Improve network interface detection to avoid crash [GH-1480]

CHANGELOG.md

@@ -21,6 +21,8 @@ BUG FIXES:
     auto-corrected ports. [GH-1472]
   - Fix obscure error when temp directory is world writable when
     adding boxes.
+  - Improved error handling around network interface detection for
+    VirtualBox [GH-1480]
 
 ## 1.1.2 (March 18, 2013)
 

lib/vagrant/errors.rb

@@ -203,6 +203,10 @@ module Vagrant
       error_key(:home_dir_not_accessible)
     end
 
+    class ForwardPortAdapterNotFound < VagrantError
+      error_key(:forward_port_adapter_not_found)
+    end
+
     class ForwardPortAutolistEmpty < VagrantError
       error_key(:auto_empty, "vagrant.actions.vm.forward_ports")
     end

plugins/providers/virtualbox/action/forward_ports.rb

@@ -50,6 +50,14 @@ module VagrantPlugins
             @env[:ui].info(I18n.t("vagrant.actions.vm.forward_ports.forwarding_entry",
                                     message_attributes))
 
+            # Verify we have the network interface to attach to
+            if !interfaces[fp.adapter]
+              raise Vagrant::Errors::ForwardPortAdapterNotFound,
+                :adapter => fp.adapter.to_s,
+                :guest => fp.guest_port.to_s,
+                :host => fp.host_port.to_s
+            end
+
             # Port forwarding requires the network interface to be a NAT interface,
             # so verify that that is the case.
             if interfaces[fp.adapter][:type] != :nat

templates/locales/en.yml

@@ -130,6 +130,14 @@ en:
         may run at any given time to avoid problems with VirtualBox inconsistencies
         occurring. Please wait for the other instance of Vagrant to end and then
         try again.
+      forward_port_adapter_not_found: |-
+        The adapter to attach a forwarded port to was not found. Please
+        verify that the given adapter is setup on the machine as a NAT
+        interface.
+
+        Host port: %{host}
+        Guest port: %{guest}
+        Adapter: %{adapter}
       gem_command_in_bundler: |-
         You cannot run the `vagrant plugin` command while in a bundler environment.
         This should generally never happen unless Vagrant is installed outside