Index

NAME
SYNOPSIS
DESCRIPTION
METHODS
CONNECTORS
AUTHOR
BUGS
TODO
SUPPORT
COPYRIGHT
LICENSE

NAME

Net::Proxy - Framework for proxying network connections in many ways

SYNOPSIS

    use Net::Proxy;

    # proxy connections from localhost:6789 to remotehost:9876
    # using standard TCP connections
    my $proxy = Net::Proxy->new(
        {   in  => { type => 'tcp', port => '6789' },
            out => { type => 'tcp', host => 'remotehost', port => '9876' },
        }
    );

    # register the proxy object
    $proxy->register();

    # and you can setup multiple proxies

    # and now proxy connections indefinitely
    Net::Proxy->mainloop();

DESCRIPTION

A Net::Proxy object represents a proxy that accepts connections and then relays the data transfered between the source and the destination.

The goal of this module is to abstract the different methods used to connect from the proxy to the destination.

A proxy is a program that transfer data across a network boundary between a client and a server. Net::Proxy introduces the concept of "connectors" (implemented as Net::Proxy::Connector subclasses), which abstract the server part (connected to the client) and the client part (connected to the server) of the proxy.

This architecture makes it easy to implement specific techniques to cross a given network boundary, possibly by using a proxy on one side of the network fence, and a reverse-proxy on the other side of the fence.

See AVAILABLE CONNECTORS for details about the existing connectors.

METHODS

If you only intend to use Net::Proxy and not write new connectors, you only need to know about new(), register() and mainloop().

Class methods

new( { in => { ... }, { out => { ... } } )

Return a new Net::Proxy object, with two connectors configured as described in the hashref.

The connector parameters are described in the table below, as well as in each connector documentation.

mainloop( $max_connections )

This method initialises all the registered Net::Proxy objects and then loops on all the sockets ready for reading, passing the data through the various Net::Proxy::Connector objets to handle the specifics of each connection.

If $max_connections is given, the proxy will stop after having fully processed that many connections. Otherwise, this method does not return.

add_listeners( @sockets )

Add the given sockets to the list of listening sockets.

watch_reader_sockets( @sockets )

Add the given sockets to the readers watch list.

watch_writer_sockets( @sockets )

Add the given sockets to the writers watch list.

remove_writer_sockets( @sockets )

Remove the given sockets from the writers watch list.

close_sockets( @sockets )

Close the given sockets and cleanup the related internal structures.

set_verbosity( $level )

Set the logging level. 0 means not messages except warnings and errors.

error( $message )

Log $message to STDERR, always.

notice( $message )

Log $message to STDERR if verbosity level is equal to 1 or more.

info( $message )

Log $message to STDERR if verbosity level is equal to 2 or more.

debug( $message )

Log $message to STDERR if verbosity level is equal to 3 or more.

(Note: throughout the Net::Proxy source code, calls to debug() are commented with ##.)

Some of the class methods are related to the socket objects that handle the actual connections.

get_peer( $socket )
set_peer( $socket, $peer ): Get or set the socket peer.
get_connector( $socket )
set_connector( $socket, $connector ): Get or set the socket connector (a Net::Proxy::Connector object).
get_state( $socket )
set_state( $socket, $state ): Get or set the socket state. Some Net::Proxy::Connector subclasses may wish to use this to store some internal information about the socket or the connection.
get_nick( $socket )
set_nick( $socket, $nickname ): Get or set the socket nickname. Typically used by Net::Proxy::Connector to give informative names to socket (used in the log messages).
get_buffer( $socket )
set_buffer( $socket, $data ): Get or set the content of the writing buffer for the socket. Used by Net::Proxy::Connector in raw_read_from() and ranw_write_to().
get_callback( $socket )
set_callback( $socket, $coderef ): Get or set the callback currently associated with the socket.
add_to_buffer( $socket, $data ): Add data to the writing buffer of the socket.

Instance methods

register(): Register a Net::Proxy object so that it will be included in the mainloop() processing.
unregister(): Unregister the Net::Proxy object.
in_connector(): Return the Net::Proxy::Connector objet that handles the incoming connection and handles the data coming from the "client" side.
out_connector(): Return the Net::Proxy::Connector objet that creates the outgoing connection and handles the data coming from the "server" side.

Statistical methods

The following methods manage some statistical information about the individual proxies:

stat_inc_opened()
stat_inc_closed(): Increment the "opened" or "closed" connection counter for this proxy.
stat_opened()
stat_closed(): Return the count of "opened" or "closed" connections for this proxy.
stat_total_opened()
stat_total_closed(): Return the total count of "opened" or "closed" connection across all proxy objects.

