Commit Graph

474 Commits

Author SHA1 Message Date
Brad Fitzpatrick
f5bfdefa00 control/controlclient: de-pointer Status.PersistView, document more
Updates #cleanup
Updates #1909

Change-Id: I31d91e120e3b299508de2136021eab3b34131a44
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-30 11:48:58 -07:00
Brad Fitzpatrick
7053e19562 control/controlclient: delete Status.Log{in,out}Finished
They were entirely redundant and 1:1 with the status field
so this turns them into methods instead.

Updates #cleanup
Updates #1909

Change-Id: I7d939750749edf7dae4c97566bbeb99f2f75adbc
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-30 11:21:06 -07:00
Brad Fitzpatrick
9ce1f5c7d2 control/controlclient: unexport Status.state, add test-only accessor
Updates #cleanup
Updates #1909

Change-Id: I38dcde6fa0de0f58ede4529992cee2e36de33dd6
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-30 10:40:05 -07:00
Brad Fitzpatrick
14320290c3 control/controlclient: merge, simplify two health check calls
I'm trying to remove some stuff from the netmap update path.

Updates #1909

Change-Id: Iad2c728dda160cd52f33ef9cf0b75b4940e0ce64
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-30 09:14:01 -07:00
David Anderson
8b492b4121 net/wsconn: accept a remote addr string and plumb it through
This makes wsconn.Conns somewhat present reasonably when they are
the client of an http.Request, rather than just put a placeholder
in that field.

Updates tailscale/corp#13777

Signed-off-by: David Anderson <danderson@tailscale.com>
2023-08-29 16:57:16 -07:00
Brad Fitzpatrick
6b882a1511 control/controlclient: clean up a few little things
De-pointer a *time.Time type, move it after the mutex which guard is,
rename two test-only methods with our conventional "ForTest" suffix.

Updates #cleanup

Change-Id: I4f4d1acd9c2de33d9c3cb6465d7349ed051aa9f9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-29 08:17:23 -07:00
Brad Fitzpatrick
55bb7314f2 control/controlclient: replace a status func with Observer interface
For now the method has only one interface (the same as the func it's
replacing) but it will grow, eventually with the goal to remove the
controlclient.Status type for most purposes.

Updates #1909

Change-Id: I715c8bf95e3f5943055a94e76af98d988558a2f2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-28 21:07:04 -07:00
Brad Fitzpatrick
590c693b96 types/logger: add AsJSON
Printing out JSON representation things in log output is pretty common.

Updates #cleanup

Change-Id: Ife2d2e321a18e6e1185efa8b699a23061ac5e5a4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-28 15:14:24 -07:00
Brad Fitzpatrick
a79b1d23b8 control/controlclient: convert PeersChanged nodes to patches internally
So even if the server doesn't support sending patches (neither the
Tailscale control server nor Headscale yet do), this makes the client
convert a changed node to its diff so the diffs can be processed
individually in a follow-up change.

This lets us make progress on #1909 without adding a dependency on
finishing the server-side part, and also means other control servers
will get the same upcoming optimizations.

And add some clientmetrics while here.

Updates #1909

Change-Id: I9533bcb8bba5227e17389f0b10dff71f33ee54ec
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-28 15:03:12 -07:00
Brad Fitzpatrick
947def7688 types/netmap: remove redundant Netmap.Hostinfo
It was in SelfNode.Hostinfo anyway. The redundant copy was just
costing us an allocation per netmap (a Hostinfo.Clone).

Updates #1909

Change-Id: Ifac568aa5f8054d9419828489442a0f4559bc099
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-22 09:54:02 -07:00
Brad Fitzpatrick
db017d3b12 control/controlclient: remove quadratic allocs in mapSession
The mapSession code was previously quadratic: N clients in a netmap
send updates proportional to N and then for each, we do N units of
work. This removes most of that "N units of work" per update. There's
still a netmap-sized slice allocation per update (that's #8963), but
that's it.

