Module: OpenID::Yadis

Defined in:
lib/openid/yadis/xri.rb,
lib/openid/yadis/xrds.rb,
lib/openid/yadis/accept.rb,
lib/openid/yadis/xrires.rb,
lib/openid/yadis/filters.rb,
lib/openid/yadis/services.rb,
lib/openid/yadis/constants.rb,
lib/openid/yadis/discovery.rb,
lib/openid/yadis/parsehtml.rb

Defined Under Namespace

Modules: XRI Classes: BasicServiceEndpoint, CompoundFilter, DiscoveryResult, TransformFilterMaker, XRDSError, XRDSFraud

Constant Summary collapse

XRD_NS_2_0 = 
"xri://$xrd*($v*2.0)"
XRDS_NS = 
"xri://$xrds"
XRDS_NAMESPACES = 
{
  "xrds" => XRDS_NS,
  "xrd" => XRD_NS_2_0,
}
YADIS_HEADER_NAME = 
"X-XRDS-Location"
YADIS_CONTENT_TYPE = 
"application/xrds+xml"
YADIS_ACCEPT_HEADER =

A value suitable for using as an accept header when performing YADIS discovery, unless the application has special requirements

generate_accept_header(
  ["text/html", 0.3],
  ["application/xhtml+xml", 0.5],
  [YADIS_CONTENT_TYPE, 1.0],
)
@@filter_type_error =

Exception raised when something is not able to be turned into a filter

TypeError.new(
  "Expected a filter, an endpoint, a callable or a list of any of these.",
)

Class Method Summary collapse

Class Method Details

.apply_filter(normalized_uri, xrd_data, flt = nil) ⇒ Object 



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# File 'lib/openid/yadis/services.rb', line 29

def self.apply_filter(normalized_uri, xrd_data, flt = nil)
  # Generate an iterable of endpoint objects given this input data,
  # presumably from the result of performing the Yadis protocol.

  flt = Yadis.make_filter(flt)
  et = Yadis.parseXRDS(xrd_data)

  endpoints = []
  each_service(et) do |service_element|
    endpoints += flt.get_service_endpoints(normalized_uri, service_element)
  end

  endpoints
end

.disable_entity_expansion ⇒ Object 



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# File 'lib/openid/yadis/xrds.rb', line 103

def self.disable_entity_expansion
  _previous_ = REXML::Document.entity_expansion_limit
  REXML::Document.entity_expansion_limit = 0
  yield
ensure
  REXML::Document.entity_expansion_limit = _previous_
end

.discover(uri) ⇒ Object

Discover services for a given URI.

uri: The identity URI as a well-formed http or https URI. The well-formedness and the protocol are not checked, but the results of this function are undefined if those properties do not hold.

returns a DiscoveryResult object

Raises DiscoveryFailure when the HTTP response does not have a 200 code.



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# File 'lib/openid/yadis/discovery.rb', line 70

def self.discover(uri)
  result = DiscoveryResult.new(uri)
  begin
    resp = OpenID.fetch(uri, nil, {"Accept" => YADIS_ACCEPT_HEADER})
  rescue Exception
    raise DiscoveryFailure.new("Failed to fetch identity URL #{uri} : #{$!}", $!)
  end
  if resp.code != "200" and resp.code != "206"
    raise DiscoveryFailure.new(
      'HTTP Response status from identity URL host is not "200".' \
        "Got status #{resp.code.inspect} for #{resp.final_url}",
      resp,
    )
  end

  # Note the URL after following redirects
  result.normalized_uri = resp.final_url

  # Attempt to find out where to go to discover the document or if
  # we already have it
  result.content_type = resp["content-type"]

  result.xrds_uri = where_is_yadis?(resp)

  if result.xrds_uri and result.used_yadis_location?
    begin
      resp = OpenID.fetch(result.xrds_uri)
    rescue StandardError
      raise DiscoveryFailure.new("Failed to fetch Yadis URL #{result.xrds_uri} : #{$!}", $!)
    end
    if resp.code != "200" and resp.code != "206"
      exc = DiscoveryFailure.new(
        'HTTP Response status from Yadis host is not "200". ' +
                             "Got status #{resp.code.inspect} for #{resp.final_url}",
        resp,
      )
      exc.identity_url = result.normalized_uri
      raise exc
    end

    result.content_type = resp["content-type"]
  end

  result.response_text = resp.body
  result
end

.each_service(xrds_tree, &block) ⇒ Object

aka iterServices in Python



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# File 'lib/openid/yadis/xrds.rb', line 130

def self.each_service(xrds_tree, &block)
  xrd = get_yadis_xrd(xrds_tree)
  xrd.each_element("Service", &block)
end

