Just fire this up and point your browser to localhost. Then submit one of the last two forms and watch the hang

#!/usr/bin/perl -w

use strict;

use Cwd qw( cwd );

use File::Spec;
$ENV{DOCUMENT_ROOT} = cwd();
chdir $ENV{DOCUMENT_ROOT};

use Data::Dumper;
use HTTP::Daemon;
use HTTP::Status;
use CGI::Simple();
use CGI();

my $port    = shift || 80;
my $docroot = shift || $ENV{DOCUMENT_ROOT};

my $d = HTTP::Daemon->new(
    Reuse     => 1,
    LocalPort => $port,
) or die "No daemon: $!\n";

warn "Ready to go!\n";
while (my $conn = $d->accept())
{
    handle_uri( $conn, $conn->get_request( 1 ));
}

sub handle_uri
{
    my ($conn, $req) = @_;
    my $uri  = $req->uri();
    
    if ($uri =~ /images/)
    {
        serve_image( $conn, $req, $uri );
    }
    else
    {
        serve_everything( $conn, $req, $uri );
    }
}

sub serve_everything
{
    my ($conn, $req) = @_;
    my $uri = $req->uri;

    $ENV{REQUEST_METHOD} = $req->method;
    $ENV{CONTENT_TYPE}   = join('; ', $req->content_type ) || '';
    $ENV{CONTENT_LENGTH} = $req->content_length || '';
    $ENV{HTTP_USER_AGENT} = join('; ', $req->user_agent ) || '';
    $ENV{SCRIPT_NAME}    = $uri->path  || 1;
    $ENV{QUERY_STRING}   = $uri->query || '';
    $ENV{HTTP_HOST} = $req->header('host');
    $ENV{REMOTE_ADDR} = $conn->peerhost();
    $ENV{REMOTE_PORT} = $conn->peerport();

    foreach my $c (qw( cookie cookies ))
    {
        $ENV{uc $c} = join(';', $req->header( $c ) ) || '';
    }

    my $cgi;
    {
#        warn '$ENV{CONTENT_LENGTH} = ',$ENV{CONTENT_LENGTH},$/;
#        local $_;
#        warn "read ", sysread($conn, $_, $ENV{CONTENT_LENGTH}, 0);
#        warn $_,$/,$/;
        local *main::STDIN = $conn;
        $cgi = CGI::Simple->new();
#        $cgi = CGI->new(); # CGI works, CGI::Simple hangs :(
    }

    $conn->send_response(
        HTTP::Response->new(
            200, 'OK',
            HTTP::Headers->new(
            Set_Cookie => $cgi->cookie(
                        -name =>'sessionID',
                        -value =>'xyzzy',
                        -expires =>'+1y',
                        -path =>'',
                        -domain => $ENV{HTTP_HOST},
                        -secure => 0
                    ),
            Content_Type => "text/html"),
            "<font size=2><pre>".
                CGI::Simple->escapeHTML(
                    scalar Dumper(
                        $conn, $req, \%ENV, $cgi
                    )
                ).
qq|
</font></pre>
<hr>
<FORM
  METHOD="GET"
  ACTION="$ENV{SCRIPT_NAME}"
  ENCTYPE="application/x-www-form-urlencoded">
    <input type="text" name"f">
    <input type="reset" name=".reset" />
    <input type="submit" name=".submit" />
</form>
<FORM
  METHOD="POST"
  ACTION="$ENV{SCRIPT_NAME}"
  ENCTYPE="application/x-www-form-urlencoded">
    <input type="text" name"f">
    <input type="reset" name=".reset" />
    <input type="submit" name=".submit" />
</form>
<FORM
  METHOD="POST"
  ACTION="$ENV{SCRIPT_NAME}"
  ENCTYPE="multipart/form-data">
    <INPUT TYPE="file" NAME="upload_file1" SIZE="42">
    <INPUT TYPE="file" NAME="upload_file2" SIZE="42">
    <input type="reset" name=".reset" />
    <input type="submit">
</FORM>
|
        )
    );

    $conn->print( 'nope', $@ ) if $@;
}

sub serve_image
{
    my ($conn, $req, $uri) = @_;
    my $file = File::Spec->catfile( $docroot, $uri );
    $conn->send_status_line( (-e $file ? 200 : 404 ) );
    $conn->send_file_response( $file );
}
[download]