[erlang-bugs] SSH Bugs

[Michael.K.Schmidt@REDACTED]

Hi Angela,

> Ingela Anderton Andin <Ingela.Anderton.Andin@REDACTED>
> Sent by: erlang-bugs-bounces@REDACTED
>
> 07/01/2014 03:50 AM
>
> To
>
> <erlang-bugs@REDACTED>,
>
> cc
>
> Subject
>
> Re: [erlang-bugs] SSH Bugs
>
> Hi!
>
> On 06/30/2014 10:37 PM, Michael.K.Schmidt@REDACTED wrote:
> >
> > Hi,
> >
> > Does anyone know what the final resolution was with this bug?
> > http://erlang.org/pipermail/erlang-patches/2013-December/004499.html
>
> Humm I can not remeber seeing this patch before! Maybe it got lost in
> the process some how :(

No worries! When I didn't see it in 17.1, I thought I would check to see if
that was the case.

>
>
> > The patch given by Anton Ryabkov seems to address the immediate bug.
Is
> > this fix ok?  Or is there a better way?
> >
> > With Anton's patch I am able to get this example to run:
> >
https://github.com/erlang/otp/blob/maint/lib/ssh/examples/ssh_sample_cli.erl

> >
> > It works with Tera Term as the client, but when I try to use PuTTY I
get
> > the following error:
> > "Disconnected:  Server protocol violation: unexpected
> > SSH2_MSG_CHANNEL_SUCCESS packet"
> >
> > I believe this worked with PuTTY before R16B03.  Did an edge case get
> > missed with this refactor?
> > https://github.com/erlang/otp/commit/
> 68263a48bfbdac4dc219a91f06af3d535d881850
>
> Possible!
>
> Have you tried it with 17.1? I think the 17.1 code semantically seems to
> be doing the same as the patch.

I'm still having trouble with 17.1.  When I make Anton's changes, TeraTerm
seems to work.

As far as PuTTY, I assume the root cause is somewhere in
ssh_connection.erl:handle_cli_msg() :

handle_cli_msg(#connection{channel_cache = Cache} = Connection,
	       #channel{user = undefined,
			remote_id = RemoteId,
			local_id = ChannelId} = Channel0, Reply0) ->

    case (catch start_cli(Connection, ChannelId)) of
	{ok, Pid} ->
	    erlang:monitor(process, Pid),
	    Channel = Channel0#channel{user = Pid},
	    ssh_channel:cache_update(Cache, Channel),
	    Reply = {connection_reply,
		     channel_success_msg(RemoteId)},
	    {{replies, [{channel_data, Pid, Reply0}, Reply]}, Connection};
	_Other ->
	    Reply = {connection_reply,
		     channel_failure_msg(RemoteId)},
	    {{replies, [Reply]}, Connection}
    end;

We start_cli() and send channel_success_msg().  Prior to the refactor I
believe this was reply_msg() instead.  If I change
	    Reply = {connection_reply,
		     channel_success_msg(RemoteId)},
	    {{replies, [{channel_data, Pid, Reply0}, Reply]}, Connection};
To:
	    {Reply, Connection1} = reply_msg(Channel, Connection, Reply0),
 	    {{replies, [Reply]}, Connection1};

Then PuTTY seems happy again. Does this seem OK?  Or am I messing something
else up by "fixing" this.

Thanks again for all the help,
Mike