Land #2952, -1 for last session ID

lib/msf/base/simple/post.rb

@@ -99,7 +99,7 @@ protected
       # Grab the session object since we need to fire an event for not
       # only the normal module_run event that all module types have to
       # report, but a specific event for sessions as well.
-      s = mod.framework.sessions[mod.datastore["SESSION"]]
+      s = mod.framework.sessions.get(mod.datastore["SESSION"].to_i)
       mod.framework.events.on_session_module_run(s, mod)
       mod.run
     rescue ::Timeout::Error => e

lib/msf/core/post_mixin.rb

@@ -74,7 +74,7 @@ module Msf::PostMixin
     return @session if @session and not session_changed?
 
     if datastore["SESSION"]
-      @session = framework.sessions[datastore["SESSION"].to_i]
+      @session = framework.sessions.get(datastore["SESSION"].to_i)
     else
       @session = nil
     end

lib/msf/core/session_manager.rb

@@ -279,7 +279,17 @@ class SessionManager < Hash
   # Returns the session associated with the supplied sid, if any.
   #
   def get(sid)
-    return self[sid.to_i]
+    session = nil
+    sid = sid.to_i
+
+    if sid > 0
+      session = self[sid]
+    elsif sid == -1
+      sid = self.keys.sort[-1]
+      session = self[sid]
+    end
+
+    session
   end
 
   #