From 97d386740f5ed4c4be09dfdd23e5b7fc3d940d42 Mon Sep 17 00:00:00 2001
From: Evgeny Soynov <esoynov@kogito.network>
Date: Mon, 29 Jun 2020 21:15:00 +0200
Subject: [PATCH 1/2] Fixes expressjs/multer#553 . Makes multer handle missing
 field names.

Without this fix fields without a name result in a "TypeError: Cannot read property 'length' of undefined"
in the underlying append-field library.

The current change allows getting an error from multer that makes it
possible to handle it in servers.
---
 lib/make-middleware.js |  1 +
 lib/multer-error.js    |  3 ++-
 test/error-handling.js | 27 +++++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/lib/make-middleware.js b/lib/make-middleware.js
index d22042ee..eb2c5a75 100644
--- a/lib/make-middleware.js
+++ b/lib/make-middleware.js
@@ -81,6 +81,7 @@ function makeMiddleware (setup) {
 
     // handle text field data
     busboy.on('field', function (fieldname, value, fieldnameTruncated, valueTruncated) {
+      if (!fieldname) return abortWithCode('LIMIT_MISSING_FIELD_NAME')
       if (fieldnameTruncated) return abortWithCode('LIMIT_FIELD_KEY')
       if (valueTruncated) return abortWithCode('LIMIT_FIELD_VALUE', fieldname)
 
diff --git a/lib/multer-error.js b/lib/multer-error.js
index 4c91d295..a1a39bb7 100644
--- a/lib/multer-error.js
+++ b/lib/multer-error.js
@@ -7,7 +7,8 @@ var errorMessages = {
   LIMIT_FIELD_KEY: 'Field name too long',
   LIMIT_FIELD_VALUE: 'Field value too long',
   LIMIT_FIELD_COUNT: 'Too many fields',
-  LIMIT_UNEXPECTED_FILE: 'Unexpected field'
+  LIMIT_UNEXPECTED_FILE: 'Unexpected field',
+  LIMIT_MISSING_FIELD_NAME: 'Field name missing'
 }
 
 function MulterError (code, field) {
diff --git a/test/error-handling.js b/test/error-handling.js
index 450173fb..ccbf9981 100644
--- a/test/error-handling.js
+++ b/test/error-handling.js
@@ -148,6 +148,33 @@ describe('Error Handling', function () {
     })
   })
 
+  it('should notify of missing field name', function (done) {
+    var req = new stream.PassThrough()
+    var storage = multer.memoryStorage()
+    var upload = multer({ storage: storage }).single('tiny0')
+    var boundary = 'AaB03x'
+    var body = [
+      '--' + boundary,
+      'Content-Disposition: form-data',
+      '',
+      'test content',
+      '--' + boundary,
+      ''
+    ].join('\r\n')
+
+    req.headers = {
+      'content-type': 'multipart/form-data; boundary=' + boundary,
+      'content-length': body.length
+    }
+
+    req.end(body)
+
+    upload(req, null, function (err) {
+      assert.strictEqual(err.code, 'LIMIT_MISSING_FIELD_NAME')
+      done()
+    })
+  })
+
   it('should report errors from storage engines', function (done) {
     var storage = multer.memoryStorage()
 

From 00cfcd74477b02c57e6a635baacee5b1af7db729 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Tue, 7 Dec 2021 12:32:52 +0100
Subject: [PATCH 2/2] Apply suggestions from code review

---
 lib/make-middleware.js | 2 +-
 lib/multer-error.js    | 2 +-
 test/error-handling.js | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/make-middleware.js b/lib/make-middleware.js
index eb2c5a75..b033cbd9 100644
--- a/lib/make-middleware.js
+++ b/lib/make-middleware.js
@@ -81,7 +81,7 @@ function makeMiddleware (setup) {
 
     // handle text field data
     busboy.on('field', function (fieldname, value, fieldnameTruncated, valueTruncated) {
-      if (!fieldname) return abortWithCode('LIMIT_MISSING_FIELD_NAME')
+      if (fieldname == null) return abortWithCode('MISSING_FIELD_NAME')
       if (fieldnameTruncated) return abortWithCode('LIMIT_FIELD_KEY')
       if (valueTruncated) return abortWithCode('LIMIT_FIELD_VALUE', fieldname)
 
diff --git a/lib/multer-error.js b/lib/multer-error.js
index a1a39bb7..d56b00e8 100644
--- a/lib/multer-error.js
+++ b/lib/multer-error.js
@@ -8,7 +8,7 @@ var errorMessages = {
   LIMIT_FIELD_VALUE: 'Field value too long',
   LIMIT_FIELD_COUNT: 'Too many fields',
   LIMIT_UNEXPECTED_FILE: 'Unexpected field',
-  LIMIT_MISSING_FIELD_NAME: 'Field name missing'
+  MISSING_FIELD_NAME: 'Field name missing'
 }
 
 function MulterError (code, field) {
diff --git a/test/error-handling.js b/test/error-handling.js
index ccbf9981..b462e16e 100644
--- a/test/error-handling.js
+++ b/test/error-handling.js
@@ -170,7 +170,7 @@ describe('Error Handling', function () {
     req.end(body)
 
     upload(req, null, function (err) {
-      assert.strictEqual(err.code, 'LIMIT_MISSING_FIELD_NAME')
+      assert.strictEqual(err.code, 'MISSING_FIELD_NAME')
       done()
     })
   })