cachesyncd/multicast.c

/***************************************************************************
 *   Copyright (C) 06/2006 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   This program 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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program 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 this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "configfile.h"
#include "logging.h"

#define DEFAULT_DEVICE	"eth0"
#define DEFAULT_GROUP	"224.0.0.1"
#define DEFAULT_PORT	2000

static struct sockaddr_in dest_addr;

int mcast_init()
{
	struct ip_mreq multiaddr;
	struct ifreq ifr;

	// open socket
	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sockfd == -1) {
		log_print(LOG_ERROR, "mcast_init: socket()");
		return -1;
	}

	// get device flags
	char *mcastdev = config_get_string("global", "mcastdev", DEFAULT_DEVICE);
	strncpy(ifr.ifr_name, mcastdev, sizeof(ifr.ifr_name));
	if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) != 0) {
		log_print(LOG_WARN, "mcast_init: ioctl(SIOCGIFFLAGS)");
		close(sockfd);
		return -1;
	}

	// check device flags
	if ((ifr.ifr_flags & (IFF_UP | IFF_MULTICAST)) != (IFF_UP | IFF_MULTICAST)) {
		log_print(LOG_WARN, "mcast_init: device %s not up");
		close(sockfd);
		return -1;
	}

	if (setsockopt(sockfd, SOL_SOCKET, SO_BINDTODEVICE, ifr.ifr_name, sizeof(ifr.ifr_name)) < 0) {
		log_print(LOG_WARN, "mcast_init: setsockopt(SO_BINDTODEVICE)");
//		close(sockfd);
//		return -1;
	}

	char *mcastgroup = config_get_string("global", "mcastgroup", DEFAULT_GROUP);
	int mcastport = config_get_int("global", "mcastport", DEFAULT_PORT);

	dest_addr.sin_family = AF_INET;
	inet_aton(mcastgroup, &dest_addr.sin_addr);
	dest_addr.sin_port = htons(mcastport);

	if (bind(sockfd, (struct sockaddr*)&dest_addr, sizeof(dest_addr)) < 0) {
		log_print(LOG_WARN, "mcast_init: bind()");
		close(sockfd);
		return -1;
	}

	// get interface address
	if (ioctl(sockfd, SIOCGIFADDR, &ifr) != 0) {
		log_print(LOG_WARN, "mcast_init: ioctl(SIOCGIFADDR)");
		close(sockfd);
		return -1;
	}

	// check address family
	if (ifr.ifr_addr.sa_family != AF_INET) {
		log_print(LOG_WARN, "mcast_init: unknown address family");
		close(sockfd);
		return -1;
	}

	char loop = 0;
	if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop))) {
		log_print(LOG_WARN, "mcast_init: setsockopt(IP_MULTICAST_LOOP)");
		close(sockfd);
		return -1;
	}

	inet_aton(mcastgroup, &multiaddr.imr_multiaddr);
	multiaddr.imr_interface.s_addr = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;

	if (setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
			&multiaddr, sizeof(multiaddr)) == -1) {
		log_print(LOG_WARN, "mcast_init: setsockopt(IP_ADD_MEMBERSHIP)");
		close(sockfd);
		return -1;
	}

	return sockfd;
}

int mcast_send(int sock, char *buf, int len)
{
	return sendto(sock, buf, len, MSG_NOSIGNAL, (const struct sockaddr*)&dest_addr, sizeof(dest_addr));
}

void msock_close(int sock)
{
	close(sock);
}