广播、组播 socket编程，附带可以编译运行的例子

#define SERV_PORT 9090

#define MULTICAST_IP "192.168.11.170"

#define BUFSIZE 128

 

int fd = -1;

 

/* 1. 创建socket fd */

if ((fd = socket (AF_INET, SOCK_DGRAM, 0)) < 0) {        //udp程序

    perror ("socket");

    exit (1);

}

 

/* 2. 绑定IP地址和端口号 */

struct sockaddr_in sin;

memset(&sin, 0, sizeof(sin))

sin.sin_family = AF_INET;

sin.sin_port = htons(SERV_PORT);                 // 网络字节序的端口号

sin.sin_addr.s_addr = htonl(INADDR_ANY);    // 服务端可以绑定任意IP

if (bind (fd, (struct sockaddr *) &sin, sizeof (sin)) < 0) {

    perror ("bind");

    exit (1);

}

 

/* 3. 创建多播组，初始化多播组结构体 */

struct ip_mreq mreq;

memset(&mreq, 0, sizeof(mreq))

mreq.imr_multiaddr.s_addr = inet_addr(MULTICAST_IP);

mreq.imr_interface.s_addr = htonl(INADDR_ANY);

 

/* 4. 把当前套接字加入到多播组 */

setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));

 

/* 5. 接收数据 */

char buf[BUFSIZE ];

struct sockaddr_in cin;

socklen_t addrlen = sizeof(cin);

recvfrom (fd, buf, BUFSIZE - 1, 0, (struct sockaddr *)&cin, &addrlen);

#define DST_PORT 9090

 

/* 1. 创建socket fd */

if ((fd = socket (AF_INET, SOCK_DGRAM, 0)) < 0) {        //UDP编程

    perror ("socket");

    exit (1);

}

 

/* 2. 允许广播设置 */

int b_br = 1;

setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &b_br, sizeof(int));

 

/*3. 指定目标IP和端口号填充 */

struct sockaddr_in sin;

memset(&sin, 0, sizeof(sin))

sin.sin_family = AF_INET;

sin.sin_port = htons (SERV_PORT);                          //网络字节序的端口号

sin.sin_addr.s_addr = inet_addr("192.168.11.255");    // 广播地址

 

 

/*4. 发送数据 */

char buf[128] = {'1','2','3','4','5','6','\0'};

sendto (fd, buf, strlen(buf), 0, (struct sockaddr *)&sin, sizeof(sin));

/* Send Multicast Datagram code example. */



#include <sys/types.h>



#include <sys/socket.h>



#include <arpa/inet.h>



#include <netinet/in.h>



#include <stdio.h>



#include <stdlib.h>



struct in_addr localInterface;



struct sockaddr_in groupSock;



int sd;



char databuf[1024] = "Multicast test message lol!";



int datalen = sizeof(databuf);



 



int main (int argc, char *argv[ ])



{



/* Create a datagram socket on which to send. */



sd = socket(AF_INET, SOCK_DGRAM, 0);



if(sd < 0)



{



  perror("Opening datagram socket error");



  exit(1);



}



else



  printf("Opening the datagram socket...OK.\n");



 



/* Initialize the group sockaddr structure with a */



/* group address of 225.1.1.1 and port 5555. */



memset((char *) &groupSock, 0, sizeof(groupSock));



groupSock.sin_family = AF_INET;



groupSock.sin_addr.s_addr = inet_addr("226.1.1.1");



groupSock.sin_port = htons(4321);



 



/* Disable loopback so you do not receive your own datagrams.



{



char loopch = 0;



if(setsockopt(sd, IPPROTO_IP, IP_MULTICAST_LOOP, (char *)&loopch, sizeof(loopch)) < 0)



{



perror("Setting IP_MULTICAST_LOOP error");



close(sd);



exit(1);



}



else



printf("Disabling the loopback...OK.\n");



}



*/



 



/* Set local interface for outbound multicast datagrams. */



/* The IP address specified must be associated with a local, */



/* multicast capable interface. */



localInterface.s_addr = inet_addr("203.106.93.94");



if(setsockopt(sd, IPPROTO_IP, IP_MULTICAST_IF, (char *)&localInterface, sizeof(localInterface)) < 0)



{



  perror("Setting local interface error");



  exit(1);



}



else



  printf("Setting the local interface...OK\n");



/* Send a message to the multicast group specified by the*/



/* groupSock sockaddr structure. */



/*int datalen = 1024;*/



if(sendto(sd, databuf, datalen, 0, (struct sockaddr*)&groupSock, sizeof(groupSock)) < 0)



{perror("Sending datagram message error");}



else



  printf("Sending datagram message...OK\n");



 



/* Try the re-read from the socket if the loopback is not disable



if(read(sd, databuf, datalen) < 0)



{



perror("Reading datagram message error\n");



close(sd);



exit(1);



}



else



{



printf("Reading datagram message from client...OK\n");



printf("The message is: %s\n", databuf);



}



*/



return 0;



}

#include "fun_interface.h"

#include <unistd.h> 

#include <string>

struct in_addr localInterface;

struct sockaddr_in groupSock;

int sd;

char databuf[1024] = "Multicast test message lol!";



int datalen = sizeof(databuf);



typedef struct {

    std::string dip;

    int sock;

    struct sockaddr_in gsock;

} test_item_t;



test_item_t sock_items[] = {

{

    .dip = "225.0.0.128"

},

{

    .dip = "225.0.0.120"

},

{

    .dip = "225.0.0.111"

},

{

    .dip = "225.0.0.110"

},

{

    .dip = "239.202.0.11"

},

{

    .dip = "239.202.255.251"

}

};



int init_sock()

{

    int sd;

    int items_size = sizeof(sock_items)/sizeof(test_item_t);

    printf("== size:%d\n",items_size);

    for(int i = 0;i < items_size;i ++) {

        sd = socket(AF_INET, SOCK_DGRAM, 0);

        if(sd < 0) {

            perror("Opening datagram socket error");

            return -1;

        } else {

            printf("open socket ....ok\n");

            sock_items[i].sock = sd;

        }



        memset((char *) &sock_items[i].gsock, 0, sizeof(sock_items[i].gsock));

        sock_items[i].gsock.sin_family = AF_INET;

        //groupSock.sin_addr.s_addr = inet_addr("226.1.1.1");

        sock_items[i].gsock.sin_addr.s_addr = inet_addr(sock_items[i].dip.c_str());

        sock_items[i].gsock.sin_port = htons(4321);



        localInterface.s_addr = inet_addr("192.168.1.12");

        //localInterface.s_addr = inet_addr("172.16.16.90");



        if(setsockopt(sd, IPPROTO_IP, IP_MULTICAST_IF, (char *)&localInterface, sizeof(localInterface)) < 0){

            perror("Setting local interface error");

            return -1;

        }else

            printf("Setting the local interface...OK\n");

    }



    return 0;

}



int main()

{

    int items_size = sizeof(sock_items)/sizeof(test_item_t);

    

    if(init_sock() != 0) {

        exit(1);

    }

    /* Send a message to the multicast group specified by the*/

    /* groupSock sockaddr structure. */

    /*int datalen = 1024;*/

    for(int i = 0;i < 100;i ++) {

        for(int j = 0;j < items_size;j ++ ) {

            if(sendto(sock_items[j].sock, databuf, datalen, 0, (struct sockaddr*)&sock_items[j].gsock, sizeof(sock_items[j].gsock)) < 0) {

                perror("Sending datagram message error");

            } else

                printf("Sending datagram message...OK\n");

        }

        sleep(3);

    }

   

    return 0;

}