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Reply to topic   Topic: Using regex results, if backreference exists include FOO
Author
csdude55



Joined: 22 Jan 2023
Posts: 17
Location: USA, Wilkesboro

PostPosted: Tue 21 Feb '23 23:56    Post subject: Using regex results, if backreference exists include FOO Reply with quote

In plain English, I'm trying to say "if 'string' starts with 'abc', set a variable of '<b>abc</b>remainder'. If it doesn't, set a variable of the entire value".

Surrounding "abc" with <b></b> is where I get hung up. The only way I can figure to do this in Apache is with two SetEnvIfExpr:

Code:
# not tested, please forgive any typos
SetEnvIfExpr "env('string') =~ /(^abc)(.+)/" var=<b>$1</b>$2

SetEnvIfExpr "-z env('var') && env('string') =~ /(.+)/" var=$1


In Perl I would probably do something like:

Code:
$string =~ s/^(abc)(.+)/foo($1)/ei;

sub foo {
  return ($_[0] eq 'abc') ?
    '<b>abc</b>' :
    $_[0];
}


Is the best method in Apache to use two SetEnvIfExpr like that?
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James Blond
Moderator


Joined: 19 Jan 2006
Posts: 7288
Location: Germany, Next to Hamburg

PostPosted: Wed 22 Feb '23 10:55    Post subject: Reply with quote

If the URL query starts with abc, set your variable to abc

Code:

<LocationMatch ^/i.php>
    <If "%{QUERY_STRING} =~ /^abc/">
        SetEnv var "abc"
    </If>
</LocationMatch>
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covener



Joined: 23 Nov 2008
Posts: 55

PostPosted: Tue 28 Feb '23 4:42    Post subject: Re: Using regex results, if backreference exists include FOO Reply with quote

you can use negative lookahead to simplify (in some sense)


Code:
SetEnvIf string (^abc)(.+) var=<b>$1</b>$2
SetEnvIf string ^(?!abc)(.+) var=$1
# testing only
SetEnvIfExpr "%{QUERY_STRING} =~ /(.*)/" string=$1
Header always set string %{string}e env=string
Header always set var %{var}e env=var

Code:

$ wget -S http://localhost/  http://localhost/?xxabc http://localhost/?abcdef 2>&1 |egrep "(var|string)"
  string:
  string: xxabc
  var: xxabc
  string: abcdef
  var: <b>abc</b>def
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