From ac98911c16e73d58c176ef5283bc9096a70dab45 Mon Sep 17 00:00:00 2001
From: Jun Ouyang <ouyangjun1999@gmail.com>
Date: Mon, 15 Jul 2024 15:38:40 +0800
Subject: [PATCH] fix(core): reduce uninitialized variable message when nginx
 return 400 (#13201)

When Kong receives abnormal traffic, it will trigger 400 responses without initializing any Nginx variable, So it will trigger report.lua error, which is unnecessary.

eg: send HTTP traffic to HTTPS port, Nginx will finalize the current request by 400 response in the TLS handshake, So it will never call any openresty HTTP processing phase, it also does not initialize any Nginx variable.

Fix #13197
https://konghq.atlassian.net/browse/FTI-6025
---
 .../fix-reports-uninitialized-variable-in-400.yml  |  4 ++++
 kong/reports.lua                                   |  6 ++++++
 kong/templates/nginx_kong.lua                      |  5 +++--
 spec/02-integration/05-proxy/22-reports_spec.lua   | 14 ++++++++++++++
 4 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 changelog/unreleased/kong/fix-reports-uninitialized-variable-in-400.yml

diff --git a/changelog/unreleased/kong/fix-reports-uninitialized-variable-in-400.yml b/changelog/unreleased/kong/fix-reports-uninitialized-variable-in-400.yml
new file mode 100644
index 000000000000..398af4beb460
--- /dev/null
+++ b/changelog/unreleased/kong/fix-reports-uninitialized-variable-in-400.yml
@@ -0,0 +1,4 @@
+message: |
+  Fixed an issue where unnecessary uninitialized variable error log is reported when 400 bad requests were received.
+type: bugfix
+scope: Core
diff --git a/kong/reports.lua b/kong/reports.lua
index edb1e236b1fe..f9c470c73d43 100644
--- a/kong/reports.lua
+++ b/kong/reports.lua
@@ -335,6 +335,12 @@ function get_current_suffix(ctx)
     return nil
   end
 
+  -- 400 case is for invalid requests, eg: if a client sends a HTTP
+  -- request to a HTTPS port, it does not initialized any Nginx variables
+  if proxy_mode == "" and kong.response.get_status() == 400 then
+    return nil
+  end
+
   log(WARN, "could not determine log suffix (scheme=", tostring(scheme),
             ", proxy_mode=", tostring(proxy_mode), ")")
 end
diff --git a/kong/templates/nginx_kong.lua b/kong/templates/nginx_kong.lua
index 1f1c2803c463..0babc66bf5e2 100644
--- a/kong/templates/nginx_kong.lua
+++ b/kong/templates/nginx_kong.lua
@@ -62,6 +62,8 @@ ssl_ciphers ${{SSL_CIPHERS}};
 $(el.name) $(el.value);
 > end
 
+uninitialized_variable_warn  off;
+
 init_by_lua_block {
 > if test and coverage then
     require 'luacov'
@@ -441,9 +443,8 @@ server {
 
     location = /kong_error_handler {
         internal;
-        default_type                 '';
 
-        uninitialized_variable_warn  off;
+        default_type                 '';
 
         rewrite_by_lua_block {;}
         access_by_lua_block  {;}
diff --git a/spec/02-integration/05-proxy/22-reports_spec.lua b/spec/02-integration/05-proxy/22-reports_spec.lua
index a34de814d5c4..25f20bbefbee 100644
--- a/spec/02-integration/05-proxy/22-reports_spec.lua
+++ b/spec/02-integration/05-proxy/22-reports_spec.lua
@@ -249,6 +249,20 @@ for _, strategy in helpers.each_strategy() do
       proxy_ssl_client:close()
     end)
 
+    it("when send http request to https port, no other error in error.log", function()
+      local https_port = assert(helpers.get_proxy_port(true))
+      local proxy_client = assert(helpers.proxy_client(nil, https_port))
+      local res = proxy_client:get("/", {
+        headers = { host  = "http-service.test" }
+      })
+      reports_send_ping({port=constants.REPORTS.STATS_TLS_PORT})
+
+      assert.response(res).has_status(400)
+      assert.logfile().has.no.line("using uninitialized")
+      assert.logfile().has.no.line("could not determine log suffix (scheme=http, proxy_mode=)")
+      proxy_client:close()
+    end)
+
     it("reports h2c requests #h2_client", function()
       local h2c_client = assert(helpers.proxy_client_h2c())
       local body, headers = h2c_client({