This PR removes the sync.Once wrapper around retrieving the MachineCertificateSubject policy
setting value, ensuring the most recent version is always used if it changes after the service starts.
Although this policy setting is used by a very limited number of customers, recent support escalations have highlighted issues caused by outdated or incorrect policy values being applied.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we update ipnlocal.NewLocalBackend to subscribe to policy change notifications
and reapply syspolicy settings to the current profile's ipn.Prefs whenever a change occurs.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This moves code that handles ExitNodeID/ExitNodeIP syspolicy settings
from (*LocalBackend).setExitNodeID to applySysPolicy.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This updates the syspolicy.LogSCMInteractions check to run at the time of an interaction,
just before logging a message, instead of during service startup. This ensures the most
recent policy setting is used if it has changed since the service started.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we move the syspolicy.FlushDNSOnSessionUnlock check from service startup
to when a session change notification is received. This ensures that the most recent policy
setting value is used if it has changed since the service started.
We also plan to handle session change notifications for unrelated reasons
and need to decouple notification subscriptions from DNS anyway.
Updates #12687
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
These delays determine how soon syspolicy change callbacks are invoked after a policy setting is updated
in a policy source. For tests, we shorten these delays to minimize unnecessary wait times. This adjustment
only affects tests that subscribe to policy change notifications and modify policy settings after they have
already been set. Initial policy settings are always available immediately without delay.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We have several places where LocalBackend instances are created for testing, but they are rarely shut down
when the tests that created them exit.
In this PR, we update newTestLocalBackend and similar functions to use testing.TB.Cleanup(lb.Shutdown)
to ensure LocalBackend instances are properly shut down during test cleanup.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we add the tailscale syspolicy command with two subcommands: list, which displays
policy settings, and reload, which forces a reload of those settings. We also update the LocalAPI
and LocalClient to facilitate these additions.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We make setting.Snapshot JSON-marshallable in preparation for returning it from the LocalAPI.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We add setting.RawValue, a new type that facilitates unmarshalling JSON numbers and arrays
as uint64 and []string (instead of float64 and []any) for policy setting values.
We then use it to make setting.RawItem JSON-marshallable and update the tests.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we implement (but do not use yet, pending #13727 review) a syspolicy/source.Store
that reads policy settings from environment variables. It converts a CamelCase setting.Key,
such as AuthKey or ExitNodeID, to a SCREAMING_SNAKE_CASE, TS_-prefixed environment
variable name, such as TS_AUTH_KEY and TS_EXIT_NODE_ID. It then looks up the variable
and attempts to parse it according to the expected value type. If the environment variable
is not set, the policy setting is considered not configured in this store (the syspolicy package
will still read it from other sources). Similarly, if the environment variable has an invalid value
for the setting type, it won't be used (though the reported/logged error will differ).
Updates #13193
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we update the syspolicy package to utilize syspolicy/rsop under the hood,
and remove syspolicy.CachingHandler, syspolicy.windowsHandler and related code
which is no longer used.
We mark the syspolicy.Handler interface and RegisterHandler/SetHandlerForTest functions
as deprecated, but keep them temporarily until they are no longer used in other repos.
We also update the package to register setting definitions for all existing policy settings
and to register the Registry-based, Windows-specific policy stores when running on Windows.
Finally, we update existing internal and external tests to use the new API and add a few more
tests and benchmarks.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We add the ClientID() method to the ipnauth.Actor interface and updated ipnserver.actor to implement it.
This method returns a unique ID of the connected client if the actor represents one. It helps link a series
of interactions initiated by the client, such as when a notification needs to be sent back to a specific session,
rather than all active sessions, in response to a certain request.
We also add LocalBackend.WatchNotificationsAs and LocalBackend.StartLoginInteractiveAs methods,
which are like WatchNotifications and StartLoginInteractive but accept an additional parameter
specifying an ipnauth.Actor who initiates the operation. We store these actor identities in
watchSession.owner and LocalBackend.authActor, respectively,and implement LocalBackend.sendTo
and related helper methods to enable sending notifications to watchSessions associated with actors
(or, more broadly, identifiable recipients).
