The previous strategy assumed clients maintained adequate state to
understand the relationship between endpoint allocation and the server
it was allocated on.
magicsock will not have awareness of the server's disco key
pre-allocation, it only understands peerAPI address at this point. The
second client to allocate on the same server could trigger
re-allocation, breaking a functional relay server endpoint.
If magicsock needs to force reallocation we can add opt-in behaviors
for this later.
Updates tailscale/corp#27502
Signed-off-by: Jordan Whited <jordan@tailscale.com>
tstime.GoDuration JSON serializes with time.Duration.String(), which is
more human-friendly than nanoseconds.
ServerEndpoint is currently experimental, therefore breaking changes
are tolerable.
Updates tailscale/corp#27502
Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit implements an experimental UDP relay server. The UDP relay
server leverages the Disco protocol for a 3-way handshake between
client and server, along with 3 new Disco message types for said
handshake. These new Disco message types are also considered
experimental, and are not yet tied to a capver.
The server expects, and imposes, a Geneve (Generic Network
Virtualization Encapsulation) header immediately following the underlay
UDP header. Geneve protocol field values have been defined for Disco
and WireGuard. The Geneve control bit must be set for the handshake
between client and server, and unset for messages relayed between
clients through the server.
Updates tailscale/corp#27101
Signed-off-by: Jordan Whited <jordan@tailscale.com>
