A TCP Proxy in Perl

http://www.catonmat.net/download/tcp-proxy2.pl

---------------------------------------------------------

by peteris krumins http://catonmat.net/about/

my friend from plurk.

use warnings;

use strict;

use IO::Socket::INET;

use IO::Select;

my @allowed_ips = ('all', '10.10.10.5');

my $ioset = IO::Select->new; my %socket_map;

my $debug = 1;

sub new_conn

{ my ($host, $port) = @_;

return IO::Socket::INET->new(

PeerAddr => $host,

PeerPort => $port

) || die "Unable to connect to $host:$port: $!"; }

sub new_server

{ my ($host, $port) = @_;

my $server = IO::Socket::INET->new(

LocalAddr => $host, LocalPort => $port,

ReuseAddr => 1,

Listen => 100

) || die "Unable to listen on $host:$port: $!"; }

sub new_connection

{

my $server = shift;

my $remote_host = shift;

my $remote_port = shift;

my $client = $server->accept;

my $client_ip = client_ip($client);

unless (client_allowed($client))

{print "Connection from $client_ip denied.\n" if $debug; $client->close; return; }

print "Connection from $client_ip accepted.\n" if $debug;

my $remote = new_conn($remote_host, $remote_port);

$ioset->add($client); $ioset->add($remote);

$socket_map{$client} = $remote;

$socket_map{$remote} = $client;

}

sub close_connection

{ my $client = shift;

my $client_ip = client_ip($client);

my $remote = $socket_map{$client};

$ioset->remove($client);

$ioset->remove($remote);

delete $socket_map{$client};

delete $socket_map{$remote};

$client->close; $remote->close;

print "Connection from $client_ip closed.\n" if $debug; }

sub client_ip

{my $client = shift; return inet_ntoa($client->sockaddr);}

sub client_allowed

{

my $client = shift;

my $client_ip = client_ip($client);

return grep { $_ eq $client_ip || $_ eq 'all' } @allowed_ips;

}

die "Usage: $0 <local port> <remote_host:remote_port>" unless @ARGV == 2;

my $local_port = shift;

my ($remote_host, $remote_port) = split ':', shift();

print "Starting a server on 0.0.0.0:$local_port\n";

my $server = new_server('0.0.0.0', $local_port);

$ioset->add($server);

while (1)

{

for my $socket ($ioset->can_read)

{

if ($socket == $server)

{ new_connection($server, $remote_host, $remote_port);}

else { next unless exists $socket_map{$socket}; my $remote = $socket_map{$socket};

my $buffer;

my $read = $socket->sysread($buffer, 4096);

if ($read) { $remote->syswrite($buffer);

} else { close_connection($socket);

} } } }