Re-implemented #generate_id in Core::Main::Crypto.

This is a better home for it since that is where other OpenSSL
crypto/token generator methods reside.

core/main/crypto.rb

@@ -39,6 +39,23 @@ module Core
       config.set('beef.api_token', token)
       token
     end
+
+    # Generates a unique identifier for DNS rules.
+    #
+    # @return [String] 8-character hex identifier
+    def self.dns_rule_id
+      id = nil
+      length = 4
+
+      begin
+        id = OpenSSL::Random.random_bytes(length).unpack('H*')[0]
+        BeEF::Core::Models::Dns::Rule.each { |rule| throw StandardError if id == rule.id }
+      rescue StandardError
+        retry
+      end
+
+      id.to_s
+    end
   
   end
 end

extensions/dns/model.rb

@@ -23,7 +23,7 @@ module BeEF
           # Hooks the model's "save" event. Generates a rule identifier and callback.
           before :save do |rule|
             rule.callback = validate_response(rule.resource, rule.response)
-            rule.id = generate_id
+            rule.id = BeEF::Core::Crypto.dns_rule_id
           end
 
         private
@@ -37,13 +37,6 @@ module BeEF
             "t.respond!('1.1.1.1')"
           end
 
-          # Generates a unique identifier for use as a primary key.
-          #
-          # @return [String] 8-character hex identifier
-          def generate_id
-            '42'
-          end
-
         end
 
       end