Set LWIP TCP connect timeout option?

Mbed OS
1

Does anyone know if there is an option to set LWIP TCP connect timeout in one of the many json files?
I think the default is 30 seconds but that is way too long for most local network applications.

I could change some settings in OS 5.15 a while ago by doing the change below in the LWPStack.cpp file and then set it to 200 to 300 mS which is ideal.

Fortunately I can still do this with OS 6.15.1 but its a pain to have to change this every time I update OS.

    LWPStack.cpp file around line 350

    netconn_set_nonblocking(s->conn, false);
    err_t err = netconn_connect(s->conn, &ip_addr, address.get_port());
    netconn_set_nonblocking(s->conn, true);

    to...

    netconn_set_nonblocking(s->conn, true);
    err_t err = netconn_connect(s->conn, &ip_addr, address.get_port());
2

Hello Paul,

As described in mbed-os/connectivity/lwipstack/mbed_lib.json the following timeout’s can be configured for the lwipstack via a mbed_app.json:

        "dhcp-timeout": {
            "help": "DHCP timeout value",
            "value": 60
        },
        ...
        "tcp-close-timeout": {
            "help": "Maximum timeout (ms) for TCP close handshaking timeout",
            "value": 1000
        },

I have never tried to use it but the first one could be the one you are looking for:
mbed_app.json:

{
    "target_overrides": {
        "*": {
            "lwip.dhcp-timeout": 1
        }
    }
}

Or perhaps the following works too.

{
    "target_overrides": {
        "*": {
            "lwip.dhcp-timeout": 0.3
        }
    }
}
3

Hello Zoltan,
Nice to hear from you!

Unfortunately no that doesn’t work, I think its tied in with blocking/non-blocking.
That gives me the same result as:

remote_device.set_timeout(200); 200ms timeout.

But I have to set that netconn_set_nonblocking to true first as below.

nsapi_error_t LWIP::socket_connect(nsapi_socket_t handle, const SocketAddress &address)
{
    struct mbed_lwip_socket *s = (struct mbed_lwip_socket *)handle;
    ip_addr_t ip_addr;

    nsapi_addr_t addr = address.get_addr();
    if (!convert_mbed_addr_to_lwip(&ip_addr, &addr)) {
        return NSAPI_ERROR_PARAMETER;
    }

    netconn_set_nonblocking(s->conn, true);
    err_t err = netconn_connect(s->conn, &ip_addr, address.get_port());
/*
    netconn_set_nonblocking(s->conn, false);
    err_t err = netconn_connect(s->conn, &ip_addr, address.get_port());
    netconn_set_nonblocking(s->conn, true);
*/
    return err_remap(err);
}

I did try again remote_device.set_blocking(false); but that does nothing for the connect timeout.

No worries, I have the work-a-around that fortunately has not been broken throughout all the mbed updates.

I can’t understand why no one else has had this issue, a 30 second blocking all other processes function makes no sense on a runtime operating system, unless I’m not using it correctly which is a high probability. I did question this with the mbed team a couple of years ago and was told it would require a lot of changes to implement and would not be backwardly compatible with other users programs, something that does not normally stop mbed changing things.