Class: OpenID::GoogleDiscovery

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

Overview

Handles the bulk of Google’s modified discovery prototcol See groups.google.com/group/google-federated-login-api/web/openid-discovery-for-hosted-domains

Constant Summary collapse

NAMESPACES = 
{
  'xrds' => 'xri://$xrd*($v*2.0)',
  'xrd' => 'xri://$xrds',
  'openid' => 'http://namespace.google.com/openid/xmlns'
}

Instance Method Summary collapse

Instance Method Details

#discover_site(domain) ⇒ Object

Handles discovery for a domain



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# File 'lib/gapps_openid.rb', line 114

def discover_site(domain)
  OpenID.logger.debug("Discovering domain #{domain}") unless OpenID.logger.nil?
  url = fetch_host_meta(domain)
  if url.nil?
    OpenID.logger.debug("#{domain} is not a Google Apps domain, aborting") unless OpenID.logger.nil?
    return nil # Not a Google Apps domain
  end
  xrds = fetch_xrds(domain, url)
  unless xrds.nil?
      endpoints = OpenID::OpenIDServiceEndpoint.from_xrds(domain, xrds)
      return [domain, OpenID.get_op_or_user_services(endpoints)]
  end
  return nil
end

#discover_user(domain, claimed_id) ⇒ Object

Handles discovery for a user’s claimed ID.



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# File 'lib/gapps_openid.rb', line 97

def discover_user(domain, claimed_id)
  OpenID.logger.debug("Discovering user identity #{claimed_id} for domain #{domain}") unless OpenID.logger.nil?
  url = fetch_host_meta(domain)
  if url.nil?
    OpenID.logger.debug("#{domain} is not a Google Apps domain, aborting") unless OpenID.logger.nil?
    return nil # Not a Google Apps domain
  end
  xrds = fetch_xrds(domain, url)
  user_url, authority = get_user_xrds_url(xrds, claimed_id)
  user_xrds = fetch_xrds(authority, user_url, false)
  return if user_xrds.nil?
  
  endpoints = OpenID::OpenIDServiceEndpoint.from_xrds(claimed_id, user_xrds)
  return [claimed_id, OpenID.get_op_or_user_services(endpoints)]
end

#fetch_host_meta(domain) ⇒ Object

Kickstart the discovery process by checking against Google’s well-known location for hosted domains. This gives us the location of the site’s XRDS doc



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# File 'lib/gapps_openid.rb', line 131

def fetch_host_meta(domain) 
  cached_value = get_cache(domain)
  return cached_value unless cached_value.nil?
  
  host_meta_url = "https://www.google.com/accounts/o8/.well-known/host-meta?hd=#{CGI::escape(domain)}"
  http_resp = OpenID.fetch(host_meta_url)
  if http_resp.code != "200" and http_resp.code != "206"
    OpenID.logger.debug("Received #{http_resp.code} when fetching #{host_meta_url}") unless OpenID.logger.nil?
    return nil
  end
  matches = /Link: <(.*)>/.match( http_resp.body )
  if matches.nil? 
    OpenID.logger.debug("No link tag found at #{host_meta_url}") unless OpenID.logger.nil?
    return nil
  end
  put_cache(domain, matches[1])
  return matches[1]
end

#fetch_xrds(authority, url, cache = true) ⇒ Object

Fetches the XRDS and verifies the signature and authority for the doc



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# File 'lib/gapps_openid.rb', line 151

def fetch_xrds(authority, url, cache=true) 
  return if url.nil?

  OpenID.logger.debug("Retrieving XRDS from #{url}") unless OpenID.logger.nil?
 
  cached_xrds = get_cache(url)
  return cached_xrds unless cached_xrds.nil?

  http_resp = OpenID.fetch(url)
  if http_resp.code != "200" and http_resp.code != "206"
    OpenID.logger.debug("Received #{http_resp.code} when fetching #{url}") unless OpenID.logger.nil?
    return nil
  end

  body = http_resp.body
  signature = http_resp["Signature"]
  signed_by = SimpleSign.verify(body, signature)
  if !signed_by.casecmp(authority) or !signed_by.casecmp('hosted-id.google.com')
    OpenID.logger.warn("Expected signature from #{authority} but found #{signed_by}") unless OpenID.logger.nil?        
    return false # Signed, but not by the right domain.
  end
  
  # Everything is OK
  if cache
    put_cache(url, body)
  end
  return body      
end

#get_cache(key) ⇒ Object 



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# File 'lib/gapps_openid.rb', line 199

def get_cache(key)
  return nil if OpenID.cache.nil?
  return OpenID.cache.read("__GAPPS_OPENID__#{key}")
end

#get_user_xrds_url(xrds, claimed_id) ⇒ Object

Process the URITemplate in the XRDS to derive the location of the claimed id’s XRDS



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# File 'lib/gapps_openid.rb', line 181

def get_user_xrds_url(xrds, claimed_id)
  types_to_match = ['http://www.iana.org/assignments/relation/describedby']
  services = OpenID::Yadis::apply_filter(claimed_id, xrds)
  services.each do | service | 
    if service.match_types(types_to_match) 
      template = REXML::XPath.first(service.service_element, '//openid:URITemplate', NAMESPACES)
      authority = REXML::XPath.first(service.service_element, '//openid:NextAuthority', NAMESPACES)
      url = template.text.gsub('{%uri}', CGI::escape(claimed_id))
      return [url, authority.text]
    end
  end
end

#perform_discovery(uri) ⇒ Object

Main entry point for discovery. Attempts to detect whether or not the URI is a raw domain name (‘mycompany.com’) vs. a user’s claimed ID (‘mycompany.com/openid?id=12345’) and performs the site or user discovery appropriately



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# File 'lib/gapps_openid.rb', line 81

def perform_discovery(uri)
  OpenID.logger.debug("Performing discovery for #{uri}") unless OpenID.logger.nil?
  begin
    parsed_uri = URI::parse(uri)
    if parsed_uri.scheme.nil?
      return discover_site(uri)
    end
    return discover_user(parsed_uri.host, uri)
  rescue Exception => e
    # If we fail, just return nothing and fallback on default discovery mechanisms
    OpenID.logger.warn("Unexpected exception performing discovery for id #{uri}: #{e}") unless OpenID.logger.nil?
    return nil
  end
end

#put_cache(key, item) ⇒ Object 



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# File 'lib/gapps_openid.rb', line 194

def put_cache(key, item)
  return if OpenID.cache.nil?
  OpenID.cache.write("__GAPPS_OPENID__#{key}", item)
end