Every netmap change, including an incremental delta of a single peer,
rebuilt the full MagicDNS state twice: dnsConfigForNetmap walked all
peers to build the dns.Config.Hosts map, and resolver.SetConfig then
walked that map again to build its reverse (PTR) index. On a tailnet
with 10k peers that is a lot of garbage per delta.
Instead, add a resolver.MagicDNSHosts hook, installed once by
LocalBackend, that the quad-100 resolver consults on demand at query
time. It is backed by nodeBackend's nodeByName, nodeByAddr, and peers
indexes, which are already maintained incrementally as netmap deltas
arrive. The subdomain-resolve capability check also moves to the hook
(checking the node's CapMap at query time), so dns.Config's
SubdomainHosts is no longer populated.
dns.Config.Hosts remains for control's DNS.ExtraRecords, which are
few and which feed the split-DNS decisions in dns.Manager's
compileConfig, and on Windows it still carries every node's records
because the hosts-file fallback path (compileHostEntries) needs the
complete enumerable set. Those compileConfig decisions also consulted
the per-node Hosts entries (hasHostsWithoutSplitDNSRoutes), so a new
Config.MagicDNSHostsUnrouted bit preserves that signal now that node
records are not listed: with MagicDNS names present but MagicDNS
domain routing off, quad-100 stays in the OS resolver path.
One small behavior change: reverse (PTR) lookups now also answer for
node addresses whose forward records are filtered out by the
IPv6-suppression rule (issue #1152), since nodeByAddr indexes all node
addresses. Previously such addresses were absent from the pushed
Hosts map and thus from the reverse index.
Updates #12542
Updates tailscale/corp#43949
Change-Id: I63b99199c2b3b124c08cb8bbaea1f63165095294
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
For dns.controld.com premium resolvers we synthesized per-resolver IPv6
addresses by encoding the resolver ID into the 2606:1a40::/48 range, but
those are legacy plaintext-DNS (port 53) endpoints that refuse TCP :443.
DoH now dials Control D's shared anycast IPs (the resolver ID stays in the
URL path), fixing SERVFAIL on IPv6-only/NAT64 networks where the v4
anycast fallback isn't reachable.
Fixes#20430
Signed-off-by: Brendan Creane <bcreane@gmail.com>
Due to a customer issue, I investigated the Windows Dnscache service more
intensively. I learned that the only time it attempts to read the NRPT
from group policy is in response to a group policy change notification.
Under the hypothesis that policy refresh is not effectively delivering GP
notifications due to its dependency on reaching a DC, I replaced our use
of the RefreshPolicyEx with the quasi-documented GenerateGPNotification API.
Tests have been updated to ensure they check that they are running as
LocalSystem, which is required for GenerateGPNotification.
Fixes#20187
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
Found with the regex `\b([A-Za-z]+) \1\b`.
Updates #cleanup
Change-Id: I4cc51784d9b6437d3d0c66b531828707f87f7fd5
Signed-off-by: Alex Chan <alexc@tailscale.com>
Cache the OS split-DNS capability while compiling DNS config and return directly for split-capable platforms that do not need the Apple base-config workaround.
This removes the base-config sentinel pointer and keeps the iOS and sandboxed macOS fallback path explicit.
Updates #1338
Change-Id: I836417c8fa775b35d3be9bc80cf6841d30cec222
Signed-off-by: Maisem Ali <maisem@bold.dev>
The macOS tailscaled DNS configurator only wrote /etc/resolver files, which can express split DNS but not a primary resolver. Teach it to configure a global resolver through the SystemConfiguration dynamic store using scutil when OSConfig has nameservers and no match domains.
Let non-sandboxed macOS tailscaled follow Linux split DNS behavior when its OS configurator reports split DNS support. This avoids synthesizing an upstream default route from the machine's base DNS when the netmap did not provide one. Keep iOS and sandboxed macOS app builds on the existing Apple base-config path because those use NetworkExtension DNS settings rather than tailscaled's /etc/resolver configurator.
Add tests for switching between split and global DNS, including cleanup of stale Tailscale-managed resolver files, removal of the dynamic-store global DNS key, and preservation of the sandboxed macOS behavior.
