Adds support to our coordinator implementations to send Error updates before disconnecting clients.
I was recently debugging a connection issue where the client was getting repeatedly disconnected from the Coordinator, but since we never send any error information it was really hard without server logs.
This PR aims to correct that, by sending a CoordinateResponse with `Error` set in cases where we disconnect a client without them asking us to.
It also logs the error whenever we get one in the client controller.
Closes#14716Closes#14717
Adds a new user-scoped tailnet API endpoint (`api/v2/tailnet`) with a new RPC stream for receiving updates on workspaces owned by a specific user, as defined in #14716.
When a stream is started, the `WorkspaceUpdatesProvider` will begin listening on the user-scoped pubsub events implemented in #14964. When a relevant event type is seen (such as a workspace state transition), the provider will query the DB for all the workspaces (and agents) owned by the user. This gets compared against the result of the previous query to produce a set of workspace updates.
Workspace updates can be requested for any user ID, however only workspaces the authorised user is permitted to `ActionRead` will have their updates streamed.
Opening a tunnel to an agent requires that the user can perform `ActionSSH` against the workspace containing it.
This adds the ability for `TunnelAuth` to also authorize incoming wireguard node IPs, preventing agents from reporting anything other than their static IP generated from the agent ID.
Fixes an issue where a MultiAgentConn isn't closed properly when the coordinator it is connected to is closed.
Since servertailnet checks whether the conn is closed before reinitializing, it is important that we check this, otherwise servertailnet can get stuck if the coordinator closes (e.g. when we switch from AGPL to PGCoordinator after decoding a license).
Spotted during a code read. ConnIO unlocks the mutex before attempting to write to the response channel, which could allow another goroutine to call Close() and close the channel, causing a panic.
Fix is to hold the mutex. This won't cause a deadlock because the `select{}` has a `default` case, so we won't block even if the receiver isn't keeping up.
Adds support for graceful disconnect to PGCoordinator. When peers gracefully disconnect, they send a disconnect message. This triggers the peer to be disconnected from all tunneled peers.
The Multi-Agent Client supports graceful disconnect, since it is in memory and we know that when it is closed, we really mean to disconnect.
The v1 agent and client Websocket connections do not support graceful disconnect, since the v1 protocol doesn't have this feature. That means that if a v1 peer connects to a v2 peer, when the v1 peer's coordinator connection is closed, the v2 peer will
see it as "lost" since we don't know whether the v1 peer meant to disconnect, or it just lost connectivity to the coordinator.
re: #10528
Refactors PG Coordinator to work with the Tailnet v2 API, including wrappers for the existing v1 API.
The debug endpoint functions, but doesn't return sensible data, that will be in another stacked PR.
Spike Curtis