We then use the above to change who receives the BrowseToURL notifications:
- For user-initiated, interactive logins, the notification is delivered only to the user who initiated the
process. If the initiating actor represents a specific connected client, the URL notification is sent back
to the same LocalAPI client that called StartLoginInteractive. Otherwise, the notification is sent to all
clients connected as that user.
Currently, we only differentiate between users on Windows, as it is inherently a multi-user OS.
- In all other cases (e.g., node key expiration), we send the notification to all connected users.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR we add syspolicy/rsop package that facilitates policy source registration
and provides access to the resultant policy merged from all registered sources for a
given scope.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
If multiple upstream DNS servers are available, quad-100 sends requests to all of them
and forwards the first successful response, if any. If no successful responses are received,
it propagates the first failure from any of them.
This PR adds some test coverage for these scenarios.
Updates #13571
Signed-off-by: Nick Khyl <nickk@tailscale.com>
When an Exit Node is used, we create a WFP rule to block all inbound and outbound traffic,
along with several rules to permit specific types of traffic. Notably, we allow all inbound and
outbound traffic to and from LocalRoutes specified in wgengine/router.Config. The list of allowed
routes always includes routes for internal interfaces, such as loopback and virtual Hyper-V/WSL2
interfaces, and may also include LAN routes if the "Allow local network access" option is enabled.
However, these permitting rules do not allow link-local multicast on the corresponding interfaces.
This results in broken mDNS/LLMNR, and potentially other similar issues, whenever an exit node is used.
In this PR, we update (*wf.Firewall).UpdatePermittedRoutes() to create rules allowing outbound and
inbound link-local multicast traffic to and from the permitted IP ranges, partially resolving the mDNS/LLMNR
and *.local name resolution issue.
Since Windows does not attempt to send mDNS/LLMNR queries if a catch-all NRPT rule is present,
it is still necessary to disable the creation of that rule using the disable-local-dns-override-via-nrpt nodeAttr.
Updates #13571
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We already disable dynamic updates by setting DisableDynamicUpdate to 1 for the Tailscale interface.
However, this does not prevent non-dynamic DNS registration from happening when `ipconfig /registerdns`
runs and in similar scenarios. Notably, dns/windowsManager.SetDNS runs `ipconfig /registerdns`,
triggering DNS registration for all interfaces that do not explicitly disable it.
In this PR, we update dns/windowsManager.disableDynamicUpdates to also set RegistrationEnabled to 0.
Fixes#13411
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We no longer need this on Windows, and it was never required on other platforms.
It just results in more short-lived connections unless we use HTTP/2.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
With the upcoming syspolicy changes, it's imperative that all syspolicy keys are defined in the syspolicy package
for proper registration. Otherwise, the corresponding policy settings will not be read.
This updates a couple of places where we still use string literals rather than syspolicy consts.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This PR changes how LocalBackend handles interactive (initiated via StartLoginInteractive) and non-interactive (e.g., due to key expiration) logins,
and when it sends the authURL to the connected clients.
Specifically,
- When a user initiates an interactive login by clicking Log In in the GUI, the LocalAPI calls StartLoginInteractive.
If an authURL is available and hasn't expired, we immediately send it to all connected clients, suggesting them to open that URL in a browser.
Otherwise, we send a login request to the control plane and set a flag indicating that an interactive login is in progress.
- When LocalBackend receives an authURL from the control plane, we check if it differs from the previous one and whether an interactive login
is in progress. If either condition is true, we notify all connected clients with the new authURL and reset the interactive login flag.
We reset the auth URL and flags upon a successful authentication, when a different user logs in and when switching Tailscale login profiles.
