[Live-devel] RTSP proxy not noticing server restart

[Jonathan Brady]

Hello,

It is possible to restart an origin server quickly enough that a live 
555 proxy server does not notice.

As a test this can be done by modifying one of the live 555 test 
programs (I was using testH264VideoStreamer) to enable 
SO_REUSEADDR/SO_REUSEPORT, then the process could be quickly killed and 
restarted without waiting for the socket to timeout.  Other examples of 
this being embedded systems that reboot quickly.

When the origin server is restarted the proxy server simply stops 
receiving data, the proxy sends DESCRIBE requests but they succeed 
because of the fast restart so the proxy never notices. Disconnecting 
all clients from the proxy server results in a PAUSE command being sent 
to the origin server, the proxy receives back an invalid session id, as 
it does with a PLAY command when another client connects, however these 
errors are ignored.

Once this has happened the only fix is to restart the proxy server, or 
stop the origin server long enough for the live 555 proxy to notice.

Is it possible to notice this situation and rectify it?

Regards,
Jonathan