in reply to Escaping %params

As mentioned in the CB $cgi->Vars may cause problems - a safer way to build the params hash is: 
my %params = map { $_ => $cgi->param($_) } $cgi->param;

[download]
And beware of params that have more than one value, e.g. checkbox groups

Update: to allow for params with multiple values: 

my %params;
for my $name ($cgi->param) {
    my @values = $cgi->param($name);
    $params{$name} = @values > 1 ? \@values : $values[0];
}

[download]
When further processing %params you will need to check if $param{$name} is an array reference.

Replies are listed 'Best First'.
Re^2: Escaping %params
by DaisyLou (Sexton) on Jan 21, 2014 at 01:37 UTC
    Thank you... Interestingly, when I use this code: 
    use warnings;
use strict;
use CGI;

use Data::Dumper;
print "Content-type: text/html\n\n";

my $cgi = CGI->new();
my %params = map { $_ => $cgi->param($_) || '' } $cgi->param;

print Dumper \%params;

    [download]
    The output is when I pass test.pl?a=\'b is: 
    $VAR1 = { 'a' => '\\\'b' };

    [download]
    ... so it looks like something in the stack is already taking care of the escaping for me. Am I worrying about nothing?
[reply]
[d/l]
[select]
      Data::Dumper is doing that - try this: 
      for my $param (keys %params) {
    print "$param: $params{$param}<br>"
}

      [download]
[reply]
[d/l]

      Data::Dumper does perl-escaping (defaults have some caveats)

      Data::Dump::pp() does better perl-escaping by default

      Neither ddumper does HTML-escaping

      You can alway do  my $cgi = CGI->new; print $cgi->header, $cgi->Dump ; to see whats inside $query

[reply]
[d/l]
      s/_/\_/g

      s/_/\_/g does nothing. You probably want  s/_/\\_/g 

      >perl -wMstrict -le
"$_ = 'a_b__c___';
 print qq{before: '$_'};
 ;;
 s/_/\_/g;
 print qq{after:  '$_'};
"
before: 'a_b__c___'
after:  'a_b__c___'

      [download]

      But please allow me to add my voice to the chorus imploring you to Just Use Placeholders!.

[reply]
[d/l]
[select]
Re^2: Escaping %params
by DaisyLou (Sexton) on Jan 21, 2014 at 15:16 UTC
    I've distilled all this advice this as best I can. 
    ============
something.lib
============
sub safer {
    my $hash = shift;
    my %safer;
    while (my ($k, $v) = each %$hash) {
        s/\\//g         for $k, $v;
        s/0x00//g       for $k, $v;
        s/0x08//g       for $k, $v;
        s/0x09//g       for $k, $v;
        s/0x0a/\n/g     for $k, $v;
        s/0x0d/\r/g     for $k, $v;
        s/"/\\"/g       for $k, $v;
        s/%/\\%/g       for $k, $v;
        s/'/\\'/g       for $k, $v;
        s/_/\_/g        for $k, $v;

        $safer{$k} = $v;
    }
    return %safer;
}

================
something.cgi...
================
use warnings;
use strict;
use CGI;
use CGI::Carp;

print "Content-type: text/html\n\n";

# marker
my $cgi = CGI->new();

$cgi->param;
my %params;

for my $name ($cgi->param) {
    my @values = $cgi->param($name);
    $params{$name} = @values > 1 ? \@values : $values[0];
}

%params=safer(\%params);
# marker

for my $param (keys %params) {
    print "$param: $params{$param}<br>"
}

    [download]
    The stuff between the two markers will replace the existing 
    sub main
{
        my $cgi = CGI->new();
        my %params = $cgi->Vars();

    [download]
    ... in the existing scripts. This is running under mod-perl (w/ regcooker). Are there any "gotchas" I should be aware of here? Thanks to all you monks for all your help!
[reply]
[d/l]
[select]

      A problem is with CGI->Vars , you never want to use CGI->Vars, CGI->Vars is for perl4, Vars mangles (encodes, serializes, packs, implodes) the data, its backwards compatibility for some 1993 stuff

      You want "escapeHTML" from CGI.pm

[reply]

In Section Seekers of Perl Wisdom