Commit Graph

1089 Commits (5f4a4c6744fbda767d5bf4b3299a16aea80c4d1c)

Author SHA1 Message Date
Jordan Whited afec2d41b4
wgengine/magicsock: remove redundant deadline from netcheck report call (#13395)
netcheck.Client.GetReport() applies its own deadlines. This 2s deadline
was causing GetReport() to never fall back to HTTPS/ICMP measurements
as it was shorter than netcheck.stunProbeTimeout, leaving no time
for fallbacks.

Updates #13394
Updates #6187

Signed-off-by: Jordan Whited <jordan@tailscale.com>
1 week ago
Nick Khyl 4dfde7bffc net/dns: disable DNS registration for Tailscale interface on Windows
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>
2 weeks ago
Jordan Whited 7aa766ee65
net/tstun: probe TCP GRO (#13376)
Disable TCP & UDP GRO if the probe fails.

torvalds/linux@e269d79c7d broke virtio_net
TCP & UDP GRO causing GRO writes to return EINVAL. The bug was then
resolved later in
torvalds/linux@89add40066. The offending
commit was pulled into various LTS releases.

Updates #13041

Signed-off-by: Jordan Whited <jordan@tailscale.com>
2 weeks ago
Andrew Dunham 7dcf65a10a net/dns: fix IsZero and Equal methods on OSConfig
Discovered this while investigating the following issue; I think it's
unrelated, but might as well fix it. Also, add a test helper for
checking things that have an IsZero method using the reflect package.

Updates tailscale/support-escalations#55

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I57b7adde43bcef9483763b561da173b4c35f49e2
2 weeks ago
Brad Fitzpatrick 3d401c11fa all: use new Go 1.23 slices.Sorted more
Updates #12912

Change-Id: If1294e5bc7b5d3cf0067535ae10db75e8b988d8b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 weeks ago
Andrea Gottardo d060b3fa02
cli: implement `tailscale dns status` (#13353)
Updates tailscale/tailscale#13326

This PR begins implementing a `tailscale dns` command group in the Tailscale CLI. It provides an initial implementation of `tailscale dns status` which dumps the state of the internal DNS forwarder.

Two new endpoints were added in LocalAPI to support the CLI functionality:

- `/netmap`: dumps a copy of the last received network map (because the CLI shouldn't have to listen to the ipn bus for a copy)
- `/dns-osconfig`: dumps the OS DNS configuration (this will be very handy for the UI clients as well, as they currently do not display this information)

My plan is to implement other subcommands mentioned in tailscale/tailscale#13326, such as `query`, in later PRs.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
2 weeks ago
Andrea Gottardo 0112da6070
net/dns: support GetBaseConfig on Darwin OSS tailscaled (#13351)
Updates tailscale/tailscale#177

It appears that the OSS distribution of `tailscaled` is currently unable to get the current system base DNS configuration, as GetBaseConfig() in manager_darwin.go is unimplemented. This PR adds a basic implementation that reads the current values in `/etc/resolv.conf`, to at least unblock DNS resolution via Quad100 if `--accept-dns` is enabled.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
2 weeks ago
Andrew Dunham 1c972bc7cb wgengine/magicsock: actually use AF_PACKET socket for raw disco
Previously, despite what the commit said, we were using a raw IP socket
that was *not* an AF_PACKET socket, and thus was subject to the host
firewall rules. Switch to using a real AF_PACKET socket to actually get
the functionality we want.

Updates #13140

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: If657daeeda9ab8d967e75a4f049c66e2bca54b78
3 weeks ago
Jordan Whited 45c97751fb
net/tstun: clarify GROFilterFunc *gro.GRO usage (#13318)
Updates #cleanup

Signed-off-by: Jordan Whited <jordan@tailscale.com>
3 weeks ago
Andrea Gottardo a584d04f8a
dns: increase TimeToVisible before DNS unavailable warning (#13317)
Updates tailscale/tailscale#13314

Some users are reporting 'DNS unavailable' spurious (?) warnings, especially on Android:

https://old.reddit.com/r/Tailscale/comments/1f2ow3w/health_warning_dns_unavailable_on_tailscale/
https://old.reddit.com/r/Tailscale/comments/1f3l2il/health_warnings_dns_unavailable_what_does_it_mean/

I suspect this is caused by having a too low TimeToVisible setting on the Warnable, which triggers the unhealthy state during slow network transitions.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
3 weeks ago
Jordan Whited 0926954cf5
net/tstun,wgengine/netstack: implement TCP GRO for local services (#13315)
Throughput improves substantially when measured via netstack loopback
(TS_DEBUG_NETSTACK_LOOPBACK_PORT).

