linux下c 實現udp組播模式

組播：傳送的資訊，小組內所有成員都能同時接受到。

組播發送端跟接收端的具體流程為：

傳送方：

a.建立socket

socket_fd=socket(af_inet,sock_dgram,0);

if(socket_fd < 0)

/*set up the destination address*/

memset(&group_addr,0,sizeof(struct sockaddr_in));
group_addr.sin_family = af_inet;
group_addr.sin_port = htons(group_port);
group_addr.sin_addr.s_addr = inet_addr("230.1.1.1");

if (sendto  (socket_fd, recmsg, strlen(recmsg), 0,  (struct sockaddr *) &group_addr,

sizeof(struct sockaddr_in)) < 0)

1.建立socket

socket_fd=socket(af_inet,sock_dgram,0);

if(socket_fd < 0)

/* allow multiple sockets to use the same port number */

if(setsockopt(socket_fd,sol_socket,so_reuseaddr,&yes,sizeof(yes))
< 0)

/*set up the local address*/

memset(&local_addr,0,sizeof(local_addr));
local_addr.sin_family = af_inet;
local_addr.sin_addr.s_addr = htonl(inaddr_any);
local_addr.sin_port = htons(group_port);              //this port must be the group port

/*bind

local address*/
if(bind(socket_fd,(struct sockaddr *)&local_addr,sizeof(local_addr)) == -1)

/*use the setsocketopt() to request joining the multicast group*/

mreq.imr_multiaddr.s_addr=inet_addr(group_ip);
mreq.imr_inte***ce.s_addr=htonl(inaddr_any);

if(setsockopt(socket_fd,ipproto_ip,ip_add_membership,&mreq,sizeof(mreq))

< 0)

bzero(recmsg, sizeof(recmsg)-1);

n = recvfrom(socket_fd, recmsg, sizeof(recmsg)-1, 0,(struct sockaddr *)&group_addr, &addr_len);
if (n < 0)  else

傳送方：

#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using
namespace
std;
int main(void)
/* allow multiple sockets to use the same port number */
if (setsockopt(socket_fd,sol_socket,so_reuseaddr,&yes,sizeof(yes)) < 0)
/*set up the destination address*/
memset(&group_addr,0,sizeof(struct sockaddr_in));
group_addr.sin_family = af_inet;
group_addr.sin_port = htons(group_port);
group_addr.sin_addr.s_addr = inet_addr("230.1.1.1");
/*set up the local address*/
memset(&local_addr,0,sizeof(local_addr));
local_addr.sin_family = af_inet;
local_addr.sin_addr.s_addr = htonl(inaddr_any);
local_addr.sin_port = htons(group_port);              //this port must be the group port
/*bind local address*/
if(bind(socket_fd,(struct sockaddr *)&local_addr,sizeof(local_addr)) == -1)
/*use the setsocketopt() to request joining the multicast group*/
mreq.imr_multiaddr.s_addr=inet_addr(group_ip);
mreq.imr_inte***ce.s_addr=htonl(inaddr_any);
if (setsockopt(socket_fd,ipproto_ip,ip_add_membership,&mreq,sizeof(mreq)) < 0)
/*loop to send or recieve*/
while(1)
if (sendto  (socket_fd, recmsg, strlen(recmsg), 0,  (struct sockaddr *) &group_addr,
sizeof(struct sockaddr_in)) < 0)
printf("'%s' send ok\n", recmsg);
}}

#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using
namespace
std;
int main(void)
/* allow multiple sockets to use the same port number */
if (setsockopt(socket_fd,sol_socket,so_reuseaddr,&yes,sizeof(yes)) < 0)
/*set up the destination address*/
memset(&group_addr,0,sizeof(struct sockaddr_in));
group_addr.sin_family = af_inet;
group_addr.sin_port = htons(group_port);
group_addr.sin_addr.s_addr = inet_addr("230.1.1.1");
/*set up the local address*/
memset(&local_addr,0,sizeof(local_addr));
local_addr.sin_family = af_inet;
local_addr.sin_addr.s_addr = htonl(inaddr_any);
local_addr.sin_port = htons(group_port);              //this port must be the group port
/*bind local address*/
if(bind(socket_fd,(struct sockaddr *)&local_addr,sizeof(local_addr)) == -1)
/*use the setsocketopt() to request joining the multicast group*/
mreq.imr_multiaddr.s_addr=inet_addr(group_ip);
mreq.imr_inte***ce.s_addr=htonl(inaddr_any);
if (setsockopt(socket_fd,ipproto_ip,ip_add_membership,&mreq,sizeof(mreq)) < 0)
/*loop to send or recieve*/
while(1)
else 
}}

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