93 lines
3.4 KiB
Ruby
93 lines
3.4 KiB
Ruby
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module DiasporaFederation
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module Discovery
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# Generates and parses Host Meta documents.
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#
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# This is a minimal implementation of the standard, only to the degree of what
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# is used for the purposes of the Diaspora* protocol. (e.g. WebFinger)
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#
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# @example Creating a Host Meta document
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# doc = HostMeta.from_base_url("https://pod.example.tld/")
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# doc.to_xml
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#
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# @example Parsing a Host Meta document
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# doc = HostMeta.from_xml(xml_string)
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# webfinger_tpl = doc.webfinger_template_url
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#
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# @see http://tools.ietf.org/html/rfc6415 RFC 6415: "Web Host Metadata"
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# @see XrdDocument
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class HostMeta
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private_class_method :new
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# create a new host-meta instance
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# @param [String] webfinger_url the webfinger-url
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def initialize(webfinger_url)
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@webfinger_url = webfinger_url
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end
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# URL fragment to append to the base URL
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WEBFINGER_SUFFIX = "/webfinger?q={uri}"
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# Returns the WebFinger URL that was used to build this instance (either from
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# xml or by giving a base URL).
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# @return [String] WebFinger template URL
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def webfinger_template_url
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@webfinger_url
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end
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# Produces the XML string for the Host Meta instance with a +Link+ element
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# containing the +webfinger_url+.
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# @return [String] XML string
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def to_xml
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doc = XrdDocument.new
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doc.links << {rel: "lrdd",
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type: "application/xrd+xml",
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template: @webfinger_url}
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doc.to_xml
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end
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# Builds a new HostMeta instance and constructs the WebFinger URL from the
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# given base URL by appending HostMeta::WEBFINGER_SUFFIX.
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# @param [String, URL] base_url the base-url for the webfinger-url
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# @return [HostMeta]
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# @raise [InvalidData] if the webfinger url is malformed
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def self.from_base_url(base_url)
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webfinger_url = "#{base_url.to_s.chomp('/')}#{WEBFINGER_SUFFIX}"
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raise InvalidData, "invalid webfinger url: #{webfinger_url}" unless webfinger_url_valid?(webfinger_url)
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new(webfinger_url)
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end
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# Reads the given Host Meta XML document string and populates the
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# +webfinger_url+.
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# @param [String] hostmeta_xml Host Meta XML string
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# @raise [InvalidData] if the xml or the webfinger url is malformed
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def self.from_xml(hostmeta_xml)
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data = XrdDocument.xml_data(hostmeta_xml)
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raise InvalidData, "received an invalid xml" unless data.key?(:links)
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webfinger_url = webfinger_url_from_xrd(data)
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raise InvalidData, "invalid webfinger url: #{webfinger_url}" unless webfinger_url_valid?(webfinger_url)
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new(webfinger_url)
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end
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# Applies some basic sanity-checking to the given URL
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# @param [String] url validation subject
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# @return [Boolean] validation result
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def self.webfinger_url_valid?(url)
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!url.nil? && url.instance_of?(String) && url =~ %r{^https?:\/\/.*\/.*\{uri\}.*}i
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end
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private_class_method :webfinger_url_valid?
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# Gets the webfinger url from an XRD data structure
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# @param [Hash] data extracted data
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# @return [String] webfinger url
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def self.webfinger_url_from_xrd(data)
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link = data[:links].find {|l| (l[:rel] == "lrdd" && l[:type] == "application/xrd+xml") }
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return link[:template] unless link.nil?
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end
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private_class_method :webfinger_url_from_xrd
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end
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end
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end
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