Before (d21ebc2):
jwhited@i5-12400-2:~$ iperf3 -V -c 100.100.100.100
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  5.77 GBytes  4.95 Gbits/sec    0 sender
[  5]   0.00-10.01  sec  5.77 GBytes  4.95 Gbits/sec      receiver

After:
jwhited@i5-12400-2:~$ iperf3 -V -c 100.100.100.100
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  12.7 GBytes  10.9 Gbits/sec    0 sender
[  5]   0.00-10.00  sec  12.7 GBytes  10.9 Gbits/sec      receiver

Updates tailscale/corp#22754

Signed-off-by: Jordan Whited <jordan@tailscale.com>
3 weeks ago
Jordan Whited 31cdbd68b1
net/tstun: fix gvisor inbound GSO packet injection (#13283)
buffs[0] was not sized to hold pkt with GSO, resulting in a panic.

Updates tailscale/corp#22511

Signed-off-by: Jordan Whited <jordan@tailscale.com>
3 weeks ago
Kristoffer Dalby a2c42d3cd4 usermetric: add initial user-facing metrics
This commit adds a new usermetric package and wires
up metrics across the tailscale client.

Updates tailscale/corp#22075

Co-authored-by: Anton Tolchanov <anton@tailscale.com>
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
4 weeks ago
Jordan Whited d097096ddc
net/tstun,wgengine/netstack: make inbound synthetic packet injection GSO-aware (#13266)
Updates tailscale/corp#22511

Signed-off-by: Jordan Whited <jordan@tailscale.com>
4 weeks ago
Ilarion Kovalchuk 0cb7eb9b75 net/dns: updated gonotify dependency to v2 that supports closable context
Signed-off-by: Ilarion Kovalchuk <illarion.kovalchuk@gmail.com>
4 weeks ago
Brad Fitzpatrick 0ff474ff37 all: fix new lint warnings from bumping staticcheck
In prep for updating to new staticcheck required for Go 1.23.

Updates #12912

Change-Id: If77892a023b79c6fa798f936fc80428fd4ce0673
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 weeks ago
Jordan Whited df6014f1d7
net/tstun,wgengine{/netstack/gro}: refactor and re-enable gVisor GRO for Linux (#13172)
In 2f27319baf we disabled GRO due to a
data race around concurrent calls to tstun.Wrapper.Write(). This commit
refactors GRO to be thread-safe, and re-enables it on Linux.

This refactor now carries a GRO type across tstun and netstack APIs
with a lifetime that is scoped to a single tstun.Wrapper.Write() call.

In 25f0a3fc8f we used build tags to
prevent importation of gVisor's GRO package on iOS as at the time we
believed it was contributing to additional memory usage on that
platform. It wasn't, so this commit simplifies and removes those
build tags.

Updates tailscale/corp#22353
Updates tailscale/corp#22125
Updates #6816

Signed-off-by: Jordan Whited <jordan@tailscale.com>
1 month ago
Andrea Gottardo 5cbbb48c2e
health/dns: reduce severity of DNS unavailable warning (#13152)
`DNS unavailable` was marked as a high severity warning. On Android (and other platforms), these trigger a system notification. Here we reduce the severity level to medium. A medium severity warning will still display the warning icon on platforms with a tray icon because of the `ImpactsConnectivity=true` flag being set here, but it won't show a notification anymore. If people enter an area with bad cellular reception, they're bound to receive so many of these notifications and we need to reduce notification fatigue.

Signed-off-by: Andrea Gottardo <andrea@tailscale.com>
1 month ago
Kyle Carberry 6c852fa817 go.{mod,sum}: migrate from nhooyr.io/websocket to github.com/coder/websocket
Coder has just adopted nhooyr/websocket which unfortunately changes the import path.

`github.com/coder/coder` imports `tailscale.com/net/wsconn` which was still pointing
to `nhooyr.io/websocket`, but this change updates it.

