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package Apache::Inject;
use 5.010000;
use strict;
our $VERSION = '0.01';
use mod_perl2;
use Apache2::CmdParms ();
use Apache2::Const qw/OR_LIMIT OR_AUTHCFG TAKE12/;
use Apache2::Log ();
use Apache2::Module ();
my @directives = (
{ name => 'Inject',
func => __PACKAGE__.'::Inject',
req_override => OR_LIMIT|OR_AUTHCFG,
args_how => TAKE12,
errmsg => 'Inject HeadFile[!] FootFile[!]' }
);
Apache2::Module::add(__PACKAGE__, \@directives);
sub Inject {
my ($self, $parms, @args) = @_;
for (@args) {
if ($_ eq ' ') {
$parms->server->log_error('Inject: Argument cannot be a single space');
}
}
# Construct directives for passing arguments to handler
my $head = $args[0];
my $foot = $args[1] || ' '; # single space signifies absence of argument
$head =~ s/\\/\\\\/; s/"/\\"/;
$foot =~ s/\\/\\\\/; s/"/\\"/;
# Add relevant directives to current configuration
$parms->add_config(['SetHandler perl-script',
'PerlResponseHandler Apache::Inject::Handler',
qq{PerlSetVar InjectHead "$head"},
qq{PerlSetVar InjectFoot "$foot"}]);
}
1;
__END__
=encoding latin1
=head1 NAME
Apache::Inject - Apache directive for injecting HTML headers and footers
=head1 SYNOPSIS
LoadModule perl_module libexec/apache24/mod_perl.so
PerlLoadModule Apache::Inject
DocumentRoot /uar/local/www/apache24/data
<Directory /usr/local/www/apache24/data>
Inject head.html foot.html
</Directory>
=head1 DESCRIPTION
Apache::Inject is a mod_perl module that adds an Apache directive
called Inject.
The Inject directive takes one or two arguments, which correspond
to the file names of two HTML files in the document root. The
contents of these files are then inserted into any requested HTML
file. The first file (the header) is inserted at the top of the
body of the requested HTML file, while the second, optional file
(the footer) is inserted at the bottom of the body.
The directive is smart enough to place the header and footer in the
proper places. The contents of the header file is inserted after
any elements belonging to E<lt>headE<gt> and before any elements
belonging to E<lt>bodyE<gt> (regardless of whether any explicit
E<lt>headE<gt> or E<lt>bodyE<gt> tag is present in the source of
the requested HTML page). Likewise, the contents of the second
file is placed before any potential final E<lt>/htmlE<gt>.
The Inject directive serves a much more specific purpose than
server-side includes. It is designed for injecting headers and
footers that belong in the E<lt>bodyE<gt> element, such as headings,
menu bars and copyright notices. While you can technically include
E<lt>headE<gt> elements in your header file, Apache::Inject will
place them in the body of the HTML page and not in the head.
The main benefit over server-side includes is that the header and
footer is specified in the server configuration instead of the HTML
files themselves. Thus, it is useful for adding headers and footers
to a large number of pre-existing static HTML pages. Furthermore,
this means that the headers and footers on all pages can be changed
at once by a single change in the server configuration.
Please note:
=over
=item *
The Inject directive is valid only inside directory sections, such
as E<lt>DirectoryE<gt>, E<lt>LocationE<gt> and E<lt>FilesMatchE<gt>
blocks. It is valid in .htaccess files if AllowOverride
Limit/AuthConfig/All is enabled.
=item *
The file paths given to Inject are relative to the B<document root>
of the current server or virtual server -- B<not> the directory to
which the current directory section or .htaccess file applies. They
should be specified without a leading slash.
=back
=head1 INSTALLATION
To install this module type the following:
perl Makefile.PL
make
make test
make install
Note that all steps in this process require mod_perl2 to be installed.
I recommend installing mod_perl2 via your operating system's package
manager or ports collection before installing Apache::Inject.
Note further that, because they depend on Apache, the tests require
an unprivileged user and will be skipped if they are run as root.
This is relevant if you install Apache::Inject via App::Cpan, which
normally runs as root.
=head1 OPERATION
Behind the scenes, the Inject directive works as an alias for
PerlResponseHandler and PerlSetVar. For example, C<Inject head.html
foot.html> results in the following configuration being added:
PerlResponseHandler Apache::Inject::Handler
PerlSetVar InjectHeader head.html
PerlSetVar InjectFooter foot.html
This results in Apache::Inject::Handler being registered as a handler
for requests to the current directory or location.
Apache::Inject::Handler accepts all requests to files where the
content type is C<text/html>. It reads the contents of the requested
file, as well as the contents of the C<InjectHeader> and C<InjectFooter>
files, concatenates them intelligently and prints their combined
contents.
=head1 DIAGNOSTICS
Apache::Inject and Apache::Inject::Handler log all errors and
warnings to the Apache log file. Below is a list of all issued
errors and warnings.
Note that whenever Apache::Inject::Handler issues an error or a
warning, this means that it also declines the request, letting
Apache handle it as it would if the Inject directive were not used.
=over
=item Error: Argument cannot be a single space
In the current implementation, the file names given to Inject are
not allowed to consist solely of a single space, as this is a special
value signifying the absence of an argument.
=item Error: InjectHead/InjectFoot should not begin with slash, as
it is already always relative to document root
The paths given to Inject are always relative to the document root,
even if the Inject directive is located within a directory section
that applies to another path.
Beginning any of the paths with a slash implies that there would
be some difference in behavior compared to omitting the slash, which
is false.
=item Error: InjectHead/InjectFoot cannot extend past document root
This error is issued if any of the paths given to Inject tries to
go above the document root by using C<../>.
=item Error: InjectHead/InjectFoot I<path/to/file> does not exist
This error is issued if any of the paths given to Inject doesn't
exist.
=item Warning: Declining request due to empty document root
This warning is issued if Apache::Inject::Handler for some reason
cannot retrieve the current document root from Apache.
=back
=head1 CAVEATS
On FreeBSD, you may need to enable the accf_http kernel module in
order for the tests to work. Note that Apache::Inject works fine
without the module; it is only the tests that require it.
=head1 AUTHOR
John Ankarström, E<lt>john [at] ankarstrom.seE<gt>
=head1 SEE ALSO
mod_perl2:
L<https://perl.apache.org/>
=head1 COPYRIGHT AND LICENSE
Copyright (C) 2021 by John Ankarström
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.32.1
or, at your option, any later version of Perl 5 you may have
available.
=cut
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