RE: Trying to get URI of CRL from certificate extension

[Yan, Bob]

Hi Akash,

I have encountered the same issue as you mentioned in your email but I still 
haven't figured out the cause of the failure. However, after I replaced "d2i(0, 
&data, ext->value->length)" function with X509V3_EXT_d2i(ext), the problem was 
gone.

Regards
Bob



________________________________
From: owner-openssl-us...@openssl.org [mailto:owner-openssl-us...@openssl.org] 
On Behalf Of Akash Deo
Sent: Thursday, May 26, 2011 11:57 PM
To: openssl-users@openssl.org
Subject: Trying to get URI of CRL from certificate extension

Hi,

I am trying to get URI of the CRL from certificate extension using below 
function:

static char *get_distribution_point(X509 *cert) {
  int                   extcount, i, j;
  const char            *extstr;
  CONF_VALUE            *nval;
  unsigned char         *data;
  X509_EXTENSION        *ext;
  X509V3_EXT_METHOD     *meth;
  STACK_OF(CONF_VALUE)  *val;

  if ((extcount = X509_get_ext_count(cert)) > 0) {
    for (i = 0; i < extcount; i++) {
      ext = X509_get_ext(cert, i);
      extstr = OBJ_nid2sn(OBJ_obj2nid(X509_EXTENSION_get_object(ext)));
      if (strcasecmp(extstr, "crlDistributionPoints")) continue;

      if (!(meth = X509V3_EXT_get(ext))) break;
      data = ext->value->data;
      val = meth->i2v(meth, meth->d2i(0, &data, ext->value->length), 0);
      for (j = 0;  j < sk_CONF_VALUE_num(val);  j++) {
        nval = sk_CONF_VALUE_value(val, j);
        if (!strcasecmp(nval->name, "URI"))
          return strdup(nval->value);
      }
    }
  }
  return 0;
}



Above function fails at
val = meth->i2v(meth, meth->d2i(0, &data, ext->value->length), 0);

Any suggestions ?

Please help

Thanks & Regards,
Akash Deo