See https://coder.com/blog/websocket

Updates #13154

Change-Id: I3dec6512472b14eae337ae22c5bcc1e3758888d5
Signed-off-by: Kyle Carberry <kyle@carberry.com>
1 month ago
Brad Fitzpatrick a61825c7b8 cmd/tta, vnet: add host firewall, env var support, more tests
In particular, tests showing that #3824 works. But that test doesn't
actually work yet; it only gets a DERP connection. (why?)

Updates #13038

Change-Id: Ie1fd1b6a38d4e90fae7e72a0b9a142a95f0b2e8f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
1 month ago
Nick Khyl f23932bd98 net/dns/resolver: log forwarded query details when TS_DEBUG_DNS_FORWARD_SEND is enabled
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>
1 month ago
Anton Tolchanov 227509547f {control,net}: close idle connections of custom transports
I noticed a few places with custom http.Transport where we are not
closing idle connections when transport is no longer used.

Updates tailscale/corp#21609

Signed-off-by: Anton Tolchanov <anton@tailscale.com>
2 months ago
VimT e3f047618b net/socks5: support UDP
Updates #7581

Signed-off-by: VimT <me@vimt.me>
2 months ago
Jordan Whited 17c88a19be
net/captivedetection: mark TestAllEndpointsAreUpAndReturnExpectedResponse flaky (#13021)
Updates #13019

Signed-off-by: Jordan Whited <jordan@tailscale.com>
2 months ago
Maisem Ali f205efcf18 net/packet/checksum: fix v6 NAT
We were copying 12 out of the 16 bytes which meant that
the 1:1 NAT required would only work if the last 4 bytes
happened to match between the new and old address, something
that our tests accidentally had. Fix it by copying the full
16 bytes and make the tests also verify the addr and use rand
addresses.

Updates #9511

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 months ago
Andrea Gottardo 4055b63b9b
net/captivedetection: exclude cellular data interfaces (#13002)
Updates tailscale/tailscale#1634

This PR optimizes captive portal detection on Android and iOS by excluding cellular data interfaces (`pdp*` and `rmnet`). As cellular networks do not present captive portals, frequent network switches between Wi-Fi and cellular would otherwise trigger captive detection unnecessarily, causing battery drain.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
2 months ago
Jordan Whited f0230ce0b5
go.mod,net/tstun,wgengine/netstack: implement gVisor TCP GRO for Linux (#12921)
This commit implements TCP GRO for packets being written to gVisor on
Linux. Windows support will follow later. The wireguard-go dependency is
updated in order to make use of newly exported IP checksum functions.
gVisor is updated in order to make use of newly exported
stack.PacketBuffer GRO logic.

TCP throughput towards gVisor, i.e. TUN write direction, is dramatically
improved as a result of this commit. Benchmarks show substantial
improvement, sometimes as high as 2x. High bandwidth-delay product
paths remain receive window limited, bottlenecked by gVisor's default
TCP receive socket buffer size. This will be addressed in a  follow-on
commit.

The iperf3 results below demonstrate the effect of this commit between
two Linux computers with i5-12400 CPUs. There is roughly ~13us of round
trip latency between them.

The first result is from commit 57856fc without TCP GRO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  4.77 GBytes  4.10 Gbits/sec   20 sender
[  5]   0.00-10.00  sec  4.77 GBytes  4.10 Gbits/sec      receiver

The second result is from this commit with TCP GRO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  10.6 GBytes  9.14 Gbits/sec   20 sender
[  5]   0.00-10.00  sec  10.6 GBytes  9.14 Gbits/sec      receiver

Updates #6816

Signed-off-by: Jordan Whited <jordan@tailscale.com>
2 months ago
Aaron Klotz 655b4f8fc5 net/netns: remove some logspam by avoiding logging parse errors due to unspecified addresses
I updated the address parsing stuff to return a specific error for
unspecified hosts passed as empty strings, and look for that
when logging errors. I explicitly did not make parseAddress return a
netip.Addr containing an unspecified address because at this layer,
in the absence of any host, we don't necessarily know the address
family we're dealing with.

For the purposes of this code I think this is fine, at least until
we implement #12588.

Fixes #12979

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
2 months ago
Brad Fitzpatrick 004dded0a8 net/tlsdial: relax self-signed cert health warning
It seems some security software or macOS itself might be MITMing TLS
(for ScreenTime?), so don't warn unless it fails x509 validation
against system roots.

