Land rapid7#18760, Ensure DNS command config loading does not crash msfconsole

Author: dwelch-r7

lib/msf/ui/console/driver.rb

@@ -80,16 +80,16 @@ def initialize(prompt = DefaultPrompt, prompt_char = DefaultPromptChar, opts = {
 
     # Initialize attributes
 
-    dns_resolver = Rex::Proto::DNS::CachedResolver.new
-    dns_resolver.extend(Rex::Proto::DNS::CustomNameserverProvider)
-    dns_resolver.load_config
-
-    # Defer loading of modules until paths from opts can be added below
-    framework_create_options = opts.merge({
-                                            'DeferModuleLoads' => true,
-                                            'CustomDnsResolver' => dns_resolver
-                                          }
-                                         )
+    framework_create_options = opts.merge({ 'DeferModuleLoads' => true })
+
+    if Msf::FeatureManager.instance.enabled?(Msf::FeatureManager::DNS_FEATURE)
+      dns_resolver = Rex::Proto::DNS::CachedResolver.new
+      dns_resolver.extend(Rex::Proto::DNS::CustomNameserverProvider)
+      dns_resolver.load_config
+
+      # Defer loading of modules until paths from opts can be added below
+      framework_create_options = framework_create_options.merge({ 'CustomDnsResolver' => dns_resolver })
+    end
     self.framework = opts['Framework'] || Msf::Simple::Framework.create(framework_create_options)
 
     if self.framework.datastore['Prompt']

lib/net/dns/resolver.rb

@@ -1084,17 +1084,21 @@ def parse_config_file
           self.domain = arr[0]
           self.nameservers = arr[1]
         else
-          IO.foreach(@config[:config_file]) do |line|
-            line.gsub!(/\s*[;#].*/,"")
-            next unless line =~ /\S/
-            case line
-            when /^\s*domain\s+(\S+)/
-              self.domain = $1
-            when /^\s*search\s+(.*)/
-              self.searchlist = $1.split(" ")
-            when /^\s*nameserver\s+(.*)/
-              self.nameservers += $1.split(" ")
+          begin
+            IO.foreach(@config[:config_file]) do |line|
+              line.gsub!(/\s*[;#].*/,"")
+              next unless line =~ /\S/
+              case line
+              when /^\s*domain\s+(\S+)/
+                self.domain = $1
+              when /^\s*search\s+(.*)/
+                self.searchlist = $1.split(" ")
+              when /^\s*nameserver\s+(.*)/
+                self.nameservers += $1.split(" ")
+              end
             end
+          rescue => e
+            @logger.error(e)
           end
         end
       end