From: Petr Špaček <petr.spacek@nic.cz>
Date: Mon, 1 Apr 2019 17:05:57 +0000 (+0200)
Subject: doh: GET support, breaks on large payloads
X-Git-Tag: v4.0.0~10^2~20
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=042d052b44f677ff029cbddc002a9a72a8e17da7;p=thirdparty%2Fknot-resolver.git

doh: GET support, breaks on large payloads

This seems to be a limitation in cqueues but we have to confirm this.
---

diff --git a/modules/http/http_doh.lua b/modules/http/http_doh.lua
index ae1367dc5..9b0f6a35c 100644
--- a/modules/http/http_doh.lua
+++ b/modules/http/http_doh.lua
@@ -1,3 +1,4 @@
+local basexx = require('basexx')
 local ffi = require('ffi')
 local condition = require('cqueues.condition')
 
@@ -35,10 +36,32 @@ end
 
 -- Trace execution of DNS queries
 local function serve_doh(h, stream)
+	local input
 	local method = h:get(':method')
-	if method ~= 'POST' then
-		return 405, 'only HTTP post is supported'
+	if method == 'POST' then
+		input = stream:get_body_chars(65536, 10)  -- FIXME: timeout
+	elseif method == 'GET' then
+		local input_b64 = string.match(h:get(':path'), '^/doh%?dns=([a-zA-Z0-9_-]+)$')
+		if not input_b64 then
+			return 400, 'base64url query not found'
+		end
+		if #input_b64 > 87380 then  -- base64url encode 65535
+			return 414, 'query parameter in URI too long'
+		end
+		input = basexx.from_url64(input_b64)
+		if not input then
+			return 400, 'invalid base64url'
+		end
+	else
+		return 405, 'only HTTP POST and GET are supported'
 	end
+
+	if #input < 12 then
+		return 400, 'input too short'
+	elseif #input > 65535 then
+		return 413, 'input too long'
+	end
+
 	local content_type = h:get('content-type') or 'application/dns-message'
 	if content_type ~= 'application/dns-message' then
 		return 415, 'only Content-Type: application/dns-message is supported'
@@ -49,12 +72,6 @@ local function serve_doh(h, stream)
 --		return 406, 'only Accept: application/dns-message is supported'
 --	end
 
-	local input = stream:get_body_chars(65536, 10)  -- FIXME: timeout
-	if #input < 12 then
-		return 400, 'bad request: input too short'
-	elseif #input > 65535 then
-		return 413, 'bad request: input too long'
-	end
 	-- Output buffer
 	local output = ''
 
@@ -65,7 +82,7 @@ local function serve_doh(h, stream)
 	local cond = condition.new()
 	local waiting, done = false, false
 	local finish_cb = function (answer, req)
-		print(tostring(answer))
+		print(tostring(answer))  -- FIXME
 
 		print('TTL: ', get_http_ttl(answer))
 
diff --git a/modules/http/http_doh.test.lua b/modules/http/http_doh.test.lua
index f3691246d..148e66014 100644
--- a/modules/http/http_doh.test.lua
+++ b/modules/http/http_doh.test.lua
@@ -1,3 +1,4 @@
+local basexx = require('basexx')
 local ffi = require('ffi')
 
 function parse_pkt(input)
@@ -49,10 +50,13 @@ else
 	end
 
 	local function check_err(req, exp_status, desc)
-		local headers = req:go(5)  -- randomly chosen timeout
+		local headers, errmsg, errno = req:go(5)  -- TODO: randomly chosen timeout
+		if errno then
+			nok(errmsg, desc .. ': ' .. errmsg)
+			return
+		end
 		local got_status = headers:get(':status')
 		same(got_status, exp_status, desc)
-		print(got_status)  -- TODO
 	end
 
 	-- test whether http interface responds and binds
@@ -85,6 +89,13 @@ else
 		check_err(req, '413', 'too long POST finishes with 413')
 	end
 
+	local function test_get_long_input()
+		local req = assert(req_templ:clone())
+		req.headers:upsert(':method', 'GET')
+		req.headers:upsert(':path', '/doh?dns=' .. basexx.to_url64(string.rep('s', 65536)))
+		check_err(req, '414', 'too long GET finishes with 414')
+	end
+
 	local function test_post_unparseable_input()
 		local req = assert(req_templ:clone())
 		req.headers:upsert(':method', 'POST')
@@ -115,6 +126,7 @@ else
 		-- test_doh_post,
 		test_post_short_input,
 		test_post_long_input,
+		test_get_long_input,
 		test_post_unparseable_input,
 		test_post_unsupp_type
 	}