From: Marek Vavruša <mvavrusa@cloudflare.com>
Date: Thu, 30 Nov 2017 00:16:08 +0000 (-0800)
Subject: modules/http: added selected records to /trace endpoint
X-Git-Tag: v2.0.0~16^2~14
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eba7b1ac19af2d7392fef624ba50bb3b732e58da;p=thirdparty%2Fknot-resolver.git

modules/http: added selected records to /trace endpoint

This allows debugging of what records were used for final answer.
---

diff --git a/daemon/lua/kres.lua b/daemon/lua/kres.lua
index ed9fc31c1..8972160a8 100644
--- a/daemon/lua/kres.lua
+++ b/daemon/lua/kres.lua
@@ -153,6 +153,26 @@ local const_rcode = {
 	BADCOOKIE  = 23,
 }
 
+-- This corresponds to `enum kr_rank`, it's not possible to do this without introspection unfortunately
+local const_rank = {
+	INITIAL = 0,
+	OMIT = 1,
+	TRY = 2,
+	INDET = 4,
+	BOGUS = 5,
+	MISMATCH = 6,
+	MISSING = 7,
+	INSECURE = 8,
+	AUTH = 16,
+	SECURE = 32
+}
+
+-- Create inverse table
+local const_rank_tostring = {}
+for k, v in pairs(const_rank) do
+	const_rank_tostring[v] = k
+end
+
 -- Metatype for RR types to allow anonymous types
 setmetatable(const_type, {
 	__index = function (t, k)
@@ -185,6 +205,7 @@ local knot_rrset_t = ffi.typeof('knot_rrset_t')
 ffi.metatype( knot_rrset_t, {
 	-- beware: `owner` and `rdata` are typed as a plain lua strings
 	--         and not the real types they represent.
+	__tostring = function(rr) return rr:txt_dump() end,
 	__index = {
 		owner = function(rr) return ffi.string(rr._owner, knot.knot_dname_size(rr._owner)) end,
 		ttl = function(rr) return tonumber(knot.knot_rrset_ttl(rr)) end,
@@ -319,6 +340,30 @@ ffi.metatype( kr_request_t, {
 	},
 })
 
+-- C array iterator
+local function c_array_iter(t, i)
+	i = i + 1
+	if i >= t.len then return end
+	return i, t.at[i][0]
+end
+
+-- Metatype for ranked record array
+local ranked_rr_array_t = ffi.typeof('ranked_rr_array_t')
+ffi.metatype(ranked_rr_array_t, {
+	__len = function(self)
+		return tonumber(self.len)
+	end,
+	__ipairs = function (self)
+		return c_array_iter, self, -1
+	end,
+	__index = {
+		get = function (self, i)
+			if i < 0 or i > self.len then return nil end
+			return self.at[i][0]
+		end,
+	}
+})
+
 -- Pretty print for domain name
 local function dname2str(dname)
 	return ffi.string(ffi.gc(C.knot_dname_to_str(nil, dname, 0), C.free))
@@ -357,6 +402,8 @@ kres = {
 	type = const_type,
 	section = const_section,
 	rcode = const_rcode,
+	rank = const_rank,
+	rank_tostring = const_rank_tostring,
 
 	-- Create a struct kr_qflags from a single flag name or a list of names.
 	mk_qflags = function (names)
diff --git a/modules/http/http_trace.lua b/modules/http/http_trace.lua
index c09973a0f..d4827bd63 100644
--- a/modules/http/http_trace.lua
+++ b/modules/http/http_trace.lua
@@ -1,6 +1,32 @@
 local ffi = require('ffi')
+local bit = require('bit')
 local condition = require('cqueues.condition')
 
+-- Buffer selected record information to a table
+local function add_selected_records(dst, records)
+	for _, rec in ipairs(records) do
+		local rank = rec.rank
+		-- Separate the referral chain verified flag
+		local verified = bit.band(rec.rank, kres.rank.AUTH)
+		if verified then
+			rank = bit.band(rank, bit.bnot(kres.rank.AUTH))
+		end
+		local rank_name = kres.rank_tostring[rank] or tostring(rank)
+		-- Write out each individual RR
+		for rr in tostring(rec.rr):gmatch('[^\n]+\n?') do
+			local row = string.format('cached: %s, rank: %s, record: %s',
+				rec.cached, rank_name:lower(), rr)
+			table.insert(dst, row)
+		end
+	end
+end
+
+local function format_selected_records(header, records)
+	if #records == 0 then return '' end
+	return string.format('%s\n%s\n', header, string.rep('-', #header))
+	       .. table.concat(records, '') .. '\n'
+end
+
 -- Trace execution of DNS queries
 local function serve_trace(h, _)
 	local path = h:get(':path')
@@ -34,6 +60,7 @@ local function serve_trace(h, _)
 	local done = false
 
 	-- Resolve query and buffer logs into table
+	local answers, authority = {}, {}
 	resolve {
 		name = qname,
 		type = qtype,
@@ -42,7 +69,10 @@ local function serve_trace(h, _)
 			req = kres.request_t(req)
 			req.trace_log = buffer_log_cb
 		end,
-		finish = function ()
+		finish = function (_, req)
+			req = kres.request_t(req)
+			add_selected_records(answers, req.answ_selected)
+			add_selected_records(authority, req.auth_selected)
 			cond:signal()
 			done = true
 		end
@@ -56,8 +86,11 @@ local function serve_trace(h, _)
 	end
 	buffer_log_cb:free()
 
-	-- Return buffered data
+	-- Build the result
 	local result = table.concat(buffer, '') .. '\n'
+	               .. format_selected_records('Used records from answer:', answers)
+	               .. format_selected_records('Used records from authority:', authority)
+	-- Return buffered data
 	if not done then
 		return 504, result
 	end