Merge pull request #102 from rails/subscription-rejection

Allow rejecting subscriptions from the channel

6 files changed, 74 insertions, 17 deletions

diff --git a/lib/action_cable/channel/base.rb b/lib/action_cable/channel/base.rb
index 2d528dfdbf..66d60d7e99 100644
--- a/lib/action_cable/channel/base.rb
+++ b/lib/action_cable/channel/base.rb
@@ -66,6 +66,22 @@ module ActionCable
     #
     # Also note that in this example, current_user is available because it was marked as an identifying attribute on the connection.
     # All such identifiers will automatically create a delegation method of the same name on the channel instance.
+    #
+    # == Rejecting subscription requests
+    #
+    # A channel can reject a subscription request in the #subscribed callback by invoking #reject!
+    #
+    # Example:
+    #
+    #   class ChatChannel < ApplicationCable::Channel
+    #     def subscribed
+    #       @room = Chat::Room[params[:room_number]]
+    #       reject! unless current_user.can_access?(@room)
+    #     end
+    #   end
+    #
+    # In this example, the subscription will be rejected if the current_user does not have access to the chat room.
+    # On the client-side, Channel#rejected callback will get invoked when the server rejects the subscription request.
     class Base
       include Callbacks
       include PeriodicTimers
@@ -74,8 +90,9 @@ module ActionCable
       include Broadcasting
 
       SUBSCRIPTION_CONFIRMATION_INTERNAL_MESSAGE = 'confirm_subscription'.freeze
+      SUBSCRIPTION_REJECTION_INTERNAL_MESSAGE = 'reject_subscription'.freeze
 
-      attr_reader :params, :connection
+      attr_reader :params, :connection, :identifier
       delegate :logger, to: :connection
 
       class << self
@@ -169,8 +186,6 @@ module ActionCable
           connection.transmit ActiveSupport::JSON.encode(identifier: @identifier, message: data)
         end
 
-
-      protected
         def defer_subscription_confirmation!
           @defer_subscription_confirmation = true
         end
@@ -183,6 +198,14 @@ module ActionCable
           @subscription_confirmation_sent
         end
 
+        def reject!
+          @reject_subscription = true
+        end
+
+        def subscription_rejected?
+          @reject_subscription
+        end
+
       private
         def delegate_connection_identifiers
           connection.identifiers.each do |identifier|
@@ -197,7 +220,12 @@ module ActionCable
           run_callbacks :subscribe do
             subscribed
           end
-          transmit_subscription_confirmation unless defer_subscription_confirmation?
+
+          if subscription_rejected?
+            reject_subscription
+          else
+            transmit_subscription_confirmation unless defer_subscription_confirmation?
+          end
         end
 
 
@@ -234,6 +262,16 @@ module ActionCable
             @subscription_confirmation_sent = true
           end
         end
+
+        def reject_subscription
+          connection.subscriptions.remove_subscription self
+          transmit_subscription_rejection
+        end
+
+        def transmit_subscription_rejection
+          logger.info "#{self.class.name} is transmitting the subscription rejection"
+          connection.transmit ActiveSupport::JSON.encode(identifier: @identifier, type: SUBSCRIPTION_REJECTION_INTERNAL_MESSAGE)
+        end
     end
   end
 end
diff --git a/lib/action_cable/connection/base.rb b/lib/action_cable/connection/base.rb
index ac45124a28..a988060d56 100644
--- a/lib/action_cable/connection/base.rb
+++ b/lib/action_cable/connection/base.rb
@@ -48,7 +48,7 @@ module ActionCable
       include InternalChannel
       include Authorization
 
