/*

   * Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved.

   *
   * This software is available to you under a choice of one of two
   * licenses.  You may choose to be licensed under the terms of the GNU
   * General Public License (GPL) Version 2, available from the file
   * COPYING in the main directory of this source tree, or the
   * OpenIB.org BSD license below:
   *
   *     Redistribution and use in source and binary forms, with or
   *     without modification, are permitted provided that the following
   *     conditions are met:
   *
   *      - Redistributions of source code must retain the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer.
   *
   *      - 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.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   *
   */
  #include <linux/kernel.h>

  #include <linux/gfp.h>

  #include <linux/in.h>
  #include <net/tcp.h>
  
  #include "rds.h"
  #include "tcp.h"

  void rds_tcp_keepalive(struct socket *sock)

  {
  	/* values below based on xs_udp_default_timeout */
  	int keepidle = 5; /* send a probe 'keepidle' secs after last data */
  	int keepcnt = 5; /* number of unack'ed probes before declaring dead */

  	sock_set_keepalive(sock->sk);

  	tcp_sock_set_keepcnt(sock->sk, keepcnt);

  	tcp_sock_set_keepidle(sock->sk, keepidle);

  	/* KEEPINTVL is the interval between successive probes. We follow
  	 * the model in xs_tcp_finish_connecting() and re-use keepidle.
  	 */

  	tcp_sock_set_keepintvl(sock->sk, keepidle);

  }

  /* rds_tcp_accept_one_path(): if accepting on cp_index > 0, make sure the
   * client's ipaddr < server's ipaddr. Otherwise, close the accepted
   * socket and force a reconneect from smaller -> larger ip addr. The reason
   * we special case cp_index 0 is to allow the rds probe ping itself to itself
   * get through efficiently.
   * Since reconnects are only initiated from the node with the numerically
   * smaller ip address, we recycle conns in RDS_CONN_ERROR on the passive side
   * by moving them to CONNECTING in this function.
   */

  static

  struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
  {
  	int i;

  	int npaths = max_t(int, 1, conn->c_npaths);

  	/* for mprds, all paths MUST be initiated by the peer

  	 * with the smaller address.
  	 */

  	if (rds_addr_cmp(&conn->c_faddr, &conn->c_laddr) >= 0) {

  		/* Make sure we initiate at least one path if this
  		 * has not already been done; rds_start_mprds() will
  		 * take care of additional paths, if necessary.
  		 */
  		if (npaths == 1)
  			rds_conn_path_connect_if_down(&conn->c_path[0]);

  		return NULL;

  	}

  	for (i = 0; i < npaths; i++) {

  		struct rds_conn_path *cp = &conn->c_path[i];
  
  		if (rds_conn_path_transition(cp, RDS_CONN_DOWN,
  					     RDS_CONN_CONNECTING) ||
  		    rds_conn_path_transition(cp, RDS_CONN_ERROR,
  					     RDS_CONN_CONNECTING)) {
  			return cp->cp_transport_data;
  		}
  	}
  	return NULL;
  }

  int rds_tcp_accept_one(struct socket *sock)

  {
  	struct socket *new_sock = NULL;
  	struct rds_connection *conn;
  	int ret;
  	struct inet_sock *inet;

  	struct rds_tcp_connection *rs_tcp = NULL;
  	int conn_state;

  	struct rds_conn_path *cp;

  	struct in6_addr *my_addr, *peer_addr;

  #if !IS_ENABLED(CONFIG_IPV6)
  	struct in6_addr saddr, daddr;
  #endif
  	int dev_if = 0;

  	if (!sock) /* module unload or netns delete in progress */
  		return -ENETUNREACH;

  	ret = sock_create_lite(sock->sk->sk_family,

  			       sock->sk->sk_type, sock->sk->sk_protocol,
  			       &new_sock);

  	if (ret)
  		goto out;

  	ret = sock->ops->accept(sock, new_sock, O_NONBLOCK, true);

  	if (ret < 0)
  		goto out;

