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Add filter examples for Cancel-Lock/-Key.

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This is a possible implementation of Cancel-Lock
and Cancel-Key. cleanfeed.local will check for
a matching Cancel-Key before accepting a cancel,
filter_nnrpd.pl will add Cancel-Locks to all
postings (and a matching Cancel-Key to cancel
messages).

See also
http://th-h.de/blog/archives/1473-INN-Cancel-Lock-und-Cancel-Key.html

Signed-off-by: Thomas Hochstein <thh@inter.net>
This commit is contained in:
Thomas Hochstein 2011-12-18 01:51:35 +01:00
parent d4dd9a5895
commit 8faa6b210c
2 changed files with 155 additions and 0 deletions
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53
filter/filter_nnrpd.pl Normal file
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#
# Do any initialization steps.
#
use Digest::MD5 qw(md5_base64);
use Digest::SHA1();
use Digest::HMAC_SHA1();
use MIME::Base64();
$CANCEL_LOCK = 'secretword';
#
# Filter
#
sub filter_post {
my $rval = "" ; # assume we'll accept.
$modify_headers = 1;
# Cancel-Lock / Cancel-Key
add_cancel_lock(\%hdr, $user);
if (exists( $hdr{"Control"} ) && $hdr{"Control"} =~ m/^cancel\s+(<[^>]+>)/i) {
my $key = calc_cancel_key($user, $1);
add_cancel_item(\%hdr, 'Cancel-Key', $key);
}
elsif (exists( $hdr{"Supersedes"} )) {
my $key = calc_cancel_key($user, $hdr{"Supersedes"});
add_cancel_item(\%hdr, 'Cancel-Key', $key);
}
return $rval;
}
#
# Cancel-Lock / Cancel-Key
#
sub add_cancel_item($$$) {
my ( $r_hdr, $name, $value ) = @_;
my $prefix = $r_hdr->{$name};
$prefix = defined($prefix) ? $prefix . ' sha1:' : 'sha1:';
$r_hdr->{$name} = $prefix . $value;
}
sub calc_cancel_key($$) {
my ( $user, $message_id ) = @_;
return MIME::Base64::encode(Digest::HMAC_SHA1::hmac_sha1($message_id, $user . $CANCEL_LOCK), '');
}
sub add_cancel_lock($$) {
my ( $r_hdr, $user ) = @_;
my $key = calc_cancel_key($user, $r_hdr->{'Message-ID'});
my $lock = MIME::Base64::encode(Digest::SHA1::sha1($key), '');
add_cancel_item($r_hdr, 'Cancel-Lock', $lock);
}