client2.c

linux环境下的网络编程的TCP客户端程序

/* client.c */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdlib.h>
#define MAXLINE 80
int             port = 8000;

int
main( int argc, char *argv[] )
{
    struct sockaddr_in pin;
    char            buf[MAXLINE];
    int             sock_fd;
    char           *str = "A default test sting";
    int             n;

    if ( argc > 1 )
    {
        str = argv[1];
    }

    bzero( &pin, sizeof( pin ) );
    pin.sin_family = AF_INET;
    inet_pton( AF_INET, "127.0.0.1", &pin.sin_addr );
    pin.sin_port = htons( port );

    sock_fd = socket( AF_INET, SOCK_STREAM, 0 );
    if ( sock_fd == -1 )
    {
        perror( "call to socket" );
        exit( 1 );
    }
    n = connect( sock_fd, ( void * ) &pin, sizeof( pin ) );
    if ( n == -1 )
    {
        perror( "call to connect" ), exit( -1 );
    }
  writeagain:
    n = write( sock_fd, str, strlen( str ) + 1 );
    if ( n == -1 )
    {
        if ( errno == EINTR )
        {
            goto writeagain;
        }
        else
        {
            perror( "call to write" );
            exit( 1 );
        }
    }
  readagain:
    n = read( sock_fd, buf, MAXLINE );
    if ( n == -1 )
    {
        if ( errno == EINTR )
        {
            goto readagain;
        }
        else
        {
            perror( "call to read" );
            exit( 1 );
        }
    }
    else if ( n == 0 )
    {
        printf( "the other side has been closed.\n" );
    }
    else
    {
        printf( "Response from server: %s\n", buf );
    }
    n = close( sock_fd );
    if ( n == -1 )
    {
        perror( "call to close" );
        exit( 1 );
    }
    return 0;
}