From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Wed, 26 Apr 2017 12:53:49 +0000 (+0200)
Subject: policy: purge pointer-casting where not necessary
X-Git-Tag: 1.3.0-rc1~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f60ad2dfb15381818f7c58e8709d7ea9479aee0;p=thirdparty%2Fknot-resolver.git

policy: purge pointer-casting where not necessary

Casting is dangerous, e.g. it's easy to misconfigure policy with
  policy.add(policy.FORWARD('some address'))
which lead to segfault without showing any indication of the cause.
Now this case will show as
  .../policy.lua:98: 'struct kr_query' has no member named 'current'
and only abort the policy module instead of the whole process.
---

diff --git a/daemon/lua/kres.lua.in b/daemon/lua/kres.lua.in
index 540c7f99f..f302a08a3 100644
--- a/daemon/lua/kres.lua.in
+++ b/daemon/lua/kres.lua.in
@@ -346,7 +346,7 @@ kres = {
 	rcode = ffi.new('struct pkt_rcode'),
 	query = query_flag,
 	CONSUME = 1, PRODUCE = 2, DONE = 4, FAIL = 8, YIELD = 16,
-	-- Metatypes
+	-- Metatypes.  Beware that any pointer will be cast silently...
 	pkt_t = function (udata) return ffi.cast('knot_pkt_t *', udata) end,
 	request_t = function (udata) return ffi.cast('struct kr_request *', udata) end,
 	-- Global API functions
diff --git a/modules/policy/policy.lua b/modules/policy/policy.lua
index 8385585fb..2c19ed854 100644
--- a/modules/policy/policy.lua
+++ b/modules/policy/policy.lua
@@ -55,7 +55,6 @@ local function mirror(target)
 	if not sink then panic('MIRROR target %s is not a valid: %s', target, err) end
 	return function(state, req)
 		if state == kres.FAIL then return state end
-		req = kres.request_t(req)
 		local query = req.qsource.packet
 		if query ~= nil then
 			sink:send(ffi.string(query.wire, query.size))
@@ -76,7 +75,6 @@ local function stub(target)
 		table.insert(list, addr2sock(target))
 	end
 	return function(state, req)
-		req = kres.request_t(req)
 		local qry = req:current()
 		-- Switch mode to stub resolver, do not track origin zone cut since it's not real authority NS
 		qry.flags = bit.band(bit.bor(qry.flags, kres.query.STUB), bit.bnot(kres.query.ALWAYS_CUT))
@@ -97,7 +95,6 @@ local function forward(target)
 		table.insert(list, addr2sock(target))
 	end
 	return function(state, req)
-		req = kres.request_t(req)
 		local qry = req:current()
 		req.options = bit.bor(bit.bor(req.options, kres.query.FORWARD), kres.query.NO_MINIMIZE)
 		qry.flags = bit.band(bit.bor(qry.flags, kres.query.FORWARD), bit.bnot(kres.query.ALWAYS_CUT))
@@ -122,7 +119,6 @@ end
 -- Set and clear some query flags
 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