Re: Detecting/parsing a hex string

[Brandon Enright <bmenrigh () ucsd edu>]

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On Wed, 08 Oct 2008 06:25:03 -0500 or thereabouts Ron
<ron () skullsecurity net> wrote:

> Hi all,
>
> I need to detect whether or not a string is an ascii representation
> of a hex string (eg, "12ab3d1a3badabeea1...."), and, if it is, to
> convert it to a binary string. Is there an easy way to do that (maybe
> with bin.pack/bin.unpack)?
>
> Thanks,
> Ron

You'll want to use a regex first to make sure the string is well
formed.  You can then use the 'H*' format string to unpack.

It isn't Lua but here is the regex and unpack:

$hex_string =~ /(?:[0-9A-Fa-f]{2})+/
$raw = unpack('H*', $hex_string);
# If there is a B* format to pack we can convert our string to 0101...
$bin_string = pack('B*', $hex_string);

I hope that at least gets you started.

Brandon

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