Individual route advertisements that are covered by existing routes are
no longer advertised. If an upstream returns 0.0.0.0, 127.x, and other
common unwanted addresses those are also rejected.
Updates #16425
Signed-off-by: James Tucker <james@tailscale.com>
The cmpx.Compare function (and associated interface) are now available
in the standard library as cmp.Compare. Remove our version of it and use
the version from the standard library.
Updates #cleanup
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I4be3ac63d466c05eb7a0babb25cb0d41816fbd53
When auto-update setting in local Prefs is unset, apply the tailnet
default value from control. This only happens once, when we apply the
default (or when the user manually overrides it), tailnet default no
longer affects the node.
Updates #16244
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
Previously, the "RunExitNode" policy merely controlled the visibility of
the "run as exit node" menu item, not the setting itself. This migrates
that setting to a preference option named "AdvertiseExitNode".
Updates ENG-2138
Change-Id: Ia6a125beb6b4563d380c6162637ce4088f1117a0
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
Due to the Sparkle preference naming convention, macsys already has a
policy key named "ApplyUpdates" that merely shows or hides the menu
item that controls if auto updates are installed, rather than directly
controlling the setting.
For other platforms, we are going to use "InstallUpdates" instead
because it seemed better than the other options that were considered.
Updates ENG-2127
Updates tailscale/corp#16247
Change-Id: Ia6a125beb6b4563d380c6162637ce4088f1117a0
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
This adds support for enforcing exit node LAN access, DNS and subnet
routes.
Adding new preference policies was getting repetitive, so this turns
some of the boilerplate into a table.
Updates tailscale/corp#15585
Updates ENG-2240
Change-Id: Iabd3c42b0ae120b3145fac066c5caa7fc4d67824
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
Previously, policies affected the default prefs for a new profile, but
that does not affect existing profiles. This change ensures that
policies are applied whenever preferences are loaded or changed, so a
CLI or GUI client that does not respect the policies will still be
overridden.
Exit node IP is dropped from this PR as it was implemented elsewhere
in #10172.
Fixestailscale/corp#15585
Change-Id: Ide4c3a4b00a64e43f506fa1fab70ef591407663f
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
Adds policy keys ExitNodeID and ExitNodeIP.
Uses the policy keys to determine the exit node in preferences.
Fixestailscale/corp#15683
Signed-off-by: Claire Wang <claire@tailscale.com>
Adds AllowedIPs to PeerStatus, allowing for easier lookup of the
routes allowed to be routed to a node. Will be using the AllowedIPs
of the self node from the web client interface to display approval
status of advertised routes.
Updates #10261
Signed-off-by: Sonia Appasamy <sonia@tailscale.com>
To be consistent with the formatting of other warnings, pass available
update health message instead of handling ClientVersion in he CLI.
Fixes#10312
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
This PR starts to persist the NetMap tailnet name in SetPrefs so that tailscaled
clients can use this value to disambiguate fast user switching from one tailnet
to another that are under the same exact login. We will also try to backfill
this information during backend starts and profile switches so that users don't
have to re-authenticate their profile. The first client to use this new
information is the CLI in 'tailscale switch -list' which now uses text/tabwriter
to display the ID, Tailnet, and Account. Since account names are ambiguous, we
allow the user to pass 'tailscale switch ID' to specify the exact tailnet they
want to switch to.
Updates #9286
Signed-off-by: Marwan Sulaiman <marwan@tailscale.com>
In DERP homeless mode, a DERP home connection is not sought or
maintained and the local node is not reachable.
Updates #3363
Updates tailscale/corp#396
Change-Id: Ibc30488ac2e3cfe4810733b96c2c9f10a51b8331
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Adds a new sync.Mutex field to the webClient struct, rather than
using the general LocalBackend mutex. Since webClientGetOrInit
(previously WebClientInit) gets called on every connection, we
want to avoid holding the lock on LocalBackend just to check if
the server is initialized.
Moves all web_client.go funcs over to using the webClient.mu field.
Updates tailscale/corp#14335
Signed-off-by: Sonia Appasamy <sonia@tailscale.com>
Now that 1.54 has released, and the new web client will be included in
1.56, we can remove the need for the node capability. This means that
all 1.55 unstable builds, and then eventually the 1.56 build, will work
without setting the node capability.
The web client still requires the "webclient" user pref, so this does
NOT mean that the web client will be on by default for all devices.