CONNECTORS

All connection types are provided with the help of specialised classes. The logic for protocol xxx is provided by the Net::Proxy::Connector::xxx class.

Connector hooks

There is a single parameter that all connectors accept: hook. Given a code reference, the code reference will be called when data is received on the corresponding socket.

The code reference should have the following signature:

    sub callback {
        my ($dataref, $sock, $connector) = @_;
        ...
    }

$dataref is a reference to the chunk of data received, $sock is a reference to the socket that received the data, and $connector is the Net::Proxy::Connector object that created the socket. This allows someone to eventually store data in a stash stored in the connector, so as to share data between sockets.

Available connectors

* tcp (Net::Proxy::Connector::tcp): This is the simplest possible proxy connector. On the "in" side, it sits waiting for incoming connections, and on the "out" side, it connects to the configured host/port.
* connect (Net::Proxy::Connector::connect): This proxy connector can connect to a TCP server though a web proxy that accepts HTTP CONNECT requests.
* dual (Net::Proxy::Connector::dual): This proxy connector is a Y-shaped connector: depending on the client behaviour right after the connection is established, it connects it to one of two services, handled by two distinct connectors.
* dummy (Net::Proxy::Connector::dummy): This proxy connector does nothing. You can use it as a template for writing new Net::Proxy::Connector classes.

Summary

This table summarises all the available Net::Proxy::Connector classes and the parameters their constructors recognise.

N/A means that the given Net::Proxy::Connector cannot be used in that position (either in or out).

     Connector  | in parameters   | out parameters
    ------------+-----------------+-----------------
     tcp        | host            | host
                | port            | port
    ------------+-----------------+-----------------
     connect    | N/A             | host
                |                 | port
                |                 | proxy_host
                |                 | proxy_port
                |                 | proxy_user
                |                 | proxy_pass
                |                 | proxy_agent
    ------------+-----------------+-----------------
     dual       | host            | N/A
                | port            |
                | timeout         |
                | server_first    |
                | client_first    |
    ------------+-----------------+-----------------
     dummy      | N/A             | N/A
    ------------+-----------------+-----------------
     ssl        | host            | host
                | port            | port
                | start_cleartext | start_cleartext
    ------------+-----------------+-----------------
     connect_ssl| N/A             | host
                |                 | port
                |                 | proxy_host
                |                 | proxy_port
                |                 | proxy_user
                |                 | proxy_pass
                |                 | proxy_agent

Net::Proxy::Connector::dummy is used as the out parameter for a Net::Proxy::Connector::dual, since the later is linked to two different connector objects.

AUTHOR

Philippe 'BooK' Bruhat, <book@cpan.org>.

BUGS

Please report any bugs or feature requests to bug-net-proxy@rt.cpan.org, or through the web interface at http://rt.cpan.org/. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

TODO

Here's my own wishlist:

Write a connector fully compatible with GNU httptunnel (http://www.nocrew.org/software/httptunnel.html).

This one will probably be named Net::Proxy::Connector::httptunnel.
Enhance the httptunnel protocol to support multiple connections.
Implement RFC 3093 - Firewall Enhancement Protocol (FEP), as Net::Proxy::Connector::FEP. This RFC was published on April 1, 2001.

This is probably impossible with Net::Proxy, since the FEP driver is a rather low-level driver (at the IP level of the network stack).
Implement DNS tunnel connectors.

See http://savannah.nongnu.org/projects/nstx/, OzymanDNS, http://www.doxpara.com/slides/BH_EU_05-Kaminsky.pdf. http://thomer.com/howtos/nstx.html for examples.
Implement an UDP connector. (Is it feasible?)
Implement a connector that can be plugged to the STDIN/STDOUT of an external process, like the ProxyCommand option of OpenSSH.
Implement Net::Proxy::Connector::unix, for UNIX sockets.
Implement ICMP tunnel connectors.

See http://www.linuxexposed.com/Articles/Hacking/Case-of-a-wireless-hack.html, http://sourceforge.net/projects/itun, http://www.cs.uit.no/~daniels/PingTunnel/, http://thomer.com/icmptx/ for examples.

Since ICMP implies low-level packet reading and writing, it may not be possible for Net::Proxy to handle it.
Look for inspiration in the Firewall-Piercing HOWTO, at http://fare.tunes.org/files/fwprc/.

Look also here: http://gray-world.net/tools/
Implement a Net::Proxy::Connector::starttls connector that can upgrade upgrade a connection to SSL transparently, even if the client or server doesn't support STARTTLS.

Martin Werthm�ller provided a full implementation of a connector that can handle IMAP connections and upgrade them to TLS if the client sends a STARTTLS command. My implementation will split this in two parts Net::Proxy::Connector::ssl and Net::Proxy::Connector::starttls, that inherits from the former.