lua-enet 5.3 for C++

enet.cpp

// Slightly modified(at least for lua5.3.4 and C++ compiler) version of love2D's lua-enet
// https://bitbucket.org/rude/love/src/6cd71997f82541ae1ef1338c8afe0d47f02f1189/src/libraries/enet/enet.cpp
// https://github.com/leafo/lua-enet (original lua-enet which is love2D's version based on)
/**
 *
 * Copyright (C) 2014 by Leaf Corcoran
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * 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 <stdlib.h>
#include <string.h>

extern "C"
{
    #define LUA_COMPAT_MODULE
    #include "lua.h"
    #include "lualib.h"
    #include "lauxlib.h"
    #include <enet/enet.h>
}

#define check_host(l, idx)\
	*(ENetHost**)luaL_checkudata(l, idx, "enet_host")

#define check_peer(l, idx)\
	*(ENetPeer**)luaL_checkudata(l, idx, "enet_peer")

/**
 * Parse address string, eg:
 *	*:5959
 *	127.0.0.1:*
 *	website.com:8080
 */
static void parse_address(lua_State *l, const char *addr_str, ENetAddress *address) {
    int host_i = 0, port_i = 0;
    char host_str[128] = {0};
    char port_str[32] = {0};
    int scanning_port = 0;
    
    char *c = (char *)addr_str;
    
    while (*c != 0) {
        if (host_i >= 128 || port_i >= 32 ) luaL_error(l, "Hostname too long");
        if (scanning_port) {
            port_str[port_i++] = *c;
        } else {
            if (*c == ':') {
                scanning_port = 1;
            } else {
                host_str[host_i++] = *c;
            }
        }
        c++;
    }
    host_str[host_i] = '\0';
    port_str[port_i] = '\0';
    
    if (host_i == 0) luaL_error(l, "Failed to parse address");
    if (port_i == 0) luaL_error(l, "Missing port in address");
    
    if (strcmp("*", host_str) == 0) {
        address->host = ENET_HOST_ANY;
    } else {
        if (enet_address_set_host(address, host_str) != 0) {
            luaL_error(l, "Failed to resolve host name");
        }
    }
    
    if (strcmp("*", port_str) == 0) {
        address->port = ENET_PORT_ANY;
    } else {
        address->port = atoi(port_str);
    }
}

/**
 * Find the index of a given peer for which we only have the pointer.
 */
static size_t find_peer_index(lua_State *l, ENetHost *enet_host, ENetPeer *peer) {
    size_t peer_index;
    for (peer_index = 0; peer_index < enet_host->peerCount; peer_index++) {
        if (peer == &(enet_host->peers[peer_index]))
            return peer_index;
    }
    
    luaL_error (l, "enet: could not find peer id!");
    
    return peer_index;
}

static void push_peer(lua_State *l, ENetPeer *peer) {
    // try to find in peer table
    lua_getfield(l, LUA_REGISTRYINDEX, "enet_peers");
    lua_pushlightuserdata(l, peer);
    lua_gettable(l, -2);
    
    if (lua_isnil(l, -1)) {
        // printf("creating new peer\n");
        lua_pop(l, 1);
        
        *(ENetPeer**)lua_newuserdata(l, sizeof(void*)) = peer;
        luaL_getmetatable(l, "enet_peer");
        lua_setmetatable(l, -2);
        
        lua_pushlightuserdata(l, peer);
        lua_pushvalue(l, -2);
        
        lua_settable(l, -4);
    }
    lua_remove(l, -2); // remove enet_peers
}

static void push_event(lua_State *l, ENetEvent *event) {
    lua_newtable(l); // event table
    
    if (event->peer) {
        push_peer(l, event->peer);
        lua_setfield(l, -2, "peer");
    }
    
    switch (event->type) {
        case ENET_EVENT_TYPE_CONNECT:
            lua_pushinteger(l, event->data);
            lua_setfield(l, -2, "data");
            
            lua_pushstring(l, "connect");
            break;
        case ENET_EVENT_TYPE_DISCONNECT:
            lua_pushinteger(l, event->data);
            lua_setfield(l, -2, "data");
            
            lua_pushstring(l, "disconnect");
            break;
        case ENET_EVENT_TYPE_RECEIVE:
            lua_pushlstring(l, (const char *)event->packet->data, event->packet->dataLength);
            lua_setfield(l, -2, "data");
            
