File Coverage

blib/lib/Plack/Middleware/ETag.pm

Criterion	Covered	Total	%
statement	55	56	98.2
branch	17	24	70.8
condition	7	14	50.0
subroutine	9	9	100.0
pod	1	1	100.0
total	89	104	85.5

package Plack::Middleware::ETag;
$Plack::Middleware::ETag::VERSION = '0.05';
# ABSTRACT: Adds automatically an ETag header.

use strict;
use warnings;
use Digest::SHA;
use Plack::Util;
use Plack::Util::Accessor
    qw( file_etag cache_control check_last_modified_header);

use parent qw/Plack::Middleware/;

sub call {
    my $self = shift;
    my $res  = $self->app->(@_);

    $self->response_cb(
        $res,
        sub {
            my $res     = shift;
            my $headers = $res->[1];
            return if ( !defined $res->[2] );
            return if ( Plack::Util::header_exists( $headers, 'ETag' ) );
            return
                if ( $self->check_last_modified_header()
                && Plack::Util::header_exists( $headers, 'Last-Modified' ) );

            my $etag;

            if ( Plack::Util::is_real_fh( $res->[2] ) ) {

                my $file_attr = $self->file_etag || [qw/inode mtime size/];
                my @stats = stat $res->[2];
                if ( $stats[9] == time - 1 ) {
                    # if the file was modified less than one second before the request
                    # it may be modified in a near future, so we return a weak etag
                    $etag = "W/";
                }
                if ( grep {/inode/} @$file_attr ) {
                    $etag .= ( sprintf "%x", $stats[1] );
                }
                if ( grep {/mtime/} @$file_attr ) {
                    $etag .= "-" if ( $etag && $etag !~ /-$/ );
                    $etag .= ( sprintf "%x", $stats[9] );
                }
                if ( grep {/size/} @$file_attr ) {
                    $etag .= "-" if ( $etag && $etag !~ /-$/ );
                    $etag .= ( sprintf "%x", $stats[7] );
                }
            } else {
                my $sha = Digest::SHA->new;
                $sha->add( @{ $res->[2] } );
                $etag = $sha->hexdigest;
            }
            Plack::Util::header_set( $headers, 'ETag', $etag );
            $self->_set_cache_control($headers);
            return;
        }
    );
}

sub _set_cache_control {
    my ( $self, $headers ) = @_;
    return unless $self->cache_control;

    if ( ref $self->cache_control && ref $self->cache_control eq 'ARRAY' ) {
        Plack::Util::header_set( $headers, 'Cache-Control',
            join( ', ', @{ $self->cache_control } ) );
    } else {
        Plack::Util::header_set( $headers, 'Cache-Control',
            'must-revalidate' );
    }
}

1;

__END__