+
+/* OCSP helper: this is *not* a full OCSP check. It just checks that
+ * each CA is valid. Additional checks must be made on the chain.
+ */
+
+static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
+{
+ /* Must be a valid CA. Should we really support the "I don't know"
+ value (2)? */
+ if(ca) return check_ca(x);
+ /* leaf certificate is checked in OCSP_verify() */
+ return 1;
+}
+
+static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
+ int ca)
+{
+ int i_ext;
+
+ /* If ca is true we must return if this is a valid CA certificate. */
+ if (ca) return check_ca(x);
+
+ /*
+ * Check the optional key usage field:
+ * if Key Usage is present, it must be one of digitalSignature
+ * and/or nonRepudiation (other values are not consistent and shall
+ * be rejected).
+ */
+ if ((x->ex_flags & EXFLAG_KUSAGE)
+ && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
+ !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
+ return 0;
+
+ /* Only time stamp key usage is permitted and it's required. */
+ if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
+ return 0;
+
+ /* Extended Key Usage MUST be critical */
+ i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, 0);
+ if (i_ext >= 0)
+ {
+ X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext);
+ if (!X509_EXTENSION_get_critical(ext))
+ return 0;
+ }
+
+ return 1;
+}
+
+static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
+{
+ return 1;
+}
+
+/* Various checks to see if one certificate issued the second.
+ * This can be used to prune a set of possible issuer certificates
+ * which have been looked up using some simple method such as by
+ * subject name.
+ * These are:
+ * 1. Check issuer_name(subject) == subject_name(issuer)
+ * 2. If akid(subject) exists check it matches issuer
+ * 3. If key_usage(issuer) exists check it supports certificate signing
+ * returns 0 for OK, positive for reason for mismatch, reasons match
+ * codes for X509_verify_cert()
+ */
+
+int X509_check_issued(X509 *issuer, X509 *subject)
+{
+ if(X509_NAME_cmp(X509_get_subject_name(issuer),
+ X509_get_issuer_name(subject)))
+ return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
+ x509v3_cache_extensions(issuer);
+ x509v3_cache_extensions(subject);
+
+ if(subject->akid)
+ {
+ int ret = X509_check_akid(issuer, subject->akid);
+ if (ret != X509_V_OK)
+ return ret;
+ }
+
+ if(subject->ex_flags & EXFLAG_PROXY)
+ {
+ if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
+ return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
+ }
+ else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
+ return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
+ return X509_V_OK;
+}
+
+int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
+ {
+
+ if(!akid)
+ return X509_V_OK;
+
+ /* Check key ids (if present) */
+ if(akid->keyid && issuer->skid &&
+ ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) )
+ return X509_V_ERR_AKID_SKID_MISMATCH;
+ /* Check serial number */
+ if(akid->serial &&
+ ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
+ return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
+ /* Check issuer name */
+ if(akid->issuer)
+ {
+ /* Ugh, for some peculiar reason AKID includes
+ * SEQUENCE OF GeneralName. So look for a DirName.
+ * There may be more than one but we only take any
+ * notice of the first.
+ */
+ GENERAL_NAMES *gens;
+ GENERAL_NAME *gen;
+ X509_NAME *nm = NULL;
+ int i;
+ gens = akid->issuer;
+ for(i = 0; i < sk_GENERAL_NAME_num(gens); i++)
+ {
+ gen = sk_GENERAL_NAME_value(gens, i);
+ if(gen->type == GEN_DIRNAME)
+ {
+ nm = gen->d.dirn;
+ break;
+ }
+ }
+ if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
+ return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
+ }
+ return X509_V_OK;
+ }
+