DER coding CRLDistributions points

[Andy Newton]

Hello,

I am attempting to DER code the id-ce-cRLDistributionPoints x509 extension. I'm 
using the pkix.asn file that accompanies libtasn1 (v2.9), but I've added some 
structures for RFC 3779. I've using asn1Parse to convert it to a C array. The 
DER coding works without error, but the resulting DER is incompatible with 
OpenSSL and dumpasn1 shows differing structures from my DER and a certificate 
that does work with OpenSSL.

Here is my code snippet that is creating the DER structure:

       // cdp is constructed as the ASN1_TYPE holding the structure of the 
extension
       ....
       // write new thing in cdp sequence
       asn1_write_value( cdp, "", "NEW", 1 );
       //
       // write cdp full name choice
       asn1_write_value( cdp, "?LAST.distributionPoint", "fullName", 1 );
       //
       // write new sequence item for cdp general name
       asn1_write_value( cdp, "?LAST.distributionPoint.fullName", "NEW", 1 );
       //
       // write cdp uniformResourceIdentifier choice
       asn1_write_value( cdp, "?LAST.distributionPoint.fullName.?LAST", 
"uniformResourceIdentifier", 1 );
       //
       // write cdp URI
       asn1_write_value( cdp, 
"?LAST.distributionPoint.fullName.?LAST.uniformResourceIdentifier",
               cert->crlDistributionPoint, strlen( cert->crlDistributionPoint ) 
);
       //
       // write NULL for cdp reasons
       asn1_write_value( cdp, "?LAST.reasons", NULL, 0 );
       //
       // write NULL for cdp cRLIssuer
       asn1_write_value( cdp, "?LAST.cRLIssuer", NULL, 0 );

>From reading RFC 5280 and the pkix.asn file, I think this is correct. However, 
>using dumpasn1 there seems to be a missing sequence. I can't figure out what 
>I'm missing nor why libtasn1 did not complain.

Any help is appreciated... and I plan to follow up this email with my dumpasn1 
output.

-andy