fix(pdk): response send function should ignore transfer-encoding corr…

…ectly (#11936)

This PR is a follow-up fix for #8698 to ignore the transfer encoding header set by the user.

The line removed in this PR seems to be conflict with the original fix and makes the original fix meaningless, so removed this line to get the expected behavior.

We have related bug reports that when using the AWS-Lambda plugin in proxy_integration mode if the lamdba function returns an arbitrary transfer-encoding header, the response sent by Kong will both contain content-length and transfer-encoding, which is an unexpected result.

Fix FTI-5028

changelog/unreleased/kong/pdk-response-send-remove-transfer-encoding.yml

@@ -0,0 +1,3 @@
+message: Fix an issue that when using kong.response.exit, the Transfer-Encoding header set by user is not removed
+type: bugfix
+scope: PDK

kong/pdk/response.lua

@@ -660,7 +660,6 @@ local function new(self, major_version)
     local has_content_length
     if headers ~= nil then
       for name, value in pairs(headers) do
-        ngx.header[name] = normalize_multi_header(value)
         local lower_name = lower(name)
         if lower_name == "transfer-encoding" or lower_name == "transfer_encoding" then
           self.log.warn("manually setting Transfer-Encoding. Ignored.")

spec/03-plugins/27-aws-lambda/99-access_spec.lua

@@ -150,6 +150,12 @@ for _, strategy in helpers.each_strategy() do
         service     = null,
       }
 
+      local route24 = bp.routes:insert {
+        hosts       = { "lambda24.com" },
+        protocols   = { "http", "https" },
+        service     = null,
+      }
+
       bp.plugins:insert {
         name     = "aws-lambda",
         route    = { id = route1.id },
@@ -463,6 +469,19 @@ for _, strategy in helpers.each_strategy() do
         }
       }
 
+      bp.plugins:insert {
+        name     = "aws-lambda",
+        route    = { id = route24.id },
+        config                 = {
+          port                 = 10001,
+          aws_key              = "mock-key",
+          aws_secret           = "mock-secret",
+          aws_region           = "us-east-1",
+          function_name        = "functionWithTransferEncodingHeader",
+          is_proxy_integration = true,
+        }
+      }
+
       fixtures.dns_mock:A({
         name = "custom.lambda.endpoint",
         address = "127.0.0.1",
@@ -1148,6 +1167,24 @@ for _, strategy in helpers.each_strategy() do
         assert.equals("https", req.vars.scheme)
       end)
 
+      it("#test2 works normally by removing transfer encoding header when proxy integration mode", function ()
+        proxy_client:set_timeout(3000)
+        assert.eventually(function ()
+          local res = assert(proxy_client:send({
+            method  = "GET",
+            path    = "/get",
+            headers = {
+              ["Host"] = "lambda24.com"
+            }
+          }))
+
+          assert.res_status(200, res)
+          assert.is_nil(res.headers["Transfer-Encoding"])
+          assert.is_nil(res.headers["transfer-encoding"])
+
+          return true
+        end).with_timeout(3).is_truthy()
+      end)
     end)
 
     describe("AWS_REGION environment is set", function()

spec/fixtures/aws-lambda.lua

@@ -57,6 +57,9 @@ local fixtures = {
                     elseif string.match(ngx.var.uri, "functionEcho") then
                       require("spec.fixtures.mock_upstream").send_default_json_response()
 
+                    elseif string.match(ngx.var.uri, "functionWithTransferEncodingHeader") then
+                      ngx.say("{\"statusCode\": 200, \"headers\": { \"Transfer-Encoding\": \"chunked\", \"transfer-encoding\": \"chunked\"}}")
+
                     elseif type(res) == 'string' then
                       ngx.header["Content-Length"] = #res + 1
                       ngx.say(res)

t/01-pdk/08-response/11-exit.t

@@ -4,7 +4,7 @@ use Test::Nginx::Socket::Lua;
 use Test::Nginx::Socket::Lua::Stream;
 do "./t/Util.pm";
 
-plan tests => repeat_each() * (blocks() * 4) + 11;
+plan tests => repeat_each() * (blocks() * 4) + 12;
 
 run_tests();
 
@@ -1128,7 +1128,7 @@ finalize stream session: 200
 
 
 
-=== TEST 18: response.exit() does not set transfer-encoding from headers
+=== TEST 44: response.exit() does not set transfer-encoding from headers
 --- http_config eval: $t::Util::HttpConfig
 --- config
     location = /t {
@@ -1148,6 +1148,7 @@ GET /t
 --- response_body
 test
 --- response_headers
+! Transfer-Encoding
 Content-Length: 5
 X-test: test
 --- error_log