Motivation:
The widely used SSL Implementation, OpenSSL, already supports Heartbeat Extension; both sending and responding to Heartbeat Messages. But, since Netty is not recognizing that extension as valid packet, peers won't be able to use this extension.
Modification:
Update SslUtils.java to recognize Heartbeat Extension as valid tls packet.
Result:
With this change, softwares using Netty + OpenSSL will be able to respond for TLS Heartbeat requests (actually taken care by OpenSSL - no need of any extra implementation from Clients)
If you are on Linux, you need additional development packages installed on your system, because you'll build the native transport.
Note that this is build-time requirement. JDK 5 (for 3.x) or 6 (for 4.0+) is enough to run your Netty-based application.
Branches to look
Development of all versions takes place in each branch whose name is identical to <majorVersion>.<minorVersion>. For example, the development of 3.9 and 4.0 resides in the branch '3.9' and the branch '4.0' respectively.