Finally, we remove the redundant dedup logic added to WatchNotifications in #12096 and revert the tests to their original state to ensure that
calling StartLoginInteractive always produces BrowseToURL notifications, either immediately or when the authURL is received from the control plane.
Fixes#13296
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We add package defining interfaces for policy stores, enabling creation of policy sources
and reading settings from them. It includes a Windows-specific PlatformPolicyStore for GP and MDM
policies stored in the Registry, and an in-memory TestStore for testing purposes.
We also include an internal package that tracks and reports policy usage metrics when a policy setting
is read from a store. Initially, it will be used only on Windows and Android, as macOS, iOS, and tvOS
report their own metrics. However, we plan to use it across all platforms eventually.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
The LocalBackend's state machine starts in NoState and soon transitions to NeedsLogin if there's no auto-start profile,
with the profileManager starting with a new empty profile. Notably, entering the NeedsLogin state blocks engine updates.
We expect the user to transition out of this state by logging in interactively, and we set WantRunning to true when
controlclient enters the StateAuthenticated state.
While our intention is correct, and completing an interactive login should set WantRunning to true, our assumption
that logging into the current Tailscale profile is the only way to transition out of the NeedsLogin state is not accurate.
Another common transition path includes an explicit profile switch (via LocalBackend.SwitchProfile) or an implicit switch
when a Windows user connects to the backend. This results in a bug where WantRunning is set to true even when it was
previously set to false, and the user expressed no intention of changing it.
A similar issue occurs when switching from (sic) a Tailnet that has seamlessRenewalEnabled, regardless of the current state
of the LocalBackend's state machine, and also results in unexpectedly set WantRunning. While this behavior is generally
undesired, it is also incorrect that it depends on the control knobs of the Tailnet we're switching from rather than
the Tailnet we're switching to. However, this issue needs to be addressed separately.
This PR updates LocalBackend.SetControlClientStatus to only set WantRunning to true in response to an interactive login
as indicated by a non-empty authURL.
Fixes#6668Fixes#11280
Updates #12756
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In preparation for multi-user and unattended mode improvements, we are
refactoring and cleaning up `ipn/ipnlocal.profileManager`. The concept of the
"current user", which is only relevant on Windows, is being deprecated and will
soon be removed to allow more than one Windows user to connect and utilize
`LocalBackend` according to that user's access rights to the device and specific
Tailscale profiles.
We plan to pass the user's identity down to the `profileManager`, where it can
be used to determine the user's access rights to a given `LoginProfile`. While
the new permission model in `ipnauth` requires more work and is currently
blocked pending PR reviews, we are updating the `profileManager` to reduce its
reliance on the concept of a single OS user being connected to the backend at
the same time.
We extract the switching to the default Tailscale profile, which may also
trigger legacy profile migration, from `profileManager.SetCurrentUserID`. This
introduces `profileManager.DefaultUserProfileID`, which returns the default
profile ID for the current user, and `profileManager.SwitchToDefaultProfile`,
which is essentially a shorthand for `pm.SwitchProfile(pm.DefaultUserProfileID())`.
Both methods will eventually be updated to accept the user's identity and
utilize that user's default profile.
We make access checks more explicit by introducing the `profileManager.checkProfileAccess`
method. The current implementation continues to use `profileManager.currentUserID`
and `LoginProfile.LocalUserID` to determine whether access to a given profile
should be granted. This will be updated to utilize the `ipnauth` package and the
new permissions model once it's ready. We also expand access checks to be used
more widely in the `profileManager`, not just when switching or listing
profiles. This includes access checks in methods like `SetPrefs` and, most notably,
`DeleteProfile` and `DeleteAllProfiles`, preventing unprivileged Windows users
from deleting Tailscale profiles owned by other users on the same device,
including profiles owned by local admins.
We extract `profileManager.ProfilePrefs` and `profileManager.SetProfilePrefs`
methods that can be used to get and set preferences of a given `LoginProfile` if
`profileManager.checkProfileAccess` permits access to it.
