Fix IRI domain name parsing for [80, 9F] chars

src/libraries/System.Private.Uri/src/System/DomainNameHelper.cs

@@ -40,7 +40,7 @@ internal static class DomainNameHelper
         private static readonly IndexOfAnyValues<char> s_iriInvalidAsciiChars = IndexOfAnyValues.Create(
             "\u0000\u0001\u0002\u0003\u0004\u0005\u0006\u0007\u0008\u0009\u000A\u000B\u000C\u000D\u000E\u000F" +
             "\u0010\u0011\u0012\u0013\u0014\u0015\u0016\u0017\u0018\u0019\u001A\u001B\u001C\u001D\u001E\u001F" +
-            " !\"#$%&'()*+,/:;<=>?@[\\]^`{|}~");
+            " !\"#$%&'()*+,/:;<=>?@[\\]^`{|}~\u007F");
 
         private static readonly IndexOfAnyValues<char> s_asciiLetterUpperOrColonChars =
             IndexOfAnyValues.Create("ABCDEFGHIJKLMNOPQRSTUVWXYZ:");
@@ -153,6 +153,13 @@ public static bool IsValid(ReadOnlySpan<char> hostname, bool iri, bool notImplic
                     ReadOnlySpan<char> label = hostname.Slice(0, labelLength);
                     if (!IsAscii(label))
                     {
+                        // s_iriInvalidAsciiChars confirmed everything in [0, 7F] range.
+                        // Chars in [80, A0) range are also invalid, check for them now.
+                        if (hostname.IndexOfAnyInRange('\u0080', '\u009F') >= 0)
+                        {
+                            return false;
+                        }
+
                         // Account for the ACE prefix ("xn--")
                         labelLength += 4;