From 84eadbe3cf6f0a9f167c8a95038e2556bb08b3bb Mon Sep 17 00:00:00 2001
From: Martok <martok@martoks-place.de>
Date: Thu, 4 May 2023 21:03:16 +0200
Subject: [PATCH] No Issue - Do not parse or return body for XHRs with
 HEAD/CONNECT method or content-length=0

Based-on: m-c 1392220, 1437360
---
 dom/xhr/XMLHttpRequestMainThread.cpp | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/dom/xhr/XMLHttpRequestMainThread.cpp b/dom/xhr/XMLHttpRequestMainThread.cpp
index c5b174b5cb..aa1fc4e908 100644
--- a/dom/xhr/XMLHttpRequestMainThread.cpp
+++ b/dom/xhr/XMLHttpRequestMainThread.cpp
@@ -602,6 +602,12 @@ XMLHttpRequestMainThread::GetResponseText(XMLHttpRequestStringSnapshot& aSnapsho
     return;
   }
 
+  // Main Fetch step 18 requires to ignore body for head/connect methods.
+  if (mRequestMethod.EqualsLiteral("HEAD") ||
+      mRequestMethod.EqualsLiteral("CONNECT")) {
+    return;
+  }
+
   // We only decode text lazily if we're also parsing to a doc.
   // Also, if we've decoded all current data already, then no need to decode
   // more.
@@ -1915,13 +1921,19 @@ XMLHttpRequestMainThread::OnStartRequest(nsIRequest *request, nsISupports *ctxt)
   }
 
   // Set up responseXML
-  bool parseBody = mResponseType == XMLHttpRequestResponseType::_empty ||
-                   mResponseType == XMLHttpRequestResponseType::Document;
-  nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(mChannel));
-  if (parseBody && httpChannel) {
-    nsAutoCString method;
-    httpChannel->GetRequestMethod(method);
-    parseBody = !method.EqualsLiteral("HEAD");
+  // Note: Main Fetch step 18 requires to ignore body for head/connect methods.
+  bool parseBody = (mResponseType == XMLHttpRequestResponseType::_empty ||
+                    mResponseType == XMLHttpRequestResponseType::Document) &&
+                   !(mRequestMethod.EqualsLiteral("HEAD") ||
+                     mRequestMethod.EqualsLiteral("CONNECT"));
+
+  if (parseBody) {
+    // Do not try to parse documents if content-length = 0
+    int64_t contentLength;
+    if (NS_SUCCEEDED(mChannel->GetContentLength(&contentLength)) &&
+        contentLength == 0) {
+      parseBody = false;
+    }
   }
 
   mIsHtml = false;