Log serial number of a client certificate

On July, I asked on the user-list how to obtain the certificate serial number of an active client:

http://thread.gmane.org/gmane.network.openvpn.user/19913

just in case sombody needs it, you'll find a two-line-patch underneath. I get now in my log:
VERIFY OK: depth=0, serial=79, emailAddress=pace/C=DE/ST=BW/L=Esslingen/O=Esslingen/OU=RZ/CN=OpenVPN2

It looks to work with openssl-issued-certificates, but shows always "-1"
with MS-certificateservices-issued-certificates (at least at me). The
reason could be the strange serialnumber (e.g. "25:87:30:51:00:03:00:00:1e:e5") given out by MS.

Patrick

@@ -753,8 +753,8 @@
       if (!retval)
        goto err;
     }
-
-  msg (D_HANDSHAKE, "VERIFY OK: depth=%d, %s", ctx->error_depth, subject);
+  long serial = ASN1_INTEGER_get (X509_get_serialNumber (ctx->current_cert));
+  msg (D_HANDSHAKE, "VERIFY OK: depth=%d, serial=%ld, %s", ctx->error_depth, serial, subject);
 
   session->verified = true;
   return 1;                    /* Accept connection */