RELNOTE: tailscaled on macOS now supports configuring global DNS resolvers.
Updates #1338
Change-Id: I9b2b61f89750a5529fc0add1cd37b1b9a355db12
Signed-off-by: Maisem Ali <maisem@bold.dev>
This adds the NotifyInitialPolicy watch option and the Policy field in
Notify so that clients can receive the effective policy snapshot via IPN
bus.
This extends policyclient.Client so ipnlocal can get and watch policy
snapshots, which is used by sysPolicyChanged to notify watchers.
User-scoped policy store registration, management, and cleanup will be
added in a follow-up
Updates tailscale/corp#42259
Signed-off-by: kari <kari@tailscale.com>
In direct mode we write resolv.conf via a temp file and rename(2), which
preserves the source's generic etc_t label instead of net_conf_t, causing
AVC denials when NetworkManager later manages the file. Run restorecon
after the rename (Linux, SELinux-enforcing, best effort) to restore the
policy-default label.
Fixes#20149
Signed-off-by: Brendan Creane <bcreane@gmail.com>
This removes deprecated magic-dns formats for 4via6 subnet routers.
These are superseded by the current format: Q-R-S-T-via-X.
Fixes#20053
Change-Id: I0eed1f057f856f248c4dc8ce3b751f6c7edcfbfd
Signed-off-by: Becky Pauley <becky@tailscale.com>
When MagicDNS is enabled but no global upstream resolvers are configured,
the forwarder only handles specific suffixes and defers other names to the
system resolver. A query it has no resolver for is expected in that case, so
don't raise the dns-forward-failing warning unless a default "." route makes
Tailscale the default resolver.
Fixes#19931
Signed-off-by: Brendan Creane <bcreane@gmail.com>
Commit 2b338dd6a8 removed watchdogEngine because it was weird
(so many methods) and increasingly unnecessary after we'd cleaned up
and simplified so much of the locking.
This adds back a watchdog, but an easier to maintain one that's more
idiomatic.
Updates #19759
Change-Id: I86c458473e126c0809f37696446ce7acf4cc4eb9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
The codegen path for map-of-slice-of-pointer fields, skipped
nil-valued entries. That dropped the key from the map.
This broke how dns.Config.Routes uses nil values sentinels.
Fixes#19730Fixes#19732Fixes#19746Fixes#19744
Change-Id: Ic6400227f4ab21b3ca0e8c0eeecf9b83d145a9ab
Signed-off-by: Fernando Serboncini <fserb@tailscale.com>
A missing hosts file is not a fatal error. We should log it, but still proceed
and create a new one instead of failing the DNS reconfiguration completely.
Fixes#19733
Signed-off-by: Nick Khyl <nickk@tailscale.com>
If another part of the client code registers a custom scheme with the
forwarder, the forwarder will check resolver addresses to see if they
match the scheme. If they do, the corresponding custom scheme handler
will be called to find the actual address for the resolver at this
moment. If the handler returns the empty string then that resolver will
be ignored.
This is useful if you want to dynamically determine where to send
certain DNS requests. It is being added to support new app connector
(conn25) work that would like to make sure it sends DNS requests to the
current connector peer in a high availability configuration.
Updates tailscale/corp#39858
Signed-off-by: Fran Bull <fran@tailscale.com>
The darwinConfigurator writes split DNS resolver files to
/etc/resolver/$SUFFIX using os.WriteFile with string concatenation.
A crafted MatchDomain value containing path traversal sequences
(e.g. "../evil") could write files outside the resolver directory.
Use os.OpenRoot to confine all file operations in SetDNS and
removeResolverFiles to the resolver directory. os.Root rejects any
path component that escapes the root, returning an error instead of
following the traversal.
Also parametrize the resolver directory path on the struct to enable
testing with t.TempDir(), and add tests.
As far as I can tell, this would require a malicious controlplane to
exploit, but still worth fixing.
Updates tailscale/corp#39751
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
The cloner's codegen for map[K][]*V fields was doing a shallow
append (copying pointer values) instead of cloning each element.
This meant that cloned structs aliased the original's pointed-to
values through the map's slice entries.
