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99705aa6b7
We had a long-standing bug in which our TUN events channel was being received from simultaneously in two places. The first is wireguard-go. At wgengine/userspace.go:366, we pass e.tundev to wireguard-go, which starts a goroutine (RoutineTUNEventReader) that receives from that channel and uses events to adjust the MTU and bring the device up/down. At wgengine/userspace.go:374, we launch a goroutine that receives from e.tundev, logs MTU changes, and triggers state updates when up/down changes occur. Events were getting delivered haphazardly between the two of them. We don't really want wireguard-go to receive the up/down events; we control the state of the device explicitly by calling device.Up. And the userspace.go loop MTU logging duplicates logging that wireguard-go does when it received MTU updates. So this change splits the single TUN events channel into up/down and other (aka MTU), and sends them to the parties that ought to receive them. I'm actually a bit surprised that this hasn't caused more visible trouble. If a down event went to wireguard-go but the subsequent up event went to userspace.go, we could end up with the wireguard-go device disappearing. I believe that this may also (somewhat accidentally) be a fix for #1790. Signed-off-by: Josh Bleecher Snyder <josharian@gmail.com>