Re: [NSE][PATCH] only show script errors in verbose mode

[David Fifield <david () bamsoftware com>]

On Wed, Sep 24, 2008 at 02:20:29PM -0600, David Fifield wrote:
> You'll have to forgive me, I'm (still) pretty new to Lua. Is there a way
> to signal a special error code that would mean a module is missing, but
> it's an error that can be ignored? The error would be raised in the
> "else" branch of the "if" in Sven's example, or it could even be raised
> in an alternate compiled openssl module that didn't have any functions,
> just raised the error. Then this special error could be ignored, and
> normal require errors could continue to be reported.

Here's what I'm thinking:

Index: SSH-hostkey.nse
===================================================================
--- SSH-hostkey.nse     (revision 10361)
+++ SSH-hostkey.nse     (working copy)
@@ -32,12 +32,15 @@
 
 require("stdnse")
 require("shortport")
-require("openssl")
 require("bin")
 require("bit")
 require("base64")
 require("hash")
 
+if not pcall(require, "openssl") then
+  error(stdnse.quiet_error("The optional openssl module is not installed"))
+end
+
 id = "SSH Hostkey"
 author = "Sven Klemm <sven () c3d2 de>"
 description = "Show SSH Hostkeys"

stdnse.quiet_error would return a type of object that NSE could check
for and avoid printing, unless debugging were enabled. Of course the
whole if..end could be bundled into its own function, something like
stdnse.quiet_require.

Another option is to raise the quiet error from within the compiled
openssl module, but I don't know if that would work as it appears the
compiled modules are loaded all at once.

David Fifield

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