Handshake failed when backend add charset into Content-Type header

[SQReder]

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• report a bug
• request a feature

Current behaviour

Undertow server forcibly add charset into Content-Type header, so response type not recognized as arrayboffer and connection fails with parser error message.

Steps to reproduce (if the current behaviour is a bug)

1. Server respond with normal handshake, with Content-Type: application/octet-stream; charset=UTF-8
2. Connection establishing fails

Expected behaviour

Connection succeed

Setup

• OS: Win 10
• browser: Chrome 70+
• engine.io version: 3.3.1

Other information (e.g. stacktraces, related issues, suggestions how to fix)

Naive fix is extend checks of content type

Index: lib/transports/polling-xhr.js
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- lib/transports/polling-xhr.js	(revision 57f9d457d593429cd66c6f1e1909835ac1fce456)
+++ lib/transports/polling-xhr.js	(date 1565959739511)
@@ -243,7 +243,7 @@
         if (xhr.readyState === 2) {
           try {
             var contentType = xhr.getResponseHeader('Content-Type');
-            if (self.supportsBinary && contentType === 'application/octet-stream') {
+            if (self.supportsBinary && contentType === 'application/octet-stream' || contentType === 'application/octet-stream; charset=UTF-8') {
               xhr.responseType = 'arraybuffer';
             }
           } catch (e) {}
@@ -355,7 +355,7 @@
     try {
       contentType = this.xhr.getResponseHeader('Content-Type');
     } catch (e) {}
-    if (contentType === 'application/octet-stream') {
+    if (contentType === 'application/octet-stream' || contentType === 'application/octet-stream; charset=UTF-8') {
       data = this.xhr.response || this.xhr.responseText;
     } else {
       data = this.xhr.responseText;