Re: instability

[Aris Adamantiadis <aris@xxxxxxxxxxxx>]

Hi Jeetu,

No problem, as long as you mutex your ssh_bind stuff. If it is in its
own thread (only one parallel execution), there is no problem.
The crash you got is typical of a missing standalone ssh_init(); before
calling ssh_connect and friends in threads.

If you are using server support, I strongly recommend that you use
libssh 0.5rc1, in which we fixed many bugs for servers. In that case,
please read http://api.libssh.org/master/libssh_tutor_threads.html for
more info on threading.

Kr,

Aris

Le 24/05/11 05:47, jeetu.golani@xxxxxxxxx a écrit :
> Hi Aris,
> 
>>With libssh 0.5, it's a little different, you have to initialize libssh
> threads and call ssh_init(). (libssh does the dirty work of
> initilalizing >libcrypto or libgcrypt).
> 
> Just want to clarify if what I'm doing for my libssh server is all
> right. In principle I have a new ssh_session created for each new
> connection into the server.
> 
> My ssh_bind is common for all threads and I call ssh_bind_listen. I have
> a ssh_session *session (therefore session is a pointer to a pointer) and
> I init this pointer first with an session = ssh_new().....I then move
> into a loop where I init an individual session element  such as
> session[session_count] = ssh_new and then move onto waiting to accept a
> connection with a ssh_bind_option...authenticating user...and finally if
> authenticated create a new glib thread for that server
> session....incremenet session_count.... and this loops.
> 
> Sorry for trying to describe code instead of pasting the relevant
> snippet here but I don't have access to my comp with the code right now.
> 
> Does the above seem in principle to be acceptable and in line with
> libssh's threading model....or would ppl recommend a better way to have
> a multi-threaded server.
> 
> Thanks,
> 
> Bye
> 
> 
> On Tue, May 24, 2011 at 2:54 AM, Paulo Panhoto <paulo.panhoto@xxxxxxxxx
> <mailto:paulo.panhoto@xxxxxxxxx>> wrote:
> 
>     There are several threads running but each session is only accessed
>     by one thread.
> 
>     Sure, it does help. thanks.
> 
> 
>     On Mon, May 23, 2011 at 6:22 PM, Aris Adamantiadis
>     <aris@xxxxxxxxxxxx <mailto:aris@xxxxxxxxxxxx>> wrote:
> 
>         Hi Paulo,
> 
>         Are you using libssh in several threads ? Libssh is threadsafe
>         under two conditions : call ssh_init() outside of threads and
>         initialize threading in the crypto library
>         (http://www.openssl.org/support/faq.html#PROG1).
>         With libssh 0.5, it's a little different, you have to initialize
>         libssh threads and call ssh_init(). (libssh does the dirty work
>         of initilalizing libcrypto or libgcrypt).
> 
>         Hope this helps,
> 
>         Aris
> 
>         Le 23/05/11 21:41, Paulo Panhoto a écrit :
> 
>             Hello,
> 
>             I'm writing a Qt app with libssh. The best approach I've got
>             was this:
>             wrap ssh in a QThread that emits signals to other components.
> 
> 
>                     session = ssh_new();
> 
>                     if (session == NULL)
>                     {
>                         throw SSHException(tr("ssh_new failed"));
>                     }
>                     const std::string & stdHost = host.toStdString();
>                     ssh_options_set(session, SSH_OPTIONS_HOST,
>             stdHost.c_str());
>                     ssh_options_set(session, SSH_OPTIONS_PORT, &port);
>                     ssh_options_set(session, SSH_OPTIONS_SSH1, &disabled);
