/*
 * Copyright (c) 2006, 2017 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/in.h>
#include <net/tcp.h>

#include "rds.h"
#include "tcp.h"

void rds_tcp_state_change(struct sock *sk)
{
        void (*state_change)(struct sock *sk);
        struct rds_conn_path *cp;
        struct rds_tcp_connection *tc;

        read_lock_bh(&sk->sk_callback_lock);
        cp = sk->sk_user_data;
        if (!cp) {
                state_change = sk->sk_state_change;
                goto out;
        }
        tc = cp->cp_transport_data;
        state_change = tc->t_orig_state_change;

        rdsdebug("sock %p state_change to %d\n", tc->t_sock, sk->sk_state);

        switch (sk->sk_state) {
        /* ignore connecting sockets as they make progress */
        case TCP_SYN_SENT:
        case TCP_SYN_RECV:
                break;
        case TCP_ESTABLISHED:
                /* Force the peer to reconnect so that we have the
                 * TCP ports going from <smaller-ip>.<transient> to
                 * <larger-ip>.<RDS_TCP_PORT>. We avoid marking the
                 * RDS connection as RDS_CONN_UP until the reconnect,
                 * to avoid RDS datagram loss.
                 */
                if (rds_addr_cmp(&cp->cp_conn->c_laddr,
                                 &cp->cp_conn->c_faddr) >= 0 &&
                    rds_conn_path_transition(cp, RDS_CONN_CONNECTING,
                                             RDS_CONN_ERROR)) {
                        rds_conn_path_drop(cp, false);
                } else {
                        rds_connect_path_complete(cp, RDS_CONN_CONNECTING);
                }
                break;
        case TCP_CLOSING:
        case TCP_TIME_WAIT:
                if (wq_has_sleeper(&tc->t_recv_done_waitq))
                        wake_up(&tc->t_recv_done_waitq);
                break;
        case TCP_CLOSE_WAIT:
        case TCP_LAST_ACK:
        case TCP_CLOSE:
                if (wq_has_sleeper(&tc->t_recv_done_waitq))
                        wake_up(&tc->t_recv_done_waitq);
                rds_conn_path_drop(cp, false);
                break;
        default:
                break;
        }
out:
        read_unlock_bh(&sk->sk_callback_lock);
        state_change(sk);
}

int rds_tcp_conn_path_connect(struct rds_conn_path *cp)
{
        struct socket *sock = NULL;
        struct sockaddr_in6 sin6;
        struct sockaddr_in sin;
        struct sockaddr *addr;
        int port_low, port_high, port;
        int port_groups, groups_left;
        int addrlen;
        bool isv6;
        int ret;
        struct rds_connection *conn = cp->cp_conn;
        struct rds_tcp_connection *tc = cp->cp_transport_data;

        /* for multipath rds,we only trigger the connection after
         * the handshake probe has determined the number of paths.
         */
        if (cp->cp_index > 0 && cp->cp_conn->c_npaths < 2)
                return -EAGAIN;

        mutex_lock(&tc->t_conn_path_lock);

        if (rds_conn_path_up(cp)) {
                mutex_unlock(&tc->t_conn_path_lock);
                return 0;
        }
        if (ipv6_addr_v4mapped(&conn->c_laddr)) {
                ret = sock_create_kern(rds_conn_net(conn), PF_INET,
                                       SOCK_STREAM, IPPROTO_TCP, &sock);
                isv6 = false;
        } else {
                ret = sock_create_kern(rds_conn_net(conn), PF_INET6,
                                       SOCK_STREAM, IPPROTO_TCP, &sock);
                isv6 = true;
        }

        if (ret < 0)
                goto out;

        if (!rds_tcp_tune(sock)) {
                ret = -EINVAL;
                goto out;
        }

        if (isv6) {
                sin6.sin6_family = AF_INET6;
                sin6.sin6_addr = conn->c_laddr;
                sin6.sin6_port = 0;
                sin6.sin6_flowinfo = 0;
                sin6.sin6_scope_id = conn->c_dev_if;
                addr = (struct sockaddr *)&sin6;
                addrlen = sizeof(sin6);
        } else {
                sin.sin_family = AF_INET;
                sin.sin_addr.s_addr = conn->c_laddr.s6_addr32[3];
                sin.sin_port = 0;
                addr = (struct sockaddr *)&sin;
                addrlen = sizeof(sin);
        }

