Land #9924, Improve debug output in ETERNALBLUE's verify_arch

modules/exploits/windows/smb/ms17_010_eternalblue.rb

@@ -278,7 +278,15 @@ class MetasploitModule < Msf::Exploit::Remote
 
   def verify_arch
     return true unless datastore['VerifyArch']
-    (dcerpc_getarch == target_arch.first) ? true : false
+
+    # XXX: This sends a new DCE/RPC packet
+    arch = dcerpc_getarch
+
+    return true if arch && arch == target_arch.first
+
+    print_warning("Target arch is #{target_arch.first}, but server returned #{arch.inspect}")
+    print_warning("The DCE/RPC service or probe may be blocked") if arch.nil?
+    false
   end
 
   def print_core_buffer(os)