Tor does not reconnect after network loss with guards used as bridges
Yawning and I have both noticed that tor can become unresponsive if either normal tor bridges or PT bridges are configured, and the client suffers a network connectivity loss. After sustained network connectivity loss, all of the orconns end up closed, and Tor will not try to reconnect to its bridges, even when new stream attempts arrive.
It is possible that Tor is simply marking all of its bridges down in this case, and is not trying to reconnect to them when the network connectivity returns, thinking they are still down?
The only way to solve this issue is to either send "SIGNAL HUP" to the control port, or to kill -HUP
pidof tor. After recieving the HUP signal, tor immediately launches new orconns and circuits for its bridges, and attaches the currently pending streams to these new circuits.
Sometimes, after this problem has happened once, tor will cease building circuits even if the network remains available.
This is extremely bad for usability, because TBB becomes completely unusable in this case, and the only thing a normal user can do is exit the whole browser and re-launch it.
This may also indicate a deeper bug with how Tor handles the liveness/'down' status of normal Guard nodes, and may cause Tor to rotate Guards more frequently than necessary.