Mirror the existing standalone-slice logic that checks
ContainsPointers(sliceType.Elem()) and generates per-element
cloning for pointer, interface, and struct types.
Regenerate net/dns and tailcfg which both had affected
map[...][]*dnstype.Resolver fields.
Fixes#19284
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
The test had two problems:
1. runFileWatcher passed hardcoded "/etc/" to the inotify watcher,
but the test filesystem uses a temp directory prefix. The watcher
was watching the real /etc/, never seeing the test's file writes.
2. The test's watchFile used gonotify.NewDirWatcher which creates
goroutines that block on real inotify syscalls. These don't work
inside synctest's fake-time bubble. The test only passed standalone
by accident: gonotify walks /etc/ on startup producing fake events
that happened to trigger trample detection at the right time.
Fix the path issue by adding ActualPath to the wholeFileFS interface,
which translates logical paths (like "/etc/resolv.conf") to real
filesystem paths (respecting any test prefix). Use it in
runFileWatcher so the inotify watch targets the correct directory.
Replace gonotify in the test with a one-shot timer that synctest can
advance through fake time, reliably triggering the trample check.
Fixes#19400
Change-Id: Idb252881ec24d0ab3b3c1d154dbdaf532db837d4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Avery found a bunch of tests that fail with -count=2.
Updates tailscale/corp#40176 (tracks making our CI detect them)
Change-Id: Ie3e4398070dd92e4fe0146badddf1254749cca20
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Co-authored-by: Avery Pennarun <apenwarr@tailscale.com>
The cloner and viewer code generators didn't handle named types
with basic underlying types (map/slice) that have their own Clone
or View methods. For example, a type like:
type Map map[string]any
func (m Map) Clone() Map { ... }
func (m Map) View() MapView { ... }
When used as a struct field, the cloner would descend into the
underlying map[string]any and fail because it can't clone the any
(interface{}) value type. Similarly, the viewer would try to create
a MapFnOf view and fail.
Fix the cloner to check for a Clone method on the named type
before falling through to the underlying type handling.
Fix the viewer to check for a View method on named map/slice types,
so the type author can provide a purpose-built safe view that
doesn't leak raw any values. Named map/slice types without a View
method fall through to normal handling, which correctly rejects
types like map[string]any as unsupported.
Updates tailscale/corp#39502 (needed by tailscale/corp#39594)
Change-Id: Iaef0192a221e02b4b8e409c99ef8398090327744
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Add a new vet analyzer that checks t.Run subtest names don't contain
characters requiring quoting when re-running via "go test -run". This
enforces the style guide rule: don't use spaces or punctuation in
subtest names.
The analyzer flags:
- Direct t.Run calls with string literal names containing spaces,
regex metacharacters, quotes, or other problematic characters
- Table-driven t.Run(tt.name, ...) calls where tt ranges over a
slice/map literal with bad name field values
Also fix all 978 existing violations across 81 test files, replacing
spaces with hyphens and shortening long sentence-like names to concise
hyphenated forms.
Updates #19242
Change-Id: Ib0ad96a111bd8e764582d1d4902fe2599454ab65
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
When racing multiple upstream DNS resolvers, a REFUSED (RCode 5) response
from a broken or misconfigured resolver could win the race and be returned
to the client before healthier resolvers had a chance to respond with a
valid answer. This caused complete DNS failure in cases where, e.g., a
broken upstream resolver returned REFUSED quickly while a working resolver
(such as 1.1.1.1) was still responding.
Previously, only SERVFAIL (RCode 2) was treated as a soft error. REFUSED
responses were returned as successful bytes and could win the race
immediately. This change also treats REFUSED as a soft error in the UDP
and TCP forwarding paths, so the race continues until a better answer
arrives. If all resolvers refuse, the first REFUSED response is returned
to the client.
Additionally, SERVFAIL responses from upstream resolvers are now returned
verbatim to the client rather than replaced with a locally synthesized
packet. Synthesized SERVFAIL responses were authoritative and guaranteed
to include a question section echoing the original query; upstream
responses carry no such guarantees but may include extended error
information (e.g. RFC 8914 extended DNS errors) that would otherwise
be lost.