.expand_service(service_element) ⇒ Object 



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# File 'lib/openid/yadis/xrds.rb', line 143

def self.expand_service(service_element)
  es = service_element.elements
  uris = es.each("URI") { |u| }
  uris = prio_sort(uris)
  types = es.each("Type/text()")
  # REXML::Text objects are not strings.
  types = types.collect { |t| t.to_s }
  uris.collect { |uri| [types, uri.text, service_element] }
end

.generate_accept_header(*elements) ⇒ Object

Generate an accept header value

str or (str, float)

-> str



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# File 'lib/openid/yadis/accept.rb', line 6

def self.generate_accept_header(*elements)
  parts = []
  elements.each do |element|
    if element.is_a?(String)
      qs = "1.0"
      mtype = element
    else
      mtype, q = element
      q = q.to_f
      raise ArgumentError.new("Invalid preference factor: #{q}") if q > 1 or q <= 0

      qs = format("%0.1f", q)
    end

    parts << [qs, mtype]
  end

  parts.sort!
  chunks = []
  parts.each do |q, mtype|
    chunks << if q == "1.0"
      mtype
    else
      format("%s; q=%s", mtype, q)
    end
  end

  chunks.join(", ")
end

.get_acceptable(accept_header, have_types) ⇒ Object 



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# File 'lib/openid/yadis/accept.rb', line 127

def self.get_acceptable(accept_header, have_types)
  # Parse the accept header and return a list of available types
  # in preferred order. If a type is unacceptable, it will not be
  # in the resulting list.
  #
  # This is a convenience wrapper around matchTypes and
  # parse_accept_header
  #
  # (str, [str]) -> [str]
  accepted = parse_accept_header(accept_header)
  preferred = match_types(accepted, have_types)
  preferred.collect { |mtype, _| mtype }
end

.get_canonical_id(iname, xrd_tree) ⇒ Object 



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# File 'lib/openid/yadis/xrds.rb', line 24

def self.get_canonical_id(iname, xrd_tree)
  # Return the CanonicalID from this XRDS document.
  #
  # @param iname: the XRI being resolved.
  # @type iname: unicode
  #
  # @param xrd_tree: The XRDS output from the resolver.
  #
  # @returns: The XRI CanonicalID or None.
  # @returntype: unicode or None

  xrd_list = []
  REXML::XPath.match(xrd_tree.root, "/xrds:XRDS/xrd:XRD", XRDS_NAMESPACES).each do |el|
    xrd_list << el
  end

  xrd_list.reverse!

  cid_elements = []

  unless xrd_list.empty?
    xrd_list[0].elements.each do |e|
      next unless e.respond_to?(:name)

      cid_elements << e if e.name == "CanonicalID"
    end
  end

  cid_element = cid_elements[0]

  return unless cid_element

  canonical_id = XRI.make_xri(cid_element.text)

  child_id = canonical_id.downcase

  xrd_list[1..-1].each do |xrd|
    parent_sought = child_id[0...child_id.rindex("!")]

    parent = XRI.make_xri(xrd.elements["CanonicalID"].text)

    if parent_sought != parent.downcase
      raise XRDSFraud.new(format(
        "%s can not come from %s",
        parent_sought,
        parent,
      ))
    end

    child_id = parent_sought
  end

  root = XRI.root_authority(iname)
  unless XRI.provider_is_authoritative(root, child_id)
    raise XRDSFraud.new(format("%s can not come from root %s", child_id, root))
  end

  canonical_id
end

.get_service_endpoints(input_url, flt = nil) ⇒ Object 



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# File 'lib/openid/yadis/services.rb', line 7

def self.get_service_endpoints(input_url, flt = nil)
  # Perform the Yadis protocol on the input URL and return an
  # iterable of resulting endpoint objects.
  #
  # @param flt: A filter object or something that is convertable
  # to a filter object (using mkFilter) that will be used to
  # generate endpoint objects. This defaults to generating
  # BasicEndpoint objects.
  result = Yadis.discover(input_url)
  begin
    endpoints = Yadis.apply_filter(
      result.normalized_uri,
      result.response_text,
      flt,
    )
  rescue XRDSError => e
    raise DiscoveryFailure.new(e.to_s, nil)
  end

