Bug 1792635 - Prevent DNS not found page from suggesting the same URI - r=mak

I modified the boolean associated with fixupCreateAlternateURI to only
be true if the host which contains the prefix and suffix differs from
the fixed up version. This will allow the boolean to be false in cases
where the fixup doesn't change the host. Then for the DNS error page,
there is a check as to whether the host or protocol was changed.

Differential Revision: https://phabricator.services.mozilla.com/D159175

docshell/base/URIFixup.sys.mjs

@@ -1284,6 +1284,7 @@ function maybeAddPrefixAndSuffix(oldHost) {
  * @throws If a non-NS_ERROR_MALFORMED_URI error occurs.
  */
 function updateHostAndScheme(info, newHost) {
+  let oldHost = info.fixedURI.host;
   let oldScheme = info.fixedURI.scheme;
   try {
     info.fixedURI = info.fixedURI
@@ -1300,6 +1301,8 @@ function updateHostAndScheme(info, newHost) {
   if (oldScheme != info.fixedURI.scheme) {
     info.fixupChangedProtocol = true;
   }
-  info.fixupCreatedAlternateURI = true;
+  if (oldHost != info.fixedURI.host) {
+    info.fixupCreatedAlternateURI = true;
+  }
   return true;
 }

docshell/test/unit/test_URIFixup_forced.js

@@ -14,22 +14,26 @@ var data = [
     // upgrade protocol.
     wrong: "http://www.example.com/",
     fixed: "https://www.example.com/",
+    noAlternateURI: true,
   },
   {
     // no difference.
     wrong: "https://www.example.com/",
     fixed: "https://www.example.com/",
     noProtocolFixup: true,
+    noAlternateURI: true,
   },
   {
     // don't add prefix when there's more than one dot.
     wrong: "http://www.example.abc.def/",
     fixed: "https://www.example.abc.def/",
+    noAlternateURI: true,
   },
   {
     // http -> https.
     wrong: "http://www.example/",
     fixed: "https://www.example/",
+    noAlternateURI: true,
   },
   {
     // domain.com -> https://www.domain.com.

toolkit/actors/NetErrorChild.jsm

@@ -89,7 +89,7 @@ class NetErrorChild extends RemotePageChild {
       this.contentWindow.location.href
     );
 
-    if (!info.fixupCreatedAlternateURI) {
+    if (!info.fixupCreatedAlternateURI && !info.fixupChangedProtocol) {
       return;
     }