  	/* sock_create_lite() does not get a hold on the owner module so we
  	 * need to do it here.  Note that sock_release() uses sock->ops to
  	 * determine if it needs to decrement the reference count.  So set
  	 * sock->ops after calling accept() in case that fails.  And there's
  	 * no need to do try_module_get() as the listener should have a hold
  	 * already.
  	 */
  	new_sock->ops = sock->ops;
  	__module_get(new_sock->ops->owner);

  	rds_tcp_keepalive(new_sock);

  	rds_tcp_tune(new_sock);
  
  	inet = inet_sk(new_sock->sk);

  #if IS_ENABLED(CONFIG_IPV6)

  	my_addr = &new_sock->sk->sk_v6_rcv_saddr;
  	peer_addr = &new_sock->sk->sk_v6_daddr;

  #else
  	ipv6_addr_set_v4mapped(inet->inet_saddr, &saddr);
  	ipv6_addr_set_v4mapped(inet->inet_daddr, &daddr);
  	my_addr = &saddr;
  	peer_addr = &daddr;
  #endif
  	rdsdebug("accepted family %d tcp %pI6c:%u -> %pI6c:%u
  ",
  		 sock->sk->sk_family,

  		 my_addr, ntohs(inet->inet_sport),
  		 peer_addr, ntohs(inet->inet_dport));

  #if IS_ENABLED(CONFIG_IPV6)

  	/* sk_bound_dev_if is not set if the peer address is not link local
  	 * address.  In this case, it happens that mcast_oif is set.  So
  	 * just use it.
  	 */
  	if ((ipv6_addr_type(my_addr) & IPV6_ADDR_LINKLOCAL) &&
  	    !(ipv6_addr_type(peer_addr) & IPV6_ADDR_LINKLOCAL)) {
  		struct ipv6_pinfo *inet6;
  
  		inet6 = inet6_sk(new_sock->sk);
  		dev_if = inet6->mcast_oif;
  	} else {
  		dev_if = new_sock->sk->sk_bound_dev_if;
  	}

  #endif

  	conn = rds_conn_create(sock_net(sock->sk),

  			       my_addr, peer_addr,

  			       &rds_tcp_transport, 0, GFP_KERNEL, dev_if);

  	if (IS_ERR(conn)) {
  		ret = PTR_ERR(conn);
  		goto out;
  	}

  	/* An incoming SYN request came in, and TCP just accepted it.

  	 *
  	 * If the client reboots, this conn will need to be cleaned up.
  	 * rds_tcp_state_change() will do that cleanup
  	 */

  	rs_tcp = rds_tcp_accept_one_path(conn);
  	if (!rs_tcp)
  		goto rst_nsk;

  	mutex_lock(&rs_tcp->t_conn_path_lock);

  	cp = rs_tcp->t_cpath;
  	conn_state = rds_conn_path_state(cp);

  	WARN_ON(conn_state == RDS_CONN_UP);
  	if (conn_state != RDS_CONN_CONNECTING && conn_state != RDS_CONN_ERROR)

  		goto rst_nsk;

  	if (rs_tcp->t_sock) {

  		/* Duelling SYN has been handled in rds_tcp_accept_one() */
  		rds_tcp_reset_callbacks(new_sock, cp);
  		/* rds_connect_path_complete() marks RDS_CONN_UP */
  		rds_connect_path_complete(cp, RDS_CONN_RESETTING);

  	} else {

  		rds_tcp_set_callbacks(new_sock, cp);
  		rds_connect_path_complete(cp, RDS_CONN_CONNECTING);

  	}

  	new_sock = NULL;
  	ret = 0;

  	if (conn->c_npaths == 0)
  		rds_send_ping(cp->cp_conn, cp->cp_index);

  	goto out;
  rst_nsk:

  	/* reset the newly returned accept sock and bail.
  	 * It is safe to set linger on new_sock because the RDS connection
  	 * has not been brought up on new_sock, so no RDS-level data could
  	 * be pending on it. By setting linger, we achieve the side-effect
  	 * of avoiding TIME_WAIT state on new_sock.
  	 */

  	sock_no_linger(new_sock->sk);

  	kernel_sock_shutdown(new_sock, SHUT_RDWR);

  	ret = 0;

  out:

  	if (rs_tcp)

  		mutex_unlock(&rs_tcp->t_conn_path_lock);

  	if (new_sock)
  		sock_release(new_sock);
  	return ret;
  }

  void rds_tcp_listen_data_ready(struct sock *sk)

