Add preliminary RADIUS dynamic authorization server (RFC 5176)

This adds the basic DAS mechanism to enable hostapd to be configured
to request dynamic authorization requests (Disconnect-Request and
CoA-Request). This commit does not add actual processing of the
requests, i.e., this will only receive and authenticate the requests
and NAK them regardless of what operation is requested.

Signed-hostap: Jouni Malinen <j@w1.fi>

src/ap/hostapd.h

@@ -85,6 +85,7 @@ struct hostapd_data {
 
 	struct radius_client_data *radius;
 	u32 acct_session_id_hi, acct_session_id_lo;
+	struct radius_das_data *radius_das;
 
 	struct iapp_data *iapp;