Class: Rack::TCTP

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/tctp.rb

Overview

This middleware enables Rack to make use of the Trusted Cloud Transfer Protocol (TCTP) for HTTP end-to-end body confidentiality and integrity.

Constant Summary collapse

DEFAULT_TCTP_DISCOVERY_INFORMATION = 
'/.*:/halecs'
TCTP_DISCOVERY_MEDIA_TYPE = 
'text/prs.tctp-discovery'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ TCTP

Initializes TCTP middleware



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# File 'lib/rack/tctp.rb', line 27

def initialize(app)
  @app = app
  @sessions = {}
end

Instance Attribute Details

#sessions ⇒ Object (readonly)

The TCTP sessions



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# File 'lib/rack/tctp.rb', line 24

def sessions
  @sessions
end

Class Method Details

.new_slug ⇒ Object

Generate a new random slug (2^64 possibilities)



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# File 'lib/rack/tctp.rb', line 19

def self.new_slug
  slug_base.convert(rand(2**64), 10)
end

.slug_base ⇒ Object

The slug URI can contain any HTTP compatible characters



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# File 'lib/rack/tctp.rb', line 14

def self.slug_base
  Radix::Base.new(Radix::BASE::B62 + ['-', '_'])
end

Instance Method Details

#call(env) ⇒ Object

Middleware call. Supports all TCTP use cases:

  • TCTP discovery

  • HALEC creation

  • HALEC handshake

  • Decrypting TCTP secured entity-bodies

  • Encrypting entity-bodies using TCTP



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# File 'lib/rack/tctp.rb', line 38

def call(env)
  begin
    req = Rack::Request.new(env)

    # Switch through TCTP use cases

    case
      when is_tctp_discovery?(req)
        # TCTP discovery

        # TODO Parameterize discovery information

        [200, {"Content-Type" => TCTP_DISCOVERY_MEDIA_TYPE, "Content-Length" => DEFAULT_TCTP_DISCOVERY_INFORMATION.length.to_s}, DEFAULT_TCTP_DISCOVERY_INFORMATION]
      when is_halec_creation?(req)
        # HALEC creation

        halec = ServerHALEC.new(url: '/halecs/' + TCTP::new_slug)

        # TODO Allow creation using predefined cookie

        session = TCTPSession.new

        # Send client_hello to server HALEC and read handshake_response

        client_hello = req.body.read
        halec.socket_there.write(client_hello)
        handshake_response = [halec.socket_there.recv(2048)]

        # Set location header and content-length

        header = {'Location' => halec.url, 'Content-Length' => handshake_response[0].length.to_s}

        # Set the TCTP session cookie header

        Rack::Utils.set_cookie_header!(header, "tctp_session_cookie", {:value => session.session_id, :path => '/', :expires => Time.now+24*60*60})

        # Persist session and HALEC

        session.halecs[halec.url] = halec
        sessions[session.session_id] = session

        [201, header, handshake_response]
      when is_halec_handshake?(req)
        # Get persisted server HALEC

        halec = @sessions[req.cookies['tctp_session_cookie']].halecs[req.path_info]

        # Write handshake message to server HALEC

        halec.socket_there.write(req.body.read)

        # Receive handshake response

        handshake_response = halec.socket_there.recv(2048)

        # Send back server HALEC response

        [200, {'Content-Length' => handshake_response.length.to_s}, [handshake_response]]
      else
        # Decrypt TCTP secured bodies

        if is_tctp_encrypted_body?(req) then
          decrypted_body = StringIO.new

          halec_url = req.body.readline.chomp

          # Gets the HALEC

          halec = @sessions[req.cookies['tctp_session_cookie']].halecs[halec_url]

          halec.socket_there.write(req.body.read)
          decrypted_body.write(halec.ssl_socket.readpartial(2 ** 26 - 1))

          req.body.string = decrypted_body.string
        end

        status, headers, body = @app.call(env)

        if is_tctp_response_requested?(req)
          # Gets the first free server HALEC for encryption

          # TODO Send error if cookie is missing

          halec = @sessions[req.cookies['tctp_session_cookie']].free_halec

          # The length of the content body

          content_body_length = 0

          # The first line

          first_line = halec.url + "\r\n"
          content_body_length += first_line.length

          # Encrypt the body. The first line of the response specifies the used HALEC

          encrypted_body = []
          encrypted_body << first_line

          # Encrypt each body fragment

          body.each do |fragment|
            bodyio = StringIO.new(fragment)

            until bodyio.eof? do
              chunk = bodyio.read(16 * 1024)
              halec.ssl_socket.write(chunk)
              encrypted_chunk = halec.socket_there.readpartial(32 * 1024)
              encrypted_body << encrypted_chunk
              content_body_length += encrypted_chunk.length
            end
          end

          # Sets the content length and encoding

          headers['Content-Length'] = content_body_length.to_s
          headers['Content-Encoding'] = 'encrypted'

          [status, headers, encrypted_body]
        else
          [status, headers, body]
        end
    end
  rescue Exception => e
    puts e
  end
end