How to specific tcp req local port number about nng HOT 6 OPEN

You can allocate a listener, and then set the NNG_OPT_LOCADDR on it. That can specify a complete address -- including the TCP port number.

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I want to specify dialer's port, should I set NNG_OPT_LOCADDR on listener?

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In reqrep demo, I call nng_dialer_get_addr in client's every loop, but the sa_addr and sa_port different from every call. Is this OK?
And how to decode the address? for example, sa_addr = 2123998088

while (1) {

  printf("CLIENT: SENDING DATE REQUEST\n");
  if ((rv = nng_send(sock, cmd, sizeof(cmd), 0)) != 0) {
	  fatal("nng_send", rv);
  }
  if ((rv = nng_recv(sock, &buf, &sz, NNG_FLAG_ALLOC)) != 0) {
	  fatal("nng_recv", rv);
  }
  
  if (sz == sizeof(uint64_t)) {
	  uint64_t now;
	  GET64(buf, now);
	  printf("CLIENT: RECEIVED DATE: ");
	  showdate((time_t) now);
  } else {
	  printf("CLIENT: GOT WRONG SIZE!\n");
  }
  nng_msleep(sleep);
  sleep++;
  if (sleep == 4) {
	  sleep = 4000;
  }
        nng_sockaddr addr;
        nng_dialer_get_addr(dialer, NNG_OPT_LOCADDR, &addr);
        printf("%d, %d\n", addr.s_in.sa_port, addr.s_in.sa_addr);
  }

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@gdamore any suggestion ?

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The documentation should indicate properly that the option for NNG_OPT_LOCADDR is an nng_sockaddr. However, be advised that the port numbers are in network byte order, not host byte order. For sa_addr, you're looking at the network byte order IP v4 address - so:

126.153.163.136

This is standard BSD socket practice.

When you call dial, by default you'll get a unique local address -- because that's the way TCP works. You can request a specific source address, but that requires you set that option on the dialer. Note that doing so will impair automatic redialing if the connection is lost, and will prevent being able to establish multiple outbound connections so I don't recommend it unless you have no choice and you know exactly what you're doing (which doesn't seem to be the case here.)

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