Re: Implementing a ssh server without ssh_bind_listen()

[Andreas Schneider <asn@xxxxxxxxxxxxxx>]

On Thursday 17 February 2011 10:19:50 you wrote:
> Hi,

Hi,
 
> I'm implementing a ssh server that doesn't listen itself, but gets
> passed a socket with an incoming connection using ssh_bind_set_fd().
> (The ssh server is embedded in an application that must handle all
> incomming socket connections.)

I suggest to use libssh-0.5rc0 which will be rc1 at the beginning of next week 
and then we plan to do libssh-0.5 after one week.

http://www.libssh.org/files/rc/libssh-0.4.90.tar.gz

Could you please try this version and report back?



	-- andreas


> I had this working with libssh 0.3.x, but after porting to the 0.4.x
> API, I'm getting errors about the incoming packets being extremely
> large after decoding.
> 
> My code for accepting a connection roughly looks like this:
> 
> sshbind = ssh_bind_new();
> session = ssh_new();
> ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_LOG_VERBOSITY_STR, "3");
> sh_bind_options_set(sshbind, SSH_BIND_OPTIONS_DSAKEY, dsakey);
> ssh_init(); // plus error check
> ssh_bind_set_fd(sshbind, TheSocket); // here I ahnd in the socket
> ssh_bind_accept(sshbind, session);  // plus error check
> ssh_accept(session); // plus error check
> do {
>   message = ssh_message_get(session);
>   ...
> }
> 
> The first ssh_message_get fails with "read_packet(): Packet len too
> high(814545073 308cf8b1)".
> 
> 
> Here is the full libssh trace:
> [3] Writing on the wire a packet having 305 bytes before
> [3] 305 bytes after comp + 10 padding bytes = 316 bytes packet
> [3] Packet size decrypted: 844 (0x34c)
> [3] Read a 844 bytes packet
> [3] 6 bytes padding, 843 bytes left in buffer
> [3] After padding, 837 bytes left in buffer
> [3] Final size 837
> [3] Type 20
> [3] Set output algorithm aes256-ctr
> [3] Set input algorithm aes256-ctr
> [3] Packet size decrypted: 140 (0x8c)
> [3] Read a 140 bytes packet
> [3] 6 bytes padding, 139 bytes left in buffer
> [3] After padding, 133 bytes left in buffer
> [3] Final size 133
> [3] Type 30
> [3] Writing on the wire a packet having 630 bytes before
> [3] 630 bytes after comp + 5 padding bytes = 636 bytes packet
> [3] Writing on the wire a packet having 1 bytes before
> [3] 1 bytes after comp + 10 padding bytes = 12 bytes packet
> [3] SSH_MSG_NEWKEYS sent
> [3] Packet size decrypted: 12 (0xc)
> [3] Read a 12 bytes packet
> [3] 10 bytes padding, 11 bytes left in buffer
> [3] After padding, 1 bytes left in buffer
> [3] Final size 1
> [3] Type 21
> [3] Got SSH_MSG_NEWKEYS
> # ssh_accept() is done, now calling ssh_message_get()
> [3] Decrypting 16 bytes
> [3] Packet size decrypted: 814545073 (0x308cf8b1)
> 
> Any ideas what is going wrong here ?
> 
> Thanks,
> Jan

-- 
Andreas Schneider                   GPG-ID: F33E3FC6
www.cryptomilk.org                asn@xxxxxxxxxxxxxx