Bit more efficient now, especially with larger netmaps:

                                 │     before     │                after                │
                                 │     sec/op     │   sec/op     vs base                │
    MapSessionDelta/size_10-8       47.935µ ±  3%   1.232µ ± 2%  -97.43% (p=0.000 n=10)
    MapSessionDelta/size_100-8      79.950µ ±  3%   1.642µ ± 2%  -97.95% (p=0.000 n=10)
    MapSessionDelta/size_1000-8    355.747µ ± 10%   4.400µ ± 1%  -98.76% (p=0.000 n=10)
    MapSessionDelta/size_10000-8   3079.71µ ±  3%   27.89µ ± 3%  -99.09% (p=0.000 n=10)
    geomean                          254.6µ         3.969µ       -98.44%

                                 │     before     │                after                 │
                                 │      B/op      │     B/op      vs base                │
    MapSessionDelta/size_10-8        9.651Ki ± 0%   2.395Ki ± 0%  -75.19% (p=0.000 n=10)
    MapSessionDelta/size_100-8      83.097Ki ± 0%   3.192Ki ± 0%  -96.16% (p=0.000 n=10)
    MapSessionDelta/size_1000-8     800.25Ki ± 0%   10.32Ki ± 0%  -98.71% (p=0.000 n=10)
    MapSessionDelta/size_10000-8   7896.04Ki ± 0%   82.32Ki ± 0%  -98.96% (p=0.000 n=10)
    geomean                          266.8Ki        8.977Ki       -96.64%

                                 │    before     │               after                │
                                 │   allocs/op   │ allocs/op   vs base                │
    MapSessionDelta/size_10-8         72.00 ± 0%   20.00 ± 0%  -72.22% (p=0.000 n=10)
    MapSessionDelta/size_100-8       523.00 ± 0%   20.00 ± 0%  -96.18% (p=0.000 n=10)
    MapSessionDelta/size_1000-8     5024.00 ± 0%   20.00 ± 0%  -99.60% (p=0.000 n=10)
    MapSessionDelta/size_10000-8   50024.00 ± 0%   20.00 ± 0%  -99.96% (p=0.000 n=10)
    geomean                          1.754k        20.00       -98.86%

Updates #1909

Change-Id: I41ee29358a5521ed762216a76d4cc5b0d16e46ac
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-22 08:59:57 -07:00
Brad Fitzpatrick
cb4a61f951 control/controlclient: don't clone self node on each NetworkMap
Drop in the bucket, but have to start somewhere.

Real wins will come once this is done for peers.

                                 │     before     │                after                │
                                 │      B/op      │     B/op       vs base              │
    MapSessionDelta/size_10-8      10.213Ki ± ∞ ¹   9.650Ki ± ∞ ¹  -5.51% (p=0.008 n=5)
    MapSessionDelta/size_100-8      83.64Ki ± ∞ ¹   83.08Ki ± ∞ ¹  -0.67% (p=0.008 n=5)
    MapSessionDelta/size_1000-8     800.8Ki ± ∞ ¹   800.3Ki ± ∞ ¹  -0.07% (p=0.008 n=5)
    MapSessionDelta/size_10000-8    7.712Mi ± ∞ ¹   7.711Mi ± ∞ ¹  -0.01% (p=0.008 n=5)
    geomean                         271.1Ki         266.8Ki        -1.59%

                                 │    before    │               after                │
                                 │  allocs/op   │  allocs/op    vs base              │
    MapSessionDelta/size_10-8       73.00 ± ∞ ¹    72.00 ± ∞ ¹  -1.37% (p=0.008 n=5)
    MapSessionDelta/size_100-8      524.0 ± ∞ ¹    523.0 ± ∞ ¹  -0.19% (p=0.008 n=5)
    MapSessionDelta/size_1000-8    5.025k ± ∞ ¹   5.024k ± ∞ ¹  -0.02% (p=0.008 n=5)
    MapSessionDelta/size_10000-8   50.02k ± ∞ ¹   50.02k ± ∞ ¹  -0.00% (p=0.040 n=5)
    geomean                        1.761k         1.754k        -0.40%

Updates #1909

Change-Id: Ie19dea3371de251d64d4373dd00422f53c2675ea
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-21 15:42:33 -07:00
Brad Fitzpatrick
84b94b3146 types/netmap, all: make NetworkMap.SelfNode a tailcfg.NodeView
Updates #1909

Change-Id: I8c470cbc147129a652c1d58eac9b790691b87606
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-21 13:34:49 -07:00
Brad Fitzpatrick
b5ff68a968 control/controlclient: flesh out mapSession to break up gigantic method
Now mapSession has a bunch more fields and methods, rather than being
just one massive func with a ton of local variables.

So far there are no major new optimizations, though. It should behave
the same as before.

This has been done with an eye towards testability (so tests can set
all the callback funcs as needed, or not, without a huge Direct client
or long-running HTTP requests), but this change doesn't add new tests
yet. That will follow in the changes which flesh out the NetmapUpdater
interface.

