Implement HTTP Digest authentication. [#1230 state:resolved] [Gregg Kellogg, Pratik Naik]

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

1 files changed, 173 insertions, 23 deletions

diff --git a/actionpack/lib/action_controller/http_authentication.rb b/actionpack/lib/action_controller/http_authentication.rb
index 2ed810db7d..c91ef2ca48 100644
--- a/actionpack/lib/action_controller/http_authentication.rb
+++ b/actionpack/lib/action_controller/http_authentication.rb
@@ -1,42 +1,42 @@
 module ActionController
   module HttpAuthentication
     # Makes it dead easy to do HTTP Basic authentication.
-    # 
+    #
     # Simple Basic example:
-    # 
+    #
     #   class PostsController < ApplicationController
     #     USER_NAME, PASSWORD = "dhh", "secret"
-    #   
+    #
     #     before_filter :authenticate, :except => [ :index ]
-    #   
+    #
     #     def index
     #       render :text => "Everyone can see me!"
     #     end
-    #   
+    #
     #     def edit
     #       render :text => "I'm only accessible if you know the password"
     #     end
-    #   
+    #
     #     private
     #       def authenticate
-    #         authenticate_or_request_with_http_basic do |user_name, password| 
+    #         authenticate_or_request_with_http_basic do |user_name, password|
     #           user_name == USER_NAME && password == PASSWORD
     #         end
     #       end
     #   end
-    # 
-    # 
-    # Here is a more advanced Basic example where only Atom feeds and the XML API is protected by HTTP authentication, 
+    #
+    #
+    # Here is a more advanced Basic example where only Atom feeds and the XML API is protected by HTTP authentication,
     # the regular HTML interface is protected by a session approach:
-    # 
+    #
     #   class ApplicationController < ActionController::Base
     #     before_filter :set_account, :authenticate
-    #   
+    #
     #     protected
     #       def set_account
     #         @account = Account.find_by_url_name(request.subdomains.first)
     #       end
-    #   
+    #
     #       def authenticate
     #         case request.format
     #         when Mime::XML, Mime::ATOM
@@ -54,24 +54,48 @@ module ActionController
     #         end
     #       end
     #   end
-    # 
-    # 
+    #
     # In your integration tests, you can do something like this:
-    # 
+    #
     #   def test_access_granted_from_xml
     #     get(
-    #       "/notes/1.xml", nil, 
+    #       "/notes/1.xml", nil,
     #       :authorization => ActionController::HttpAuthentication::Basic.encode_credentials(users(:dhh).name, users(:dhh).password)
     #     )
-    # 
+    #
     #     assert_equal 200, status
     #   end
-    #  
-    #  
+    #
+    # Simple Digest example:
+    #
+    #   class PostsController < ApplicationController
+    #     USERS = {"dhh" => "secret"}
+    #
+    #     before_filter :authenticate, :except => [:index]
+    #
+    #     def index
+    #       render :text => "Everyone can see me!"
+    #     end
+    #
+    #     def edit
+    #       render :text => "I'm only accessible if you know the password"
+    #     end
+    #
+    #     private
+    #       def authenticate
+    #         authenticate_or_request_with_http_digest(realm) do |username|
+    #           USERS[username]
+    #         end
+    #       end
+    #   end
+    #
+    # NOTE: The +authenticate_or_request_with_http_digest+ block must return the user's password so the framework can appropriately
+    #       hash it to check the user's credentials. Returning +nil+ will cause authentication to fail.
+    #
     # On shared hosts, Apache sometimes doesn't pass authentication headers to
     # FCGI instances. If your environment matches this description and you cannot
     # authenticate, try this rule in your Apache setup:
-    # 
+    #
     #   RewriteRule ^(.*)$ dispatch.fcgi [E=X-HTTP_AUTHORIZATION:%{HTTP:Authorization},QSA,L]
     module Basic
       extend self
@@ -99,14 +123,14 @@ module ActionController
       def user_name_and_password(request)
         decode_credentials(request).split(/:/, 2)
       end
-  
+
       def authorization(request)
         request.env['HTTP_AUTHORIZATION']   ||
         request.env['X-HTTP_AUTHORIZATION'] ||
         request.env['X_HTTP_AUTHORIZATION'] ||
         request.env['REDIRECT_X_HTTP_AUTHORIZATION']
       end
-    
+
       def decode_credentials(request)
         ActiveSupport::Base64.decode64(authorization(request).split.last || '')
       end
@@ -120,5 +144,131 @@ module ActionController
         controller.__send__ :render, :text => "HTTP Basic: Access denied.\n", :status => :unauthorized
       end
     end
+
+    module Digest
+      extend self
+
+      module ControllerMethods
+        def authenticate_or_request_with_http_digest(realm = "Application", &password_procedure)
+          authenticate_with_http_digest(realm, &password_procedure) || request_http_digest_authentication(realm)
+        end
+
+        # Authenticate with HTTP Digest, returns true or false
+        def authenticate_with_http_digest(realm = "Application", &password_procedure)
+          HttpAuthentication::Digest.authenticate(self, realm, &password_procedure)
+        end
+
+        # Render output including the HTTP Digest authentication header
+        def request_http_digest_authentication(realm = "Application", message = nil)
+          HttpAuthentication::Digest.authentication_request(self, realm, message)
+        end
+      end
+
+      # Returns false on a valid response, true otherwise
+      def authenticate(controller, realm, &password_procedure)
