/*
 * Copyright (C) Ambroz Bizjak <ambrop7@gmail.com>
 * Contributions:
 * Transparent DNS: Copyright (C) Kerem Hadimli <kerem.hadimli@gmail.com>
 * 
 * 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 name of the author nor the
 *    names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 
 * 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 AUTHOR 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 <misc/debug.h>
#include <base/BLog.h>

#include <tun2socks/SocksUdpGwClient.h>

#include <generated/blog_channel_SocksUdpGwClient.h>

static void free_socks (SocksUdpGwClient *o);
static void try_connect (SocksUdpGwClient *o);
static void reconnect_timer_handler (SocksUdpGwClient *o);
static void socks_client_handler (SocksUdpGwClient *o, int event);
static void udpgw_handler_servererror (SocksUdpGwClient *o);
static void udpgw_handler_received (SocksUdpGwClient *o, BAddr local_addr, BAddr remote_addr, const uint8_t *data, int data_len);

static void free_socks (SocksUdpGwClient *o)
{
    ASSERT(o->have_socks)
    
    // disconnect udpgw client from SOCKS
    if (o->socks_up) {
        UdpGwClient_DisconnectServer(&o->udpgw_client);
    }
    
    // free SOCKS client
    BSocksClient_Free(&o->socks_client);
    
    // set have no SOCKS
    o->have_socks = 0;
}

static void try_connect (SocksUdpGwClient *o)
{
    ASSERT(!o->have_socks)
    ASSERT(!BTimer_IsRunning(&o->reconnect_timer))
    
    // init SOCKS client
    if (!BSocksClient_Init(&o->socks_client, o->socks_server_addr, o->auth_info, o->num_auth_info, o->remote_udpgw_addr, (BSocksClient_handler)socks_client_handler, o, o->reactor)) {
        BLog(BLOG_ERROR, "BSocksClient_Init failed");
        goto fail0;
    }
    
    // set have SOCKS
    o->have_socks = 1;
    
    // set SOCKS not up
    o->socks_up = 0;
    
    return;
    
fail0:
    // set reconnect timer
    BReactor_SetTimer(o->reactor, &o->reconnect_timer);
}

static void reconnect_timer_handler (SocksUdpGwClient *o)
{
    DebugObject_Access(&o->d_obj);
    ASSERT(!o->have_socks)
    
    // try connecting
    try_connect(o);
}

static void socks_client_handler (SocksUdpGwClient *o, int event)
{
    DebugObject_Access(&o->d_obj);
    ASSERT(o->have_socks)
    
    switch (event) {
        case BSOCKSCLIENT_EVENT_UP: {
            ASSERT(!o->socks_up)
            
            BLog(BLOG_INFO, "SOCKS up");
            
            // connect udpgw client to SOCKS
            if (!UdpGwClient_ConnectServer(&o->udpgw_client, BSocksClient_GetSendInterface(&o->socks_client), BSocksClient_GetRecvInterface(&o->socks_client))) {
                BLog(BLOG_ERROR, "UdpGwClient_ConnectServer failed");
                goto fail0;
            }
            
            // set SOCKS up
            o->socks_up = 1;
            
            return;
            
        fail0:
            // free SOCKS
            free_socks(o);
            
            // set reconnect timer
            BReactor_SetTimer(o->reactor, &o->reconnect_timer);
        } break;
        
        case BSOCKSCLIENT_EVENT_ERROR:
        case BSOCKSCLIENT_EVENT_ERROR_CLOSED: {
            BLog(BLOG_INFO, "SOCKS error");
            
            // free SOCKS
            free_socks(o);
            
            // set reconnect timer
            BReactor_SetTimer(o->reactor, &o->reconnect_timer);
        } break;
        
        default: ASSERT(0);
    }
}

static void udpgw_handler_servererror (SocksUdpGwClient *o)
{
    DebugObject_Access(&o->d_obj);
    ASSERT(o->have_socks)
    ASSERT(o->socks_up)
    
    BLog(BLOG_ERROR, "client reports server error");
    
    // free SOCKS
    free_socks(o);
    
    // set reconnect timer
    BReactor_SetTimer(o->reactor, &o->reconnect_timer);
}

static void udpgw_handler_received (SocksUdpGwClient *o, BAddr local_addr, BAddr remote_addr, const uint8_t *data, int data_len)
{
    DebugObject_Access(&o->d_obj);
    
    // submit to user
    o->handler_received(o->user, local_addr, remote_addr, data, data_len);
    return;
}

int SocksUdpGwClient_Init (SocksUdpGwClient *o, int udp_mtu, int max_connections, int send_buffer_size, btime_t keepalive_time,
                           BAddr socks_server_addr, const struct BSocksClient_auth_info *auth_info, size_t num_auth_info,
                           BAddr remote_udpgw_addr, btime_t reconnect_time, BReactor *reactor, void *user,
                           SocksUdpGwClient_handler_received handler_received)
{
    // see asserts in UdpGwClient_Init
    ASSERT(!BAddr_IsInvalid(&socks_server_addr))
    ASSERT(remote_udpgw_addr.type == BADDR_TYPE_IPV4 || remote_udpgw_addr.type == BADDR_TYPE_IPV6)
    
    // init arguments
    o->udp_mtu = udp_mtu;
    o->socks_server_addr = socks_server_addr;
    o->auth_info = auth_info;
    o->num_auth_info = num_auth_info;
    o->remote_udpgw_addr = remote_udpgw_addr;
    o->reactor = reactor;
    o->user = user;
    o->handler_received = handler_received;
    
    // init udpgw client
    if (!UdpGwClient_Init(&o->udpgw_client, udp_mtu, max_connections, send_buffer_size, keepalive_time, o->reactor, o,
                          (UdpGwClient_handler_servererror)udpgw_handler_servererror,
                          (UdpGwClient_handler_received)udpgw_handler_received
    )) {
        goto fail0;
    }
    
    // init reconnect timer
    BTimer_Init(&o->reconnect_timer, reconnect_time, (BTimer_handler)reconnect_timer_handler, o);
    
    // set have no SOCKS
    o->have_socks = 0;
    
    // try connecting
    try_connect(o);
    
    DebugObject_Init(&o->d_obj);
    return 1;
    
fail0:
    return 0;
}

void SocksUdpGwClient_Free (SocksUdpGwClient *o)
{
    DebugObject_Free(&o->d_obj);
    
    // free SOCKS
    if (o->have_socks) {
        free_socks(o);
    }
    
    // free reconnect timer
    BReactor_RemoveTimer(o->reactor, &o->reconnect_timer);
    
    // free udpgw client
    UdpGwClient_Free(&o->udpgw_client);
}

void SocksUdpGwClient_SubmitPacket (SocksUdpGwClient *o, BAddr local_addr, BAddr remote_addr, int is_dns, const uint8_t *data, int data_len)
{
    DebugObject_Access(&o->d_obj);
    // see asserts in UdpGwClient_SubmitPacket
    
    // submit to udpgw client
    UdpGwClient_SubmitPacket(&o->udpgw_client, local_addr, remote_addr, is_dns, data, data_len);
}