Re: ssh client does not timeout if the network fails after

Hi Dan,

Thanks for your reply.

Yes, it can, but there is nothing to do with that (except for at least
> Linux,
> which always returns remaining timeout in the select() timeout parameter).
> Fortunately signals are relatively rare, so the timeout deviation is IMHO
> not
> essential. There are also other possible reasons for deviation, for
> example
> sending the packet to another end while network is down.


Agree. I was thinking to record the start time and subtract the elapsed time
when an interrupt happens. But I guess we can save that trouble since
signals are rare.


> > I also noticed that in server_alive_check() function, we check
> > if (++server_alive_timeouts > options.server_alive_count_max). Should it
> be
> > >=? According to the comment in ssh_config, if ServerAliveInterval
> equals to
> > 30 and ServerAliveCountMax equals to 3, ssh disconnects after 90
> seconds.
> > But with the current server_alive_check, we actually disconnects after
> 120
> > seconds.
> >
> Not right. Pay attention at '++server_alive_timeouts >
> options.server_alive_count_max' expression. server_alive_timeouts is
> pre-incremented there, that is it's incremented value is used while
> evaluating
> the expression, so the count begins with 1 rather than 0 there.


But still, when options.server_alive_count_max=1, we should exit after the
first timeout.

Some notices I (unfortunately) forgot to meantion previously:
>
> > diff -puN sshconnect.c~old sshconnect.c
> > --- sshconnect.c~old 2007-07-25 16:59:36.000000000 -0700
> > +++ sshconnect.c 2007-07-26 11:46:48.000000000 -0700
> > @@ -404,6 +404,28 @@ ssh_exchange_identification(void)
> > int minor1 = PROTOCOL_MINOR_1;
> > u_int i, n;
> >
> > + if (options.server_alive_interval) {
> > + fd_set rfds;
> > + struct timeval timeo;
> > + int read_timeouts, ret;
> > +
> > + FD_SET(connection_in, &rfds);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> (1) This should be placed inside the cycle before select() since on error
> (even
> EINTR) rfds along with timeo becomes undefined according to spec.


Thanks for catching this.

Jiaying
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