SHUTDOWN_MASK;
	tipc_sk_leave(tsk);
	tipc_sk_withdraw(tsk, 0, NULL);
	__skb_queue_purge(&tsk->mc_method.deferredq);
	sk_stop_timer(sk, &sk->sk_timer);
	tipc_sk_remove(tsk);

	sock_orphan(sk);
	/* Reject any messages that accumulated in backlog queue */
	release_sock(sk);
	tipc_dest_list_purge(&tsk->cong_links);
	tsk->cong_link_cnt = 0;
	call_rcu(&tsk->rcu, tipc_sk_callback);
	sock->sk = NULL;

	return 0;
}

/**
 * tipc_bind - associate or disassocate TIPC name(s) with a socket
 * @sock: socket structure
 * @uaddr: socket address describing name(s) and desired operation
 * @uaddr_len: size of socket address data structure
 *
 * Name and name sequence binding is indicated using a positive scope value;
 * a negative scope value unbinds the specified name.  Specifying no name
 * (i.e. a socket address length of 0) unbinds all names from the socket.
 *
 * Returns 0 on success, errno otherwise
 *
 * NOTE: This routine doesn't need to take the socket lock since it doesn't
 *       access any non-constant socket information.
 */
static int tipc_bind(struct socket *sock, struct sockaddr *uaddr,
		     int uaddr_len)
{
	struct sock *sk = sock->sk;
	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
	struct tipc_sock *tsk = tipc_sk(sk);
	int res = -EINVAL;

	lock_sock(sk);
	if (unlikely(!uaddr_len)) {
		res = tipc_sk_withdraw(tsk, 0, NULL);
		goto exit;
	}
	if (tsk->group) {
		res = -EACCES;
		goto exit;
	}
	if (uaddr_len < sizeof(struct sockaddr_tipc)) {
		res = -EINVAL;
		goto exit;
	}
	if (addr->family != AF_TIPC) {
		res = -EAFNOSUPPORT;
		goto exit;
	}

	if (addr->addrtype == TIPC_ADDR_NAME)
		addr->addr.nameseq.upper = addr->addr.nameseq.lower;
	else if (addr->addrtype != TIPC_ADDR_NAMESEQ) {
		res = -EAFNOSUPPORT;
		goto exit;
	}

	if ((addr->addr.nameseq.type < TIPC_RESERVED_TYPES) &&
	    (addr->addr.nameseq.type != TIPC_TOP_SRV) &&
	    (addr->addr.nameseq.type != TIPC_CFG_SRV)) {
		res = -EACCES;
		goto exit;
	}

	res = (addr->scope >= 0) ?
		tipc_sk_publish(tsk, addr->scope, &addr->addr.nameseq) :
		tipc_sk_withdraw(tsk, -addr->scope, &addr->addr.nameseq);
exit:
	release_sock(sk);
	return res;
}

/**
 * tipc_getname - get port ID of socket or peer socket
 * @sock: socket structure
 * @uaddr: area for returned socket address
 * @uaddr_len: area for returned length of socket address
 * @peer: 0 = own ID, 1 = current peer ID, 2 = current/former peer ID
 *
 * Returns 0 on success, errno otherwise
 *
 * NOTE: This routine doesn't need to take the socket lock since it only
 *       accesses socket information that is unchanging (or which changes in
 *       a completely predictable manner).
 */
static int tipc_getname(struct socket *sock, struct sockaddr *uaddr,
			int peer)
{
	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
	struct sock *sk = sock->sk;
	struct tipc_sock *tsk = tipc_sk(sk);

	memset(addr, 0, sizeof(*addr));
	if (peer) {
		if ((!tipc_sk_connected(sk)) &&
		    ((peer != 2) || (sk->sk_state != TIPC_DISCONNECTING)))
			return -ENOTCONN;
		addr->addr.id.ref = tsk_peer_port(tsk);
		addr->addr.id.node = tsk_peer_node(tsk);
	} else {
		addr->addr.id.ref = tsk->portid;
		addr->addr.id.node = tipc_own_addr(sock_net(sk));
	}

	addr->addrtype = TIPC_ADDR_ID;
	addr->family = AF_TIPC;
	addr->scope = 0;
	addr->addr.name.domain = 0;

	return sizeof(*addr);
}

/**
 * tipc_poll - read and possibly block on pollmask
 * @file: file structure associated with the socket
 * @sock: socket for which to calculate the poll bits
 * @wait: ???
 *
 * Returns pollmask value
 *
 * COMMENTARY:
 * It appears that the usual socket locking mechanisms are not useful here
 * since the pollmask info is potentially out-of-date the moment this routine
 * exits.  TCP and other protocols seem to rely on higher level poll routines
 * to handle any preventable race conditions, so TIPC will do the same ...
 *
 * IMPORTANT: The fact that a read or write operation is indicated does NOT
 * imply that the operation will succeed, merely that it should be performed
 * and will not block.
 */
static __poll_t tipc_poll(struct file *file, struct socket *sock,
			      poll_table *wait)
{
	struct sock *sk = sock->sk;
	struct tipc_sock *tsk = tipc_sk(sk);
	__poll_t revents = 0;

