// GetCriticalExtension returns a requested critical extension. It also remove it from the list
// of unhandled critical extensions
func GetCriticalExtension(cert *x509.Certificate, oid asn1.ObjectIdentifier) ([]byte, error) {
for i, ext := range cert.UnhandledCriticalExtensions {
if IntArrayEquals(ext, oid) {
cert.UnhandledCriticalExtensions = append(cert.UnhandledCriticalExtensions[:i], cert.UnhandledCriticalExtensions[i+1:]...)
break
}
}
for _, ext := range cert.Extensions {
if IntArrayEquals(ext.Id, oid) {
return ext.Value, nil
}
}
return nil, errors.New("Failed retrieving extension.")
}