toxcore/core/network.c

/* network.h
 *
 * Functions for the core networking.
 *
 *  Copyright (C) 2013 Tox project All Rights Reserved.
 *
 *  This file is part of Tox.
 *
 *  Tox is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Tox is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with Tox.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "network.h"

/* returns current UNIX time in microseconds (us). */
uint64_t current_time(void)
{
    uint64_t time;
#ifdef WIN32
    /* This probably works fine */
    FILETIME ft;
    GetSystemTimeAsFileTime(&ft);
    time = ft.dwHighDateTime;
    time <<= 32;
    time |= ft.dwLowDateTime;
    time -= 116444736000000000UL;
    return time / 10;
#else
    struct timeval a;
    gettimeofday(&a, NULL);
    time = 1000000UL * a.tv_sec + a.tv_usec;
    return time;
#endif
}

/* return a random number
   NOTE: this function should probably not be used where cryptographic randomness is absolutely necessary */
uint32_t random_int(void)
{
#ifndef VANILLA_NACL
    //NOTE: this function comes from libsodium
    return randombytes_random();
#else
    return random();
#endif
}

/* our UDP socket, a global variable. */
static int sock;

/* Basic network functions:
   Function to send packet(data) of length length to ip_port */
int sendpacket(IP_Port ip_port, uint8_t *data, uint32_t length)
{
    ADDR addr = {AF_INET, ip_port.port, ip_port.ip};
    return sendto(sock, (char *) data, length, 0, (struct sockaddr *)&addr, sizeof(addr));
}

/* Function to receive data, ip and port of sender is put into ip_port
   the packet data into data
   the packet length into length.
   dump all empty packets. */
static int receivepacket(IP_Port *ip_port, uint8_t *data, uint32_t *length)
{
    ADDR addr;
#ifdef WIN32
    int addrlen = sizeof(addr);
#else
    uint32_t addrlen = sizeof(addr);
#endif
    (*(int32_t *)length) = recvfrom(sock, (char *) data, MAX_UDP_PACKET_SIZE, 0, (struct sockaddr *)&addr, &addrlen);

    if (*(int32_t *)length <= 0)
        return -1; /* nothing received or empty packet */

    ip_port->ip = addr.ip;
    ip_port->port = addr.port;
    return 0;
}

static packet_handler_callback packethandlers[256] = {0};

void networking_registerhandler(uint8_t byte, packet_handler_callback cb)
{
    packethandlers[byte] = cb;
}

void networking_poll()
{
    IP_Port ip_port;
    uint8_t data[MAX_UDP_PACKET_SIZE];
    uint32_t length;

    while (receivepacket(&ip_port, data, &length) != -1) {
        if (length < 1) continue;

        if (!packethandlers[data[0]]) continue;

        packethandlers[data[0]](ip_port, data, length);
    }
}

/* initialize networking
   bind to ip and port
   ip must be in network order EX: 127.0.0.1 = (7F000001)
   port is in host byte order (this means don't worry about it)
   returns 0 if no problems
   returns -1 if there are problems */
int init_networking(IP ip, uint16_t port)
{
#ifdef WIN32
    WSADATA wsaData;

    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != NO_ERROR)
        return -1;

#else
    srandom((uint32_t)current_time());
#endif
    srand((uint32_t)current_time());

    /* initialize our socket */
    sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

    /* Check for socket error */
#ifdef WIN32

    if (sock == INVALID_SOCKET) /* MSDN recommends this */
        return -1;

#else

    if (sock < 0)
        return -1;

#endif

    /* Functions to increase the size of the send and receive UDP buffers
       NOTE: uncomment if necessary */
    /*
    int n = 1024 * 1024 * 2;
    if(setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char*)&n, sizeof(n)) == -1)
    {
        return -1;
    }

    if(setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char*)&n, sizeof(n)) == -1)
        return -1;
    */

    /* Enable broadcast on socket */
    int broadcast = 1;
    setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (char *)&broadcast, sizeof(broadcast));

    /* Set socket nonblocking */
#ifdef WIN32
    /* I think this works for windows */
    u_long mode = 1;
    /* ioctl(sock, FIONBIO, &mode); */
    ioctlsocket(sock, FIONBIO, &mode);
#else
    fcntl(sock, F_SETFL, O_NONBLOCK, 1);
#endif

    /* Bind our socket to port PORT and address 0.0.0.0 */
    ADDR addr = {AF_INET, htons(port), ip};
    bind(sock, (struct sockaddr *)&addr, sizeof(addr));

    return 0;
}

/* function to cleanup networking stuff */
void shutdown_networking(void)
{
#ifdef WIN32
    closesocket(sock);
    WSACleanup();
#else
    close(sock);
#endif
    return;
}

/*
  resolve_addr():
    address should represent IPv4 or a hostname with A record

    returns a data in network byte order that can be used to set IP.i or IP_Port.ip.i
    returns 0 on failure

    TODO: Fix ipv6 support
*/
uint32_t resolve_addr(const char *address)
{
    struct addrinfo *server = NULL;
    struct addrinfo  hints;
    int              rc;
    uint32_t         addr;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family   = AF_INET;    // IPv4 only right now.
    hints.ai_socktype = SOCK_DGRAM; // type of socket Tox uses.

    rc = getaddrinfo(address, "echo", &hints, &server);

    // Lookup failed.
    if (rc != 0) {
        return 0;
    }

    // IPv4 records only..
    if (server->ai_family != AF_INET) {
        freeaddrinfo(server);
        return 0;
    }


    addr = ((struct sockaddr_in *)server->ai_addr)->sin_addr.s_addr;

    freeaddrinfo(server);
    return addr;
}