UDP---广播的实现

服务器端：指定客户端为地址为.255的广播，端口号固定，给sfd给广播权限
客户端：必须固定端口地址和服务器发送的广播端口一致；

server：

  1 #include<stdio.h>
  2 #include<netinet/in.h>
  3 #include<stdlib.h>
  4 #include<unistd.h>
  5 #include<sys/types.h>
  6 #include<sys/socket.h>
  7 #include<assert.h>
  8 #include<arpa/inet.h>
  9 #include<string.h>
 10 #include<ctype.h>
 11 #define BUFF_SIZE 64
 12 #define BROADCAST "192.168.1.255"
 13 int main(int argc, char*argv[])
 14 {
 15     if(argc < 3)
 16     {
 17         printf("argc less 3\n");
 18         exit(1);
 19     }
 20     const char * ip=argv[1];
 21     int port=atoi(argv[2]);
 22 
 23     struct sockaddr_in saddr,caddr;
 24 
 25     int sfd = socket(AF_INET,SOCK_DGRAM,0);
 26 
 27     int flag;
 28     setsockopt(sfd,SOL_SOCKET,SO_BROADCAST,&flag,sizeof(flag));
 29 
 30     bzero(&saddr,sizeof(saddr));
 31     saddr.sin_family=AF_INET;
 32     saddr.sin_port=htons(port);
 33     inet_pton(AF_INET,ip,&saddr.sin_addr.s_addr);
 34     int ret = bind(sfd,(struct sockaddr*)&saddr,sizeof(saddr));
 35     assert(ret != -1);
 36 
 37     char buff[BUFF_SIZE],str[BUFF_SIZE];
 38     int i=0;
 39     memset(buff,'\0',BUFF_SIZE);
 40 
 41 
 42     bzero(&caddr,sizeof(saddr));
 43     caddr.sin_family=AF_INET;
 44     caddr.sin_port=htons(9000);
 45     inet_pton(AF_INET,BROADCAST,&saddr.sin_addr.s_addr);
 46     while(1)
 47     {
 48         sprintf(buff,"server message %d \b",i++);
 49         sendto(sfd,buff,strlen(buff),0,(struct sockaddr*)&caddr,sizeof(caddr));
 50         printf("send buff = %s\n",buff);
 51         sleep(1);
 52     }
 53 
 54     close(sfd);
 55     return 0;
 56 }

执行服务器：
send buff = server message 0
send buff = server message 1
send buff = server message 2
send buff = server message 3
send buff = server message 4
send buff = server message 5
send buff = server message 6
send buff = server message 7
send buff = server message 8
send buff = server message 9
send buff = server message 10

client

 1 #include<stdio.h>
  2 #include<netinet/in.h>
  3 #include<stdlib.h>
  4 #include<sys/types.h>
  5 #include<sys/socket.h>
  6 #include<assert.h>
  7 #include<arpa/inet.h>
  8 #include<string.h>
  9 #include<unistd.h>
 10 #include<ctype.h>
 11 #define BUFF_SIZE 64
 12 int main(int argc, char*argv[])
 13 {
 14     const char * ip="0.0.0.0";
 15     int port=atoi("9000");
 16 
 17     struct sockaddr_in caddr;
 18     caddr.sin_family=AF_INET;
 19     caddr.sin_port=htons(port);
 20     inet_pton(AF_INET,ip,&caddr.sin_addr.s_addr);
 21 
 22     int cfd = socket(AF_INET,SOCK_DGRAM,0);
 23     bind(cfd,(struct sockaddr*)&caddr,sizeof(caddr));
 24     char buff[BUFF_SIZE],str[BUFF_SIZE];
 25     int i;
 26     memset(buff,'\0',BUFF_SIZE);
 27     while(1)
 28     {
 29 
 30         int ret = recvfrom(cfd,buff,BUFF_SIZE-1,0,NULL,NULL);
 31         assert(ret!=-1);
 32         write(STDOUT_FILENO,buff,ret);
 33         printf("\n");
 34 
 35     }
 36 
 37     return 0;
 38 }

执行客户端：
server message 0
server message 1
server message 2
server message 3
server message 4
server message 5
server message 6
server message 7
server message 8
server message 9

来源：CSDN

作者：YanWenCheng_

链接：https://blog.csdn.net/YanWenCheng_/article/details/104359792