How do I access the HTTP Header of request in a CGI script?

Question

I\'ve used Perl a bit for small applications and test code, but I\'m new to networking and CGI.

I get how to make the header of a request (using CGI.pm and printing

Answer 1

They're supplied as environment variables, such as

HTTP_HEADERATTRIBUTE=value

You may have to do something to configure your web server to supply such a variable, though.

Answer 2

The CGI module has a http() function you can use to that purpose:

#!/usr/bin/perl --
use strict;
use warnings;
use CGI;

my $q = CGI->new;
my %headers = map { $_ => $q->http($_) } $q->http();

print $q->header('text/plain');
print "Got the following headers:\n";
for my $header ( keys %headers ) {
    print "$header: $headers{$header}\n";
}

Try it out; the above gives me:

$ curl http://localhost/test.cgi -H "HeaderAttribute: value"
Got the following headers:
HTTP_HEADERATTRIBUTE: value
HTTP_ACCEPT: */*
HTTP_HOST: localhost
HTTP_USER_AGENT: curl/7.21.0 (i686-pc-linux-gnu) libcurl/7.21.0 OpenSSL/0.9.8o zlib/1.2.3.4 libidn/1.18

Answer 3

In addition to the CGI.pm http() method you can get HTTP headers information from the environment variables.

So in case you are using something like CGI::Minimal, which doesn't have the http method. you can do something like:

  my $header = 'HTTP_X_REQUESTED_WITH';

  if (exists $ENV{$header} && lc $ENV{$header} eq 'xmlhttprequest') {
   _do_some_ajaxian_stuff();
  }