We also update `profileManager.setUnattendedModeAsConfigured` to always enable
unattended mode on Windows if `Prefs.ForceDaemon` is true in the current
`LoginProfile`, even if `profileManager.currentUserID` is `""`. This facilitates
enabling unattended mode via `tailscale up --unattended` even if
`tailscale-ipn.exe` is not running, such as when a Group Policy or MDM-deployed
script runs at boot time, or when Tailscale is used on a Server Code or otherwise
headless Windows environments. See #12239, #2137, #3186 and
https://github.com/tailscale/tailscale/pull/6255#issuecomment-2016623838 for
details.
Fixes#12239
Updates tailscale/corp#18342
Updates #3186
Updates #2137
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Currently, we use PermitRead/PermitWrite/PermitCert permission flags to determine which operations are allowed for a LocalAPI client.
These checks are performed when localapi.Handler handles a request. Additionally, certain operations (e.g., changing the serve config)
requires the connected user to be a local admin. This approach is inherently racey and is subject to TOCTOU issues.
We consider it to be more critical on Windows environments, which are inherently multi-user, and therefore we prevent more than one
OS user from connecting and utilizing the LocalBackend at the same time. However, the same type of issues is also applicable to other
platforms when switching between profiles that have different OperatorUser values in ipn.Prefs.
We'd like to allow more than one Windows user to connect, but limit what they can see and do based on their access rights on the device
(e.g., an local admin or not) and to the currently active LoginProfile (e.g., owner/operator or not), while preventing TOCTOU issues on Windows
and other platforms. Therefore, we'd like to pass an actor from the LocalAPI to the LocalBackend to represent the user performing the operation.
The LocalBackend, or the profileManager down the line, will then check the actor's access rights to perform a given operation on the device
and against the current (and/or the target) profile.
This PR does not change the current permission model in any way, but it introduces the concept of an actor and includes some preparatory
work to pass it around. Temporarily, the ipnauth.Actor interface has methods like IsLocalSystem and IsLocalAdmin, which are only relevant
to the current permission model. It also lacks methods that will actually be used in the new model. We'll be adding these gradually in the next
PRs and removing the deprecated methods and the Permit* flags at the end of the transition.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We have several checked type assertions to *types.Named in both cmd/cloner and cmd/viewer.
As Go 1.23 updates the go/types package to produce Alias type nodes for type aliases,
these type assertions no longer work as expected unless the new behavior is disabled
with gotypesalias=0.
In this PR, we add codegen.NamedTypeOf(t types.Type), which functions like t.(*types.Named)
but also unrolls type aliases. We then use it in place of type assertions in the cmd/cloner and
cmd/viewer packages where appropriate.
We also update type switches to include *types.Alias alongside *types.Named in relevant cases,
remove *types.Struct cases when switching on types.Type.Underlying and update the tests
with more cases where type aliases can be used.
Updates #13224
Updates #12912
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Go 1.23 updates the go/types package to produce Alias type nodes for type aliases, unless disabled with gotypesalias=0.
This new default behavior breaks codegen.LookupMethod, which uses checked type assertions to types.Named and
types.Interface, as only named types and interfaces have methods.
In this PR, we update codegen.LookupMethod to perform method lookup on the right-hand side of the alias declaration
and clearly switch on the supported type nodes types. We also improve support for various edge cases, such as when an alias
is used as a type parameter constraint, and add tests for the LookupMethod function.
Additionally, we update cmd/viewer/tests to include types with aliases used in type fields and generic type constraints.
Updates #13224
Updates #12912
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This adds a new package containing generic types to be used for defining preference hierarchies.
These include prefs.Item, prefs.List, prefs.StructList, and prefs.StructMap. Each of these types
represents a configurable preference, holding the preference's state, value, and metadata.
