Fix response transformer hang. See issues #1260 and #1207

kong/plugins/response-transformer/handler.lua

@@ -2,8 +2,12 @@ local BasePlugin = require "kong.plugins.base_plugin"
 local body_filter = require "kong.plugins.response-transformer.body_transformer"
 local header_filter = require "kong.plugins.response-transformer.header_transformer"
 
+local is_body_transform_set = header_filter.is_body_transform_set
+local is_json_body = header_filter.is_json_body
+
 local ResponseTransformerHandler = BasePlugin:extend()
 
+
 function ResponseTransformerHandler:new()
   ResponseTransformerHandler.super.new(self, "response-transformer")
 end
@@ -20,7 +24,8 @@ end
 
 function ResponseTransformerHandler:body_filter(conf)
   ResponseTransformerHandler.super.body_filter(self)
-  if body_filter.is_json_body(ngx.header["content-type"]) then
+
+  if is_body_transform_set(conf) and is_json_body(ngx.header["content-type"]) then
     local chunk, eof = ngx.arg[1], ngx.arg[2]
     if eof then
       local body = body_filter.transform_json_body(conf, ngx.ctx.buffer)

kong/plugins/response-transformer/header_transformer.lua

@@ -40,6 +40,10 @@ local function is_body_transform_set(conf)
   return #conf.add.json > 0  or #conf.remove.json > 0 or #conf.replace.json > 0 or #conf.append.json > 0
 end
 
+-- export utility functions
+_M.is_json_body = is_json_body
+_M.is_body_transform_set = is_body_transform_set
+
 ---
 --   # Example:
 --   ngx.headers = header_filter.transform_headers(conf, ngx.headers)

spec/plugins/response-transformer/skip_body_spec.lua

@@ -0,0 +1,85 @@
+-- Related to issue https://github.com/Mashape/kong/issues/1207 
+-- unit test to check body remains unaltered
+describe("response-transformer body-check", function()
+
+  local old_ngx, handler
+
+  setup(function()
+    old_ngx = ngx
+    _G.ngx = {       -- busted requires explicit _G to access the global environment
+      log = function() end,
+      header = {
+          ["content-type"] = "application/json",
+        },
+      arg = {},
+      ctx = {
+          buffer = "",
+        },
+    }
+    handler = require("kong.plugins.response-transformer.handler")
+    handler:new()
+  end)
+
+  teardown(function()
+    ngx = old_ngx
+  end)
+
+  it("check the body to remain unaltered if no transforms have been set", function()
+    -- only a header transform, no body changes
+    local conf = {
+      remove = {
+        headers = {"h1", "h2", "h3"},
+        json = {}
+      },
+      add = {
+        headers = {},
+        json = {},
+      },
+      append = {
+        headers = {},
+        json = {},
+      },
+      replace = {
+        headers = {},
+        json = {},
+      },
+    }
+    local body = [[
+
+  {
+    "id": 1,
+    "name": "Some One",
+    "username": "Bretchen",
+    "email": "Not@here.com",
+    "address": {
+      "street": "Down Town street",
+      "suite": "Apt. 23",
+      "city": "Gwendoline"
+    },
+    "phone": "1-783-729-8531 x56442",
+    "website": "hardwork.org",
+    "company": {
+      "name": "BestBuy",
+      "catchPhrase": "just a bunch of words",
+      "bs": "bullshit words"
+    }
+  }
+
+]]
+
+    ngx.arg[1] = body
+    handler:body_filter(conf)
+    local result = ngx.arg[1]
+    ngx.arg[1] = ""
+    ngx.arg[2] = true -- end of body marker
+    handler:body_filter(conf)
+    result = result .. ngx.arg[1]
+
+    -- body filter should not execute, it would parse and reencode the json, removing
+    -- the whitespace. So check equality to make sure whitespace is still there, and hence
+    -- body was not touched.
+    assert.are.same(body, result)
+
+  end)
+
+end)