Bug 1848874 - Removed network.dns.limit_253_chars pref. r=necko-reviewers,valentin

Differential Revision: https://phabricator.services.mozilla.com/D186573

modules/libpref/init/StaticPrefList.yaml

@@ -11762,14 +11762,6 @@
   value: false
   mirror: always
 
-# When this pref is true we enforce a 253 character limit on domains we try to
-# resolve. See bug 1264117. If it doesn't cause any web-compat issues we can
-# remove it in a few releases
-- name: network.dns.limit_253_chars
-  type: RelaxedAtomicBool
-  value: true
-  mirror: always
-
 # When this pref is true, we copy the host name to a fresh string before
 # calling into getaddrinfo.
 - name: network.dns.copy_string_before_call

netwerk/base/nsURLHelper.cpp

@@ -872,9 +872,8 @@ void net_ParseRequestContentType(const nsACString& aHeaderStr,
 }
 
 bool net_IsValidHostName(const nsACString& host) {
-  // A DNS name is limited to 255 bytes on the wire.
-  // In practice this means the host name is limited to 253 ascii characters.
-  if (StaticPrefs::network_dns_limit_253_chars() && host.Length() > 253) {
+  // The host name is limited to 253 ascii characters.
+  if (host.Length() > 253) {
     return false;
   }
 

netwerk/test/unit/test_channel_long_domain.js

@@ -1,7 +1,6 @@
 // Tests that domains longer than 253 characters fail to load when pref is true
 
 add_task(async function test_long_domain_fails() {
-  Services.prefs.setBoolPref("network.dns.limit_253_chars", true);
   let domain = "http://" + "a".repeat(254);
 
   let req = await new Promise(resolve => {
@@ -12,6 +11,4 @@ add_task(async function test_long_domain_fails() {
     chan.asyncOpen(new ChannelListener(resolve, null, CL_EXPECT_FAILURE));
   });
   Assert.equal(req.status, Cr.NS_ERROR_UNKNOWN_HOST, "Request should fail");
-
-  Services.prefs.clearUserPref("network.dns.limit_253_chars");
 });

netwerk/test/unit/test_dns_service.js

@@ -89,8 +89,6 @@ add_task(
     domain = "a".repeat(254);
     overrideService.addIPOverride(domain, "1.2.3.4");
 
-    Services.prefs.setBoolPref("network.dns.limit_253_chars", true);
-
     if (mozinfo.socketprocess_networking) {
       // When using the socket process, the call fails asynchronously.
       Services.dns.asyncResolve(
@@ -121,23 +119,5 @@ add_task(
         "Should throw for large domains"
       );
     }
-
-    listener = new Listener();
-    domain = "a".repeat(254);
-    Services.prefs.setBoolPref("network.dns.limit_253_chars", false);
-    Services.dns.asyncResolve(
-      domain,
-      Ci.nsIDNSService.RESOLVE_TYPE_DEFAULT,
-      Ci.nsIDNSService.RESOLVE_CANONICAL_NAME,
-      null, // resolverInfo
-      listener,
-      mainThread,
-      defaultOriginAttributes
-    );
-    [, , inStatus] = await listener;
-    Assert.equal(inStatus, Cr.NS_OK);
-
-    Services.prefs.clearUserPref("network.dns.limit_253_chars");
-    overrideService.clearOverrides();
   }
 );