Fixes#19024
Signed-off-by: Brendan Creane <bcreane@gmail.com>
I omitted a lot of the min/max modernizers because they didn't
result in more clear code.
Some of it's older "for x := range 123".
Also: errors.AsType, any, fmt.Appendf, etc.
Updates #18682
Change-Id: I83a451577f33877f962766a5b65ce86f7696471c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
The new version of app connector (conn25) needs to read DNS responses
for domains it is interested in and store and swap out IP addresses.
Add a hook to dns manager to enable this.
Give the conn25 updated netmaps so that it knows when to assign
connecting addresses and from what pool.
Assign an address when we see a DNS response for a domain we are
interested in, but don't do anything with the address yet.
Updates tailscale/corp#34252
Signed-off-by: Fran Bull <fran@tailscale.com>
This adds a new ControlKnob to make MagicDNS IPv6 registration
(telling systemd/etc) opt-out rather than opt-in.
Updates #15404
Change-Id: If008e1cb046b792c6aff7bb1d7c58638f7d650b1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
In the absence of a better mechanism, writing unqualified hostnames to the hosts file may be required
for MagicDNS to work on some Windows environments, such as domain-joined machines. It can also
improve MagicDNS performance on non-domain joined devices when we are not the device's primary
DNS resolver.
At the same time, updating the hosts file can be slow and expensive, especially when it already contains
many entries, as was previously reported in #14327. It may also have negative side effects, such as interfering
with the system's DNS resolution policies.
Additionally, to fix#18712, we had to extend hosts file usage to domain-joined machines when we are not
the primary DNS resolver. For the reasons above, this change may introduce risk.
To allow customers to disable hosts file updates remotely without disabling MagicDNS entirely, whether on
domain-joined machines or not, this PR introduces the `disable-hosts-file-updates` node attribute.
Updates #18712
Updates #14327
Signed-off-by: Nick Khyl <nickk@tailscale.com>
On domain-joined Windows devices the primary search domain (the one the device is joined to)
always takes precedence over other search domains. This breaks MagicDNS when we are the primary
resolver on the device (see #18712). To work around this Windows behavior, we should write MagicDNS
host names the hosts file just as we do when we're not the primary resolver.
This commit does exactly that.
Fixes#18712
Signed-off-by: Nick Khyl <nickk@tailscale.com>
fixestailscale/tailscale#18436
Queries can still make their way to the forwarder when accept-dns is disabled.
Since we have not configured the forwarder if --accept-dns is false, this errors out
(correctly) but it also generates a persistent health warning. This forwards the
Pref setting all the way through the stack to the forwarder so that we can be more
judicious about when we decide that the forward path is unintentionally missing, vs
simply not configured.
Testing:
tailscale set --accept-dns=false. (or from the GUI)
dig @100.100.100.100 example.com
tailscale status
No dns related health warnings should be surfaced.
Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
The forwarder was not setting the Truncated (TC) flag when UDP DNS
responses exceeded either the EDNS buffer size (if present) or the
RFC 1035 default 512-byte limit. This affected DoH, TCP fallback,
and UDP response paths.
The fix ensures checkResponseSizeAndSetTC is called in all code paths
that return UDP responses, enforcing both EDNS and default UDP size
limits.
Added comprehensive unit tests and consolidated duplicate test helpers.
Updates #18107
Signed-off-by: Brendan Creane <bcreane@gmail.com>
This adds a new node capability 'dns-subdomain-resolve' that signals
that all of hosts' subdomains should resolve to the same IP address.
It allows wildcard matching on any node marked with this capability.
This change also includes an util/dnsname utility function that lets
us access the parent of a full qualified domain name. MagicDNS takes
this function and recursively searchs for a matching real node name.
One important thing to observe is that, in this context, a subdomain
can have multiple sub labels. This means that for a given node named
machine, both my.machine and be.my.machine will be a positive match.
