UDP编程之三

 1 #include <apue.h>
 2 
 3 #define PORT 8088
 4 
 5 #define MULTIIP "225.0.0.1"
 6 
 7 int main(int argc,char **argv)
 8 {
 9     if(argc!=2)
10     {
11         printf("%s <msg>\n",argv[0]);
12         exit(0);
13     }
14 
15     int sockfd;
16     if((sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)
17         ERR("socket failed");
18     
19     struct sockaddr_in peer;
20     CLEAR(peer);
21     peer.sin_family = AF_INET;
22     peer.sin_port = htons(PORT);
23     inet_pton(AF_INET,MULTIIP,&peer.sin_addr);
24 
25     if(sendto(sockfd,argv[1],strlen(argv[1]),0,(struct sockaddr*)&peer,sizeof(peer))<0)
26         ERR("send failed");
27     
28     close(sockfd);
29     return 0;
30 }

 1 #include <apue.h>
 2 
 3 #define PORT 8088
 4 #define MULTIIP "225.0.0.1"
 5 
 6 int main(int argc,char **argv)
 7 {
 8     int sockfd;
 9     if((sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)
10         ERR("socket failed");
11     
12     struct sockaddr_in ipv4;
13     CLEAR(ipv4);
14     ipv4.sin_family = AF_INET;
15     ipv4.sin_port = htons(PORT);
16     ipv4.sin_addr.s_addr = htonl(INADDR_ANY);
17     if(bind(sockfd,(struct sockaddr*)&ipv4,sizeof(ipv4))<0)
18         ERR("bind failed");
19         
20     //加入组
21     #if 0
22     struct ip_mreq{    
23         struct in_addr imr_multiaddr;   /* IP multicast address of group */
24         struct in_addr imr_interface;   /* local IP address of interface */;
25     }
26     #endif
27     struct ip_mreq mreq;
28     inet_pton(AF_INET,MULTIIP,&mreq.imr_multiaddr);
29     mreq.imr_interface.s_addr = INADDR_ANY;
30     if(setsockopt(sockfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq))<0)
31         ERR("setsockopt failed");
32 
33     int n;
34     char buf[255];
35     while(1)
36     {
37         if((n = recvfrom(sockfd,buf,sizeof(buf),0,NULL,NULL))<0)
38             ERR("recv failed");
39         buf[n] = 0;
40         printf("%s\n",buf);
41     }
42 
43     //离开组
44     if(setsockopt(sockfd,IPPROTO_IP,IP_DROP_MEMBERSHIP,&mreq,sizeof(mreq))<0)
45         ERR("setsockopt failed");
46 
47     close(sockfd);
48     return 0;
49 }