Updates #3198

Change-Id: I6ea381b5bb6385b3d51da4a1468c0d803236b7bf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 months ago
Aaron Klotz 0def4f8e38 net/netns: on Windows, fall back to default interface index when unspecified address is passed to ControlC and bindToInterfaceByRoute is enabled
We were returning an error instead of binding to the default interface.

Updates #12979

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
2 months ago
Jordan Whited 7bc2ddaedc
go.mod,net/tstun,wgengine/netstack: implement gVisor TCP GSO for Linux (#12869)
This commit implements TCP GSO for packets being read from gVisor on
Linux. Windows support will follow later. The wireguard-go dependency is
updated in order to make use of newly exported GSO logic from its tun
package.

A new gVisor stack.LinkEndpoint implementation has been established
(linkEndpoint) that is loosely modeled after its predecessor
(channel.Endpoint). This new implementation supports GSO of monster TCP
segments up to 64K in size, whereas channel.Endpoint only supports up to
32K. linkEndpoint will also be required for GRO, which will be
implemented in a follow-on commit.

TCP throughput from gVisor, i.e. TUN read direction, is dramatically
improved as a result of this commit. Benchmarks show substantial
improvement through a wide range of RTT and loss conditions, sometimes
as high as 5x.

The iperf3 results below demonstrate the effect of this commit between
two Linux computers with i5-12400 CPUs. There is roughly ~13us of round
trip latency between them.

The first result is from commit 57856fc without TCP GSO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  2.51 GBytes  2.15 Gbits/sec  154 sender
[  5]   0.00-10.00  sec  2.49 GBytes  2.14 Gbits/sec      receiver

The second result is from this commit with TCP GSO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  12.6 GBytes  10.8 Gbits/sec    6 sender
[  5]   0.00-10.00  sec  12.6 GBytes  10.8 Gbits/sec      receiver

Updates #6816

Signed-off-by: Jordan Whited <jordan@tailscale.com>
2 months ago
Andrea Gottardo 949b15d858
net/captivedetection: call SetHealthy once connectivity restored (#12974)
Fixes tailscale/tailscale#12973
Updates tailscale/tailscale#1634

There was a logic issue in the captive detection code we shipped in https://github.com/tailscale/tailscale/pull/12707.

Assume a captive portal has been detected, and the user notified. Upon switching to another Wi-Fi that does *not* have a captive portal, we were issuing a signal to interrupt any pending captive detection attempt. However, we were not also setting the `captive-portal-detected` warnable to healthy. The result was that any "captive portal detected" alert would not be cleared from the UI.

Also fixes a broken log statement value.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
2 months ago
Jonathan Nobels 8a8ecac6a7
net/dns, cmd/tailscaled: plumb system health tracker into dns cleanup (#12969)
fixes tailscale#12968

The dns manager cleanup func was getting passed a nil
health tracker, which will panic.  Fixed to pass it
the system health tracker.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
2 months ago
Jonathan Nobels 19b0c8a024
net/dns, health: raise health warning for failing forwarded DNS queries (#12888)
updates tailscale/corp#21823

Misconfigured, broken, or blocked DNS will often present as
"internet is broken'" to the end user.  This  plumbs the health tracker
into the dns manager and forwarder and adds a health warning
with a 5 second delay that is raised on failures in the forwarder and
lowered on successes.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
2 months ago
Andrea Gottardo 6840f471c0
net/dnsfallback: set CanPort80 in static DERPMap (#12929)
Updates tailscale/corp#21949

As discussed with @raggi, this PR updates the static DERPMap embedded in the client to reflect the availability of HTTP on the DERP servers run by Tailscale.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
2 months ago
Andrea Gottardo 90be06bd5b
health: introduce captive-portal-detected Warnable (#12707)
Updates tailscale/tailscale#1634

This PR introduces a new `captive-portal-detected` Warnable which is set to an unhealthy state whenever a captive portal is detected on the local network, preventing Tailscale from connecting.



ipn/ipnlocal: fix captive portal loop shutdown


Change-Id: I7cafdbce68463a16260091bcec1741501a070c95

net/captivedetection: fix mutex misuse

ipn/ipnlocal: ensure that we don't fail to start the timer


Change-Id: I3e43fb19264d793e8707c5031c0898e48e3e7465

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
2 months ago
Jordan Whited f0b9d3f477
net/tstun: fix docstring for Wrapper.SetWGConfig (#12796)
Updates #cleanup

Signed-off-by: Jordan Whited <jordan@tailscale.com>
2 months ago
KevinLiang10 8d7b78f3f7 net/dns/publicdns: remove additional information in DOH URL passed to IPv6 address generation for controlD.
This commit truncates any additional information (mainly hostnames) that's passed to controlD via DOH URL in DoHIPsOfBase.
This change is to make sure only resolverID is passed to controlDv6Gen but not the additional information.

