When using ZMQ_SUB ，ZMQ_ TCP_ KEEPALIVE_ IDLE does not work

[ml232528]

Please use this template for reporting suspected bugs or requests for help.

Issue description

One end uses ZMQ_PUB to send data, and the other end uses ZMQSUB to receive data,ZMQ TCP KEEPALIVE IDLE does not work in ZMQSUB mode. ZMQPUB is ok.

Environment

• libzmq version (commit hash if unreleased): 4.3.4
• OS: windwos 11.

Minimal test code / Steps to reproduce the issue

zmqSubscriber_ = zmq_socket(, ZMQ_SUB); zmq_socketmonitor(zmqSubscriber, , ZMQ_EVENT_ALL); zmqconnect(zmqSubscriber, ); zmqsetsockopt(zmqSubscriber, ZMQ_SUBSCRIBE, ); int r = 1; zmqsetsockopt(zmqSubscriber, ZMQ_CONFLATE, &r, sizeof(r)); r = 5; zmqsetsockopt(zmqSubscriber, ZMQ_TCP_KEEPALIVE_IDLE, &r, sizeof(r)); zmqsetsockopt(zmqSubscriber, ZMQ_TCP_KEEPALIVE_CNT, &r, sizeof(r)); r = 1; zmqsetsockopt(zmqSubscriber, ZMQ_TCP_KEEPALIVE_INTVL, &r, sizeof(r)); zmqsetsockopt(zmqSubscriber, ZMQ_TCP_KEEPALIVE, &r, sizeof(r));

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

By tracking the source code,the setsockopt function stores the correct value. int zmq::optionst::setsockopt (int option, const void *optval_, sizet optvallen) ：options.cpp

But in the tune_socket function, it becomes -1。 bool zmq::tcp_connecter_t::tune_socket (const fdt fd) ：tcp_connecter.cpp

What's the expected result?

I hope the KEEPALIVE mechanism can work。

[ml232528]

resolved： Set KEEPALIVE before connect.