Land rapid7#8419, ETERNALBLUE fixes (round two)

Hope I resolved the conflicts correctly.

Author: wvu

modules/exploits/windows/smb/ms17_010_eternalblue.rb

@@ -195,7 +195,9 @@ def smb_eternalblue(process_name, grooms)
       code, raw = smb1_get_response(sock)
 
       code_str = "0x" + code.to_i.to_s(16).upcase
-      if code == 0xc000000d # STATUS_INVALID_PARAMETER (0xC000000D)
+      if code.nil?
+        print_error("Did not receive a response from exploit packet")
+      elsif code == 0xc000000d # STATUS_INVALID_PARAMETER (0xC000000D)
         print_good("ETERNALBLUE overwrite completed successfully (#{code_str})!")
       else
         print_warning("ETERNALBLUE overwrite returned unexpected status code (#{code_str})!")
@@ -288,6 +290,10 @@ def smb1_anonymous_connect_ipc()
 
     code, raw, response = smb1_get_response(sock)
 
+    if code.nil?
+      raise RubySMB::Error::UnexpectedStatusCode, "No response to login request"
+    end
+
     unless code == 0 # WindowsError::NTStatus::STATUS_SUCCESS
       raise RubySMB::Error::UnexpectedStatusCode, "Error with anonymous login"
     end
@@ -366,6 +372,7 @@ def smb1_get_response(sock)
       break unless raw.nil? or raw.empty?
     end
 
+    return nil unless raw
     response = RubySMB::SMB1::SMBHeader.read(raw[4..-1])
     code = response.nt_status
     return code, raw, response