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
Simply reading the taildrop directory can pop up security dialogs
on platforms like macOS. Avoid this by only performing garbage collection
of partial and deleted files after the first received taildrop file,
which would have prompted the security dialog window.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This change exposes SilentDisco as a control knob, and plumbs it down to
magicsock.endpoint. No changes are being made to magicsock.endpoint
disco behavior, yet.
Updates #540
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Co-authored-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Some conditional paths may otherwise skip the hostinfo update, so kick
it off asynchronously as other code paths do.
Updates tailscale/corp#15437
Signed-off-by: James Tucker <james@tailscale.com>
The local web client has the same characteristic as tailscale serve, in
that it needs a local listener to allow for connections from the local
machine itself when running in kernel networking mode.
This change renames and adapts the existing serveListener to allow it to
be used by the web client as well.
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
As part of tailnet-lock netmap processing, the LocalBackend mutex
is unlocked so we can potentially make a network call. Its possible
(during shutdown or while the control client is being reset) for
b.cc to become nil before the lock is picked up again.
Fixes: #9554
Signed-off-by: Tom DNetto <tom@tailscale.com>
App connectors handle DNS requests for app domains over PeerAPI,
but a safety check verifies the requesting peer has at least permission
to send traffic to 0.0.0.0:53 (or 2000:: for IPv6) before handling the DNS
request. The correct filter rules are synthesized by the coordination server
and sent down, but the address needs to be part of the 'local net' for the
filter package to even bother checking the filter rules, so we set them here.
See: https://github.com/tailscale/corp/issues/11961 for more information.
Signed-off-by: Tom DNetto <tom@tailscale.com>
Updates: ENG-2405
Require that requests to servers in manage mode are made to the
Tailscale IP (either ipv4 or ipv6) or quad-100. Also set various
security headers on those responses. These might be too restrictive,
but we can relax them as needed.
Allow requests to /ok (even in manage mode) with no checks. This will be
used for the connectivity check from a login client to see if the
management client is reachable.
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
if the user pref and nodecap for the new web client are enabled, serve
the client over requests to 100.100.100.100. Today, that is just a
static page that lists the local Tailcale IP addresses.
For now, this will render the readonly full management client, with an
"access" button that sends the user through check mode. After
completing check mode, they will still be in the read-only view, since
they are not accessing the client over Tailscale.
Instead, quad100 should serve the lobby client that has a "manage"
button that will open the management client on the Tailscale IP (and
trigger check mode). That is something we'll fix in a subsequent PR in
the web client code itself.
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
The design changed during integration and testing, resulting in the
earlier implementation growing in the appc package to be intended now
only for the sniproxy implementation. That code is moved to it's final
location, and the current App Connector code is now renamed.
Updates tailscale/corp#15437
Signed-off-by: James Tucker <james@tailscale.com>
Now uses webClientAtomicBool as the source of truth for whether the web
client should be running in tailscaled, with it updated when either the
RunWebClient pref or CapabilityPreviewWebClient node capability changes.
This avoids requiring holding the LocalBackend lock on each call to
ShouldRunWebClient to check for the CapabilityPreviewWebClient value.
Updates tailscale/corp#14335
Signed-off-by: Sonia Appasamy <sonia@tailscale.com>
The AppConnector is now configured by the mapcap from the control plane.
Updates tailscale/corp#15437
Signed-off-by: James Tucker <james@tailscale.com>
An EmbeddedAppConnector is added that when configured observes DNS
responses from the PeerAPI. If a response is found matching a configured
domain, routes are advertised when necessary.
The wiring from a configuration in the netmap capmap is not yet done, so
while the connector can be enabled, no domains can yet be added.
Updates tailscale/corp#15437
Signed-off-by: James Tucker <james@tailscale.com>
WebClientShutdown tries to acquire the b.mu lock, so run it in a go
routine so that it can finish shutdown after setPrefsLockedOnEntry is
finished. This is the same reason b.sshServer.Shutdown is run in a go
routine.
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
For consistency and clarity around what the LocalBackend.web field
is used for.
Updates tailscale/corp#14335
Signed-off-by: Sonia Appasamy <sonia@tailscale.com>
instead of starting a separate server listening on a particular port,
use the TCPHandlerForDst method to intercept requests for the special
web client port (currently 5252, probably configurable later).
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
This is not currently exposed as a user-settable preference through
`tailscale up` or `tailscale set`. Instead, the preference is set when
turning the web client on and off via localapi. In a subsequent commit,
the pref will be used to automatically start the web client on startup
when appropriate.
Updates tailscale/corp#14335
Signed-off-by: Will Norris <will@tailscale.com>
Allows for serving the web interface from tailscaled, with the
ability to start and stop the server via localapi endpoints
(/web/start and /web/stop).
