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package Plack::Middleware::ConditionalGET;
use strict;
use parent qw( Plack::Middleware );
use Plack::Util;
sub call {
my $self = shift;
my $env = shift;
my $res = $self->app->($env);
return $res unless $env->{REQUEST_METHOD} =~ /^(GET|HEAD)$/;
$self->response_cb($res, sub {
my $res = shift;
my $h = Plack::Util::headers($res->[1]);
if ( $self->etag_matches($h, $env) || $self->not_modified_since($h, $env) ) {
$res->[0] = 304;
$h->remove($_) for qw( Content-Type Content-Length Content-Disposition );
if ($res->[2]) {
$res->[2] = [];
}
else {
my $done;
return sub {
unless ($done) {
return q{};
}
$done = 1;
return defined $_[0] ? q{} : undef;
};
}
}
});
}
no warnings 'uninitialized';
# RFC 2616 14.25 says it's OK and expected to use 'eq' :)
# > Note: When handling an If-Modified-Since header field, some
# > servers will use an exact date comparison function, rather than a
# > less-than function, for deciding whether to send a 304 ...
sub etag_matches {
my($self, $h, $env) = @_;
$h->exists('ETag') && $h->get('ETag') eq _value($env->{HTTP_IF_NONE_MATCH});
}
sub not_modified_since {
my($self, $h, $env) = @_;
$h->exists('Last-Modified') && $h->get('Last-Modified') eq _value($env->{HTTP_IF_MODIFIED_SINCE});
}
sub _value {
my $str = shift;
# IE sends wrong formatted value(i.e. "Thu, 03 Dec 2009 01:46:32 GMT; length=17936")
$str =~ s/;.*$//;
return $str;
}
1;
__END__
=head1 NAME
Plack::Middleware::ConditionalGET - Middleware to enable conditional GET
=head1 SYNOPSIS
builder {
enable "ConditionalGET";
....
};
=head1 DESCRIPTION
This middleware enables conditional GET and HEAD using
C<If-None-Match> and C<If-Modified-Since> header. The application
should set either or both of C<Last-Modified> or C<ETag> response
headers per RFC 2616. When either of the conditions is met, the
response body is set to be zero length and the status is set to 304
Not Modified.
=head1 SEE ALSO
Rack::ConditionalGet
=cut
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