	sock_poll_wait(file, sock, wait);
	trace_tipc_sk_poll(sk, NULL, TIPC_DUMP_ALL, " ");

	if (sk->sk_shutdown & RCV_SHUTDOWN)
		revents |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
	if (sk->sk_shutdown == SHUTDOWN_MASK)
		revents |= EPOLLHUP;

	switch (sk->sk_state) {
	case TIPC_ESTABLISHED:
		if (!tsk->cong_link_cnt && !tsk_conn_cong(tsk))
			revents |= EPOLLOUT;
		/* fall through */
	case TIPC_LISTEN:
	case TIPC_CONNECTING:
		if (!skb_queue_empty(&sk->sk_receive_queue))
			revents |= EPOLLIN | EPOLLRDNORM;
		break;
	case TIPC_OPEN:
		if (tsk->group_is_open && !tsk->cong_link_cnt)
			revents |= EPOLLOUT;
		if (!tipc_sk_type_connectionless(sk))
			break;
		if (skb_queue_empty(&sk->sk_receive_queue))
			break;
		revents |= EPOLLIN | EPOLLRDNORM;
		break;
	case TIPC_DISCONNECTING:
		revents = EPOLLIN | EPOLLRDNORM | EPOLLHUP;
		break;
	}
	return revents;
}

/**
 * tipc_sendmcast - send multicast message
 * @sock: socket structure
 * @seq: destination address
 * @msg: message to send
 * @dlen: length of data to send
 * @timeout: timeout to wait for wakeup
 *
 * Called from function tipc_sendmsg(), which has done all sanity checks
 * Returns the number of bytes sent on success, or errno
 */
static int tipc_sendmcast(struct  socket *sock, struct tipc_name_seq *seq,
			  struct msghdr *msg, size_t dlen, long timeout)
{
	struct sock *sk = sock->sk;
	struct tipc_sock *tsk = tipc_sk(sk);
	struct tipc_msg *hdr = &tsk->phdr;
	struct net *net = sock_net(sk);
	int mtu = tipc_bcast_get_mtu(net);
	struct tipc_mc_method *method = &tsk->mc_method;
	struct sk_buff_head pkts;
	struct tipc_nlist dsts;
	int rc;

	if (tsk->group)
		return -EACCES;

	/* Block or return if any destination link is congested */
	rc = tipc_wait_for_cond(sock, &timeout, !tsk->cong_link_cnt);
	if (unlikely(rc))
		return rc;

	/* Lookup destination nodes */
	tipc_nlist_init(&dsts, tipc_own_addr(net));
	tipc_nametbl_lookup_dst_nodes(net, seq->type, seq->lower,
				      seq->upper, &dsts);
	if (!dsts.local && !dsts.remote)
		return -EHOSTUNREACH;

	/* Build message header */
	msg_set_type(hdr, TIPC_MCAST_MSG);
	msg_set_hdr_sz(hdr, MCAST_H_SIZE);
	msg_set_lookup_scope(hdr, TIPC_CLUSTER_SCOPE);
	msg_set_destport(hdr, 0);
	msg_set_destnode(hdr, 0);
	msg_set_nametype(hdr, seq->type);
	msg_set_namelower(hdr, seq->lower);
	msg_set_nameupper(hdr, seq->upper);

	/* Build message as chain of buffers */
	__skb_queue_head_init(&pkts);
	rc = tipc_msg_build(hdr, msg, 0, dlen, mtu, &pkts);

	/* Send message if build was successful */
	if (unlikely(rc == dlen)) {
		trace_tipc_sk_sendmcast(sk, skb_peek(&pkts),
					TIPC_DUMP_SK_SNDQ, " ");
		rc = tipc_mcast_xmit(net, &pkts, method, &dsts,
				     &tsk->cong_link_cnt);
	}

	tipc_nlist_purge(&dsts);

	return rc ? rc : dlen;
}

/**
 * tipc_send_group_msg - send a message to a member in the group
 * @net: network namespace
 * @m: message to send
 * @mb: group member
 * @dnode: destination node
 * @dport: destination port
 * @dlen: total length of message data
 */
static int tipc_send_group_msg(struct net *net, struct tipc_sock *tsk,
			       struct msghdr *m, struct tipc_member *mb,
			       u32 dnode, u32 dport, int dlen)
{
	u16 bc_snd_nxt = tipc_group_bc_snd_nxt(tsk->group);
	struct tipc_mc_method *method = &tsk->mc_method;
	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
	struct tipc_msg *hdr = &tsk->phdr;
	struct sk_buff_head pkts;
	int mtu, rc;