Updates: #7946
Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com>
2 months ago
Brad Fitzpatrick c6af5bbfe8 all: add test for package comments, fix, add comments as needed
Updates #cleanup

Change-Id: Ic4304e909d2131a95a38b26911f49e7b1729aaef
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 months ago
Maisem Ali 2238ca8a05 go.mod: bump bart
Updates #bart

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 months ago
Nick Khyl 8bd442ba8c util/winutil/gp, net/dns: add package for Group Policy API
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>
2 months ago
Jonathan Nobels 4e5ef5b628
net/dns: fix broken dns benchmark tests (#12686)
Updates tailscale/corp#20677

The recover function wasn't getting set in the benchmark
tests.  Default changed to an empty func.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
3 months ago
James Tucker b565a9faa7 cmd/xdpderper: add autodetection for default interface name
This makes deployment easier in hetrogenous environments.

Updates ENG-4274

Signed-off-by: James Tucker <james@tailscale.com>
3 months ago
Brad Fitzpatrick 9766f0e110 net/dns: move mutex before the field it guards
And some misc doc tweaks for idiomatic Go style.

Updates #cleanup

Change-Id: I3ca45f78aaca037f433538b847fd6a9571a2d918
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 months ago
Andrew Dunham 0323dd01b2 ci: enable checklocks workflow for specific packages
This turns the checklocks workflow into a real check, and adds
annotations to a few basic packages as a starting point.

Updates #12625

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I2b0185bae05a843b5257980fc6bde732b1bdd93f
3 months ago
Andrew Dunham 53a5d00fff net/dns: ensure /etc/resolv.conf is world-readable even with a umask
Previously, if we had a umask set (e.g. 0027) that prevented creating a
world-readable file, /etc/resolv.conf would be created without the o+r
bit and thus other users may be unable to resolve DNS.

Since a umask only applies to file creation, chmod the file after
creation and before renaming it to ensure that it has the appropriate
permissions.

Updates #12609

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I2a05d64f4f3a8ee8683a70be17a7da0e70933137
3 months ago
Andrew Dunham a475c435ec net/dns/resolver: fix test failure
Updates #cleanup

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0e815a69ee44ca0ff7c0ea0ca3c6904bbf67ed1f
3 months ago
Jonathan Nobels 27033c6277
net/dns: recheck DNS config on SERVFAIL errors (#12547)
Fixes tailscale/corp#20677

Replaces the original attempt to rectify this (by injecting a netMon
event) which was both heavy handed, and missed cases where the
netMon event was "minor".

On apple platforms, the fetching the interface's nameservers can
and does return an empty list in certain situations.   Apple's API
in particular is very limiting here.  The header hints at notifications
for dns changes which would let us react ahead of time, but it's all
private APIs.

To avoid remaining in the state where we end up with no
nameservers but we absolutely need them, we'll react
to a lack of upstream nameservers by attempting to re-query
the OS.

We'll rate limit this to space out the attempts.   It seems relatively
harmless to attempt a reconfig every 5 seconds (triggered
by an incoming query) if the network is in this broken state.

Missing nameservers might possibly be a persistent condition
(vs a transient error), but that would  also imply that something
out of our control is badly misconfigured.

Tested by randomly returning [] for the nameservers.   When switching
between Wifi networks, or cell->wifi, this will randomly trigger
the bug, and we appear to reliably heal the DNS state.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
3 months ago
Aaron Klotz 7dd76c3411 net/netns: add Windows support for bind-to-interface-by-route
This is implemented via GetBestInterfaceEx. Should we encounter errors
or fail to resolve a valid, non-Tailscale interface, we fall back to
returning the index for the default interface instead.

Fixes #12551

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
3 months ago
Aaron Klotz d7a4f9d31c net/dns: ensure multiple hosts with the same IP address are combined into a single HostEntry
This ensures that each line has a unique IP address.

Fixes #11939

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
3 months ago