The metadata includes the default value (if it differs from the zero value of the Go type)
and flags indicating whether a preference is managed via syspolicy or is hidden/read-only for
another reason. This information can be marshaled and sent to the GUI, CLI and web clients
as a source of truth regarding preference configuration, management, and visibility/mutability states.
We plan to use these types to define device preferences, such as the updater preferences,
the permission mode to be used on Windows with #tailscale/corp#18342, and certain global options
that are currently exposed as tailscaled flags. We also aim to eventually use these types for
profile-local preferences in ipn.Prefs and and as a replacement for ipn.MaskedPrefs.
The generic preference types are compatible with the tailscale.com/cmd/viewer and
tailscale.com/cmd/cloner utilities.
Updates #12736
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This PR modifies viewTypeForContainerType to use the last type parameter of a container type
as the value type, enabling the implementation of map-like container types where the second-to-last
(usually first) type parameter serves as the key type.
It also adds a MapContainer type to test the code generation.
Updates #12736
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Package setting contains types for defining and representing policy settings.
It facilitates the registration of setting definitions using Register and RegisterDefinition,
and the retrieval of registered setting definitions via Definitions and DefinitionOf.
This package is intended for use primarily within the syspolicy package hierarchy,
and added in a preparation for the next PRs.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Troubleshooting DNS resolution issues often requires additional information.
This PR expands the effect of the TS_DEBUG_DNS_FORWARD_SEND envknob to forwarder.forwardWithDestChan,
and includes the request type, domain name length, and the first 3 bytes of the domain's SHA-256 hash in the output.
Fixes#13070
Signed-off-by: Nick Khyl <nickk@tailscale.com>
It is sometimes necessary to change a global lazy.SyncValue for the duration of a test. This PR adds a (*SyncValue[T]).SetForTest method to facilitate that.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
The standard library includes these for strings and byte slices,
but it lacks similar functions for generic slices of comparable types.
Although they are not as commonly used, these functions are useful
in scenarios such as working with field index sequences (i.e., []int)
via reflection.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This adds support for container-like types such as Container[T] that
don't explicitly specify a view type for T. Instead, a package implementing
a container type should also implement and export a ContainerView[T, V] type
and a ContainerViewOf(*Container[T]) ContainerView[T, V] function, which
returns a view for the specified container, inferring the element view type V
from the element type T.
Updates #12736
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Windows requires routes to have a nexthop. Routes created using the interface's local IP address or an unspecified IP address ("0.0.0.0" or "::") as the nexthop are considered on-link routes. Notably, Windows treats on-link subnet routes differently, reserving the last IP in the range as the broadcast IP and therefore prohibiting TCP connections to it, resulting in WSA error 10049: "The requested address is not valid in its context. This does not happen with single-host routes, such as routes to Tailscale IP addresses, but becomes a problem with advertised subnets when all IPs in the range should be reachable.
Before Windows 8, only routes created with an unspecified IP address were considered on-link, so our previous approach of using the interface's own IP as the nexthop likely worked on Windows 7.
This PR updates configureInterface to use the TailscaleServiceIP (100.100.100.100) and its IPv6 counterpart as the nexthop for subnet routes.
Fixestailscale/support-escalations#57
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This adds support for generic types and interfaces to our cloner and viewer codegens.
It updates these packages to determine whether to make shallow or deep copies based
on the type parameter constraints. Additionally, if a template parameter or an interface
type has View() and Clone() methods, we'll use them for getters and the cloner of the
owning structure.
Updates #12736
Signed-off-by: Nick Khyl <nickk@tailscale.com>
This adds a package with GP-related functions and types to be used in the future PRs.
It also updates nrptRuleDatabase to use the new package instead of its own gpNotificationWatcher implementation.
Updates #12687
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Without this rule, Windows 8.1 and newer devices issue parallel DNS requests to DNS servers
associated with all network adapters, even when "Override local DNS" is enabled and/or
a Mullvad exit node is being used, resulting in DNS leaks.
