Class: Purr::Server

Inherits:
Object
  • Object
show all
Defined in:
lib/purr/server.rb

Overview

This class implements a Rack-based server with socket hijacking and proxying to a remote TCP endpoint.

The remote TCP endpoint selection is implemented by passing a block to the class instantiation. If any kind of error happens during the hijacking process a 404 error is returned to the requester.

Instance Method Summary collapse

Constructor Details

#initialize {|env| ... } ⇒ Server

Returns a new instance of Server.

Yields:

  • (env) —

    The block responsible for the remote TCP endpoint selection

Yield Parameters:

  • env (Hash) —

    The environment hash returned by the Rack middleware

Yield Returns:

  • (Array[String, Integer]) —

    The host:port pair as a two element array

Raises:

  • (ArgumentError) —

    If the passed block takes other number of arguments than one



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# File 'lib/purr/server.rb', line 15

def initialize(&block)
  raise ArgumentError, 'The method requires a block with a single argument' unless block && block.arity == 1

  @remote = block
  @proxy = SurroGate.new

  @transmitter = Thread.new do
    loop do
      @proxy.select(1000)

      @proxy.each_ready do |left, right|
        begin
          right.write_nonblock(left.read_nonblock(4096))
        rescue => ex
          # FIXME: env is not available here, logging is probably bad in this way
          # logger(env, :info, "Connection #{left} <-> #{right} closed due to #{ex}")
          cleanup(left, right)
        end
      end
    end
  end

  @transmitter.abort_on_exception = true
end

Instance Method Details

#call(env) ⇒ Object

Method required by the Rack API

See Also:



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# File 'lib/purr/server.rb', line 43

def call(env)
  upgrade = parse_headers(env)
  # Return with a 404 error if the upgrade header is not present
  return not_found unless %i(websocket purr).include?(upgrade)

  host, port = @remote.call(env)
  # Return with a 404 error if no host:port pair was determined
  if host.nil? || port.nil?
    logger(env, :error, "No matching endpoint found for request incoming from #{env['REMOTE_ADDR']}")
    return not_found
  end

  # Hijack the HTTP socket from the Rack middleware
  http = env['rack.hijack'].call
  # Write a proper HTTP response
  http.write(http_response(upgrade))
  # Open the remote TCP socket
  sock = TCPSocket.new(host, port)

  # Start proxying
  @proxy.push(http, sock)
  logger(env, :info, "Redirecting incoming request from #{env['REMOTE_ADDR']} to [#{host}]:#{port}")

  # Rack requires this line below
  return [200, {}, []]
rescue => ex
  logger(env, :error, "#{ex.class} happened for #{env['REMOTE_ADDR']} trying to access #{host}:#{port}")
  cleanup(http, sock)
  return not_found # Return with a 404 error
end