【网络编程】Linux多播简单实现

#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char *argv[])
{
    if (argc != 3)
    {
        printf("Usage:./exec [multicast_ip] [port]\n");
        exit(-1);
    }
    struct sockaddr_in servsend;
    socklen_t len = sizeof(struct sockaddr_in);
    int ret;
    
    int sendfd = socket(AF_INET, SOCK_DGRAM, 0);
    /* 目的地址为多播地址 */
    servsend.sin_addr.s_addr = inet_addr(argv[1]);
    servsend.sin_port = htons(atoi(argv[2]));
    servsend.sin_family = AF_INET;

    u_char off = 1;
/*开启外出数据包的回馈*/
    setsockopt(sendfd, IPPROTO_IP, IP_MULTICAST_LOOP, &off, sizeof(off));

    /* 选择多播外出接口 */
    char buf[256];
    struct in_addr in;
    in.s_addr = inet_addr("192.168.1.115");
    setsockopt(sendfd, IPPROTO_IP, IP_MULTICAST_IF, &in, sizeof(in));

    
    while (1)
    {
        sprintf(buf, "I am random [%d]", (int)random()%100);
        ret = sendto(sendfd, buf, strlen(buf), 0, (struct sockaddr *)&servsend, len);
        if (ret < 0)
        {
            printf("sendto error\n");
            exit(-1);
        }
        sleep(2);
    }
    return 0;
}

#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[])
{
if (argc != 3)
{
printf("Usage:./exec [multicast_ip] [port]\n");
exit(-1);
}
int ret;
struct sockaddr_in servrecv;
int len = sizeof(servrecv);
int recvfd = socket(AF_INET, SOCK_DGRAM, 0);
const int on = 1;
ret = setsockopt(recvfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
if (ret < 0)
{
printf("setsockopt error\n");
exit(-1);
}

servrecv.sin_port = htons(atoi(argv[2]));
servrecv.sin_addr.s_addr = htonl(INADDR_ANY);
servrecv.sin_family = AF_INET;
ret = bind(recvfd, (struct sockaddr *)&servrecv, len);

if (ret < 0)
{
printf("bind error\n");
exit(-1);
}

/* 加入多播组 */
struct ip_mreq mreq;
mreq.imr_multiaddr.s_addr = inet_addr(argv[1]);
mreq.imr_interface.s_addr = inet_addr("192.168.1.115");
ret = setsockopt(recvfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));

if (ret < 0)
{
printf("setsockopt error(2)\n");
exit(-1);
}
struct sockaddr_in in;
while (1)
{
char buf[256];
memset(buf, 0, 256);
len = sizeof(in);
ret = recvfrom(recvfd, buf, 256, 0, (struct sockaddr *)&in, &len);
if (ret < 0)
{
printf("recvfrom error\n");
exit(-1);
}
printf("%s\n", buf);
}
return 0;
}