Add filter examples for Cancel-Lock/-Key.

[usenet/INN.git] / filter / filter_nnrpd.pl

diff --git a/filter/filter_nnrpd.pl b/filter/filter_nnrpd.pl
new file mode 100644 (file)
index 0000000..a66425b
--- /dev/null
+++ b/filter/filter_nnrpd.pl
@@ -0,0 +1,53 @@
+#
+# 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);
+}
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