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/* client.c */
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
/* Adresse für multicast IP */
static char *host_name = "224.0.0.1";
static int port = 6666;
static struct ip_mreq command;
static int setup_multicast_socket(void)
{
int loop = 1;
int socket_descriptor;
struct sockaddr_in sin;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = htonl(INADDR_ANY);
sin.sin_port = htons(port);
if ((socket_descriptor = socket(AF_INET,
SOCK_DGRAM, IPPROTO_UDP)) == -1) {
perror("socket()");
exit(EXIT_FAILURE);
}
/* Mehr Prozessen erlauben, denselben Port zu nutzen */
loop = 1;
if (setsockopt(socket_descriptor,
SOL_SOCKET,
SO_REUSEADDR, &loop, sizeof(loop)) < 0) {
perror("setsockopt:SO_REUSEADDR");
exit(EXIT_FAILURE);
}
if (bind(socket_descriptor, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
perror("bind");
exit(EXIT_FAILURE);
}
/* Broadcast auf dieser Maschine zulassen */
loop = 1;
if (setsockopt(socket_descriptor,
IPPROTO_IP,
IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0) {
perror("setsockopt:IP_MULTICAST_LOOP");
exit(EXIT_FAILURE);
}
/* Join the broadcast group: */
command.imr_multiaddr.s_addr = inet_addr(host_name);
command.imr_interface.s_addr = htonl(INADDR_ANY);
if (command.imr_multiaddr.s_addr == -1) {
perror("Keine Multicast-Adresse\n");
exit(EXIT_FAILURE);
}
if (setsockopt(socket_descriptor,
IPPROTO_IP,
IP_ADD_MEMBERSHIP, &command, sizeof(command)) < 0) {
perror("setsockopt:IP_ADD_MEMBERSHIP");
}
if(fcntl(socket_descriptor, F_SETFL, fcntl(socket_descriptor, F_GETFL) | O_NONBLOCK) < 0) {
perror("fcntl:SOCK_SET_NONBLOCK");
}
// memset(&sin, 0, sizeof(sin));
// sin.sin_family = AF_INET;
// sin.sin_port = htons(57286);
// inet_pton(AF_INET, "192.168.5.48", &sin.sin_addr);
// if (connect(socket_descriptor, (struct sockaddr *) &sin, sizeof(sin)) !=0 ) {
// perror ("connect()");
// }
return socket_descriptor;
}
int main(void)
{
int iter = 0;
socklen_t sin_len;
char message[256];
int socket;
struct sockaddr_in sin;
struct hostent *server_host_name;
if ((server_host_name = gethostbyname(host_name)) == 0) {
perror("gethostbyname");
exit(EXIT_FAILURE);
}
socket = setup_multicast_socket();
/* Broadcast-Nachrichten empfangen */
// while (iter++ <= 10) {
while (++iter <= INT_MAX) {
sin_len = sizeof(sin);
char addr[32];
int port;
while (!recvfrom(socket, message, 256, 0, (struct sockaddr *)&sin,
&sin_len)) {
}
inet_ntop(AF_INET, &sin.sin_addr, addr, 32);
port = ntohs(sin.sin_port);
printf("Message %d von %s:%d: %s\n", iter, addr, port, message);
sendto(socket, "Received your message", sizeof("Received your message"), 0, (struct sockaddr *)&sin,
sin_len);
}
/* Multicast-Socket aus der Gruppe entfernen */
if (setsockopt(socket,
IPPROTO_IP,
IP_DROP_MEMBERSHIP, &command, sizeof(command)) < 0) {
perror("setsockopt:IP_DROP_MEMBERSHIP");
}
close(socket);
return EXIT_SUCCESS;
}
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