One solution is to strip out all characters in the user-supplied data that aren't explicitly allowed and then generate your regex based off of that.
Update -- Try this sample code:
#!/usr/bin/perl
use warnings;
use strict;
my $query = shift;
die "usage: $0 query-string\n"
if not $query;
print "Original query: '$query'\n";
$query =~ s/[^\w\*]//g;
print "Safe query: '$query'\n";
$query =~ s/\*/\\w\*/g;
print "Parsed query: '$query'\n";
while (<DATA>) {
print "match: $_"
if /$query/i;
}
__DATA__
invitation
information
Isolation
InFlaTiOn
IATION
In our nation
it requires concentration
at ionizing radiation
Note that "at ionizing radiation" matches because the iation in radiation matches. Did you just miss that, or should it not match?
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Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
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Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
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Want more info? How to link
or How to display code and escape characters
are good places to start.
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