Re: Fwd: [Patch] Add forward-listening feature (tcpip-forward)

[Vic Lee <llyzs@xxxxxxx>]

Hi Aris,

Yes, actually I also notice the potential issue, that there's no way to
tell a REJECT response from a packet receiving error, by just using rc
returned from packet_wait. SSH_AGAIN is also not enough in this case
because I am using blocking call. Probably a new code like SSH_REJECT
should be invented, but that's just a thought.

Thanks,

Vic

On Fri, 2009-08-14 at 11:47 +0200, Aris Adamantiadis wrote:
> Vic,
> 
> Doing as you proposed is okay. There are no garanties that packet_wait
> won't return anything different later (if we don't rewrite it meanwhile).
> I was already convinced this function could return SSH_AGAIN
> 
> Aris
> Vic Lee a écrit :
> > Hi Aris,
> >
> > I just check packet_wait function, it seems that it will only return
> > SSH_OK or SSH_ERROR. So I assume "if (rc) { ..." is checking for
> > SSH_ERROR. Do you think it should be changed to "if (rc == SSH_ERROR)"
> > instead?
> >
> > I was able to capture incoming connections because of the call to
> > function ssh_handle_packets, which will push incoming channel requests
> > into ssh_message_list, then a loop to poll the message list.
> >
> > Thanks,
> >
> > Vic
> >
> >   
> >> Hello Vic,
> >>
> >> The patch is almost perfect. Just these lines :
> >> +  rc = packet_wait(session, SSH2_MSG_REQUEST_SUCCESS, 1);
> >> +  if (rc) {
> >> +    if (session->in_packet.type == SSH2_MSG_REQUEST_FAILURE) {
> >> Could you please check rc for SSH_ERROR and return it to the caller ?
> >>
> >> I also wonder how you catch the incoming connections from the server.
> >>
> >> Thanks,
> >>
> >> Aris
> >>
> >> Vic Lee a écrit : 
> >>
> >>
> >>         Hi,
> >>         
> >>         So I complete another feature I need for libssh. For your
> >>         review, this
> >>         patch added three new API:
> >>         
> >>         o channel_forward_listen : send tcpip-forward global request
> >>         
> >>         o channel_forward_accept : accept/poll an incoming connection
> >>         (the codes
> >>         were merge with channel_accept_x11 with a static function
> >>         channel_accept)
> >>         
> >>         o channel_forward_cancel : send cancel-tcpip-forward global
> >>         request
> >>         
> >>         During testing I also encounter openssh server sending back a
> >>         SSH2_MSG_DEBUG message, and I have to modify packet.c to
> >>         bypass this
> >>         message.
> >>         
> >>         The only thing that I am not able to test is to use 0 as port
> >>         number,
> >>         and the server is supposed to return an available port number,
> >>         but
> >>         openssh server simply reject it. Anyway, I don't need to use 0
> >>         port
> >>         number and all the rest are working fine for me.
> >>         
> >>         Thanks,
> >>         
> >>         Vic
> >>
> >>
> >>
> >>     
> >
> >
> >
> >   
> 
>