Hi Rob,
In my case there was no need to implement a callback on my own to handle
these global keep-alive messages. As I wrote in my earlier message: As
long as you see the lines you posted, all is fine: even when the lib
doesn't know the request type, it sends a message back ("type unknown")
to the server, which is enough to keep the connection alive.
My actual problem was this: While the main loop was polling on the local
listening socket, the lib's default handlers were not called. Here is
the relevant part of my main loop:
event = ssh_event_new();
ssh_event_add_session(event, session);
bind(listensock, ...);
while(1) {
while (1) {
channels[0]=NULL; // set the first channel we want to read from
channels[1]=NULL;
FD_ZERO(&fds);
FD_SET(listensock, &fds);
max_fd = listensock + 1;
tv.tv_sec = 0;
tv.tv_usec = 100000;
sout_len = 0;
rc = select(max_fd, &fds, NULL, NULL, &tv);
if (-1 == rc && EINTR == errno)
continue;
else if (rc > 0) {
if (FD_ISSET(listensock, &fds)) {
printf("FD_ISSET\n");
forwardsock = accept(listensock, NULL, &sout_len);
if (forwardsock < 0) {
perror("accept failed");
goto shutdown;
}
else {
printf("Local client connected.\n");
break;
}
}
}
else if (0 > rc) {
perror("waiting on listening socket");
goto shutdown;
}
ssh_event_dopoll(event, 10);
}
channel = ssh_channel_new(session);
ssh_channel_open_forward(channel, ...);
while (1) { /* read/write from/to socket/channel */ }
}
What I was missing in the beginning was call of
ssh_event_add_session(event, session) and later in the polling loop:
ssh_event_dopoll(event, 10);
I hope this helps!
Till
On 25.04.2018 14:25, Duff, Rob (Nokia - US/Plano) wrote:
> The discussion thread sounds like it is what I need.
>
> I saw that g4-lisz was able to solve it by adding the session to the event.
> Could you post the pseudo code example with this change in place?
>
> Thanks so much!
> Rob
>
>
> -----Original Message-----
> From: Andreas Schneider [mailto:a...@cryptomilk.org]
> Sent: Wednesday, April 25, 2018 12:41 AM
> To: libssh@libssh.org
> Subject: Re: Help with OpenSSH Keep Alive
>
> On Tuesday, 24 April 2018 23:25:06 CEST Duff, Rob (Nokia - US/Plano) wrote:
>> Hello,
>>
>> I am writing a client app which connects to an OpenSSH server, and
>> opens a forwarding tunnel, then waits for another application to send
>> requests, forwards those to the tunnel, and returns responses.
>> Apparently, the server is sending global keep alive messages, and the
>> my client is not responding to them.
>>
>> [2018/04/24 16:06:34.843907, 2] ssh_packet_global_request: Received
>> SSH_MSG_GLOBAL_REQUEST packet [2018/04/24 16:06:34.843907, 2]
>> ssh_packet_global_request: UNKNOWN SSH_MSG_GLOBAL_REQUEST
>> keepal...@openssh.com 1 [2018/04/24 16:06:34.844907, 1] ssh_packet_process:
>> Couldn't do anything with packet type 80
>>
>> Is there any sample/example code for both registering a callback to
>> handle these keepalives, and also using the polling context mechanism?
> We just had this question a few days ago (April 9th).
>
> https://www.libssh.org/archive/libssh/2018-04/0000001.html
>
>
> I'm still hoping someone will improve the docs :-) (hint)
>
>
> Andreas
>