Updates #1909

Change-Id: Iad4e7442d5bbbe2614bd4b1dc4b02e27504898df
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-21 10:38:32 -07:00
Brad Fitzpatrick
165f0116f1 types/netmap: move some mutations earlier, remove, document some fields
And optimize the Persist setting a bit, allocating later and only mutating
fields when there's been a Node change.

Updates #1909

Change-Id: Iaddfd9e88ef76e1d18e8d0a41926eb44d0955312
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-20 16:26:11 -07:00
Brad Fitzpatrick
21170fb175 control/controlclient: scope a variable tighter, de-pointer a *time.Time
Just misc cleanups.

Updates #1909

Change-Id: I9d64cb6c46d634eb5fdf725c13a6c5e514e02e9a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-20 15:06:24 -07:00
Brad Fitzpatrick
4511e7d64e ipn/ipnstate: add PeerStatus.AltSharerUserID, stop mangling Node.User
In b987b2ab18 (2021-01-12) when we introduced sharing we mapped
the sharer to the userid at a low layer, mostly to fix the display of
"tailscale status" and the client UIs, but also some tests.

The commit earlier today, 7dec09d169, removed the 2.5yo option
to let clients disable that automatic mapping, as clearly we were never
getting around to it.

This plumbs the Sharer UserID all the way to ipnstatus so the CLI
itself can choose to print out the Sharer's identity over the node's
original owner.

Then we stop mangling Node.User and let clients decide how they want
to render things.

To ease the migration for the Windows GUI (which currently operates on
tailcfg.Node via the NetMap from WatchIPNBus, instead of PeerStatus),
a new method Node.SharerOrUser is added to do the mapping of
Sharer-else-User.

Updates #1909
Updates tailscale/corp#1183

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-20 08:18:52 -07:00
Brad Fitzpatrick
7dec09d169 control/controlclient: remove Opts.KeepSharerAndUserSplit
It was added 2.5 years ago in c1dabd9436 but was never used.
Clearly that migration didn't matter.

We can attempt this again later if/when this matters.

Meanwhile this simplifies the code and thus makes working on other
current efforts in these parts of the code easier.

Updates #1909

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-19 15:06:05 -07:00
Brad Fitzpatrick
58a4fd43d8 types/netmap, all: use read-only tailcfg.NodeView in NetworkMap
Updates #8948

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-18 20:04:35 -07:00
Brad Fitzpatrick
af2e4909b6 all: remove some Debug fields, NetworkMap.Debug, Reconfig Debug arg
Updates #8923

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-17 19:04:30 -07:00
Brad Fitzpatrick
121d1d002c tailcfg: add nodeAttrs for forcing OneCGNAT on/off [capver 71]
Updates #8923

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-17 13:32:12 -07:00
Brad Fitzpatrick
25663b1307 tailcfg: remove most Debug fields, move bulk to nodeAttrs [capver 70]
Now a nodeAttr: ForceBackgroundSTUN, DERPRoute, TrimWGConfig,
DisableSubnetsIfPAC, DisableUPnP.

Kept support for, but also now a NodeAttr: RandomizeClientPort.

Removed: SetForceBackgroundSTUN, SetRandomizeClientPort (both never
used, sadly... never got around to them. But nodeAttrs are better
anyway), EnableSilentDisco (will be a nodeAttr later when that effort
resumes).

Updates #8923

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-17 10:52:47 -07:00
Brad Fitzpatrick
239ad57446 tailcfg: move LogHeapPprof from Debug to c2n [capver 69]
And delete Debug.GoroutineDumpURL, which was already in c2n.

Updates #8923

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-16 20:35:04 -07:00
Brad Fitzpatrick
1fcae42055 control/controlclient: move lastUpdateGenInformed to tighter scope
No need to have it on Auto or be behind a mutex; it's only read/written
from a single goroutine. Move it there.

Updates tailscale/corp#5761

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-13 10:39:17 -07:00
Brad Fitzpatrick
2398993804 control/controlclient: refactor in prep for optimized delta handling
See issue. This is a baby step towards passing through deltas
end-to-end from node to control back to node and down to the various
engine subsystems, not computing diffs from two full netmaps at
various levels. This will then let us support larger netmaps without
burning CPU.

But this change itself changes no behavior. It just changes a func
type to an interface with one method. That paves the way for future
changes to then add new NetmapUpdater methods that do more
fine-grained work than updating the whole world.