            lua_pushinteger(l, event->channelID);
            lua_setfield(l, -2, "channel");
            
            lua_pushstring(l, "receive");
            
            enet_packet_destroy(event->packet);
            break;
        case ENET_EVENT_TYPE_NONE:
            lua_pushstring(l, "none");
            break;
    }
    
    lua_setfield(l, -2, "type");
}

/**
 * Read a packet off the stack as a string
 * idx is position of string
 */
static ENetPacket *read_packet(lua_State *l, int idx, enet_uint8 *channel_id) {
    size_t size;
    int argc = lua_gettop(l);
    const void *data = luaL_checklstring(l, idx, &size);
    ENetPacket *packet;
    
    enet_uint32 flags = ENET_PACKET_FLAG_RELIABLE;
    *channel_id = 0;
    
    if (argc >= idx+2 && !lua_isnil(l, idx+2)) {
        const char *flag_str = luaL_checkstring(l, idx+2);
        if (strcmp("unsequenced", flag_str) == 0) {
            flags = ENET_PACKET_FLAG_UNSEQUENCED;
        } else if (strcmp("reliable", flag_str) == 0) {
            flags = ENET_PACKET_FLAG_RELIABLE;
        } else if (strcmp("unreliable", flag_str) == 0) {
            flags = 0;
        } else {
            luaL_error(l, "Unknown packet flag: %s", flag_str);
        }
    }
    
    if (argc >= idx+1 && !lua_isnil(l, idx+1)) {
        *channel_id = (int) luaL_checknumber(l, idx+1);
    }
    
    packet = enet_packet_create(data, size, flags);
    if (packet == NULL) {
        luaL_error(l, "Failed to create packet");
    }
    
    return packet;
}

/**
 * Create a new host
 * Args:
 *	address (nil for client)
 *	[peer_count = 64]
 *	[channel_count = 1]
 *	[in_bandwidth = 0]
 *	[out_bandwidth = 0]
 */
static int host_create(lua_State *l) {
    ENetHost *host;
    size_t peer_count = 64, channel_count = 1;
    enet_uint32 in_bandwidth = 0, out_bandwidth = 0;
    
    int have_address = 1;
    ENetAddress address;
    
    if (lua_gettop(l) == 0 || lua_isnil(l, 1)) {
        have_address = 0;
    } else {
        parse_address(l, luaL_checkstring(l, 1), &address);
    }
    
    switch (lua_gettop(l)) {
        case 5:
            if (!lua_isnil(l, 5)) out_bandwidth = (int) luaL_checknumber(l, 5);
        case 4:
            if (!lua_isnil(l, 4)) in_bandwidth = (int) luaL_checknumber(l, 4);
        case 3:
            if (!lua_isnil(l, 3)) channel_count = (int) luaL_checknumber(l, 3);
        case 2:
            if (!lua_isnil(l, 2)) peer_count = (int) luaL_checknumber(l, 2);
    }
    
    // printf("host create, peers=%d, channels=%d, in=%d, out=%d\n",
    //		peer_count, channel_count, in_bandwidth, out_bandwidth);
    host = enet_host_create(have_address ? &address : NULL, peer_count,
                            channel_count, in_bandwidth, out_bandwidth);
    
    if (host == NULL) {
        lua_pushnil (l);
        lua_pushstring(l, "enet: failed to create host (already listening?)");
        return 2;
    }
    
    *(ENetHost**)lua_newuserdata(l, sizeof(void*)) = host;
    luaL_getmetatable(l, "enet_host");
    lua_setmetatable(l, -2);
    
    return 1;
}

static int linked_version(lua_State *l) {
    lua_pushfstring(l, "%d.%d.%d",
                    ENET_VERSION_GET_MAJOR(enet_linked_version()),
                    ENET_VERSION_GET_MINOR(enet_linked_version()),
                    ENET_VERSION_GET_PATCH(enet_linked_version()));
    return 1;
}

