#!/usr/bin/perl
#use strict;
use IO::Socket;
use IO::Select;

$progname = $0;
$progname =~ s,.*[/\\],,;  # use basename only
$progname =~ s/\.\w*$//; # strip extension, if any

$VERSION = sprintf("%d.%02d", q$Revision: 1.0 $ =~ /(\d+)\.(\d+)/);

($lPort, $proxyStr, $remoteStr) = @ARGV;
unless (defined($proxyStr) and defined($remoteStr)) {
	print "use: localProxy [<localPort>] <proxy addr>:<proxy port> ".
		"<remote addr>:<remote port>\n";
	my $DISTNAME = 'findProxy ' . $VERSION;
	die <<"EOT";
This is findProxy $VERSION ($DISTNAME)

Author: wayne\@nym.alias.net

This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
EOT
	};
($proxyAddr, $proxyPort) = split(/:/, $proxyStr);
($host, $port) = split(/:/, $remoteStr);

$port=($port or 8080); #default to port 80 if not specified
$type='CONNECT'; # make this more general later
$murdered=0;
$makeNewConnection=1; $firstTime=1; 

$protocol = getprotobyname("tcp");
while ($makeNewConnection and !$murdered)	{

	#make the daemon (this may not be necessary inside this loop)
	#but it gets closed often
	$lPort=10000 + $port;
	socket(INC, PF_INET, SOCK_STREAM, $protocol) || die "socket:$!";
	setsockopt (INC, SOL_SOCKET, SO_REUSEADDR, pack ("l", 1)) || 
		die "setsockopt:$!";
	bind(INC,sockaddr_in($lPort,INADDR_ANY)) || die "bind: $!";
	if ($firstTime) {print STDOUT "connect to localhost port $lPort now\n";
		$firstTime=0};
	listen(INC,10) || die "listen:$!";	#allows 10 connections at a time 
										#(5 is the default), 
										#drops through here on 
										#the first one

	accept(OUT,INC) || die "accept:$!"; #accept 1 connection only for now
										#I need to handle this better, 
										#it *should* be easy, we don't do 
										#much on each connection!
	$fhin = $fhout = \*OUT;

	&makeConnection(); #connect to the proxy
	# hot buffers everywhere
	foreach ( \*PROXY, $fhin, $fhout, STDOUT ) {
		select($_); 
		$|=1
		};

	# Send command to proxy:
	print PROXY "$type $host:$port HTTP/1.1\r\n";	#change \r\n to 
													#$CRLF for Macs
													#HTTP/1.1 ok too.
	print PROXY "Host: $host\r\n";			#not necessary, even for HTTP/1.1
	print PROXY "Content-Length: 0\r\n";	#not necessary
	print PROXY "\r\n";

	# Wait for HTTP status code, die if you don't get a 2xx code.
	($status) = (split(/\s+/,<PROXY>))[1];
	die "failed to CONNECT to $host:$port" unless ($status);

	die "bad response code CONNECTING to $host:$port" unless 
		( int($status/100) == 2 );

	# Skip through remaining part of HTTP header (until blank line)
	while (<PROXY>)	{
		last if ( /^[\r\n]+$/ );
		};
		
	#connected through to remote server
	#now relay packets
	$s = IO::Select->new($fhin,\*PROXY);

	$makeNewConnection=0;

	while ( ! $makeNewConnection and !$murdered) {
		foreach $fh ( $s->can_read(10) ) {
			#0 indicates end of input, but sometimes it's undefined (?)		
			if (!($num = sysread($fh,$_,4096)) or $murdered) { 
					$s->remove($fh);
					close $fh;
					$s->remove($fhin);
					close $fhin;
					$makeNewConnection=1; #reopen all the sockets etc. 
						#a web proxy will be closing the connection 
						#after each GET/POST.
					};

			if ($num) {syswrite( ((fileno($fh)==fileno($fhin)) 
				?PROXY :$fhout),$_,$num)};
			}
		}; # while (!makenewConnection
	};  # while (run and makeNewConnection)
1;

sub makeConnection{
	# connect to proxy server ...
	socket (PROXY, PF_INET, SOCK_STREAM, $protocol) or
		die("Failed to create socket:$!");
	connect (PROXY, sockaddr_in($proxyPort,inet_aton($proxyAddr))) or
	#		die("Failed to connect to $proxyAddr port $proxyPort: $!");
		do {print "Failed to connect to $proxyAddr port $proxyPort\n";
		print "it's either dead, or your access is blocked\n";
		exit};
	select(\*PROXY); $|=1;		#make it hot
	};
	
sub signal_handler {
    $murdered=1;	#we've been killed; must have done something wrong
	};