+ /**
+ * verify an incoming request.
+ *
+ * \pre request message is pointed by req->rq_reqbuf, size is
+ * req->rq_reqdata_len; and the message has been unpacked to
+ * host byte order.
+ *
+ * \retval SECSVC_OK success, req->rq_reqmsg point to request message
+ * in clear text, size is req->rq_reqlen; req->rq_svc_ctx is set;
+ * req->rq_sp_from is decoded from request.
+ * \retval SECSVC_COMPLETE success, the request has been fully
+ * processed, and reply message has been prepared; req->rq_sp_from is
+ * decoded from request.
+ * \retval SECSVC_DROP failed, this request should be dropped.
+ *
+ * \see null_accept(), plain_accept(), gss_svc_accept_kr().
+ */