Ubuntu下实现回射服务器-服务器端重启问题（二）教程

服务器端重启后会出现地址被占用的情况，主要原因是程序调用bind后的地址没被释放，服务端程序处于TIME\_WAIT状态，用netstat -an|grep TIME\_WAIT可以查看到，所以服务器端在绑定端口前要进行地址重用操作

 1 #include<stdio.h>
 2 #include <sys/types.h>          /* See NOTES */
 3 #include <sys/socket.h>
 4 #include <netinet/ip.h>
 5 #include <errno.h>
 6 #include <stdlib.h>
 7 #include <netinet/in.h>
 8 #include <arpa/inet.h>
 9 #include <unistd.h>
10 #include <string.h>
11 
12 int main(){
13     int socketfd;
14     socketfd=socket(PF_INET,SOCK_STREAM,0);
15     if(socketfd<0){
16         perror("socket");
17         exit(EXIT_FAILURE);
18     }
19 
20     struct sockaddr_in sockaddress;
21     sockaddress.sin_family=AF_INET;
22     sockaddress.sin_port=htons(5188);
23     sockaddress.sin_addr.s_addr=htonl(INADDR_ANY);//INADDR_ANY接收任何地址的连接
24     //sockaddress.sin_addr.s_addr=inet_addr("127.0.0.1");//也可以是这种方式
25 
26     int on=1;
27     if (setsockopt(socketfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on))<0){
28       perror("setsockopt");
29       exit(EXIT_FAILURE);
30     }
31 
32     if(bind(socketfd,(struct sockaddr*)&sockaddress,sizeof(sockaddress))<0){
33         perror("bind");
34         exit(EXIT_FAILURE);
35     }
36 
37     if ( listen(socketfd,SOMAXCONN)<0){
38         perror("listen");
39         exit(EXIT_FAILURE);
40     }
41 
42     int conn;
43     struct sockaddr_in peeraddr;
44     socklen_t len=sizeof(struct sockaddr_in);
45     conn=accept(socketfd,(struct sockaddr*)&peeraddr,&len);
46         if (conn<0){
47       perror("accept");
48       exit(EXIT_FAILURE);
49     }
50     printf("client ip:%s port:%d\n",inet_ntoa(peeraddr.sin_addr),ntohs(peeraddr.sin_port));
51 
52     char recvbuffer[1024];
53        while(1){
54      memset(recvbuffer,0,sizeof(recvbuffer));
55          read(conn,&recvbuffer,sizeof(recvbuffer));
56      fputs(recvbuffer,stdout);
57      write(conn,recvbuffer,strlen(recvbuffer));
58        }
59        close(socketfd);
60        close(conn);
61 
62        return 0;
63 
64 }

请关注这一句：

setsockopt(socketfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on)