mirror of
https://github.com/outbackdingo/firezone.git
synced 2026-01-27 10:18:54 +00:00
90d10a8634
The event-loop inside `Tunnel` processes input according to a certain priority. We only take input from lower priority sources when the higher priority sources are not ready. The current priorities are: - Flush all buffers - Read from UDP sockets - Read from TUN device - Read from DNS servers - Process recursive DNS queries - Check timeout The idea of this priority ordering is to keep all kinds of processing bounded and "finish" any kind of work that is on-going before taking on new work. Anything that sits in a buffer is basically done with processing and just needs to be written out to the network / device. Arriving UDP packets have already traversed the network and been encrypted on the other end, meaning they are higher priority than reading from the TUN device. Packets from the TUN device still need to be encrypted and sent to the remote. Whilst there is merit in this design, it also bears the potential of starving input sources further down if the top ones are extremely busy. To prevent this, we refactor `Io` to read from all input sources and present it to the event-loop as a batch, allowing all sources to make progress before looping around. Since this event-loop has first been conceived, we have refactored `Io` to use background threads for the UDP sockets and TUN device, meaning they will make progress by themselves anyway until the channels to the main-thread fill up. As such, there shouldn't be any latency increase in processing packets even though we are performing slightly more work per event-loop tick. This kind of batch-processing highlights a problem: Bailing out with an error midway through processing a batch leaves the remainder of the batch unprocessed, essentially dropping packets. To fix this, we introduce a new `TunnelError` type that presents a collection of errors that we encountered while processing the batch. This might actually also be a problem with what is currently in `main` because we are already batch-processing packets there but possibly are bailing out midway through the batch. --------- Signed-off-by: Thomas Eizinger <thomas@eizinger.io> Co-authored-by: Mariusz Klochowicz <mariusz@klochowicz.com>
Connlib
Firezone's connectivity library shared by all clients.
Building Connlib
You shouldn't need to build connlib directly; it's typically built as a dependency of one of the other Firezone components. See READMEs in those directories for relevant instructions.