Updates #1909

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-08-12 16:09:58 -07:00
M. J. Fromberger
9e24a6508a
control/controlclient: avert a data race when logging (#8863)
The read of the synced field for logging takes place outside the lock, and
races with other (locked) writes of this field, including for example the one
at current line 556 in mapRoutine.

Updates tailscale/corp#13856

Change-Id: I056b36d7a93025aafdf73528dd7645f10b791af6
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
2023-08-11 18:49:40 -07:00
Maisem Ali
d16946854f control/controlclient: add Auto.updateRoutine
Instead of having updates replace the map polls, create
a third goroutine which is solely responsible for making
sure that control is aware of the latest client state.

This also makes it so that the streaming map polls are only
broken when there are auth changes, or the client is paused.

Updates tailscale/corp#5761

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-08-10 12:23:08 -07:00
Andrew Lytvynov
90081a25ca
control/controlhttp: remove tstest.Clock from tests (#8830)
These specific tests rely on some timers in the controlhttp code.
Without time moving forward and timers triggering, the tests fail.

Updates #8587

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
2023-08-09 15:03:22 -07:00
Maisem Ali
734928d3cb control/controlclient: make Direct own all changes to Persist
It was being modified in two places in Direct for the auth routine
and then in LocalBackend when a new NetMap was received. This was
confusing, so make Direct also own changes to Persist when a new
NetMap is received.

Updates #7726

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-08-08 13:43:37 -06:00
Maisem Ali
6aaf1d48df types/persist: drop duplicated Persist.LoginName
It was duplicated from Persist.UserProfile.LoginName, drop it.

Updates #7726

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-08-08 13:43:37 -06:00
Maisem Ali
17ed2da94d control/controlclient: use ptr.To
Updates #cleanup

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-08-08 10:47:24 -06:00
salman aljammaz
25a7204bb4
wgengine,ipn,cmd/tailscale: add size option to ping (#8739)
This adds the capability to pad disco ping message payloads to reach a
specified size. It also plumbs it through to the tailscale ping -size
flag.

Disco pings used for actual endpoint discovery do not use this yet.

Updates #311.

Signed-off-by: salman <salman@tailscale.com>
Co-authored-by: Val <valerie@tailscale.com>
2023-08-08 13:11:28 +01:00
Claire Wang
a17c45fd6e
control: use tstime instead of time (#8595)
Updates #8587
Signed-off-by: Claire Wang <claire@tailscale.com>
2023-08-04 19:29:44 -04:00
Maisem Ali
60e5761d60 control/controlclient: reset backoff in mapRoutine on netmap recv
We were never resetting the backoff in streaming mapResponses.
The call to `PollNetMap` always returns with an error. Changing that contract
is harder, so manually reset backoff when a netmap is received.

Updates tailscale/corp#12894

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-07-13 21:08:28 -07:00
Andrew Dunham
7aba0b0d78 net/netcheck, tailcfg: add DERPHomeParams and use it
This allows providing additional information to the client about how to
select a home DERP region, such as preferring a given DERP region over
all others.

Updates #8603

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I7c4a270f31d8585112fab5408799ffba5b75266f
2023-07-13 22:41:21 -04:00
Maisem Ali
9d1a3a995c control/controlclient: use ctx passed down to NoiseClient.getConn
Without this, the client would just get stuck dialing even if the
context was canceled.

Updates tailscale/corp#12590

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-07-07 15:11:44 -07:00
Maisem Ali
c11af12a49 .github: actually run tests in CI
Updates #cleanup

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-06-25 15:57:28 -07:00
Brad Fitzpatrick
7c1068b7ac util/goroutines: let ScrubbedGoroutineDump get only current stack
ScrubbedGoroutineDump previously only returned the stacks of all
goroutines. I also want to be able to use this for only the current
goroutine's stack. Add a bool param to support both ways.

Updates tailscale/corp#5149

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2023-06-23 12:50:45 -07:00
Andrew Dunham
42fd964090 control/controlclient: use dnscache.Resolver for Noise client
This passes the *dnscache.Resolver down from the Direct client into the
Noise client and from there into the controlhttp client. This retains
the Resolver so that it can share state across calls instead of creating
a new resolver.

Updates #4845
Updates #6110

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ia5d6af1870f3b5b5d7dd5685d775dcf300aec7af
2023-05-01 13:22:10 -07:00
Mihai Parparita
7330aa593e all: avoid repeated default interface lookups
On some platforms (notably macOS and iOS) we look up the default
interface to bind outgoing connections to. This is both duplicated
work and results in logspam when the default interface is not available
(i.e. when a phone has no connectivity, we log an error and thus cause
more things that we will try to upload and fail).

