#!/usr/bin/perl  
  
#==============  
# Date: 2012-11-03  
# User: wcdj  
#==============  
  
use Socket;  
use Carp;  
use FileHandle;  
  
# [1] use port 8080 by default, unless overridden on command line  
$port = (@ARGV ? $ARGV[0] : 8080);  
  
# [2] create local TCP socket and set it to listen for connections  
$proto = getprotobyname('tcp');  
socket(S, PF_INET, SOCK_STREAM, $proto) || die;  
setsockopt(S, SOL_SOCKET, SO_REUSEADDR, pack("l", 1)) || die;  
bind(S, sockaddr_in($port, INADDR_ANY)) || die;  
listen(S, SOMAXCONN) || die;  
  
# [3] print a startup message  
printf("<<< perl_web_svr accepting on port %d >>>\n\n", $port);  
  
while (1)  
{  
    # [4] wait for a connection C(Client)  
    $cport_caddr = accept(C, S);  
    ($cport, $caddr) = sockaddr_in($cport_caddr);  
    C->autoflush(1);  
  
    # [5] print who the connection is from  
    $cname = gethostbyaddr($caddr, AF_INET);  
    printf("<<< request from [%s] >>>\n", $cname);  
  
    # [6] read request msg until blank line, and print on screen  
    while ($line = <C>)  
    {  
        print $line;  
        if ($line =~ /^\r/) {last; }  
    }  
  
    # [7] prompt for response msg, and input response lines,  
    #     sending response lines to client, until solitary "."  
    printf("<<< type response followed by '.' >>>\n");  
  
    while ($line = <STDIN>)  
    {  
        $line =~ s/\r//;  
        $line =~ s/\n//;  
        if ($line =~ /^\./) {last; }  
        print C $line . "\r\n";  
    }  
  
    close(C);  
      
}