[PATCH] Respect WG protocol reserved bytes

[Laura Zelenku]

If the client send some data in reserved bytes you will have logs full of errors because the message gets type from 4 bytes instead of 1 byte (like it is in protocol description).
I would like implementation respects protocol - https://www.wireguard.com/papers/wireguard.pdf . Yes, in our project we use reserved bytes.

I know that when there are zeros in reserved bytes, everything is correct. But if you receive some non-zero value in reserved bytes?

Laura

> On 17. 3. 2021, at 13:35, Aaron Jones <me at aaronmdjones.net> wrote:
> 
> On 17/03/2021 07:55, Laura Zelenku wrote:
>> Packet that respects WG protocol contains Type on first byte followed by
>> three reserved bytes. Because wireguard-go implementation uses element
>> pools it is required to make sure that reserved bytes are cleared for
>> outgoing traffic (can get dirty by "bad" clients). Clearing reserved
>> bytes is also for backwards compatibility.
> 
> Encoding the message type as a little-endian 32-bit integer already
> takes care of setting the reserved bytes to zero; e.g. for a packet of
> message type 1 (handshake initiation), its little-endian 32-bit encoding
> is the following sequence of bytes: [ 0x01 0x00 0x00 0x00 ].
> 
> This is also the approach used for checking message types on the
> receiving end, so packets whose reserved bytes are non-zero are already
> discarded as being those of unknown types of message.
> 
> Regards,
> Aaron Jones
> 


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