Land #10773, session.platform TypeError fix

This also adds an "unknown" platform class.

lib/metasploit/framework/login_scanner/ssh.rb

@@ -165,12 +165,14 @@ module Metasploit
             'aix'
           when /Win32|Windows/
             'windows'
-          when /Unknown command or computer name/
+          when /Unknown command or computer name|Line has invalid autocommand/
             'cisco-ios'
           when /unknown keyword/ # ScreenOS
             'juniper'
           when /JUNOS Base OS/ #JunOS
             'juniper'
+          else
+            'unknown'
           end
         end
 

lib/msf/base/serializer/readable_text.rb

@@ -892,8 +892,8 @@ class ReadableText
       sess_checkin = "<none>"
       sess_registration = "No"
 
-      if session.respond_to?(:platform)
-        sess_type << " " + session.platform
+      if session.respond_to?(:platform) && session.platform
+        sess_type << " #{session.platform}"
       end
 
       if session.respond_to?(:last_checkin) && session.last_checkin

lib/msf/core/module/platform.rb

@@ -190,11 +190,23 @@ class Msf::Module::Platform
   #
   ##
 
+  #
+  # Unknown
+  #
+  # This is a special case for when we're completely unsure of the
+  # platform, such as a crash or default case in code.  Only
+  # utilize this as a catch-all.
+  #
+  class Unknown < Msf::Module::Platform
+    Rank = 0 # safeguard with 0 since the platform is completely unknown
+    Alias = "unknown"
+  end
+
   #
   # Windows
   #
   class Windows < Msf::Module::Platform
-    Rank  = 100
+    Rank = 100
     # Windows 95
     class W95 < Windows
       Rank = 100