/**
 * Serice a host
 * Args:
 *	timeout
 *
 * Return
 *	nil on no event
 *	an event table on event
 */
static int host_service(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    ENetEvent event;
    int timeout = 0, out;
    
    if (lua_gettop(l) > 1)
        timeout = (int) luaL_checknumber(l, 2);
    
    out = enet_host_service(host, &event, timeout);
    if (out == 0) return 0;
    if (out < 0) return luaL_error(l, "Error during service");
    
    push_event(l, &event);
    return 1;
}

/**
 * Dispatch a single event if available
 */
static int host_check_events(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    ENetEvent event;
    int out = enet_host_check_events(host, &event);
    if (out == 0) return 0;
    if (out < 0) return luaL_error(l, "Error checking event");
    
    push_event(l, &event);
    return 1;
}

/**
 * Enables an adaptive order-2 PPM range coder for the transmitted data of
 * all peers.
 */
static int host_compress_with_range_coder(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    int result = enet_host_compress_with_range_coder (host);
    if (result == 0) {
        lua_pushboolean (l, 1);
    } else {
        lua_pushboolean (l, 0);
    }
    
    return 1;
}

/**
 * Connect a host to an address
 * Args:
 *	the address
 *	[channel_count = 1]
 *	[data = 0]
 */
static int host_connect(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    ENetAddress address;
    ENetPeer *peer;
    
    enet_uint32 data = 0;
    size_t channel_count = 1;
    
    parse_address(l, luaL_checkstring(l, 2), &address);
    
    switch (lua_gettop(l)) {
        case 4:
            if (!lua_isnil(l, 4)) data = (int) luaL_checknumber(l, 4);
        case 3:
            if (!lua_isnil(l, 3)) channel_count = (int) luaL_checknumber(l, 3);
    }
    
    // printf("host connect, channels=%d, data=%d\n", channel_count, data);
    peer = enet_host_connect(host, &address, channel_count, data);
    
    if (peer == NULL) {
        return luaL_error(l, "Failed to create peer");
    }
    
    push_peer(l, peer);
    
    return 1;
}

static int host_flush(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    enet_host_flush(host);
    return 0;
}

static int host_broadcast(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    enet_uint8 channel_id;
    ENetPacket *packet = read_packet(l, 2, &channel_id);
    enet_host_broadcast(host, channel_id, packet);
    return 0;
}

// Args: limit:number
static int host_channel_limit(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    int limit = (int) luaL_checknumber(l, 2);
    enet_host_channel_limit(host, limit);
    return 0;
}

static int host_bandwidth_limit(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    enet_uint32 in_bandwidth = (int) luaL_checknumber(l, 2);
    enet_uint32 out_bandwidth = (int) luaL_checknumber(l, 2);
    enet_host_bandwidth_limit(host, in_bandwidth, out_bandwidth);
    return 0;
}

static int host_get_socket_address(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    ENetAddress address;
    enet_socket_get_address (host->socket, &address);
    
    lua_pushfstring(l, "%d.%d.%d.%d:%d",
                    ((address.host) & 0xFF),
                    ((address.host >> 8) & 0xFF),
                    ((address.host >> 16) & 0xFF),
                    (address.host >> 24& 0xFF),
                    address.port);
    return 1;
}
static int host_total_sent_data(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    lua_pushinteger (l, host->totalSentData);
    
    return 1;
}

static int host_total_received_data(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    lua_pushinteger (l, host->totalReceivedData);
    
    return 1;
}
static int host_service_time(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    lua_pushinteger (l, host->serviceTime);
    
    return 1;
}

static int host_peer_count(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    lua_pushinteger (l, host->peerCount);
    
    return 1;
}

static int host_get_peer(lua_State *l) {
    ENetHost *host = check_host(l, 1);
    if (!host) {
        return luaL_error(l, "Tried to index a nil host!");
    }
    
    int peer_index = (int) luaL_checknumber(l, 2) - 1;
    
    if (peer_index < 0 || ((size_t) peer_index) >= host->peerCount) {
        luaL_argerror (l, 2, "Invalid peer index");
    }
    
    ENetPeer *peer = &(host->peers[peer_index]);
    
    push_peer (l, peer);
    return 1;
}

static int host_gc(lua_State *l) {
    // We have to manually grab the userdata so that we can set it to NULL.
    ENetHost** host = (ENetHost**)luaL_checkudata(l, 1, "enet_host");
    // We don't want to crash by destroying a non-existant host.
    if (*host) {
        enet_host_destroy(*host);
    }
    *host = NULL;
    return 0;
}

static int peer_tostring(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    char host_str[128];
    enet_address_get_host_ip(&peer->address, host_str, 128);
    
    lua_pushstring(l, host_str);
    lua_pushstring(l, ":");
    lua_pushinteger(l, peer->address.port);
    lua_concat(l, 3);
    return 1;
}

static int peer_ping(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    enet_peer_ping(peer);
    return 0;
}