  [result.normalized_uri, endpoints]
end

.get_yadis_xrd(xrds_tree) ⇒ Object

Raises:



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# File 'lib/openid/yadis/xrds.rb', line 118

def self.get_yadis_xrd(xrds_tree)
  REXML::XPath.each(
    xrds_tree.root,
    "/xrds:XRDS/xrd:XRD[last()]",
    XRDS_NAMESPACES,
  ) do |el|
    return el
  end
  raise XRDSError.new("No XRD element found.")
end

.html_yadis_location(html) ⇒ Object 



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# File 'lib/openid/yadis/parsehtml.rb', line 9

def self.html_yadis_location(html)
  parser = HTMLTokenizer.new(html)

  # to keep track of whether or not we are in the head element
  in_head = false

  begin
    while el = parser.getTag(
      "head",
      "/head",
      "meta",
      "body",
      "/body",
      "html",
      "script",
    )

      # we are leaving head or have reached body, so we bail
      return if ["/head", "body", "/body"].member?(el.tag_name)

      if el.tag_name == "head" && !(el.to_s[-2] == "/")
        in_head = true # tag ends with a /: a short tag
      end
      next unless in_head

      if el.tag_name == "script" && !(el.to_s[-2] == "/")
        parser.getTag("/script") # tag ends with a /: a short tag
      end

      return if el.tag_name == "html"

      next unless el.tag_name == "meta" and (equiv = el.attr_hash["http-equiv"])
      if %w[x-xrds-location x-yadis-location].member?(equiv.downcase) &&
          el.attr_hash.member?("content")
        return CGI.unescapeHTML(el.attr_hash["content"])
      end
    end
  rescue HTMLTokenizerError # just stop parsing if there's an error
  end
end

.is_xrds?(xrds_tree) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/openid/yadis/xrds.rb', line 111

def self.is_xrds?(xrds_tree)
  xrds_root = xrds_tree.root
  (!xrds_root.nil? and
    xrds_root.name == "XRDS" and
    xrds_root.namespace == XRDS_NS)
end

.make_filter(parts) ⇒ Object

Convert a filter-convertable thing into a filter

parts should be a filter, an endpoint, a callable, or a list of any of these.



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# File 'lib/openid/yadis/filters.rb', line 143

def self.make_filter(parts)
  # Convert the parts into a list, and pass to mk_compound_filter
  parts = [BasicServiceEndpoint] if parts.nil?

  return mk_compound_filter(parts) if parts.is_a?(Array)

  mk_compound_filter([parts])
end

.match_types(accept_types, have_types) ⇒ Object 



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# File 'lib/openid/yadis/accept.rb', line 75

def self.match_types(accept_types, have_types)
  # Given the result of parsing an Accept: header, and the
  # available MIME types, return the acceptable types with their
  # quality markdowns.
  #
  # For example:
  #
  # >>> acceptable = parse_accept_header('text/html, text/plain; q=0.5')
  # >>> matchTypes(acceptable, ['text/plain', 'text/html', 'image/jpeg'])
  # [('text/html', 1.0), ('text/plain', 0.5)]
  #
  # Type signature: ([(str, str, float)], [str]) -> [(str, float)]
  default = if accept_types.nil? or accept_types == []
    # Accept all of them
    1
  else
    0
  end

  match_main = {}
  match_sub = {}
  accept_types.each do |main, sub, q|
    if main == "*"
      default = [default, q].max
      next
    elsif sub == "*"
      match_main[main] = [match_main.fetch(main, 0), q].max
    else
      match_sub[[main, sub]] = [match_sub.fetch([main, sub], 0), q].max
    end
  end

  accepted_list = []
  order_maintainer = 0
  have_types.each do |mtype|
    main, sub = mtype.split("/", 2)
    q = if match_sub.member?([main, sub])
      match_sub[[main, sub]]
    else
      match_main.fetch(main, default)
    end

    if q != 0
      accepted_list << [1 - q, order_maintainer, q, mtype]
      order_maintainer += 1
    end
  end

  accepted_list.sort!
  accepted_list.collect { |_, _, q, mtype| [mtype, q] }
end

.mk_compound_filter(parts) ⇒ Object

Create a filter out of a list of filter-like things

Used by make_filter

parts should be a list of things that can be passed to make_filter

Raises:

  • (TypeError) 