+        authorization(controller.request) && validate_digest_response(controller, realm, &password_procedure)
+      end
+
+      def authorization(request)
+        request.env['HTTP_AUTHORIZATION']   ||
+        request.env['X-HTTP_AUTHORIZATION'] ||
+        request.env['X_HTTP_AUTHORIZATION'] ||
+        request.env['REDIRECT_X_HTTP_AUTHORIZATION']
+      end
+
+      # Raises error unless the request credentials response value matches the expected value.
+      def validate_digest_response(controller, realm, &password_procedure)
+        credentials = decode_credentials_header(controller.request)
+        valid_nonce = validate_nonce(controller.request, credentials[:nonce])
+
+        if valid_nonce && realm == credentials[:realm] && opaque(controller.request.session.session_id) == credentials[:opaque]
+          password = password_procedure.call(credentials[:username])
+          expected = expected_response(controller.request.env['REQUEST_METHOD'], controller.request.url, credentials, password)
+          expected == credentials[:response]
+        end
+      end
+
+      # Returns the expected response for a request of +http_method+ to +uri+ with the decoded +credentials+ and the expected +password+
+      def expected_response(http_method, uri, credentials, password)
+        ha1 = ::Digest::MD5.hexdigest([credentials[:username], credentials[:realm], password].join(':'))
+        ha2 = ::Digest::MD5.hexdigest([http_method.to_s.upcase, uri].join(':'))
+        ::Digest::MD5.hexdigest([ha1, credentials[:nonce], credentials[:nc], credentials[:cnonce], credentials[:qop], ha2].join(':'))
+      end
+
+      def encode_credentials(http_method, credentials, password)
+        credentials[:response] = expected_response(http_method, credentials[:uri], credentials, password)
+        "Digest " + credentials.sort_by {|x| x[0].to_s }.inject([]) {|a, v| a << "#{v[0]}='#{v[1]}'" }.join(', ')
+      end
+
+      def decode_credentials_header(request)
+        decode_credentials(authorization(request))
+      end
+
+      def decode_credentials(header)
+        header.to_s.gsub(/^Digest\s+/,'').split(',').inject({}) do |hash, pair|
+          key, value = pair.split('=', 2)
+          hash[key.strip.to_sym] = value.to_s.gsub(/^"|"$/,'').gsub(/'/, '')
+          hash
+        end
+      end
+
+      def authentication_header(controller, realm)
+        session_id = controller.request.session.session_id
+        controller.headers["WWW-Authenticate"] = %(Digest realm="#{realm}", qop="auth", algorithm=MD5, nonce="#{nonce(session_id)}", opaque="#{opaque(session_id)}")
+      end
+
+      def authentication_request(controller, realm, message = nil)
+        message ||= "HTTP Digest: Access denied.\n"
+        authentication_header(controller, realm)
+        controller.__send__ :render, :text => message, :status => :unauthorized
+      end
+
+      # Uses an MD5 digest based on time to generate a value to be used only once.
+      #
+      # A server-specified data string which should be uniquely generated each time a 401 response is made.
+      # It is recommended that this string be base64 or hexadecimal data.
+      # Specifically, since the string is passed in the header lines as a quoted string, the double-quote character is not allowed.
+      #
+      # The contents of the nonce are implementation dependent.
+      # The quality of the implementation depends on a good choice.
+      # A nonce might, for example, be constructed as the base 64 encoding of
+      #
+      # => time-stamp H(time-stamp ":" ETag ":" private-key)
+      #
+      # where time-stamp is a server-generated time or other non-repeating value,
+      # ETag is the value of the HTTP ETag header associated with the requested entity,
+      # and private-key is data known only to the server.
+      # With a nonce of this form a server would recalculate the hash portion after receiving the client authentication header and
+      # reject the request if it did not match the nonce from that header or
+      # if the time-stamp value is not recent enough. In this way the server can limit the time of the nonce's validity.
+      # The inclusion of the ETag prevents a replay request for an updated version of the resource.
+      # (Note: including the IP address of the client in the nonce would appear to offer the server the ability
+      # to limit the reuse of the nonce to the same client that originally got it.
+      # However, that would break proxy farms, where requests from a single user often go through different proxies in the farm.
+      # Also, IP address spoofing is not that hard.)
+      #
+      # An implementation might choose not to accept a previously used nonce or a previously used digest, in order to
+      # protect against a replay attack. Or, an implementation might choose to use one-time nonces or digests for
+      # POST or PUT requests and a time-stamp for GET requests. For more details on the issues involved see Section 4
+      # of this document.
+      #
+      # The nonce is opaque to the client.
+      def nonce(session_id, time = Time.now)
+        t = time.to_i
+        hashed = [t, session_id]
+        digest = ::Digest::MD5.hexdigest(hashed.join(":"))
+        Base64.encode64("#{t}:#{digest}").gsub("\n", '')
+      end
+
+      def validate_nonce(request, value)
+        t = Base64.decode64(value).split(":").first.to_i
+        nonce(request.session.session_id, t) == value && (t - Time.now.to_i).abs <= 10 * 60
+      end
+
+      # Opaque based on digest of session_id
+      def opaque(session_id)
+        Base64.encode64(::Digest::MD5::hexdigest(session_id)).gsub("\n", '')
+      end
+    end
   end
 end