	/* Complete message header */
	msg_set_type(hdr, TIPC_GRP_UCAST_MSG);
	msg_set_hdr_sz(hdr, GROUP_H_SIZE);
	msg_set_destport(hdr, dport);
	msg_set_destnode(hdr, dnode);
	msg_set_grp_bc_seqno(hdr, bc_snd_nxt);

	/* Build message as chain of buffers */
	__skb_queue_head_init(&pkts);
	mtu = tipc_node_get_mtu(net, dnode, tsk->portid, false);
	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
	if (unlikely(rc != dlen))
		return rc;

	/* Send message */
	rc = tipc_node_xmit(net, &pkts, dnode, tsk->portid);
	if (unlikely(rc == -ELINKCONG)) {
		tipc_dest_push(&tsk->cong_links, dnode, 0);
		tsk->cong_link_cnt++;
	}

	/* Update send window */
	tipc_group_update_member(mb, blks);

	/* A broadcast sent within next EXPIRE period must follow same path */
	method->rcast = true;
	method->mandatory = true;
	return dlen;
}

/**
 * tipc_send_group_unicast - send message to a member in the group
 * @sock: socket structure
 * @m: message to send
 * @dlen: total length of message data
 * @timeout: timeout to wait for wakeup
 *
 * Called from function tipc_sendmsg(), which has done all sanity checks
 * Returns the number of bytes sent on success, or errno
 */
static int tipc_send_group_unicast(struct socket *sock, struct msghdr *m,
				   int dlen, long timeout)
{
	struct sock *sk = sock->sk;
	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
	struct tipc_sock *tsk = tipc_sk(sk);
	struct net *net = sock_net(sk);
	struct tipc_member *mb = NULL;
	u32 node, port;
	int rc;

	node = dest->addr.id.node;
	port = dest->addr.id.ref;
	if (!port && !node)
		return -EHOSTUNREACH;

	/* Block or return if destination link or member is congested */
	rc = tipc_wait_for_cond(sock, &timeout,
				!tipc_dest_find(&tsk->cong_links, node, 0) &&
				tsk->group &&
				!tipc_group_cong(tsk->group, node, port, blks,
						 &mb));
	if (unlikely(rc))
		return rc;

	if (unlikely(!mb))
		return -EHOSTUNREACH;

	rc = tipc_send_group_msg(net, tsk, m, mb, node, port, dlen);

	return rc ? rc : dlen;
}

/**
 * tipc_send_group_anycast - send message to any member with given identity
 * @sock: socket structure
 * @m: message to send
 * @dlen: total length of message data
 * @timeout: timeout to wait for wakeup
 *
 * Called from function tipc_sendmsg(), which has done all sanity checks
 * Returns the number of bytes sent on success, or errno
 */
static int tipc_send_group_anycast(struct socket *sock, struct msghdr *m,
				   int dlen, long timeout)
{
	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
	struct sock *sk = sock->sk;
	struct tipc_sock *tsk = tipc_sk(sk);
	struct list_head *cong_links = &tsk->cong_links;
	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
	struct tipc_msg *hdr = &tsk->phdr;
	struct tipc_member *first = NULL;
	struct tipc_member *mbr = NULL;
	struct net *net = sock_net(sk);
	u32 node, port, exclude;
	struct list_head dsts;
	u32 type, inst, scope;
	int lookups = 0;
	int dstcnt, rc;
	bool cong;

	INIT_LIST_HEAD(&dsts);

	type = msg_nametype(hdr);
	inst = dest->addr.name.name.instance;
	scope = msg_lookup_scope(hdr);

	while (++lookups < 4) {
		exclude = tipc_group_exclude(tsk->group);

		first = NULL;

		/* Look for a non-congested destination member, if any */
		while (1) {
			if (!tipc_nametbl_lookup(net, type, inst, scope, &dsts,
						 &dstcnt, exclude, false))
				return -EHOSTUNREACH;
			tipc_dest_pop(&dsts, &node, &port);
			cong = tipc_group_cong(tsk->group, node, port, blks,
					       &mbr);
			if (!cong)
				break;
			if (mbr == first)
				break;
			if (!first)
				first = mbr;
		}

		/* Start over if destination was not in member list */
		if (unlikely(!mbr))
			continue;

		if (likely(!cong && !tipc_dest_find(cong_links, node, 0)))
			break;

		/* Block or return if destination link or member is congested */
		rc = tipc_wait_for_cond(sock, &timeout,
					!tipc_dest_find(cong_links, node, 0) &&
					tsk->group &&
					!tipc_group_cong(tsk->group, node, port,
							 blks, &mbr));
		if (unlikely(rc))
			return rc;

		/* Send, unless destination disappeared while waiting */
		if (likely(mbr))
			break;
	}

	if (unlikely(lookups >= 4))
		return -EHOSTUNREACH;