This will be used to run the new full management web client,
which will only be accessible over Tailscale (with an extra auth
check step over noise) from the daemon. This switch also allows
us to run the web interface as a long-lived service in environments
where the CLI version is restricted to CGI, allowing us to manage
certain auth state in memory.
ipn/ipnlocal/web is stubbed out in ipn/ipnlocal/web_stub for
ios builds to satisfy ios restriction from adding "text/template"
and "html/template" dependencies.
Updates tailscale/corp#14335
Signed-off-by: Sonia Appasamy <sonia@tailscale.com>
On Windows, the idiomatic way to check access on a named pipe is for
the server to impersonate the client on its current OS thread, perform
access checks using the client's access token, and then revert the OS
thread's access token back to its true self.
The access token is a better representation of the client's rights than just
a username/userid check, as it represents the client's effective rights
at connection time, which might differ from their normal rights.
This patch updates safesocket to do the aforementioned impersonation,
extract the token handle, and then revert the impersonation. We retain
the token handle for the remaining duration of the connection (the token
continues to be valid even after we have reverted back to self).
Since the token is a property of the connection, I changed ipnauth to wrap
the concrete net.Conn to include the token. I then plumbed that change
through ipnlocal, ipnserver, and localapi as necessary.
I also added a PermitLocalAdmin flag to the localapi Handler which I intend
to use for controlling access to a few new localapi endpoints intended
for configuring auto-update.
Updates https://github.com/tailscale/tailscale/issues/755
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
It would end up resetting whatever hostinfo we had constructed
and leave the backend statemachine in a broken state.
This fixes that by storing the PushDeviceToken on the LocalBackend
and populating it on Hostinfo before passing it to controlclient.
Updates tailscale/corp#8940
Updates tailscale/corp#15367
Signed-off-by: Maisem Ali <maisem@tailscale.com>
The value being passed was the same as whats on b.hostinfo, so just
use that directly.
Updates #cleanup
Signed-off-by: Maisem Ali <maisem@tailscale.com>
This adds a check to prevent changes to ServeConfig if tailscaled
is run with a Locked config.
Missed in 1fc3573446.
Updates #1412
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Ensure that when a userspace proxy config is reloaded,
connections for any removed proxies are safely closed
Updates tailscale/tailscale#9725
Signed-off-by: Irbe Krumina <irbe@tailscale.com>
File resumption requires keeping partial files around for some time,
but we must still eventually delete them if never resumed.
Thus, we implement asynchronous file deletion, which could
spawn a background goroutine to delete the files.
We also use the same mechanism for deleting files on Windows,
where a file can't be deleted if there is still an open file handle.
We can enqueue those with the asynchronous file deleter as well.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
The old code would always retain value `true` if it was set once, even
if you then change `prefs.AutoUpdate.Apply` to `false`.
Instead of using the previous value, use the default (envknob) value to
OR with.
Updates #755
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
We add the following API:
* type FileChecksums
* type Checksum
* func Manager.PartialFiles
* func Manager.HashPartialFile
* func ResumeReader
The Manager methods provide the ability to query for partial files
and retrieve a list of checksums for a given partial file.
The ResumeReader function is a helper that wraps an io.Reader
to discard content that is identical locally and remotely.
The FileChecksums type represents the checksums of a file
and is safe to JSON marshal and send over the wire.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Co-authored-by: Rhea Ghosh <rhea@tailscale.com>
Changes made:
* Move all HTTP related functionality from taildrop to ipnlocal.
* Add two arguments to taildrop.Manager.PutFile to specify
an opaque client ID and a resume offset (both unused for now).
* Cleanup the logic of taildrop.Manager.PutFile
to be easier to follow.
* Implement file conflict handling where duplicate files are renamed
(e.g., "IMG_1234.jpg" -> "IMG_1234 (2).jpg").
* Implement file de-duplication where "renaming" a partial file
simply deletes it if it already exists with the same contents.
* Detect conflicting active puts where a second concurrent put
results in an error.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Co-authored-by: Rhea Ghosh <rhea@tailscale.com>
Changes made:
* Unexport declarations specific to internal taildrop functionality.
* Document all exported functionality.
* Move TestRedactErr to the taildrop package.
* Rename and invert Handler.DirectFileDoFinalRename as AvoidFinalRename.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Over time all taildrop functionality will be contained in the
taildrop package. This will include end to end unit tests. This is
simply the first smallest piece to move over.
