Linux里UDP协议 广播和接收测试 C语言

UDP协议是面向无连接的，和TCP比起来少了繁琐的三次握手，但是在安全性上没有保障，不过对于聊天来说一般都是用的这个，下面是一个测试UDP协议的简单实验：

server：

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/types.h>          /* See NOTES */#include <sys/socket.h>    //socket() #include <netinet/in.h>   // inet_addr()#include <arpa/inet.h>#include <unistd.h>        // read()/ write#include <errno.h>extern int errno;int main(int argc, char *argv[]){   int fd = socket(AF_INET, SOCK_DGRAM, 0);   fprintf(stderr, "socket id = %d\n", fd);   // 地址复用   int on = 1;   setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));   struct sockaddr_in servaddr;   servaddr.sin_family = AF_INET;   if(argc == 2)      servaddr.sin_port =  htons(atoi(argv[1]));   else      servaddr.sin_port   = htons(8877);   servaddr.sin_addr.s_addr = htonl(INADDR_ANY); // 0.0.0.0   //servaddr.sin_addr.s_addr = htonl(127.0.0.1); // 0.0.0.0   int ret = bind(fd, (struct sockaddr *)&servaddr, sizeof(servaddr));   if(ret < 0)   {      fprintf(stderr, "error:%s\n", strerror(errno));      close(fd);      return -1;   }   struct sockaddr_in peer;  // 保存对方的地址信息   socklen_t size;   char buff[1024];   int cnt;   char ip[16];   while(1)   {      bzero(&peer, sizeof(peer));      size = sizeof(peer);      //recv      cnt = recvfrom(fd, buff, 1024, 0, (struct sockaddr *)&peer, &size);      printf("ip:%s, port:%d\n", inet_ntoa(peer.sin_addr), ntohs(peer.sin_port));      inet_ntop(AF_INET, &(peer.sin_addr), ip, 16);      printf("ip:%s, port:%d\n", ip, ntohs(peer.sin_port));      printf("recv: %s\n", buff);      if(cnt <= 0)         fprintf(stderr, "recv error or end\n");      else         sendto(fd, buff, cnt, 0, (struct sockaddr *)&peer, sizeof(peer));   }   close(fd);   return 0;}

broad：

#include<stdio.h>#include<stdlib.h>#include<string.h>#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#include<unistd.h>#include<errno.h>int main(int argc,char *argv[]){   int fd = socket(AF_INET,SOCK_DGRAM,0);    int on = 1;   setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on));   int br =1;   setsockopt(fd,SOL_SOCKET,SO_BROADCAST,&br,sizeof(br));   struct sockaddr_in broadcast;   broadcast.sin_family = AF_INET;   broadcast.sin_port = htons(8877);   broadcast.sin_addr.s_addr = inet_addr("255.255.255.255");   char *pts = "Dge";   while(1)   {      sendto(fd,pts,strlen(pts)+1,0,(struct sockaddr *)&broadcast,sizeof(broadcast));      sleep(1);   }      close(fd);   return 0;}