C++实现一个简单的服务器客户端聊天程序——非阻塞套接字

一服务端代码

#include <stdlib.h>
#include <sys/types.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include "unistd.h"
#include "errno.h"
#include <arpa/inet.h> //for inet_ntoa

int main()
{
    int sfp,nfp;
    struct sockaddr_in s_add,c_add;
    socklen_t sin_size;
    unsigned short portnum=10051;

    printf("Hello,I am a server,Welcome to connect me !\r\n");
    sfp = socket(AF_INET, SOCK_STREAM, 0);
    if(-1 == sfp)
    {
        printf("socket fail ! \r\n");
        return -1;
    }
    printf("socket ok !\r\n");


    int on = 1;
    setsockopt( sfp, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on) );//允许地址的立即重用


    bzero(&s_add,sizeof(struct sockaddr_in));
    s_add.sin_family=AF_INET;
    s_add.sin_addr.s_addr=htonl(INADDR_ANY);
    s_add.sin_port=htons(portnum);

    if(-1 == bind(sfp,(struct sockaddr *)(&s_add), sizeof(struct sockaddr)))
    {
        printf("bind fail:%d!\r\n",errno);
        return -1;
    }
    printf("bind ok !\r\n");

    if(-1 == listen(sfp,5)) //在套接字上监听
    {
        printf("listen fail !\r\n");
        return -1;
    }
    printf("listen ok\r\n");

    while(1)
    {
        sin_size = sizeof(struct sockaddr_in);

        nfp = accept(sfp, (struct sockaddr *)(&c_add), &sin_size);  
        if(-1 == nfp)
        {
            printf("accept fail !\r\n");
            return -1;
        }
        printf("accept ok!\r\nServer start get connect from ip=%s,port=%d\r\n",inet_ntoa(c_add.sin_addr)  ,ntohs(c_add.sin_port));


        if(-1 == write(nfp,"hello,client,you are welcome! \r\n",32))
        {
            printf("write fail!\r\n");
            return -1;
        }
        printf("write ok!\r\n");
        close(nfp);

        puts("continue to listen(y/n)?");
        char ch[2];
        scanf("%s", ch, 2); //读控制台两个字符，包括回车符
        if (ch[0] != 'y') //如果不是y就退出循环
            break;


    }

    printf("bye!\n");
    close(sfp); //关闭套接字
    return 0;
}

二客户端程序

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <assert.h>
#include <stdio.h>
#include <time.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>

#define BUFFER_SIZE 1023

int setnonblocking( int fd )
{
    int old_option = fcntl( fd, F_GETFL );
    int new_option = old_option | O_NONBLOCK;
    fcntl( fd, F_SETFL, new_option );
    return old_option;
}

int unblock_connect( const char* ip, int port, int time )
{
    int ret = 0;
    struct sockaddr_in address;
    bzero( &address, sizeof( address ) );
    address.sin_family = AF_INET;
    inet_pton( AF_INET, ip, &address.sin_addr );
    address.sin_port = htons( port );

    int sockfd = socket( PF_INET, SOCK_STREAM, 0 );
    int fdopt = setnonblocking( sockfd );
    ret = connect( sockfd, ( struct sockaddr* )&address, sizeof( address ) );
    printf("connect ret code = %d\n", ret);
    if ( ret == 0 )
    {
        printf( "connect with server immediately\n" );
        fcntl( sockfd, F_SETFL, fdopt );   //set old optional back
        return sockfd;
    }
    //unblock mode --> connect return immediately! ret = -1 & errno=EINPROGRESS
    else if ( errno != EINPROGRESS )
    {
        printf("ret = %d\n", ret);
        printf( "unblock connect failed!\n" );
        return -1;
    }
    else if (errno == EINPROGRESS)
    {
        printf( "unblock mode socket is connecting...\n" );
    }

    //use select to check write event, if the socket is writable, then
    //connect is complete successfully!
    fd_set readfds;
    fd_set writefds;
    struct timeval timeout;

    FD_ZERO( &readfds );
    FD_SET( sockfd, &writefds );

    timeout.tv_sec = time; //timeout is 10 minutes
    timeout.tv_usec = 0;

    ret = select( sockfd + 1, NULL, &writefds, NULL, &timeout );
    if ( ret <= 0 )
    {
        printf( "connection time out\n" );
        close( sockfd );
        return -1;
    }

    if ( ! FD_ISSET( sockfd, &writefds  ) )
    {
        printf( "no events on sockfd found\n" );
        close( sockfd );
        return -1;
    }

    int error = 0;
    socklen_t length = sizeof( error );
    if( getsockopt( sockfd, SOL_SOCKET, SO_ERROR, &error, &length ) < 0 )
    {
        printf( "get socket option failed\n" );
        close( sockfd );
        return -1;
    }

    if( error != 0 )
    {
        printf( "connection failed after select with the error: %d \n", error );
        close( sockfd );
        return -1;
    }

    //connection successful!
    printf( "connection ready after select with the socket: %d \n", sockfd );
    fcntl( sockfd, F_SETFL, fdopt ); //set old optional back

     printf("connect ok !\r\n");

    int recbytes;
    int sin_size;
    char buffer[1024]={0};   

    
    if(-1 == (recbytes = read(sockfd,buffer,1024)))  //接收数据
    {
        printf("read data fail !\r\n");
        return -1;
    }
    printf("read ok:");

    buffer[recbytes]='\0';
    printf("%s\r\n",buffer);

    return sockfd;
}


int main( int argc, char* argv[] )
{
     
    const char ip[] = "192.168.0.110";
    int port = 10051;

    int sockfd = unblock_connect( ip, port, 1);
    if ( sockfd < 0 )
    {
        printf("sockfd error! return -1\n");
        return 1;
    }
    close(sockfd);
    return 0;
}

三运行

1 服务端先运行

[root@localhost test]# g++ test.cpp -o test
[root@localhost test]# ./test
Hello,I am a server,Welcome to connect me !
socket ok !
bind ok !
listen ok

2 客户端再运行

[root@localhost test]# g++ client.cpp -o client
[root@localhost test]# ./client
connect ret code = -1
unblock mode socket is connecting...
connection ready after select with the socket: 3
connect ok !
read ok:hello,client,you are welcome!

3 此时服务端结果

[root@localhost test]# g++ test.cpp -o test
[root@localhost test]# ./test
Hello,I am a server,Welcome to connect me !
socket ok !
bind ok !
listen ok
accept ok!
Server start get connect from ip=192.168.0.120,port=60652
write ok!
continue to listen(y/n)?
y

C++实现一个简单的服务器客户端聊天程序——非阻塞套接字

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