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[32];
    char * p;
    int pid;

    if(argc != 3)
    {
        perror("use: ./client [hostname] [username]");
        exit(-1);
    }
    p=username;
    strcpy(p,argv[2]);
    printf("username:%s
",username);
    host=gethostbyname(argv[1]);
    if(host==NULL)
    {
        perror("fail to get host by name.");
        exit(-1);
    }
    printf("Success to get host by name ...
");

    //创建socket
    if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
    {
        perror("fail to establish a socket");
        exit(1);
    }
    printf("Success to establish a socket...
");

    /*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),8);

    /*connect the socket*/
    if(connect(sockfd,(struct sockaddr *)&servAddr,sizeof(struct sockaddr_in))==-1)
    {
        perror("fail to connect the socket");
        exit(1);
    }
    printf("Success to connect the socket...
");

    //send-recv 一些返回指没有判断，具体可以看server.c
    if((pid=fork())<0)
    {
        perror("fork error
");
    }
    else if(pid>0)/*child*/
    {
        while(1)
        {
            fgets(sendBuf,MAX_BUF,stdin);
            send(sockfd,sendBuf,strlen(sendBuf),0);
            memset(sendBuf,0,sizeof(sendBuf));
        }
    }
    else
    {
        while(1)
        {
            recv(sockfd,recvBuf,MAX_BUF,0);
            printf("Server:%s
",recvBuf);
            memset(recvBuf,0,sizeof(recvBuf));
        }
    }

    return 0;
}

　　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=1;
    int sinSize=0;
    char username[32];
    int pid;

    if(argc != 2)
    {
        printf("usage: ./server [username]
");
        exit(1);
    }
    strcpy(username,argv[1]);
    printf("username:%s
",username);

    /*establish a socket*/
    if((sockfd = socket(AF_INET,SOCK_STREAM,0))==-1)
    {
        perror("fail to establish a socket");
        exit(1);
    }
    printf("Success to establish a socket...
");

    /*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),8);

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

    /*bind socket*/
    if(bind(sockfd,(struct sockaddr *)&serverSockaddr,sizeof(struct sockaddr))==-1)
    {
        perror("fail to bind");
        exit(1);
    }
    printf("Success to bind the socket...
");

    /*listen on the socket*/
    if(listen(sockfd,BACKLOG)==-1)
    {
        perror("fail to listen");
        exit(1);
    }

    /*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))==-1) 
    {
        perror("fail to accept");
        exit(1);
    }
    printf("Success to accpet a connection request...
");
    printf(" %s join in!
",inet_ntoa(clientSockaddr.sin_addr));

    if((pid=fork())<0)
    {
        perror("fork error
");
    }
    else if(pid>0)/*child*/
    {
        /*send datas to client*/
        while(1)
        {
            fgets(sendBuf,MAX_DATA_SIZE,stdin);
            if((sendSize=send(clientfd,sendBuf,strlen(sendBuf),0))!=strlen(sendBuf))
            {
                perror("fail to send datas");
                exit(1);
            }
            printf("Success to send datas
");
            memset(sendBuf,0,MAX_DATA_SIZE);
        }
    }
    else
    {
        while(1)
        {
            /*receive datas from client*/
            if((recvSize=recv(clientfd,recvBuf,MAX_DATA_SIZE,0))==-1)
            {
                perror("fail to receive datas");
                exit(1);
            }
            printf("Client:%s
",recvBuf);
            memset(recvBuf,0,MAX_DATA_SIZE);
        }

    }

    return 0;
}

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