-      attr_reader :server, :env
+      attr_reader :server, :env, :subscriptions
       delegate :worker_pool, :pubsub, to: :server
 
       attr_reader :logger
@@ -140,7 +140,7 @@ module ActionCable
 
       private
         attr_reader :websocket
-        attr_reader :subscriptions, :message_buffer
+        attr_reader :message_buffer
 
         def on_open
           connect if respond_to?(:connect)
diff --git a/lib/action_cable/connection/subscriptions.rb b/lib/action_cable/connection/subscriptions.rb
index 229be2a316..6199db4898 100644
--- a/lib/action_cable/connection/subscriptions.rb
+++ b/lib/action_cable/connection/subscriptions.rb
@@ -37,8 +37,12 @@ module ActionCable
 
       def remove(data)
         logger.info "Unsubscribing from channel: #{data['identifier']}"
-        subscriptions[data['identifier']].unsubscribe_from_channel
-        subscriptions.delete(data['identifier'])
+        remove_subscription subscriptions[data['identifier']]
+      end
+
+      def remove_subscription(subscription)
+        subscription.unsubscribe_from_channel
+        subscriptions.delete(subscription.identifier)
       end
 
       def perform_action(data)
diff --git a/lib/assets/javascripts/cable.coffee b/lib/assets/javascripts/cable.coffee
index 476d90ef72..fca5e095b5 100644
--- a/lib/assets/javascripts/cable.coffee
+++ b/lib/assets/javascripts/cable.coffee
@@ -5,6 +5,7 @@
   PING_IDENTIFIER: "_ping"
   INTERNAL_MESSAGES:
     SUBSCRIPTION_CONFIRMATION: 'confirm_subscription'
+    SUBSCRIPTION_REJECTION: 'reject_subscription'
 
   createConsumer: (url) ->
     new Cable.Consumer url
diff --git a/lib/assets/javascripts/cable/connection.coffee b/lib/assets/javascripts/cable/connection.coffee
index 33159130c7..b6b99413dc 100644
--- a/lib/assets/javascripts/cable/connection.coffee
+++ b/lib/assets/javascripts/cable/connection.coffee
@@ -55,12 +55,17 @@ class Cable.Connection
       {identifier, message, type} = JSON.parse(event.data)
 
       if type?
-        switch type
-          when Cable.INTERNAL_MESSAGES.SUBSCRIPTION_CONFIRMATION
-            @consumer.subscriptions.notify(identifier, "connected")
+        @handleTypeMessage(type)
       else
         @consumer.subscriptions.notify(identifier, "received", message)
 
+    onTypeMessage: (type) ->
+      switch type
+        when Cable.INTERNAL_MESSAGES.SUBSCRIPTION_CONFIRMATION
+          @consumer.subscriptions.notify(identifier, "connected")
+        when Cable.INTERNAL_MESSAGES.SUBSCRIPTION_REJECTION
+          @consumer.subscriptions.reject(identifier)
+
     open: ->
       @disconnected = false
       @consumer.subscriptions.reload()
diff --git a/lib/assets/javascripts/cable/subscriptions.coffee b/lib/assets/javascripts/cable/subscriptions.coffee
index 4efb384ee2..13db32eb2c 100644
--- a/lib/assets/javascripts/cable/subscriptions.coffee
+++ b/lib/assets/javascripts/cable/subscriptions.coffee
@@ -23,18 +23,27 @@ class Cable.Subscriptions
     @notify(subscription, "initialized")
     @sendCommand(subscription, "subscribe")
 
-  reload: ->
-    for subscription in @subscriptions
-      @sendCommand(subscription, "subscribe")
-
   remove: (subscription) ->
-    @subscriptions = (s for s in @subscriptions when s isnt subscription)
+    @forget(subscription)
+
     unless @findAll(subscription.identifier).length
       @sendCommand(subscription, "unsubscribe")
 
+  reject: (identifier) ->
+    for subscription in @findAll(identifier)
+      @forget(subscription)
+      @notify(subscription, "rejected")
+
+  forget: (subscription) ->
+    @subscriptions = (s for s in @subscriptions when s isnt subscription)
+
   findAll: (identifier) ->
     s for s in @subscriptions when s.identifier is identifier
 
+  reload: ->
+    for subscription in @subscriptions
+      @sendCommand(subscription, "subscribe")
+
   notifyAll: (callbackName, args...) ->
     for subscription in @subscriptions
       @notify(subscription, callbackName, args...)
@@ -48,7 +57,7 @@ class Cable.Subscriptions
     for subscription in subscriptions
       subscription[callbackName]?(args...)
 
-      if callbackName in ["initialized", "connected", "disconnected"]
+      if callbackName in ["initialized", "connected", "disconnected", "rejected"]
         {identifier} = subscription
         @record(notification: {identifier, callbackName, args})