When the topic length of sub exceeds 15kb, xpub crashes when calling zmq_msg_recv.

[devsuncj]

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Issue description

I am using clrzmq4 to call libzmq. When the topic length of sub exceeds 15kb, xpub crashes when calling zmq_msg_recv.

Environment

• libzmq version (commit hash if unreleased): 4.3.5
• OS: Windows

Minimal test code / Steps to reproduce the issue

var xpub = new ZSocket(ZSocketType.XPUB);
xpub.Bind("tcp://*:6666");
Task.Run(() => {
var msg = xpub.ReceiveMessage(); //Calling this code will result in a crash. When the topic length of sub exceeds 15kb
});
var subSocket = new ZSocket(ZSocketType.SUB);
subSocket.Connect("tcp://localhost:6666");
byte[] dataArray = new byte[1024 * 16];
for (int i = 0; i < dataArray.Length; i++)
{
dataArray[i] = 111;
}
subSocket.Subscribe(dataArray);

What's the actual result? (include assertion message & call stack if applicable)

When the topic length of sub exceeds 15kb, xpub crashes when calling zmq_msg_recv.

What's the expected result?

The expected result is the normal completion of subscribing to data.