HttpServerConnection performs TLS shutdown without a timeout

[julianbrost]

HttpServerConnection::Disconnect() calls async_shutdown() on the TLS stream:

icinga2/lib/remote/httpserverconnection.cpp

Line 98 in 01a6c4c

m_Stream->next_layer().async_shutdown(yc[ec]);

This performs a TLS shutdown which involves network IO. There's no timeout implemented, so if this happens on a stale connection, this may result in the code waiting for this at least for a long time, maybe even indefinitely.

I think it's time to move the code for shutting down connections into a common function and do it right there once and using that everywhere as this is not the first time we encounter this problem.

ref/IP/48306