ASN1_get_object
inf = ASN1_get_object(&p, &len, &tag, &xclass, length);
r = ASN1_get_object(&cpy_start, &hdr_len, &hdr_tag,
inf = ASN1_get_object(&q, &slen, &tag, &xclass, len - off);
j = ASN1_get_object(&p, &len, &tag, &xclass, length);
int ASN1_get_object(const unsigned char **pp, long *plength, int *ptag,