From 631ada0c645dc84c6df8788f5a7eb2b8100acea5 Mon Sep 17 00:00:00 2001
From: Douglas Christopher Wilson <doug@somethingdoug.com>
Date: Fri, 29 Apr 2022 13:34:47 -0400
Subject: [PATCH] Fix hanging on large stack of sync routes

fixes #4899
---
 History.md          |  5 +++++
 lib/router/index.js | 14 ++++++--------
 test/Router.js      | 18 +++++++++++++++++-
 3 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/History.md b/History.md
index 32e75b391e..b052c577f7 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,8 @@
+unreleased
+==========
+
+  * Fix hanging on large stack of sync routes
+
 4.18.0 / 2022-04-25
 ===================
 
diff --git a/lib/router/index.js b/lib/router/index.js
index f4c8c0a79e..5174c34f45 100644
--- a/lib/router/index.js
+++ b/lib/router/index.js
@@ -279,14 +279,14 @@ proto.handle = function handle(req, res, out) {
     // this should be done for the layer
     self.process_params(layer, paramcalled, req, res, function (err) {
       if (err) {
-        return next(layerError || err);
+        next(layerError || err)
+      } else if (route) {
+        layer.handle_request(req, res, next)
+      } else {
+        trim_prefix(layer, layerError, layerPath, path)
       }
 
-      if (route) {
-        return layer.handle_request(req, res, next);
-      }
-
-      trim_prefix(layer, layerError, layerPath, path);
+      sync = 0
     });
   }
 
@@ -327,8 +327,6 @@ proto.handle = function handle(req, res, out) {
     } else {
       layer.handle_request(req, res, next);
     }
-
-    sync = 0
   }
 };
 
diff --git a/test/Router.js b/test/Router.js
index bf5a31ffdd..fcfee80625 100644
--- a/test/Router.js
+++ b/test/Router.js
@@ -78,7 +78,23 @@ describe('Router', function(){
     router.handle({ url: '/', method: 'GET' }, { end: done });
   });
 
-  it('should not stack overflow with a large sync stack', function (done) {
+  it('should not stack overflow with a large sync route stack', function (done) {
+    this.timeout(5000) // long-running test
+
+    var router = new Router()
+
+    for (var i = 0; i < 6000; i++) {
+      router.get('/foo', function (req, res, next) { next() })
+    }
+
+    router.get('/foo', function (req, res) {
+      res.end()
+    })
+
+    router.handle({ url: '/foo', method: 'GET' }, { end: done })
+  })
+
+  it('should not stack overflow with a large sync middleware stack', function (done) {
     this.timeout(5000) // long-running test
 
     var router = new Router()