        /* encode cp->cp_index in lowest bits of source-port */
        inet_get_local_port_range(rds_conn_net(conn), &port_low, &port_high);
        port_low = ALIGN(port_low, RDS_MPATH_WORKERS);
        port_groups = (port_high - port_low + 1) / RDS_MPATH_WORKERS;
        ret = -EADDRINUSE;
        groups_left = port_groups;
        while (groups_left-- > 0 && ret) {
                if (++tc->t_client_port_group >= port_groups)
                        tc->t_client_port_group = 0;
                port =  port_low +
                        tc->t_client_port_group * RDS_MPATH_WORKERS +
                        cp->cp_index;

                if (isv6)
                        sin6.sin6_port = htons(port);
                else
                        sin.sin_port = htons(port);
                ret = kernel_bind(sock, (struct sockaddr_unsized *)addr,
                                  addrlen);
        }
        if (ret) {
                rdsdebug("bind failed with %d at address %pI6c\n",
                         ret, &conn->c_laddr);
                goto out;
        }

        if (isv6) {
                sin6.sin6_family = AF_INET6;
                sin6.sin6_addr = conn->c_faddr;
                sin6.sin6_port = htons(RDS_TCP_PORT);
                sin6.sin6_flowinfo = 0;
                sin6.sin6_scope_id = conn->c_dev_if;
                addr = (struct sockaddr *)&sin6;
                addrlen = sizeof(sin6);
        } else {
                sin.sin_family = AF_INET;
                sin.sin_addr.s_addr = conn->c_faddr.s6_addr32[3];
                sin.sin_port = htons(RDS_TCP_PORT);
                addr = (struct sockaddr *)&sin;
                addrlen = sizeof(sin);
        }

        /*
         * once we call connect() we can start getting callbacks and they
         * own the socket
         */
        rds_tcp_set_callbacks(sock, cp);
        ret = kernel_connect(sock, (struct sockaddr_unsized *)addr, addrlen, O_NONBLOCK);

        rdsdebug("connect to address %pI6c returned %d\n", &conn->c_faddr, ret);
        if (ret == -EINPROGRESS)
                ret = 0;
        if (ret == 0) {
                rds_tcp_keepalive(sock);
                sock = NULL;
        } else {
                rds_tcp_restore_callbacks(sock, cp->cp_transport_data);
        }

out:
        mutex_unlock(&tc->t_conn_path_lock);
        if (sock)
                sock_release(sock);
        return ret;
}

/*
 * Before killing the tcp socket this needs to serialize with callbacks.  The
 * caller has already grabbed the sending sem so we're serialized with other
 * senders.
 *
 * TCP calls the callbacks with the sock lock so we hold it while we reset the
 * callbacks to those set by TCP.  Our callbacks won't execute again once we
 * hold the sock lock.
 */
void rds_tcp_conn_path_shutdown(struct rds_conn_path *cp)
{
        struct rds_tcp_connection *tc = cp->cp_transport_data;
        struct socket *sock = tc->t_sock;
        struct sock *sk;
        unsigned int rounds;

        rdsdebug("shutting down conn %p tc %p sock %p\n",
                 cp->cp_conn, tc, sock);

        if (sock) {
                sk = sock->sk;
                if (rds_destroy_pending(cp->cp_conn))
                        sock_no_linger(sk);

                sock->ops->shutdown(sock, SHUT_WR);

                /* after sending FIN,
                 * wait until we processed all incoming messages
                 * and we're sure that there won't be any more:
                 * i.e. state CLOSING, TIME_WAIT, CLOSE_WAIT,
                 * LAST_ACK, or CLOSE (RFC 793).
                 *
                 * Give up waiting after 5 seconds and allow messages
                 * to theoretically get dropped, if the TCP transition
                 * didn't happen.
                 */
                rounds = 0;
                do {
                        /* we need to ensure messages are dequeued here
                         * since "rds_recv_worker" only dispatches messages
                         * while the connection is still in RDS_CONN_UP
                         * and there is no guarantee that "rds_tcp_data_ready"
                         * was called nor that "sk_data_ready" still points to
                         * it.
                         */
                        rds_tcp_recv_path(cp);
                } while (!wait_event_timeout(tc->t_recv_done_waitq,
                                (sk->sk_state == TCP_CLOSING ||
                                 sk->sk_state == TCP_TIME_WAIT ||
                                 sk->sk_state == TCP_CLOSE_WAIT ||
                                 sk->sk_state == TCP_LAST_ACK ||
                                 sk->sk_state == TCP_CLOSE) &&
                                skb_queue_empty_lockless(&sk->sk_receive_queue),
                                msecs_to_jiffies(100)) &&
                         ++rounds < 50);
                lock_sock(sk);

                /* discard messages that the peer received already */
                tc->t_last_seen_una = rds_tcp_snd_una(tc);
                rds_send_path_drop_acked(cp, rds_tcp_snd_una(tc),
                                         rds_tcp_is_acked);

                rds_tcp_restore_callbacks(sock, tc); /* tc->tc_sock = NULL */

                release_sock(sk);
                sock_release(sock);
        }

        if (tc->t_tinc) {
                rds_inc_put(&tc->t_tinc->ti_inc);
                tc->t_tinc = NULL;
        }
        tc->t_tinc_hdr_rem = sizeof(struct rds_header);
        tc->t_tinc_data_rem = 0;
}