Updates tailscale/tailscale#1634
This PR introduces a new `captive-portal-detected` Warnable which is set to an unhealthy state whenever a captive portal is detected on the local network, preventing Tailscale from connecting.
ipn/ipnlocal: fix captive portal loop shutdown
Change-Id: I7cafdbce68463a16260091bcec1741501a070c95
net/captivedetection: fix mutex misuse
ipn/ipnlocal: ensure that we don't fail to start the timer
Change-Id: I3e43fb19264d793e8707c5031c0898e48e3e7465
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
