-extern bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_t mykey, ecdsa_t hiskey, const char *label, size_t labellen, send_data_t send_data, receive_record_t receive_record);
+extern void sptps_log_quiet(sptps_t *s, int s_errno, const char *format, va_list ap);
+extern void sptps_log_stderr(sptps_t *s, int s_errno, const char *format, va_list ap);
+extern void (*sptps_log)(sptps_t *s, int s_errno, const char *format, va_list ap);
+extern bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_t *mykey, ecdsa_t *hiskey, const char *label, size_t labellen, send_data_t send_data, receive_record_t receive_record);