news_receiver.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 30

void error_handling(char *buf)
{
	fputs(buf, stderr);
	fputc('\n',stderr);
	exit(1);
}

int main(int argc, char const *argv[])
{
	int recv_sock;
	int str_len =0;
	char buf[BUF_SIZE];
	struct sockaddr_in adr;
	struct ip_mreq join_adr;

	if (argc != 3)
	{
		printf("Usage : %s <GroupIP> <port>\n", argv[0]);
		exit(1);
	}

	recv_sock = socket(PF_INET, SOCK_DGRAM, 0);
	memset(&adr, 0, sizeof(adr));
	adr.sin_family = AF_INET;
	adr.sin_addr.s_addr = htonl(INADDR_ANY);
	adr.sin_port = htons(atoi(argv[2]));    

	if(bind(recv_sock, (struct sockaddr*)&adr, sizeof(adr)) == -1)
		error_handling("bind error");

	inet_aton(argv[1],&join_adr.imr_multiaddr);
	join_adr.imr_interface.s_addr = htonl(INADDR_ANY);

	setsockopt(recv_sock, IPPROTO_TP, IP_ADD_MEMBERSHIP, (void*)&join_adr, sizeof(join_adr));

	while(1)
	{
		// fputs("&str_len",stdout);
		str_len = recvfrom(recv_sock, buf, BUF_SIZE-1, 0, NULL, 0);
		// printf("%d\n", str_len);
		if(str_len < 0)
			break;
		buf[str_len] = 0;
		fputs(buf, stdout);
	}
	close(recv_sock);
	return 0;
}