Class: Msf::Sessions::Modem::UdpChannel

Inherits:
ChannelBase show all
Includes:
Rex::IO::DatagramAbstraction
Defined in:
lib/msf/base/sessions/modem.rb

Overview

Generic UDP channel

Mirrors the Meterpreter UDP channel (Rex::Post::Meterpreter::Extensions::Stdapi::Net::SocketSubsystem::UdpChannel): it builds a real UDP socketpair via Rex::IO::DatagramAbstraction and hands the framework an lsock extended with Rex::Socket::Udp, so the returned object is a drop-in UDPSocket-alike (send/sendto/recv/recvfrom/read/write).

Outbound datagrams are routed to the modem connection’s send() via the DirectChannelWrite mixin; inbound datagrams drained from recv are written into rsock followed by the sender’s sockaddr (the same two-write trick Meterpreter’s Datagram#dio_write_handler uses) so recvfrom() can reconstruct [data, host, port].

Defined Under Namespace

Modules: DirectChannelWrite, SocketInterface

Instance Attribute Summary

Attributes inherited from ChannelBase

#cid, #params

Instance Method Summary collapse

Methods inherited from ChannelBase

#close, #closed?, #remote_closed, #remote_closed?

Constructor Details

#initialize(session, cid, conn, params) ⇒ UdpChannel

Create a new UdpChannel.

Parameters:

  • session (Modem) —

    parent session

  • cid (Integer) —

    channel ID, unique within the session

  • conn (#recv) —

    modem connection object

  • params (Rex::Socket::Parameters) 


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# File 'lib/msf/base/sessions/modem.rb', line 313

def initialize(session, cid, conn, params)
  initialize_abstraction
  super

  lsock.extend(Rex::Socket::Udp)
  lsock.initsock
  lsock.extend(SocketInterface)
  lsock.extend(DirectChannelWrite)
  lsock.channel = self

  rsock.extend(SocketInterface)
  rsock.channel = self

  @sockaddr = Rex::Socket.to_sockaddr(@params.peerhost, @params.peerport)
  start_reader_thread('ModemUdpChannelReader') do |data|
    if data.is_a?(::String) && !data.empty?
      rsock.syswrite(data)
      rsock.syswrite(@sockaddr)
    end
    true
  rescue ::StandardError
    false
  end

  session.add_channel(self)
end

Instance Method Details

#dio_write(buf) ⇒ Object

Send a datagram toward the peer through the modem connection. Invoked by the lsock’s DirectChannelWrite#syswrite and SocketInterface#send.



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# File 'lib/msf/base/sessions/modem.rb', line 344

def dio_write(buf)
  send_to_connection(buf)
end