udp.c

/* udp.c
 * By Ron
 * Created August, 2008
 *
 * (See LICENSE.txt)
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef WIN32
#include <winsock2.h>
#else
#include <netdb.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#endif

#include "udp.h"

int udp_create_socket(uint16_t port, char *local_address)
{
	int    s;
	int    value = 1;
	struct sockaddr_in sox;

	s = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);

	if(s < 0)
		nbdie("udp: couldn't create socket");

	if(setsockopt(s, SOL_SOCKET, SO_BROADCAST, (void*)&value, sizeof(int)) < 0)
		nbdie("udp: couldn't set socket to SO_BROADCAST");

	sox.sin_addr.s_addr = inet_addr(local_address);
	sox.sin_family      = AF_INET;
	sox.sin_port        = htons(port);

    if(sox.sin_addr.s_addr == INADDR_NONE)
		nbdie("udp: couldn't parse local address");

	if(bind(s, (struct sockaddr *)&sox, sizeof(struct sockaddr_in)) < 0)
		nbdie("udp: couldn't bind to port (are you running as root?)");

	return s;
}

size_t udp_read(int s, void *buffer, size_t buffer_length, struct sockaddr_in *from)
{
	size_t received;
	socklen_t fromlen = sizeof(struct sockaddr_in);

	memset(from, 0, sizeof(struct sockaddr));

	received = recvfrom(s, buffer, buffer_length, 0, (struct sockaddr *)from, &fromlen);

	if( received < 0 )
		nbdie("udp: couldn't receive data");

	return received;
}

void udp_send(int sock, char *address, uint16_t port, void *data, size_t length)
{
	int    result;
	struct sockaddr_in serv_addr;
	struct hostent *server;

	/* Look up the host */
	server = gethostbyname(address);
	if(!server)
	{
		fprintf(stderr, "Couldn't find host %s\n", address);
	}
	else
	{
		/* Set up the server address */
		memset(&serv_addr, '\0', sizeof(serv_addr));
		serv_addr.sin_family = AF_INET;
		serv_addr.sin_port   = htons(port);
		memcpy(&serv_addr.sin_addr, server->h_addr_list[0], server->h_length);

		result = sendto(sock, data, length, 0, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr_in));

		if( result < 0 )
			nbdie("udp: couldn't send data");
	}
}

int udp_close(int s)
{
#ifdef WIN32
	return closesocket(s);
#else
	return close(s);
#endif
}