Linux组播编程

$cat receiver.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <string.h>

#define HELLO_PORT  8888
#define HELLO_GROUP "239.1.1.1"
#define MSGBUFSIZE 256

int main(int argc, char *argv[])
{
    struct sockaddr_in addr;
    int fd, nbytes,addrlen;
    struct ip_mreq mreq;
    char msgbuf[MSGBUFSIZE];
    u_int yes=1;

    if ((fd=socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
        perror("socket");
        exit(1);
    }

    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
    {
        perror("Reusing ADDR failed");
        exit(1);
    }

    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(HELLO_PORT);

    if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0)
    {
        perror("bind");
        exit(1);
    }

    mreq.imr_multiaddr.s_addr = inet_addr(HELLO_GROUP);
    mreq.imr_interface.s_addr = htonl(INADDR_ANY);
    if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
    {
        perror("setsockopt");
        exit(1);
    }

    while (1)
    {
        addrlen=sizeof(addr);
        if ((nbytes=recvfrom(fd, msgbuf, MSGBUFSIZE, 0, \
            (struct sockaddr *)&addr, (socklen_t *)&addrlen)) < 0)
        {
            perror("recvfrom");
            exit(1);
        }
        puts(msgbuf);
    }

    return 0;
}

$cat sender.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <string.h>

#define HELLO_PORT 8888
#define HELLO_GROUP "239.1.1.1"
int main(int argc, char *argv[])
{
    struct sockaddr_in addr;
    int fd, cnt;
    struct ip_mreq mreq;
    char *message = "Hello, World!";

    if ((fd=socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
        perror("socket");
        exit(1);
    }

    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr(HELLO_GROUP);
    addr.sin_port=htons(HELLO_PORT);

    while (1)
    {
        if (sendto(fd,message, strlen(message), 0, (struct sockaddr *)&addr, sizeof(addr)) < 0)
        {
            perror("sendto");
            exit(1);
        }
        sleep(1);
    }

    return 0;
}

注意： 需要交换机开启组播相关配置。