There is no functionality change in this commit.
Updates tailscale/corp#14772
Signed-off-by: Rhea Ghosh <rhea@tailscale.com>
Co-authored-by: Joseph Tsai <joetsai@tailscale.com>
Advertise it on Android (it looks like it already works once advertised).
And both advertise & likely fix it on iOS. Yet untested.
Updates #9672
Change-Id: If3b7e97f011dea61e7e75aff23dcc178b6cf9123
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Make the 'tailscale debug component-logs' command print the component names for
which extra logging can be turned on, for easier discoverability of debug
functions.
Updates #cleanup
Co-authored-by: Paul Scott <paul@tailscale.com>
Signed-off-by: Val <valerie@tailscale.com>
Thanks to @qur and @eric for debugging!
Fixes#6973
Change-Id: Ib2cf8f030cf595cc73dd061c72e78ac19f5fae5d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Control sends ExitNodeDNSResolvers when configured for IsWireGuardOnly
nodes that are to be used as the default resolver with a lower
precedence than split DNS, and a lower precedence than "Override local
DNS", but otherwise before local DNS is used when the exit node is in
use.
Neither of the below changes were problematic, but appeared so alongside
a number of other client and external changes. See tailscale/corp#14809.
Reland ea9dd8fabc.
Reland d52ab181c3.
Updates #9377
Updates tailscale/corp#14809
Signed-off-by: James Tucker <james@tailscale.com>
This PR ensures zombie foregrounds are shutdown if a new
ServeConfig is created that wipes the ongoing foreground ones.
For example, "tailscale serve|funnel reset|off" should close
all open sessions.
Updates #8489
Signed-off-by: Marwan Sulaiman <marwan@tailscale.com>
For loading testing & profiling the cost of full netmap updates.
Updates #1909
Change-Id: I0afdf5de9967f8d95c7f81d5b531ed1c92c3208f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
9538e9f970 broke LocalBackend.WhoIs
where you can no longer lookup yourself in WhoIs.
This occurs because the LocalBackend.peers map only contains peers.
If we fail to lookup a peer, double-check whether it is ourself.
Fixes#9470
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Co-authored-by: Rhea Ghosh <rhea@tailscale.com>
The initial implementation directly mirrored the behavior of Tailscale
exit nodes, where the WireGuard exit node DNS took precedence over other
configuration.
This adjusted implementation treats the WireGuard DNS
resolvers as a lower precedence default resolver than the tailnet
default resolver, and allows split DNS configuration as well.
This also adds test coverage to the existing DNS selection behavior with
respect to default resolvers and split DNS routes for Tailscale exit
nodes above cap 25. There may be some refinement to do in the logic in
those cases, as split DNS may not be working as we intend, though that
would be a pre-existing and separate issue.
Updates #9377
Signed-off-by: James Tucker <james@tailscale.com>
Like PeerCapMap, add a field to `tailcfg.Node` which provides
a map of Capability to raw JSON messages which are deferred to be
parsed later by the application code which cares about the specific
capabilities. This effectively allows us to prototype new behavior
without having to commit to a schema in tailcfg, and it also opens up
the possibilities to develop custom behavior in tsnet applications w/o
having to plumb through application specific data in the MapResponse.
Updates #4217
Signed-off-by: Maisem Ali <maisem@tailscale.com>
And convert all callers over to the methods that check SelfNode.
Now we don't have multiple ways to express things in tests (setting
fields on SelfNode vs NetworkMap, sometimes inconsistently) and don't
have multiple ways to check those two fields (often only checking one
or the other).
Updates #9443
Change-Id: I2d7ba1cf6556142d219fae2be6f484f528756e3c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We have some flaky integration tests elsewhere that have no one place
to ask about the state of the world. This makes LocalBackend be that
place (as it's basically there anyway) but doesn't yet add the ForTest
accessor method.
This adds a LocalBackend.peers map[NodeID]NodeView that is
incrementally updated as mutations arrive. And then we start moving
away from using NetMap.Peers at runtime (UpdateStatus no longer uses
it now). And remove another copy of NodeView in the LocalBackend
nodeByAddr map. Change that to point into b.peers instead.
Future changes will then start streaming whole-node-granularity peer
change updates to WatchIPNBus clients, tracking statefully per client
what each has seen. This will get the GUI clients from receiving less
of a JSON storm of updates all the time.
Updates #1909
Change-Id: I14a976ca9f493bdf02ba7e6e05217363dcf422e5
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
NetworkMap.Addresses is redundant with the SelfNode.Addresses. This
works towards a TODO to delete NetworkMap.Addresses and replace it
with a method.
