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ccee476daa
When a NAT between the Client and Gateway remaps the source port to 3478, it is tricky to de-multiplex that p2p traffic from the packets we receive from a relay. Currently, we handle this edge-case by dropping these packets which effectively forces a fallback to a relayed connection. Remapping onto exactly this port is likely to be quite rare in practice which is why this behaviour was implemented in the first place. We can however do better than that by remembering, which relays we have previously been connected to. That is because the problem with traffic on port 3478 isn't so much the correct handling in case it _is_ p2p traffic: We can simply check whether the IP is one of the relays we are connected to. The problem is the mis-classification as p2p traffic in case they are packets from a relay that we have disconnected from, causing a log-spam of "unknown packet". To gracefully handle this, we now remember up to 64 relay IPs that we have been connected to in the past. This ensures we can correctly classify traffic from previous relays as such and drop the packet whilst at the same time continuing processing of packets from unknown origins which likely then is p2p traffic. The effect of this is that we can now establish direct connections to peers, even if a NAT inbetween remaps their source port to 3478. To make this fix easier, we precede it with a refactoring of introducing an `Allocations` container for the map of `Allocations`. This allows us to easily track, when we remove a value from the map and then remember the relay's IPs. This came up as part of test failures in #10887. --------- Signed-off-by: Thomas Eizinger <thomas@eizinger.io> Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.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.