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From: Aaron Jones <me@aaronmdjones.net>
To: wireguard@lists.zx2c4.com
Subject: Re: [PATCH] Respect WG protocol reserved bytes
Date: Wed, 17 Mar 2021 12:35:56 +0000	[thread overview]
Message-ID: <f5126d40-4ea7-193a-93dd-ab816af3bb7e@aaronmdjones.net> (raw)
In-Reply-To: <9C811F88-FD21-47D0-B3FE-A14FD5BC1816@wandera.com>


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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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  reply	other threads:[~2021-03-17 12:36 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-17  7:55 [PATCH] Respect WG protocol reserved bytes Laura Zelenku
2021-03-17 12:35 ` Aaron Jones [this message]
2021-03-17 12:53   ` Laura Zelenku
2021-03-17 13:10     ` Jason A. Donenfeld

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