TCP网络编程-优快云博客

本文链接：https://blog.youkuaiyun.com/tripleCC/article/details/24808321

本文深入探讨了TCP网络编程的基本模型，包括服务器端和客户端的实现流程，并展示了如何使用多线程进行高效的数据处理。通过具体的程序例程，详细解释了socket操作、连接建立、数据读写等关键步骤，同时介绍了如何利用fork()函数实现子进程处理客户端请求，确保服务器能够同时响应多个并发连接。

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TCP网络编程基本模型：
UNIX环境高级编程435页。
程序例程：
服务器：
#include
#include
#include
#include
#include
#include

#define portnumber 3333

int main( int argc, char **argv )
{
    int        sockfd;
    int     new_fd;
    int     sin_size;
    int     nbytes;
    char    buffer[1024];
    struct sockaddr_in    server_addr;
    struct sockaddr_in    client_addr;

    if( (sockfd=socket(AF_INET, SOCK_STREAM, 0)) == -1 )
    {
        perror( "socket error\n" );
        exit( 1 );
    }
    bzero( &server_addr, sizeof(struct sockaddr_in) );
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl( INADDR_ANY );
    server_addr.sin_port = htons( portnumber );
    if( bind(sockfd, (struct sockaddr *)(&server_addr), sizeof(struct sockaddr)) == -1 )
    {
        perror( "bind error\n" );
        exit( 1 );
    }
    if( listen(sockfd, 5) == -1 )
    {
        perror( "listen error\n" );
        exit( 1 );
    }

    sin_size = sizeof( struct sockaddr_in );
    while( 1 )
    {
        if( (new_fd=accept(sockfd, (struct sockaddr *)(&client_addr), &sin_size)) == -1 )
        {
            perror( "accept error\n" );
            exit( 1 );
        }
        fprintf( stdout," server get %s ", inet_ntoa(client_addr.sin_addr) );

        if( (nbytes=read(new_fd, buffer, 1024)) == -1 )
        {
            perror( "read error\n" );
            exit( 1 );
        }
        buffer[nbytes] = '\0';
        printf( "received %s\n", buffer );

        close( new_fd );
    }

    exit( 0 );
}

客户端：
#include
#include
#include
#include
#include

#define portnumber 3333

int main( int argc, char **argv )
{
    int sockfd;
    char buffer[1024];
    struct sockaddr_in server_addr;

    sockfd = socket( AF_INET, SOCK_STREAM, 0 );

    bzero( &server_addr, sizeof(server_addr) );
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons( portnumber );
    server_addr.sin_addr.s_addr = inet_addr( "127.0.1.1" );
    if( connect(sockfd, (struct sockaddr *)(&server_addr), sizeof(struct sockaddr)) == -1 )
    {
        perror( "connet error\n" );
        exit( 1 );
    }

    printf( "please input char: \n");

    fgets( buffer, 1024, stdin );
    write( sockfd, buffer, strlen(buffer) );

    close( sockfd );
    exit( 0 );
}

遇到的问题：
刚开始由于在客户端中没有建立套接字，即
sockfd = socket( AF_INET, SOCK_STREAM, 0 );这一句，导致connect文件总是返回pemission denied。

多线程TCP编程：
while( 1 )
    {
        if( (new_fd=accept(sockfd, (struct sockaddr *)(&client_addr), &sin_size)) == -1 )
        {
            perror( "accept error\n" );
            exit( 1 );
        }
        fprintf( stdout," server get %s\n ", inet_ntoa(client_addr.sin_addr) );
        if( fork() == 0 )
        {

        if( (nbytes=read(new_fd, buffer, 1024)) == -1 )
        {
            perror( "read error\n" );
            exit( 1 );
        }
        buffer[nbytes] = '\0';
        printf( "received %s\n", buffer );

        close( new_fd );
        }
    }
主要思想是一个线程处理连接任务，连接后的事务用创建的子进程处理