Re: asynchronous channel write

[g4-lisz@xxxxxxxxxxxx]

Hi Torsten,

the "trick" is called ssh_set_blocking(session, 0);

But be careful, this affects everything in the session.

My write loop looks lile this:

    blocking = ssh_is_blocking(session);
    ssh_set_blocking(session, 0);

    if (len > 0) {
        if (ssh_channel_is_open(channel)) {
            wr = 0;
            do {
                i = ssh_channel_write(channel, buf, len);
                if (i < 0) {
                    log("Error writing on the direct-tcpip channel: %d", i);
                    len = wr;
                    break;
                }
                wr += i;
                log("channel_write (%d from %d)", wr, len);
            } while (i > 0 && wr < len);
        }
        else {
            log("Can't write on closed channel!");
        }
    }

    ssh_set_blocking(session, blocking);

Greetings,
Till

On 13.01.20 17:48, Torsten Kuehnel wrote:
> Working on the reference implementation of the ncot library i am
> confronted with the follwoing use case:
>
> Data packets are to be received and send from/to several simultaneous
> open ssh-like encrypted channels to instances of the same program
> running on other hosts over the network.
>
> The one client-server connection -> one thread paradigm does not fit
> so well. Packets have to be validated, act upon and processed in
> different ways, and need to be resend to other connections - this is
> the real part of the implementation.
>
> So my approach currently is the following one:
>
> A mainloop with ssh_event_dopoll manages to call my channel callbacks
> i have established during initialization of the several sessions. But
> when it comes to write my packets over the channels, libssh only offers
> a blocking ssh_channel_write call what is not what i want.
>
> When the poll returns with write possible, i usually try to write as
> much as i can and send tells me how much succeded. How can i achieve
> this behaviour using libssh ?
>
> thanks for any insights in advance, keep up the good work !
>
> -- Torsten Kuehnel
> <tdkuehnel@xxxxxxxxxxxxxxxxxxxxx>
>