Allow more permissive char set in SNI headers (#12147)

Motivation:

As explained in issue #11819, certain chars such as ":" in the SNI header cause the netty pipeline to blow up.

Modifications:

By converting strings to byte arrays first, we can allow chars like ":"

Result:

Netty will have a more permissive char set allowed for SNI headers.


Co-authored-by: Norman Maurer <norman_maurer@apple.com>
Co-authored-by: Aayush Atharva <hyperx.pro@outlook.com>

handler/src/main/java/io/netty/handler/ssl/Java8SslUtils.java

@@ -16,6 +16,7 @@
 package io.netty.handler.ssl;
 
 import io.netty.util.internal.SuppressJava6Requirement;
+import io.netty.util.CharsetUtil;
 
 import javax.net.ssl.SNIHostName;
 import javax.net.ssl.SNIMatcher;
@@ -69,7 +70,7 @@ static List getSniHostNames(List<String> names) {
         }
         List<SNIServerName> sniServerNames = new ArrayList<SNIServerName>(names.size());
         for (String name: names) {
-            sniServerNames.add(new SNIHostName(name));
+            sniServerNames.add(new SNIHostName(name.getBytes(CharsetUtil.UTF_8)));
         }
         return sniServerNames;
     }