Ignore requests for non-existent channels

This works around a bug in some ssh servers, where channel requests
are sent to channels after the channels have been closed.

CHANGELOG.rdoc

@@ -1,5 +1,7 @@
 === unreleased
 
+* Ignore requests for non-existent channels (workaround ssh server bug) [Jamis Buck]
+
 * Add terminate! method for hard shutdown scenarios [Jamis Buck]
 
 * Revert to pre-2.0.7 key-loading behavior by default, but load private-key if public-key doesn't exist [Jamis Buck]

lib/net/ssh/connection/session.rb

@@ -46,6 +46,16 @@ class Session
     # The list of callbacks for pending requests. See #send_global_request.
     attr_reader :pending_requests #:nodoc:
 
+    class NilChannel
+      def initialize(session)
+        @session = session
+      end
+
+      def method_missing(sym, *args)
+        @session.lwarn { "ignoring request #{sym.inspect} for non-existent (closed?) channel; probably ssh server bug" }
+      end
+    end
+
     # Create a new connection service instance atop the given transport
     # layer. Initializes the listeners to be only the underlying socket object.
     def initialize(transport, options={})
@@ -55,7 +65,7 @@ def initialize(transport, options={})
       @options = options
 
       @channel_id_counter = -1
-      @channels = {}
+      @channels = Hash.new(NilChannel.new(self))
       @listeners = { transport.socket => nil }
       @pending_requests = []
       @channel_open_handlers = {}

test/connection/test_session.rb

@@ -257,6 +257,11 @@ def test_channel_window_adjust_packet_should_be_routed_to_corresponding_channel
       process_times(2)
     end
 
+    def test_channel_request_for_nonexistant_channel_should_be_ignored
+      transport.return(CHANNEL_REQUEST, :long, 14, :string, "testing", :bool, false)
+      assert_nothing_raised { process_times(2) }
+    end
+
     def test_channel_request_packet_should_be_routed_to_corresponding_channel
       channel_at(14).expects(:do_request).with("testing", false, Net::SSH::Buffer.new)
       transport.return(CHANNEL_REQUEST, :long, 14, :string, "testing", :bool, false)
@@ -480,4 +485,4 @@ def process_times(n)
       end
   end
 
-end
+end