Socket网络编程--聊天程序(2)

　　上一节简单如何通过Socket创建一个连接，然后进行通信。只是每个人只能说一句话。而且还是必须说完才会接收到信息，总之是很不方便的事情。所以这一小节我们将对上一次的程序进行修改，修改成每个人可以多说话，主要是通过Linux下多进程fork实现的。

　　一对一，server和client是每个人都可以多说几句话

　　由于控制台度数据的函数fgets是阻塞函数，要每个人都可以多说话，这里我使用的是读取和发送都在不同的进程里面，使之互相没有影响。

　　fork函数

　　#include <unistd.h>

　　pid_t fork(void);    //返回值：子进程中返回0，父进程中返回子进程ID，出错返回-1

　　client.c

 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>
 #include <string.h>
 #include <netdb.h> //for gethostbyname
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>

 #define MAX_BUF 4096
 #define SERVER_PORT 12138

 int main(int argc,char *argv[])
 {
     int sockfd;//socket
     char sendBuf[MAX_BUF],recvBuf[MAX_BUF];
     int sendSize,recvSize;//用于记录记录发送和接收到数据的大小
     struct hostent * host;
     struct sockaddr_in servAddr;
     char username[];
     char * p;
     int pid;

     if(argc != )
     {
         perror("use: ./client [hostname] [username]");
         exit(-);
     }
     p=username;
     strcpy(p,argv[]);
     printf("username:%s\n",username);
     host=gethostbyname(argv[]);
     if(host==NULL)
     {
         perror("fail to get host by name.");
         exit(-);
     }
     printf("Success to get host by name ...\n");

     //创建socket
     if((sockfd=socket(AF_INET,SOCK_STREAM,))==-)
     {
         perror("fail to establish a socket");
         exit();
     }
     printf("Success to establish a socket...\n");

     /*init sockaddr_in*/
     servAddr.sin_family=AF_INET;
     servAddr.sin_port=htons(SERVER_PORT);
     servAddr.sin_addr=*((struct in_addr *)host->h_addr);
     bzero(&(servAddr.sin_zero),);

     /*connect the socket*/
     if(connect(sockfd,(struct sockaddr *)&servAddr,sizeof(struct sockaddr_in))==-)
     {
         perror("fail to connect the socket");
         exit();
     }
     printf("Success to connect the socket...\n");

     //send-recv 一些返回指没有判断，具体可以看server.c
     if((pid=fork())<)
     {
         perror("fork error\n");
     }
     else if(pid>)/*child*/
     {
         while()
         {
             fgets(sendBuf,MAX_BUF,stdin);
             send(sockfd,sendBuf,strlen(sendBuf),);
             memset(sendBuf,,sizeof(sendBuf));
         }
     }
     else
     {
         while()
         {
             recv(sockfd,recvBuf,MAX_BUF,);
             printf("Server:%s\n",recvBuf);
             memset(recvBuf,,sizeof(recvBuf));
         }
     }

     return ;
 }

　　server.c

 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>
 #include <string.h>
 #include <netdb.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/un.h>
 #include <sys/ioctl.h>
 #include <sys/wait.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>

 #define SERVER_PORT 12138
 #define BACKLOG 20
 #define MAX_CON_NO 10
 #define MAX_DATA_SIZE 4096

 int main(int argc,char *argv[])
 {
     struct sockaddr_in serverSockaddr,clientSockaddr;
     char sendBuf[MAX_DATA_SIZE],recvBuf[MAX_DATA_SIZE];
     int sendSize,recvSize;
     int sockfd,clientfd;
     int on=;
     int sinSize=;
     char username[];
     int pid;

     if(argc != )
     {
         printf("usage: ./server [username]\n");
         exit();
     }
     strcpy(username,argv[]);
     printf("username:%s\n",username);

     /*establish a socket*/
     if((sockfd = socket(AF_INET,SOCK_STREAM,))==-)
     {
         perror("fail to establish a socket");
         exit();
     }
     printf("Success to establish a socket...\n");

     /*init sockaddr_in*/
     serverSockaddr.sin_family=AF_INET;
     serverSockaddr.sin_port=htons(SERVER_PORT);
     serverSockaddr.sin_addr.s_addr=htonl(INADDR_ANY);
     bzero(&(serverSockaddr.sin_zero),);

     setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on));

     /*bind socket*/
     if(bind(sockfd,(struct sockaddr *)&serverSockaddr,sizeof(struct sockaddr))==-)
     {
         perror("fail to bind");
         exit();
     }
     printf("Success to bind the socket...\n");

     /*listen on the socket*/
     if(listen(sockfd,BACKLOG)==-)
     {
         perror("fail to listen");
         exit();
     }

     /*accept a client's request*/  //这里的sinSize还没有处理，具体看下一节
     if((clientfd=accept(sockfd,(struct sockaddr  *)&clientSockaddr, &sinSize))==-)
     {
         perror("fail to accept");
         exit();
     }
     printf("Success to accpet a connection request...\n");
     printf(" %s join in!\n",inet_ntoa(clientSockaddr.sin_addr));

     if((pid=fork())<)
     {
         perror("fork error\n");
     }
     else if(pid>)/*child*/
     {
         /*send datas to client*/
         while()
         {
             fgets(sendBuf,MAX_DATA_SIZE,stdin);
             if((sendSize=send(clientfd,sendBuf,strlen(sendBuf),))!=strlen(sendBuf))
             {
                 perror("fail to send datas");
                 exit();
             }
             printf("Success to send datas\n");
             memset(sendBuf,,MAX_DATA_SIZE);
         }
     }
     else
     {
         while()
         {
             /*receive datas from client*/
             if((recvSize=recv(clientfd,recvBuf,MAX_DATA_SIZE,))==-)
             {
                 perror("fail to receive datas");
                 exit();
             }
             printf("Client:%s\n",recvBuf);
             memset(recvBuf,,MAX_DATA_SIZE);
         }

     }

     return ;
 }

　　本文地址: http://www.cnblogs.com/wunaozai/p/3870194.html