static int peer_throttle_configure(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    enet_uint32 interval = (int) luaL_checknumber(l, 2);
    enet_uint32 acceleration = (int) luaL_checknumber(l, 3);
    enet_uint32 deceleration = (int) luaL_checknumber(l, 4);
    
    enet_peer_throttle_configure(peer, interval, acceleration, deceleration);
    return 0;
}

static int peer_round_trip_time(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    if (lua_gettop(l) > 1) {
        enet_uint32 round_trip_time = (int) luaL_checknumber(l, 2);
        peer->roundTripTime = round_trip_time;
    }
    
    lua_pushinteger (l, peer->roundTripTime);
    
    return 1;
}

static int peer_last_round_trip_time(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    if (lua_gettop(l) > 1) {
        enet_uint32 round_trip_time = (int) luaL_checknumber(l, 2);
        peer->lastRoundTripTime = round_trip_time;
    }
    lua_pushinteger (l, peer->lastRoundTripTime);
    
    return 1;
}

static int peer_ping_interval(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    if (lua_gettop(l) > 1) {
        enet_uint32 interval = (int) luaL_checknumber(l, 2);
        enet_peer_ping_interval (peer, interval);
    }
    
    lua_pushinteger (l, peer->pingInterval);
    
    return 1;
}

static int peer_timeout(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    enet_uint32 timeout_limit = 0;
    enet_uint32 timeout_minimum = 0;
    enet_uint32 timeout_maximum = 0;
    
    switch (lua_gettop(l)) {
        case 4:
            if (!lua_isnil(l, 4)) timeout_maximum = (int) luaL_checknumber(l, 4);
        case 3:
            if (!lua_isnil(l, 3)) timeout_minimum = (int) luaL_checknumber(l, 3);
        case 2:
            if (!lua_isnil(l, 2)) timeout_limit = (int) luaL_checknumber(l, 2);
    }
    
    enet_peer_timeout (peer, timeout_limit, timeout_minimum, timeout_maximum);
    
    lua_pushinteger (l, peer->timeoutLimit);
    lua_pushinteger (l, peer->timeoutMinimum);
    lua_pushinteger (l, peer->timeoutMaximum);
    
    return 3;
}

static int peer_disconnect(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    enet_uint32 data = lua_gettop(l) > 1 ? (int) luaL_checknumber(l, 2) : 0;
    enet_peer_disconnect(peer, data);
    return 0;
}

static int peer_disconnect_now(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    enet_uint32 data = lua_gettop(l) > 1 ? (int) luaL_checknumber(l, 2) : 0;
    enet_peer_disconnect_now(peer, data);
    return 0;
}

static int peer_disconnect_later(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    enet_uint32 data = lua_gettop(l) > 1 ? (int) luaL_checknumber(l, 2) : 0;
    enet_peer_disconnect_later(peer, data);
    return 0;
}

static int peer_index(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    size_t peer_index = find_peer_index (l, peer->host, peer);
    lua_pushinteger (l, peer_index + 1);
    
    return 1;
}

static int peer_state(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    switch (peer->state) {
        case (ENET_PEER_STATE_DISCONNECTED):
            lua_pushstring (l, "disconnected");
            break;
        case (ENET_PEER_STATE_CONNECTING):
            lua_pushstring (l, "connecting");
            break;
        case (ENET_PEER_STATE_ACKNOWLEDGING_CONNECT):
            lua_pushstring (l, "acknowledging_connect");
            break;
        case (ENET_PEER_STATE_CONNECTION_PENDING):
            lua_pushstring (l, "connection_pending");
            break;
        case (ENET_PEER_STATE_CONNECTION_SUCCEEDED):
            lua_pushstring (l, "connection_succeeded");
            break;
        case (ENET_PEER_STATE_CONNECTED):
            lua_pushstring (l, "connected");
            break;
        case (ENET_PEER_STATE_DISCONNECT_LATER):
            lua_pushstring (l, "disconnect_later");
            break;
        case (ENET_PEER_STATE_DISCONNECTING):
            lua_pushstring (l, "disconnecting");
            break;
        case (ENET_PEER_STATE_ACKNOWLEDGING_DISCONNECT):
            lua_pushstring (l, "acknowledging_disconnect");
            break;
        case (ENET_PEER_STATE_ZOMBIE):
            lua_pushstring (l, "zombie");
            break;
        default:
            lua_pushstring (l, "unknown");
    }
    