This also adds "disable-local-dns-override-via-nrpt" nodeAttr that can be used to disable
the new behavior if needed.
Fixestailscale/corp#20718
Signed-off-by: Nick Khyl <nickk@tailscale.com>
As quad-100 is an authoritative server for 4via6 domains, it should always return responses
with a response code of 0 (indicating no error) when resolving records for these domains.
If there's no resource record of the specified type (e.g. A), it should return a response
with an empty answer section rather than NXDomain. Such a response indicates that there
is at least one RR of a different type (e.g., AAAA), suggesting the Windows stub resolver
to look for it.
Fixestailscale/corp#20767
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Now that tsdial.Dialer.UserDial has been updated to honor the configured routes
and dial external network addresses without going through Tailscale, while also being
able to dial a node/subnet router on the tailnet, we can start using UserDial to forward
DNS requests. This is primarily needed for DNS over TCP when forwarding requests
to internal DNS servers, but we also update getKnownDoHClientForProvider to use it.
Updates tailscale/corp#18725
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We'd like to use tsdial.Dialer.UserDial instead of SystemDial for DNS over TCP.
This is primarily necessary to properly dial internal DNS servers accessible
over Tailscale and subnet routes. However, to avoid issues when switching
between Wi-Fi and cellular, we need to ensure that we don't retain connections
to any external addresses on the old interface. Therefore, we need to determine
which dialer to use internally based on the configured routes.
This plumbs routes and localRoutes from router.Config to tsdial.Dialer,
and updates UserDial to use either the peer dialer or the system dialer,
depending on the network address and the configured routes.
Updates tailscale/corp#18725
Fixes#4529
Signed-off-by: Nick Khyl <nickk@tailscale.com>
The Network Location Awareness service identifies networks authenticated against
an Active Directory domain and categorizes them as "Domain Authenticated".
This includes the Tailscale network if a Domain Controller is reachable through it.
If a network is categories as NLM_NETWORK_CATEGORY_DOMAIN_AUTHENTICATED,
it is not possible to override its category, and we shouldn't attempt to do so.
Additionally, our Windows Firewall rules should be compatible with both private
and domain networks.
This fixes both issues.
Fixes#11813
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Package winenv provides information about the current Windows environment.
This includes details such as whether the device is a server or workstation,
and if it is AD domain-joined, MDM-registered, or neither.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Tailscaled becomes inoperative if the Tailscale Tunnel wintun adapter is abruptly removed.
wireguard-go closes the device in case of a read error, but tailscaled keeps running.
This adds detection of a closed WireGuard device, triggering a graceful shutdown of tailscaled.
It is then restarted by the tailscaled watchdog service process.
Fixes#11222
Signed-off-by: Nick Khyl <nickk@tailscale.com>
The WinTun adapter may have been removed by the time we're closing
the dns.windowsManager, and its associated interface registry key might
also have been deleted. We shouldn't use winutil.OpenKeyWait and wait
for the interface key to appear when performing a cleanup as a part of
the windowsManager shutdown.
Updates #11222
Signed-off-by: Nick Khyl <nickk@tailscale.com>
When the portable Monitor creates a winMon via newOSMon, we register
address and route change callbacks with Windows. Once a callback is hit,
it starts a goroutine that attempts to send the event into messagec and returns.
The newly started goroutine then blocks until it can send to the channel.
However, if the monitor is never started and winMon.Receive is never called,
the goroutines remain indefinitely blocked, leading to goroutine leaks and
significant memory consumption in the tailscaled service process on Windows.
Unlike the tailscaled subprocess, the service process creates but never starts
a Monitor.
This PR adds a check within the callbacks to confirm the monitor's active status,
and exits immediately if the monitor hasn't started.
Updates #9864
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this commit, we have updated the build process for our Windows DLLs
to link statically with libgcc, ensuring our Windows DLLs are self-contained.
Updates #10617
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Nick KhylandNick Khyl