#!/usr/bin/perl

use warnings;
use strict;
;
use XML::Simple qw(:strict);
use Data::Dumper;

my $xml =q(<?xml version="1.0"?>
 <response>
  <files>
   <file file_url="http://server.domain/file1.exe">
    file1.exe
   </file>
   <file file_url="http://server.domain/file2.zip">
    file2.zip
   </file>    
  </files>
 </response>
);

my $ref = XMLin($xml, forcearray => [ qw(files) ], keyattr => [] );

my %files;

for my $elem(@{$ref->{files}}){
    my $filesref = $elem->{file};
    $files{$_->{content}} = $_->{file_url} for(@$filesref);
}

print Dumper(\%files);