This is similar to #9389.
Updates #cleanup
Change-Id: Id000509ca5d16bb636401763d41bdb5f38513ba0
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
* Remove unnecessary mutexes (there's no concurrency)
* Simplify LocalBackend.UpdateStatus using the StatusBuilder.WantPeers
field that was added in 0f604923d3, removing passing around some
method values into func args. And then merge two methods.
More remains, but this is a start.
Updates #9433
Change-Id: Iaf2d7ec6e4e590799f00bae185465a4fd089b822
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This enables installing default resolvers specified by
tailcfg.Node.ExitNodeDNSResolvers when the exit node is selected.
Updates #9377
Signed-off-by: James Tucker <james@tailscale.com>
It has one user (LocalBackend) which can ask magicsock itself.
Updates #cleanup
Change-Id: I8c03cbb1e5ba57b0b442621b5fa467030c14a2e2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
(continuing the mission of removing rando methods from the Engine
interface that we don't need anymore)
Updates #cleanup
Change-Id: Id5190917596bf04d7185c3b331a852724a3f5a16
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We always have one. Stop pretending we might not.
Instead, add one early panic in NewLocalBackend if we actually don't.
Updates #cleanup
Change-Id: Iba4b78ed22cb6248e59c2b01a79355ca7a200ec8
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
LocalBackend can talk to magicsock on its own to do this without
the "Engine" being involved.
(Continuing a little side quest of cleaning up the Engine
interface...)
Updates #cleanup
Change-Id: I8654acdca2b883b1bd557fdc0cfb90cd3a418a62
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
It had exactly one user: netstack. Just have LocalBackend notify
netstack when here's a new netmap instead, simplifying the bloated
Engine interface that has grown a bunch of non-Engine-y things.
(plenty of rando stuff remains after this, but it's a start)
Updates #cleanup
Change-Id: I45e10ab48119e962fc4967a95167656e35b141d8
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Currently only the top four most popular changes: endpoints, DERP
home, online, and LastSeen.
Updates #1909
Change-Id: I03152da176b2b95232b56acabfb55dcdfaa16b79
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
I missed connecting some controlknobs.Knobs pieces in 4e91cf20a8
resulting in that breaking control knobs entirely.
Whoops.
The fix in ipn/ipnlocal (where it makes a new controlclient) but to
atone, I also added integration tests. Those integration tests use
a new "tailscale debug control-knobs" which by itself might be useful
for future debugging.
Updates #9351
Change-Id: Id9c89c8637746d879d5da67b9ac4e0d2367a3f0d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Previously two tsnet nodes in the same process couldn't have disjoint
sets of controlknob settings from control as both would overwrite each
other's global variables.
This plumbs a new controlknobs.Knobs type around everywhere and hangs
the knobs sent by control on that instead.
Updates #9351
Change-Id: I75338646d36813ed971b4ffad6f9a8b41ec91560
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
All platforms use it at this point, including iOS which was the
original hold out for memory reasons. No more reason to make it
optional.
Updates #9332
Change-Id: I743fbc2f370921a852fbcebf4eb9821e2bdd3086
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Cache the last `ClientVersion` value that was received from coordination
server and pass it in the localapi `/status` response.
When running `tailscale status`, print a message if `RunningAsLatest` is
`false`.
Updates #6907
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
Log some progress info to make updates more debuggable. Also, track
whether an active update is already started and return an error if
a concurrent update is attempted.
Some planned future PRs:
* add JSON output to `tailscale update`
* use JSON output from `tailscale update` to provide a more detailed
status of in-progress update (stage, download progress, etc)
Updates #6907
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
This PR adds a new field to the serve config that can be used to identify which serves are in "foreground mode" and then can also be used to ensure they do not get persisted to disk so that if Tailscaled gets ungracefully shutdown, the reloaded ServeConfig will not have those ports opened.
Updates #8489
Signed-off-by: Marwan Sulaiman <marwan@tailscale.com>
This PR removes the per request logging to the CLI as the CLI
will not be displaying those logs initially.
Updates #8489
Signed-off-by: Marwan Sulaiman <marwan@tailscale.com>
This PR adds a new field to the ServeConfig which maps
WatchIPNBus session ids to foreground serve configs.
The PR also adds a DeleteForegroundSession method to ensure the config
gets cleaned up on sessions ending.
Note this field is not currently used but will be in follow up work.
Updates #8489
Signed-off-by: Marwan Sulaiman <marwan@tailscale.com>