>                     ssh_options_set(session, SSH_OPTIONS_SSH2, &enabled);
> 
>                     emit stateChanged(CONNECTING);
>                     emit debugInfo(tr("Conecting to
>             %0:%1").arg(host).arg(port));
>                     if (ssh_connect(session) != SSH_OK)
>                     {
>                         throw SSHException(QString("ssh_connect:
>             %1").arg(ssh_get_error(session)));
>                     }
> 
>             This piece of code is causing me trouble: I'm running it on
>             a opensuse
>             11.3 and tested it with libssh 0.4.2 (the "branding"
>             release) and 0.4.8.
> 
>             When I compile it against OpenSSL, I get aborts due to
>             double free
>             inside libcrypto: works most of the time when I run it natively.
>             Nevertheless, when the program is run via xming server, the
>             error rate
>             is almost 100%
>             libopenssl 1.0.0-6.7.1 - x86_64
> 
>             #0  0x00007ffff5aca9e5 in raise () from /lib64/libc.so.6
>             #1  0x00007ffff5acbee6 in abort () from /lib64/libc.so.6
>             #2  0x00007ffff5b05c53 in __libc_message () from
>             /lib64/libc.so.6
>             #3  0x00007ffff5b0b226 in malloc_printerr () from
>             /lib64/libc.so.6
>             #4  0x00007ffff5b0e8e3 in _int_realloc () from /lib64/libc.so.6
>             #5  0x00007ffff5b10142 in realloc () from /lib64/libc.so.6
>             #6  0x00007ffff4ca6d4f in CRYPTO_realloc () from
>             /lib64/libcrypto.so.1.0.0
>             #7  0x00007ffff4d0d2a8 in lh_insert () from
>             /lib64/libcrypto.so.1.0.0
>             #8  0x00007ffff4ca980c in OBJ_NAME_add () from
>             /lib64/libcrypto.so.1.0.0
>             #9  0x00007ffff4d1a66b in OpenSSL_add_all_digests () from
>             /lib64/libcrypto.so.1.0.0
>             #10 0x00007ffff7bac3cc in ssh_crypto_init () at
>             /home/paulo/Downloads/oss-src/libssh-0.4.8/libssh/dh.c:144
>             #11 0x00007ffff7bae8f1 in ssh_init () at
>             /home/paulo/Downloads/oss-src/libssh-0.4.8/libssh/init.c:47
>             #12 0x00007ffff7ba929c in ssh_connect (session=0xc3b8e0)
> 
>             If I compile it against libgcrypt, it fails all the time due
>             to an
>             assertion failure --  ath.c:193: _gcry_ath_mutex_lock:
>             Assertion `*lock
>             == ((ath_mutex_t) 0)' failed.
>             libgcrypt  1.4.4-6.1 - x86-64
> 
>             #0  0x00007ffff5ac79e5 in raise () from /lib64/libc.so.6
>             #1  0x00007ffff5ac8ee6 in abort () from /lib64/libc.so.6
>             #2  0x00007ffff4fdcaa8 in ?? () from /lib64/libgcrypt.so.11
>             #3  0x00007ffff4fdd1c7 in ?? () from /lib64/libgcrypt.so.11
>             #4  0x00007ffff4fd75f6 in ?? () from /lib64/libgcrypt.so.11
>             #5  0x00007ffff4fd7792 in ?? () from /lib64/libgcrypt.so.11
>             #6  0x00007ffff7ba8f7b in ssh_crypto_init ()
>                 at
>             /home/paulo/Downloads/oss-src/libssh-0.4.8/libssh/dh.c:115
>             #7  0x00007ffff7bab961 in ssh_init ()
>                 at
>             /home/paulo/Downloads/oss-src/libssh-0.4.8/libssh/init.c:47
>             #8  0x00007ffff7ba5ebc in ssh_connect (session=0xccf260)
>                 at
>             /home/paulo/Downloads/oss-src/libssh-0.4.8/libssh/client.c:516
> 
>             Am I missing any steps?? Is openSSL the best library to
>             compile with??
> 
>             Any idea is appreciated.
> 
>             Regards,
> 
>             Paulo.
> 
> 
> 
>