Fixed by passing around a netmon.Monitor to more places, so that we can
use its cached interface state.

Fixes #7850
Updates #7621

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2023-04-20 15:46:01 -07:00
Mihai Parparita
4722f7e322 all: move network monitoring from wgengine/monitor to net/netmon
We're using it in more and more places, and it's not really specific to
our use of Wireguard (and does more just link/interface monitoring).

Also removes the separate interface we had for it in sockstats -- it's
a small enough package (we already pull in all of its dependencies
via other paths) that it's not worth the extra complexity.

Updates #7621
Updates #7850

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2023-04-20 10:15:59 -07:00
Andrew Dunham
280255acae
various: add golangci-lint, fix issues (#7905)
This adds an initial and intentionally minimal configuration for
golang-ci, fixes the issues reported, and adds a GitHub Action to check
new pull requests against this linter configuration.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8f38fbc315836a19a094d0d3e986758b9313f163
2023-04-17 18:38:24 -04:00
Mihai Parparita
9a655a1d58 net/dnsfallback: more explicitly pass through logf function
Redoes the approach from #5550 and #7539 to explicitly pass in the logf
function, instead of having global state that can be overridden.

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2023-04-17 12:06:23 -07:00
Mihai Parparita
edb02b63f8 net/sockstats: pass in logger to sockstats.WithSockStats
Using log.Printf may end up being printed out to the console, which
is not desirable. I noticed this when I was investigating some client
logs with `sockstats: trace "NetcheckClient" was overwritten by another`.
That turns to be harmless/expected (the netcheck client will fall back
to the DERP client in some cases, which does its own sockstats trace).

However, the log output could be visible to users if running the
`tailscale netcheck` CLI command, which would be needlessly confusing.

Updates tailscale/corp#9230

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2023-04-12 18:40:03 -07:00
Kurnia D Win
9526858b1e control/controlclient: fix accidental backoff reset
Signed-off-by: Kurnia D Win <kurnia.d.win@gmail.com>
2023-03-15 10:25:48 -07:00
Andrew Dunham
83fa17d26c various: pass logger.Logf through to more places
Updates #7537

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Id89acab70ea678c8c7ff0f44792d54c7223337c6
2023-03-12 12:38:38 -04:00
Maisem Ali
be027a9899 control/controlclient: improve handling of concurrent lite map requests
This reverts commit 6eca47b16c and fixes forward.

Previously the first ever streaming MapRequest that a client sent would also
set ReadOnly to true as it didn't have any endpoints and expected/relied on the
map poll to restart as soon as it got endpoints. However with 48f6c1eba4,
we would no longer restart MapRequests as frequently as we used to, so control
would only ever get the first streaming MapRequest which had ReadOnly=true.

Control would treat this as an uninteresting request and would not send it
any further netmaps, while the client would happily stay in the map poll forever
while litemap updates happened in parallel.

This makes it so that we never set `ReadOnly=true` when we are doing a streaming
MapRequest. This is no longer necessary either as most endpoint discovery happens
over disco anyway.

Co-authored-by: Andrew Dunham <andrew@du.nham.ca>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-03-09 11:36:44 -08:00
Tom DNetto
ce99474317 all: implement preauth-key support with tailnet lock
Signed-off-by: Tom DNetto <tom@tailscale.com>
2023-03-08 11:56:46 -10:00
Tom DNetto
6eca47b16c Revert "control/controlclient: improve handling of concurrent lite map requests"
This reverts commit 48f6c1eba4.

It unfortunately breaks mapresponse wakeups.

Signed-off-by: Tom DNetto <tom@tailscale.com>
2023-03-08 09:47:44 -10:00
Andrew Dunham
48f6c1eba4 control/controlclient: improve handling of concurrent lite map requests
Prior to this change, if we were in the middle of a lite map update we'd
tear down the entire map session and restart it. With this change, we'll
cancel an in-flight lite map request up to 10 times and restart before
we tear down the streaming map request. We tear down everything after 10
retries to ensure that a steady stream of calls to sendNewMapRequest
doesn't fail to make progress by repeatedly canceling and restarting.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Co-authored-by: Maisem Ali <maisem@tailscale.com>
Change-Id: I9392bf8cf674e7a58ccd1e476039300a359ef3b1
2023-03-07 19:29:55 -05:00