Apache::AuthDigest::API - mod_perl API for Digest authentication

Apache-AuthDigest documentation Contained in the Apache-AuthDigest distribution.

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NAME

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Apache::AuthDigest::API - mod_perl API for Digest authentication

SYNOPSIS

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  PerlModule Apache::AuthDigest::API
  PerlModule My::DigestAuthenticator

  <Location /protected>
    PerlAuthenHandler My::DigestAuthenticator
    Require valid-user
    AuthType Digest
    AuthName "cookbook"
  </Location>

DESCRIPTION

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Apache::AuthDigest::API is a simple API for interacting with Digest authentication. For more information on Digest authentication, see RFC 2617: ftp://ftp.isi.edu/in-notes/rfc2617.txt

The API itself is very similar to the API mod_perl offers natively for Basic authentication:

  mod_perl's Basic support       AuthDigest::API equivalent

    my $r = shift;                 $r = Apache::AuthDigest::API->new(shift)

    $r->get_basic_auth_pw()        $r->get_digest_auth_response()       

    $r->note_basic_auth_failure    $r->note_digest_auth_failure()

    [none]                         $r->compare_digest_response()

see Recipe 13.8 in the mod_perl Developer's Cookbook for a far more detailed explanantion than will be covered here.

new()

creates a new Apache::AuthDigest::API object. Apache::AuthDigest::API is a subclass of the Apache class so, with the exception of the addition of new methods, $r can be used the same as if it were a normal Apache object

  my $r = Apache::AuthDigest::API->new(Apache->request);
get_digest_auth_response()

this parses out the authentication header sent by the client. it returns a status and a reference to a hash representing the client Digest request (if any).

  my ($status, $response) = $r->get_digest_auth_response;
  return $status unless $status == OK;
note_digest_auth_failure()

sets the proper authentication headers which prompt a client to send a proper Digest request in order to access the requested resource.

  $r->note_digest_auth_failure;
  return AUTH_REQUIRED;
compare_digest_response()

this method represents a shortcut for comparing a client Digest request with whatever credentials are stored on the server. the first argument is the hash reference returned by get_digest_auth_response(). the second argument is a MD5 digest of the user credentials. the credentials should be in the form

  user:realm:password

before they are hashed. the following Perl one-liner will generate a suitable digest:

  $ perl -MDigest::MD5 -e'print Digest::MD5::md5_hex("user:realm:password"),"\n"'

EXAMPLE

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for a complete example, see the My/DigestAuthenticator.pm file in the test suite for this package, as well as AuthDigest.pm. In general, the steps are the same as for Basic authentication, examples of which abound on CPAN, the Eagle book, and the Cookbook:

  use Apache::AuthDigest::API;

  sub handler {

    my $r = Apache::AuthDigest::API->new(shift);

    my ($status, $response) = $r->get_digest_auth_response;

    return $status unless $status == OK;

    my $digest = my_get_user_credentials_routine($r->user, $r->auth_name);

    return OK if $r->compare_digest_response($response, $digest);

    $r->note_digest_auth_failure;
    return AUTH_REQUIRED;
  }

NOTES

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this module essentially mimics the Digest implementation provided by mod_digest.c that ships with Apache. there is another implementation, classified as "experimental" that also ships with Apache, mod_auth_digest.c, which is more complete wrt RFC 2617. of particular interest is that the mod_digest implementation does not work with MSIE (so neither does this implemenation). at some point, Apache::AuthDigest::API::Full will implement a completely compliant API - this will have to do for now.

FEATURES/BUGS

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none that I know of yet, but consider this alphaware.

SEE ALSO

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perl(1), mod_perl(1), Apache(3), Apache::AuthDigest(3)

AUTHORS

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Geoffrey Young <geoff@modperlcookbook.org>

Paul Lindner <paul@modperlcookbook.org>

Randy Kobes <randy@modperlcookbook.org>

COPYRIGHT

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Copyright (c) 2002, Geoffrey Young, Paul Lindner, Randy Kobes.

All rights reserved.

This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself.

HISTORY

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This code is derived from the Cookbook::DigestAPI module, available as part of "The mod_perl Developer's Cookbook".

For more information, visit http://www.modperlcookbook.org/

Apache-AuthDigest documentation Contained in the Apache-AuthDigest distribution. 
package Apache::AuthDigest::API;

use Apache;
use Apache::Log;
use Apache::Constants qw(OK DECLINED SERVER_ERROR AUTH_REQUIRED);

use 5.006;
use Digest::MD5;
use HTTP::Headers::Util qw(split_header_words);
use DynaLoader;

use strict;

our $VERSION = '0.021';
our @ISA = qw(DynaLoader Apache);

__PACKAGE__->bootstrap($VERSION);

sub new {

  my ($class, $r) = @_;

  $r ||= Apache->request;

  return bless { r => $r }, $class;
}

sub get_digest_auth_response {

  my $r = shift;

  my $log = $r->server->log;

  my $auth_type = $r->auth_type;
  my $auth_name = $r->auth_name;

  # Check that we're supposed to be handling this.
  unless (lc($auth_type) eq 'digest') {
    $log->info("AuthType $auth_type not supported by ", ref($r));
    return DECLINED;
  }

  # Check that AuthName was set.
  unless ($auth_name) {
    $log->error("AuthName not set");
    return SERVER_ERROR;
  }

  my $response = $r->parse_digest_header;

  unless ($response) {
    $log->info("Client did not supply a Digest response");

    $r->note_digest_auth_failure;
    return AUTH_REQUIRED;
  }
  
  # Make sure that the response contained all the right info.
  foreach my $key (qw(username realm nonce uri response)) {
    unless ($response->{$key}) {
      $log->warn("Required key '$key' not present in response");
  
      $r->note_digest_auth_failure;
      return AUTH_REQUIRED;
    }
  }

  # Ok, we're good to go. Set some info for the request
  # and return the response information so it can be checked.
  $r->user($response->{username});
  $r->connection->auth_type('Digest');

  return (OK, $response);
}

sub compare_digest_response {
  # Compare a response hash from get_digest_auth_response()
  # against a pre-calculated digest (e.g., a3165385201a7ba52a12e88cb606bc76).

  my ($r, $response, $digest) = @_;

  my $md5 = Digest::MD5->new;

  $md5->add(join ":", ($r->method, $response->{uri}));

  $md5->add(join ":", ($digest, $response->{nonce}, $md5->hexdigest));

  return $response->{response} eq $md5->hexdigest;
}

# this is not part of the official API
sub parse_digest_header {

  my $r = shift;

  my $log = $r->server->log;

  # Get the response to the Digest challenge.
  my $header_type = $r->proxyreq ? 'Proxy-Authorization' : 'Authorization';

  my $header_info = $r->headers_in->get($header_type);

  $log->info("Apache::AuthDigest::API - parsing $header_type: $header_info");

  # ease my pain
  my @parsed_header = split_header_words($header_info);

  my %response = map { $_->[0] => $_->[1] } @parsed_header;

  # take care of the first attribute, which is stuck in with Digest
  $response{$parsed_header[0]->[2]} = $parsed_header[0]->[3];

  # We issued a Digest challenge - make sure we got Digest back.
  return unless exists $response{Digest};
    
  return \%response;
}

1;

__END__