Class: PSRP::MessageEncoder

Inherits:
Message
  • Object
show all
Defined in:
lib/wsmv/psrp_message.rb

Overview

PowerShell Remoting Protocol base message. download.microsoft.com/download/9/5/E/95EF66AF-9026-4BB0-A41D-A4F81802D92C/%5BMS-PSRP%5D.pdf

Constant Summary collapse

TEMPLATES = 
{
  SESSION_CAPABILITY: 'session_capability',
  INIT_RUNSPACEPOOL: 'init_runspacepool',
  CREATE_PIPELINE: 'create_pipeline',
  RUNSPACE_AVAILABILITY: 'runspace_availability'

}
@@obj_id = 
0

Constants inherited from Message

PSRP::Message::BLOB_HEADER_LEN, PSRP::Message::BLOB_MAX_LEN, PSRP::Message::MESSAGE_TYPES

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Message

#uuid_to_windows_guid_bytes

Constructor Details

#initialize(shell_id, command_id, message_type, context = nil) ⇒ MessageEncoder

Returns a new instance of MessageEncoder.

Parameters:

  • payload (String) —

    The PSRP payload as serialized XML



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# File 'lib/wsmv/psrp_message.rb', line 163

def initialize(shell_id, command_id, message_type, context = nil)
  fail 'shell_id cannot be nil' if shell_id.nil?
  @@obj_id += 1
  @id = @@obj_id
  @shell_id = shell_id
  @command_id = command_id
  @message_type = MESSAGE_TYPES[message_type]
  @payload = render(TEMPLATES[message_type], context).force_encoding('utf-8').bytes

  num_fragments = 1
  num_fragments += (@payload.length / BLOB_MAX_LEN)
  if (@payload.length % BLOB_MAX_LEN) == 0
    num_fragments -= 1
  end

  @fragments = []

  for i in 0..(num_fragments - 1)
    start_pos = (i * BLOB_MAX_LEN)
    end_pos = ((i + 1) * BLOB_MAX_LEN) - 1

    if num_fragments == 1
      flags = [3]
    elsif i == 0
      flags = [1]
    elsif i == (num_fragments - 1)
      flags = [2]
    else
      flags = [0]
    end

    @fragments.push(bytes(@payload[start_pos..end_pos], i, flags))
  end      
end

Instance Attribute Details

#fragments ⇒ Object (readonly)

Returns the value of attribute fragments.



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# File 'lib/wsmv/psrp_message.rb', line 143

def fragments
  @fragments
end

Instance Method Details

#bytes(blob, frag_id, flags) ⇒ Array<Byte>

Returns the raw PSRP message bytes ready for transfer to Windows inside a WinRM message. rubocop:disable Metrics/AbcSize

Returns:

  • (Array<Byte>) —

    Unencoded raw byte array of the PSRP message.



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# File 'lib/wsmv/psrp_message.rb', line 214

def bytes(blob, frag_id, flags)

  # Packet fragment headers
  message = message_id
  message += fragment_id(frag_id)
  message += flags

  if frag_id == 0
    # packet fragment header
    message += blob_length(blob, BLOB_HEADER_LEN)

    # PSRP message header
    message += blob_destination
    message += message_type
    message += runspace_pool_id
    message += pipeline_id
    message += byte_order_mark + blob
  
  else
    # packet fragment header
    message += blob_length(blob, 0)
    # PSRP fragment
    message += blob
  end
  message
end

#render(template, context = nil) ⇒ String

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Renders the specified template with the given context

Parameters:

  • template (String) —

    The base filename of the PSRP message template.

  • context (Hash) (defaults to: nil) —

    Any options required for rendering the template.

Returns:

  • (String) —

    The rendered XML PSRP message.



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# File 'lib/wsmv/psrp_message.rb', line 203

def render(template, context = nil)
  template_path = File.expand_path(
    "#{File.dirname(__FILE__)}/templates/#{template}.xml.erb")
  template = File.read(template_path)
  Erubis::Eruby.new(template).result(context)
end