  {

  	void (*ready)(struct sock *sk);

  
  	rdsdebug("listen data ready sk %p
  ", sk);

  	read_lock_bh(&sk->sk_callback_lock);

  	ready = sk->sk_user_data;

  	if (!ready) { /* check for teardown race */

  		ready = sk->sk_data_ready;
  		goto out;
  	}
  
  	/*
  	 * ->sk_data_ready is also called for a newly established child socket
  	 * before it has been accepted and the accepter has set up their
  	 * data_ready.. we only want to queue listen work for our listening
  	 * socket

  	 *
  	 * (*ready)() may be null if we are racing with netns delete, and
  	 * the listen socket is being torn down.

  	 */
  	if (sk->sk_state == TCP_LISTEN)

  		rds_tcp_accept_work(sk);

  	else
  		ready = rds_tcp_listen_sock_def_readable(sock_net(sk));

  
  out:

  	read_unlock_bh(&sk->sk_callback_lock);

  	if (ready)
  		ready(sk);

  }

  struct socket *rds_tcp_listen_init(struct net *net, bool isv6)

  {

  	struct socket *sock = NULL;

  	struct sockaddr_storage ss;
  	struct sockaddr_in6 *sin6;
  	struct sockaddr_in *sin;
  	int addr_len;

  	int ret;

  	ret = sock_create_kern(net, isv6 ? PF_INET6 : PF_INET, SOCK_STREAM,
  			       IPPROTO_TCP, &sock);
  	if (ret < 0) {
  		rdsdebug("could not create %s listener socket: %d
  ",
  			 isv6 ? "IPv6" : "IPv4", ret);

  		goto out;

  	}

  	sock->sk->sk_reuse = SK_CAN_REUSE;

  	tcp_sock_set_nodelay(sock->sk);

  
  	write_lock_bh(&sock->sk->sk_callback_lock);
  	sock->sk->sk_user_data = sock->sk->sk_data_ready;
  	sock->sk->sk_data_ready = rds_tcp_listen_data_ready;
  	write_unlock_bh(&sock->sk->sk_callback_lock);

  	if (isv6) {
  		sin6 = (struct sockaddr_in6 *)&ss;
  		sin6->sin6_family = PF_INET6;
  		sin6->sin6_addr = in6addr_any;
  		sin6->sin6_port = (__force u16)htons(RDS_TCP_PORT);
  		sin6->sin6_scope_id = 0;
  		sin6->sin6_flowinfo = 0;
  		addr_len = sizeof(*sin6);
  	} else {
  		sin = (struct sockaddr_in *)&ss;
  		sin->sin_family = PF_INET;
  		sin->sin_addr.s_addr = INADDR_ANY;
  		sin->sin_port = (__force u16)htons(RDS_TCP_PORT);
  		addr_len = sizeof(*sin);
  	}

  	ret = sock->ops->bind(sock, (struct sockaddr *)&ss, addr_len);
  	if (ret < 0) {
  		rdsdebug("could not bind %s listener socket: %d
  ",
  			 isv6 ? "IPv6" : "IPv4", ret);

  		goto out;

  	}

  
  	ret = sock->ops->listen(sock, 64);
  	if (ret < 0)
  		goto out;

  	return sock;

  out:
  	if (sock)
  		sock_release(sock);

  	return NULL;

  }

  void rds_tcp_listen_stop(struct socket *sock, struct work_struct *acceptor)

  {

  	struct sock *sk;

  	if (!sock)

  		return;
  
  	sk = sock->sk;
  
  	/* serialize with and prevent further callbacks */
  	lock_sock(sk);
  	write_lock_bh(&sk->sk_callback_lock);
  	if (sk->sk_user_data) {
  		sk->sk_data_ready = sk->sk_user_data;
  		sk->sk_user_data = NULL;
  	}
  	write_unlock_bh(&sk->sk_callback_lock);
  	release_sock(sk);
  
  	/* wait for accepts to stop and close the socket */
  	flush_workqueue(rds_wq);

  	flush_work(acceptor);

  	sock_release(sock);

  }