C++：组播代码实现

以下为C++：组播代码实现

multicast_recver.cpp

// it's a demo to receive multicast udp data with the one of multi net interfaces....

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <iostream>

using namespace std;

#define MULTICAST_IP "224.0.1.135"

#define MULTICAST_PORT 60000

int main(void)
{
char recmsg[256];

int n;
int socket_fd;
struct sockaddr_in group_addr; //multicast address
struct sockaddr_in local_addr; //local address
struct ip_mreq mreq;
socklen_t addr_len = sizeof(group_addr);
u_int yes;

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

/*set up the local address*/
memset(&local_addr,0,sizeof(local_addr));
local_addr.sin_family = AF_INET;

// 设定本地监听必须是0.0.0.0 (htonl(INADDR_ANY)) 这里是关键！
local_addr.sin_addr.s_addr = inet_addr("0.0.0.0");

//this port must be the multicast port
local_addr.sin_port = htons(MULTICAST_PORT);

/*set reuse*/
if (setsockopt(socket_fd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(yes)) < 0)
{
perror("Reusing ADDR failed");
exit(1);
}

/*bind local address*/
if(bind(socket_fd,(struct sockaddr *)&local_addr,sizeof(local_addr)) == -1)
{
perror("Binding the multicast!");
exit(1);
}


//john in multicast
mreq.imr_multiaddr.s_addr=inet_addr(MULTICAST_IP);
//mreq.imr_interface.s_addr=htonl(INADDR_ANY);

  // 设定用本地新网卡地址来接收组播. 这里是关键！
mreq.imr_interface.s_addr=inet_addr("180.0.0.109");
if (setsockopt(socket_fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0)
{
perror("setsockopt multicast!");
exit(1);
}

/*set up the destination address*/
memset(&group_addr,0,sizeof(struct sockaddr_in));
group_addr.sin_family = AF_INET;
group_addr.sin_port = htons(MULTICAST_PORT);
group_addr.sin_addr.s_addr = inet_addr(MULTICAST_IP);

/*loop to send or recieve*/
while(1)
{

bzero(recmsg, sizeof(recmsg)-1);
n_len = recvfrom(socket_fd, recmsg, sizeof(recmsg)-1, 0,
(struct sockaddr *) &group_addr, &addr_len);
if (n_len < 0) {
printf("recvfrom err in udp talk!\n");
exit(4);
} else {
/* success recieve the information */
recmsg[n] = 0;
printf("peer:%s \n", recmsg);
}

}

return 0;
}

multicast_sender.cpp

#include <iostream>

#include <string.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <netinet/in.h>

using namespace std;

const int BUF_SIZE = 1024;

#define MULTICAST_IP "224.0.1.135"

#define MULTICAST_PORT 60000

int main()

{

int sockfd = socket(AF_INET, SOCK_DGRAM, 0);

if (sockfd == -1) {

perror("socket creation failed");

return 1;

}

struct sockaddr_in addr;

memset(&addr, 0, sizeof(addr));

addr.sin_family = AF_INET;

addr.sin_addr.s_addr = inet_addr(MULTICAST_IP);

addr.sin_port = htons(MULTICAST_PORT);

string message = "Hello, multicast!";

if (sendto(sockfd, message.c_str(), message.length(), 0, (struct sockaddr *)&addr, sizeof(addr)) == -1)

{

perror("sendto failed");

close(sockfd);

return 1;

}

else

{

cout << "Message sent successfully to " << multicast_ip << ":" << multicast_port << endl;

}

close(sockfd);

return 0;

}