policy: add policy.FLAGS, (un)setting query flags

modules/policy/policy.lua

@@ -97,9 +97,20 @@ local function reroute(tbl, names)
 	return ren.rule(prefixes)
 end
 
+-- Set and clear some query flags (TODO: documentation).
+local function flags(opts_set, opts_clear)
+	return function(state, req)
+		req = kres.request_t(req)
+		local qry = req:current()
+		qry.flags = bit.band(bit.bor(qry.flags, opts_set or 0), bit.bnot(opts_clear or 0))
+		return nil -- chain rule
+	end
+end
+
 local policy = {
 	-- Policies
-	PASS = 1, DENY = 2, DROP = 3, TC = 4, QTRACE = 5, FORWARD = forward, REROUTE = reroute, MIRROR = mirror,
+	PASS = 1, DENY = 2, DROP = 3, TC = 4, QTRACE = 5,
+	FORWARD = forward, REROUTE = reroute, MIRROR = mirror, FLAGS = flags,
 	-- Special values
 	ANY = 0,
 }