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# File 'lib/openid/yadis/filters.rb', line 157

def self.mk_compound_filter(parts)
  raise TypeError, "#{parts.inspect} is not iterable" unless parts.respond_to?(:each)

  # Separate into a list of callables and a list of filter objects
  transformers = []
  filters = []
  parts.each do |subfilter|
    if !subfilter.is_a?(Array)
      # If it's not an iterable
      if subfilter.respond_to?(:get_service_endpoints)
        # It's a full filter
        filters << subfilter
      elsif subfilter.respond_to?(:from_basic_service_endpoint)
        # It's an endpoint object, so put its endpoint conversion
        # attribute into the list of endpoint transformers
        transformers << subfilter.method(:from_basic_service_endpoint)
      elsif subfilter.respond_to?(:call)
        # It's a proc, so add it to the list of endpoint
        # transformers
        transformers << subfilter
      else
        raise @@filter_type_error
      end
    else
      filters << mk_compound_filter(subfilter)
    end
  end

  filters << TransformFilterMaker.new(transformers) if transformers.length > 0

  return filters[0] if filters.length == 1

  CompoundFilter.new(filters)
end

.parse_accept_header(value) ⇒ Object 



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# File 'lib/openid/yadis/accept.rb', line 36

def self.parse_accept_header(value)
  # Parse an accept header, ignoring any accept-extensions
  #
  # returns a list of tuples containing main MIME type, MIME
  # subtype, and quality markdown.
  #
  # str -> [(str, str, float)]
  chunks = value.split(",", -1).collect { |v| v.strip }
  accept = []
  chunks.each do |chunk|
    parts = chunk.split(";", -1).collect { |s| s.strip }

    mtype = parts.shift
    if mtype.index("/").nil?
      # This is not a MIME type, so ignore the bad data
      next
    end

    main, sub = mtype.split("/", 2)

    q = nil
    parts.each do |ext|
      unless ext.index("=").nil?
        k, v = ext.split("=", 2)
        q = v.to_f if k == "q"
      end
    end

    q = 1.0 if q.nil?

    accept << [q, main, sub]
  end

  accept.sort!
  accept.reverse!

  accept.collect { |q, main, sub| [main, sub, q] }
end

.parseXRDS(text) ⇒ Object 



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# File 'lib/openid/yadis/xrds.rb', line 87

def self.parseXRDS(text)
  disable_entity_expansion do
    raise XRDSError.new("Not an XRDS document.") if text.nil?

    begin
      d = REXML::Document.new(text)
    rescue RuntimeError
      raise XRDSError.new("Not an XRDS document. Failed to parse XML.")
    end

    return d if is_xrds?(d)

    raise XRDSError.new("Not an XRDS document.")
  end
end

.prio_sort(elements) ⇒ Object

Sort a list of elements that have priority attributes.



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# File 'lib/openid/yadis/xrds.rb', line 154

def self.prio_sort(elements)
  elements.sort do |a, b|
    a.attribute("priority").to_s.to_i <=> b.attribute("priority").to_s.to_i
  end
end

.services(xrds_tree) ⇒ Object 



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# File 'lib/openid/yadis/xrds.rb', line 135

def self.services(xrds_tree)
  s = []
  each_service(xrds_tree) do |service|
    s << service
  end
  s
end

.where_is_yadis?(resp) ⇒ Boolean

Given a HTTPResponse, return the location of the Yadis document.

May be the URL just retrieved, another URL, or None, if I can’t find any.

non-blocking

Returns:

  • (Boolean) 


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# File 'lib/openid/yadis/discovery.rb', line 124

def self.where_is_yadis?(resp)
  # Attempt to find out where to go to discover the document or if
  # we already have it
  content_type = resp["content-type"]

  # According to the spec, the content-type header must be an
  # exact match, or else we have to look for an indirection.
  if !content_type.nil? and !content_type.to_s.empty? and
      content_type.split(";", 2)[0].downcase == YADIS_CONTENT_TYPE
    return resp.final_url
  else
    # Try the header
    yadis_loc = resp[YADIS_HEADER_NAME.downcase]

    if yadis_loc.nil?
      # Parse as HTML if the header is missing.
      #
      # XXX: do we want to do something with content-type, like
      # have a whitelist or a blacklist (for detecting that it's
      # HTML)?
      yadis_loc = Yadis.html_yadis_location(resp.body)
    end
  end

  yadis_loc
end