    return 1;
}

static int peer_connect_id(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    lua_pushinteger (l, peer->connectID);
    
    return 1;
}


static int peer_reset(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    enet_peer_reset(peer);
    return 0;
}

static int peer_receive(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    ENetPacket *packet;
    enet_uint8 channel_id = 0;
    
    if (lua_gettop(l) > 1) {
        channel_id = (int) luaL_checknumber(l, 2);
    }
    
    packet = enet_peer_receive(peer, &channel_id);
    if (packet == NULL) return 0;
    
    lua_pushlstring(l, (const char *)packet->data, packet->dataLength);
    lua_pushinteger(l, channel_id);
    
    enet_packet_destroy(packet);
    return 2;
}


/**
 * Send a lua string to a peer
 * Args:
 *	packet data, string
 *	channel id
 *	flags ["reliable", nil]
 *
 */
static int peer_send(lua_State *l) {
    ENetPeer *peer = check_peer(l, 1);
    
    enet_uint8 channel_id;
    ENetPacket *packet = read_packet(l, 2, &channel_id);
    
    // printf("sending, channel_id=%d\n", channel_id);
    int ret = enet_peer_send(peer, channel_id, packet);
    if (ret < 0) {
        enet_packet_destroy(packet);
    }
    
    lua_pushinteger(l, ret);
    
    return 1;
}

static const struct luaL_Reg enet_funcs [] = {
        {"host_create", host_create},
        {"linked_version", linked_version},
        {NULL, NULL}
};

static const struct luaL_Reg enet_host_funcs [] = {
        {"service", host_service},
        {"check_events", host_check_events},
        {"compress_with_range_coder", host_compress_with_range_coder},
        {"connect", host_connect},
        {"flush", host_flush},
        {"broadcast", host_broadcast},
        {"channel_limit", host_channel_limit},
        {"bandwidth_limit", host_bandwidth_limit},
        // Since ENetSocket isn't part of enet-lua, we should try to keep
        // naming conventions the same as the rest of the lib.
        {"get_socket_address", host_get_socket_address},
        // We need this function to free up our ports when needed!
        {"destroy", host_gc},
        
        // additional convenience functions (mostly accessors)
        {"total_sent_data", host_total_sent_data},
        {"total_received_data", host_total_received_data},
        {"service_time", host_service_time},
        {"peer_count", host_peer_count},
        {"get_peer", host_get_peer},
        {NULL, NULL}
};

static const struct luaL_Reg enet_peer_funcs [] = {
        {"disconnect", peer_disconnect},
        {"disconnect_now", peer_disconnect_now},
        {"disconnect_later", peer_disconnect_later},
        {"reset", peer_reset},
        {"ping", peer_ping},
        {"receive", peer_receive},
        {"send", peer_send},
        {"throttle_configure", peer_throttle_configure},
        {"ping_interval", peer_ping_interval},
        {"timeout", peer_timeout},
        
        // additional convenience functions to member variables
        {"index", peer_index},
        {"state", peer_state},
        {"connect_id", peer_connect_id},
        {"round_trip_time", peer_round_trip_time},
        {"last_round_trip_time", peer_last_round_trip_time},
        {NULL, NULL}
};

extern "C" int luaopen_enet(lua_State *l) {
    enet_initialize();
    atexit(enet_deinitialize);
    
    // create metatables
    luaL_newmetatable(l, "enet_host");
    lua_newtable(l); // index
    luaL_openlib(l, NULL, enet_host_funcs, 0);
    lua_setfield(l, -2, "__index");
    lua_pushcfunction(l, host_gc);
    lua_setfield(l, -2, "__gc");
    
    luaL_newmetatable(l, "enet_peer");
    lua_newtable(l);
    luaL_openlib(l, NULL, enet_peer_funcs, 0);
    lua_setfield(l, -2, "__index");
    lua_pushcfunction(l, peer_tostring);
    lua_setfield(l, -2, "__tostring");
    
    // set up peer table
    lua_newtable(l);
    
    lua_newtable(l); // metatable
    lua_pushstring(l, "v");
    lua_setfield(l, -2, "__mode");
    lua_setmetatable(l, -2);
    
    lua_setfield(l, LUA_REGISTRYINDEX, "enet_peers");
    
    luaL_openlib(l, NULL, enet_funcs, 0);
    
    // return the enet table created with luaL_register
    return 1;
}