udp.c

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 /* -- Includes -- */
/* system libraries */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
/* project libraries */
#include "udp.h"
#include "config.h"
#include "def.h"

 /* -- Defines -- */

/* -- Functions -- */


int udp_init_broadcast(udp_t *udp)
{
    // Local variables
    int broadcastEnable = 1;

    // Open socket
    if((udp->sd_send = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == s_ERROR) {
        printf("udp_init_broadcast: could not open a send socket.\n");
        return s_ERROR;
    }

    // Enable broadcast
    if(setsockopt(udp->sd_send, SOL_SOCKET, SO_BROADCAST, &broadcastEnable, sizeof(broadcastEnable)) == s_ERROR) {
        printf("udp_init_broadcast: could not enable broadcast.\n");
        return s_ERROR;
    }

    // Configure IP and port
    memset((char *) &udp->sock_send, 0, sizeof(udp->sock_send));
    udp->sock_send.sin_family = AF_INET;
    udp->sock_send.sin_port = htons(udp->port);

    if(inet_pton(AF_INET, udp->broadcast_ip, &udp->sock_send.sin_addr) == s_ERROR) {
        printf("udp_init_broadcast: inet_pton failed.\n");
        return s_ERROR;
    }


    return s_OK;
}

int udp_init_receive(udp_t *udp)
{
    // Open socket
    if((udp->sd_recv = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == s_ERROR) {
        printf("udp_init_receive: could not open a receive socket.\n");
        return s_ERROR;
    }

    // Configure IP and port
    memset((char *) &udp->sock_recv, 0, sizeof(udp->sock_recv));
    udp->sock_recv.sin_family = AF_INET;
    udp->sock_recv.sin_port = htons(udp->port);
    udp->sock_recv.sin_addr.s_addr = htonl(INADDR_ANY);

    // Bind socket
    if(bind(udp->sd_recv, (struct sockaddr *)&udp->sock_recv, sizeof(udp->sock_recv)) == s_ERROR) {
        printf("udp_init_receive: could not bind a socket.\n");
        return s_ERROR;
    }

    // Sender socket len
    udp->sock_conn_len = sizeof(udp->sock_conn);

    return s_OK;
}

udp_t *udp_open(char *broadcast_ip, int port, int packet_size)
{
    // Allocate memory for UDP structure
    udp_t *udp = (udp_t *)malloc(sizeof(udp_t));

    strcpy(udp->broadcast_ip, broadcast_ip);
    udp->port = port;
    udp->packet_size = packet_size;

    // Initialize broadcasting
    if(udp_init_broadcast(udp) == s_ERROR)
        return NULL;

    // Initialize reception
    if(udp_init_receive(udp) == s_ERROR)
        return NULL;

    return udp;
}

int udp_close(udp_t *udp)
{
    int res;

    // Close sockets
    res = close(udp->sd_send);
    res += close(udp->sd_recv);

    // Free memory
    free(udp);

    if(res < 0)
    {
        printf("udp_close: could not close UDP sockets.\n");
        return s_ERROR;
    }
    else
    {
        return s_OK;
    }
}

int udp_broadcast(udp_t *udp, char *packet, int len)
{

    // Broadcast UDP packet/datagram
    if(sendto(udp->sd_send, packet, len, 0, (struct sockaddr *)&udp->sock_send, sizeof(udp->sock_send)) == s_ERROR) {
        printf("udp_broadcast: could not send UDP packet.\n");
        return s_ERROR;
    }

    return s_OK;
}

int udp_receive(udp_t *udp, char *packet, int *len)
{
    // Local variables
    int n;
    struct timeval tv;

    // Configure timer for select()
    tv.tv_sec = 0;
    tv.tv_usec = 1000;
    fd_set infds;
    FD_ZERO(&infds);
    FD_SET(udp->sd_recv, &infds);

    // Receive
    // while
    if((n = select(udp->sd_recv + 1, &infds, NULL, NULL, &tv)))
    {
        // Receive packet/datagram
        if((*len = recvfrom(    udp->sd_recv,
                                packet,
                                udp->packet_size,
                                0,
                                (struct sockaddr *)&udp->sock_conn,
                                &udp->sock_conn_len)) == s_ERROR)
        {
            printf("udp_receive: could not receive UDP packet.\n");
            return s_ERROR;
        }

        // End string
        packet[*len] = '\0';

        // Print received packet content and information
        /*printf("recv from %s:%d - data: %s\n",
            inet_ntoa(udp->sock_conn.sin_addr),
            ntohs(udp->sock_conn.sin_port),
            packet);*/

        return s_OK;
    }

    return s_ERROR;
}