Class: Jabber::SASL::DigestMD5

Inherits:
Base
  • Object
show all
Defined in:
lib/xmpp4r/sasl.rb

Overview

SASL DIGEST-MD5 authentication helper (RFC2831)

Instance Method Summary collapse

Constructor Details

#initialize(stream) ⇒ DigestMD5

Sends the wished auth mechanism and wait for a challenge

(proceed with DigestMD5#auth)



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# File 'lib/xmpp4r/sasl.rb', line 99

def initialize(stream)
  super

  challenge = {}
  error = nil
  @stream.send(generate_auth('DIGEST-MD5')) { |reply|
    if reply.name == 'challenge' and reply.namespace == NS_SASL
      challenge = decode_challenge(reply.text)
    else
      error = reply.first_element(nil).name
    end
    true
  }
  raise error if error

  @nonce = challenge['nonce']
  @realm = challenge['realm']
end

Instance Method Details

#auth(password) ⇒ Object

  • Send a response

  • Wait for the server’s challenge (which aren’t checked)

  • Send a blind response to the server’s challenge



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# File 'lib/xmpp4r/sasl.rb', line 170

def auth(password)
  response = {}
  response['nonce'] = @nonce
  response['charset'] = 'utf-8'
  response['username'] = @stream.jid.node
  response['realm'] = @realm || @stream.jid.domain
  response['cnonce'] = generate_nonce
  response['nc'] = '00000001'
  response['qop'] = 'auth'
  response['digest-uri'] = "xmpp/#{@stream.jid.domain}"
  response['response'] = response_value(@stream.jid.node, response['realm'], response['digest-uri'], password, @nonce, response['cnonce'], response['qop'], response['authzid'])
  response.each { |key,value|
    unless %w(nc qop response charset).include? key
      response[key] = "\"#{value}\""
    end
  }

  response_text = response.collect { |k,v| "#{k}=#{v}" }.join(',')
  Jabber::debuglog("SASL DIGEST-MD5 response:\n#{response_text}\n#{response.inspect}")

  r = REXML::Element.new('response')
  r.add_namespace NS_SASL
  r.text = Base64::encode64(response_text).gsub(/\s/, '')

  success_already = false
  error = nil
  # This send hangs sometimes waiting in Stream#send on threadblock.wait (with Openfire 3.6.4 at least);
  #  since the calback here is pretty simple, that likely means it never receives a response stanza
  #  therefore we should put in a timeout on send, and do some retries here (okay since its the first message)
  # TODO Verify if 1 second timeout, and 3 tries are good settings
  # TODO Add test/spec when/if they are created
  tries = 3
  begin
    @stream.send(r, 1) { |reply|
      if reply.name == 'success'
        success_already = true
      elsif reply.name != 'challenge'
        error = reply.first_element(nil).name
      end
      true
    }
  rescue Timeout::Error
    retry if (tries -= 1) > 0
    # TODO create a SASL::AuthError to handle this and other direct raise calls
    raise "Failed to send SASL::DigestMD5 response"
  end

  return if success_already
  raise error if error

  # TODO: check the challenge from the server

  r.text = nil
  @stream.send(r) { |reply|
    if reply.name != 'success'
      error = reply.first_element(nil).name
    end
    true
  }

  raise error if error
end

#decode_challenge(challenge) ⇒ Object 



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# File 'lib/xmpp4r/sasl.rb', line 118

def decode_challenge(challenge)
  text = Base64::decode64(challenge)
  res = {}

  state = :key
  key = ''
  value = ''
  text.scan(/./) do |ch|
    if state == :key
      if ch == '='
        state = :value
      else
        key += ch
      end

    elsif state == :value
      if ch == ','
        # due to our home-made parsing of the challenge, the key could have
        # leading whitespace. strip it, or that would break jabberd2 support.
        key = key.strip
        res[key] = value
        key = ''
        value = ''
        state = :key
      elsif ch == '"' and value == ''
        state = :quote
      else
        value += ch
      end

    elsif state == :quote
      if ch == '"'
        state = :value
      else
        value += ch
      end
    end
  end
  # due to our home-made parsing of the challenge, the key could have
  # leading whitespace. strip it, or that would break jabberd2 support.
  key = key.strip
  res[key] = value unless key == ''

  Jabber::debuglog("SASL DIGEST-MD5 challenge:\n#{text}\n#{res.inspect}")

  res
end