>> Thanks for your suggestion Alex, but I'm using the non-blocking API exactly >> as you advised: I call libssh2_session_free with the same paramerters until >> either it returns something different than EAGAIN, or the timeout happens. >> In my case, when the remote device goes down ungracefully, any amount of >> seconds wait will result in timeout: I even tried 15 seconds. I suppose >> resource destruction should be instant. It looks like libssh is waiting for >> something inside there, whereas I want it to just free all resources... > > That make it sound like a bug. Can you tell us how to repeat this problem? Can > you single-step through the code and see where the problem lies? > > Which libssh2 vesion are you using?
Hi Daniel, well, here is why it happens: on session free it attempts to send eof when freeing a channel, and performs transport_read, which returns EAGAIN and propagates it up the stack. The problem as I see it is that the current session and channel closing functions try to do it gracefully by means of notifying the server side about their intention to quit the connection. In my scenario, which can be reproduced by simply unplugging ethernet cable from the device running sshd, any attempt to perform communication on the channel will result in EAGAIN, cause the network stack sees the network is not ready, and SIGPIPE won't come up in the next hour or so. So knowing that the connection is now zomby, I want to have a means to destroy the session and channel resources without trying to communicate it to the other party. Such function would not return EAGAIN in any case, cause it is just about freeing structures... So far I just leave the session open and close the underlying socket. Of course, I don't make any calls to libssh2 on that session, cause that would result in a delayed crash, but anyway it is better than the sockets leak. I run libssh2-1.4.3. Again, thanks for the great library!
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