Hi All,
I have been using libssh2-0.14 for the past 10 months now (since last
october) in my application, and dealing with its various bugs, making it
compile/work on Windows and all major *nix platforms.
One of the most serious bug we have encountered is the one mentioned below.
It leads to an infinite loop in the library. In a scenario where there are
multiple threads trying to make their own connections, this simply means CPU
usage getting launched, and the calling application hangs.
I had earlier reported this issue on this mailing list. I am surprised this
is still persisting till 0.17. We should quickly fix it now.
The fix I have tried is:
-- if (ret == 0) continue;
++ if (ret == 0)
{
session->socket_state = LIBSSH2_SOCKET_DISCONNECTED;
return -1;
}
This bug is present at 2 places:
a) in session.c during the banner exchange, as mentioned below.
b) in packet.c inside libssh2_blocking_read() again we have a continue when
ret == 0.
Regards,
Satish
On 8/8/07, Sullivan, David J. <djms_at_bear.com> wrote:
>
> In src/session.c, libssh2_session_startup() sets the session socket to
> blocking mode, calls libssh2_banner_send() then calls
> libssh2_banner_receive().
>
> If the connection is dropped by the client between those two calls,
> libssh2_banner_receive() hard loops doing recv()'s that are returning 0.
>
> The culprit seems to be the "if (ret <= 0) continue;" code. Placing the
> continue in the loop above (which is "if (ret < 0 )") and adding code to
> check for zero seems to do the trick:
>
> } else {
> /* Some kinda error */
> session->banner_TxRx_state = libssh2_NB_state_idle;
> session->banner_TxRx_total_send = 0;
> return 1;
> }
> continue;
> }
>
> if (ret == 0) {
> /* EOF */
> session->banner_TxRx_state = libssh2_NB_state_idle;
> session->banner_TxRx_total_send = 0;
> return 1;
> }
>
> David
>
>
>
>
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Received on 2007-08-08