Updates #1196
Signed-off-by: Fernando Serboncini <fserb@tailscale.com>
When tailscaled gets started with userspace networking, it won't
modify your system's network configuration. For this, it creates
a noopManager for DNS management. noopManager correctly observes
that there's no real OS DNS to send queries to. This leads to we
completely dropping any DNS internal resolution from `dns query`
This change alters this so that even without a base config we'll
still allow the internal resolver to handle internal DNS queries
Fixes#18354
Signed-off-by: Fernando Serboncini <fserb@tailscale.com>
Someone asked me if we use DNS-over-HTTPS if the system's resolver is an
IP address that supports DoH and there's no global nameserver set (i.e.
no "Override DNS servers" set). I didn't know the answer offhand, and it
took a while for me to figure it out. The answer is yes, in cases where
we take over the system's DNS configuration and read the base config, we
do upgrade any DoH-capable resolver to use DoH. Here's a test that
verifies this behaviour (and hopefully helps as documentation the next
time someone has this question).
Updates #cleanup
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
This file was never truly necessary and has never actually been used in
the history of Tailscale's open source releases.
A Brief History of AUTHORS files
---
The AUTHORS file was a pattern developed at Google, originally for
Chromium, then adopted by Go and a bunch of other projects. The problem
was that Chromium originally had a copyright line only recognizing
Google as the copyright holder. Because Google (and most open source
projects) do not require copyright assignemnt for contributions, each
contributor maintains their copyright. Some large corporate contributors
then tried to add their own name to the copyright line in the LICENSE
file or in file headers. This quickly becomes unwieldy, and puts a
tremendous burden on anyone building on top of Chromium, since the
license requires that they keep all copyright lines intact.
The compromise was to create an AUTHORS file that would list all of the
copyright holders. The LICENSE file and source file headers would then
include that list by reference, listing the copyright holder as "The
Chromium Authors".
This also become cumbersome to simply keep the file up to date with a
high rate of new contributors. Plus it's not always obvious who the
copyright holder is. Sometimes it is the individual making the
contribution, but many times it may be their employer. There is no way
for the proejct maintainer to know.
Eventually, Google changed their policy to no longer recommend trying to
keep the AUTHORS file up to date proactively, and instead to only add to
it when requested: https://opensource.google/docs/releasing/authors.
They are also clear that:
> Adding contributors to the AUTHORS file is entirely within the
> project's discretion and has no implications for copyright ownership.
It was primarily added to appease a small number of large contributors
that insisted that they be recognized as copyright holders (which was
entirely their right to do). But it's not truly necessary, and not even
the most accurate way of identifying contributors and/or copyright
holders.
In practice, we've never added anyone to our AUTHORS file. It only lists
Tailscale, so it's not really serving any purpose. It also causes
confusion because Tailscalars put the "Tailscale Inc & AUTHORS" header
in other open source repos which don't actually have an AUTHORS file, so
it's ambiguous what that means.
Instead, we just acknowledge that the contributors to Tailscale (whoever
they are) are copyright holders for their individual contributions. We
also have the benefit of using the DCO (developercertificate.org) which
provides some additional certification of their right to make the
contribution.
The source file changes were purely mechanical with:
git ls-files | xargs sed -i -e 's/\(Tailscale Inc &\) AUTHORS/\1 contributors/g'
Updates #cleanup
Change-Id: Ia101a4a3005adb9118051b3416f5a64a4a45987d
Signed-off-by: Will Norris <will@tailscale.com>
When the TS_DEBUG_DNS_FORWARD_SEND envknob is turned on, also log the
source IP:port of the query that tailscaled is forwarding.
Updates tailscale/corp#35374
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
When using the resolve.conf file for setting DNS, it is possible that
some other services will trample the file and overwrite our set DNS
server. Experiments has shown this to be a racy error depending on how
quickly processes start.
Make an attempt to trample back the file a limited number of times if
the file is changed.
Updates #16635
Signed-off-by: Claus Lensbøl <claus@tailscale.com>
I got sidetracked apparently and never finished writing this Clone
code in 316afe7d02 (#17448). (It really should use views instead.)
And then I missed one of the users of "routerChanged" that was broken up
into "routerChanged" vs "dnsChanged".
This broke integration tests elsewhere.
Fixes#17506
Change-Id: I533bf0fcf3da9ac6eb4a6cdef03b8df2c1fb4c8e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Saves 45 KB from the min build, no longer pulling in deephash or
util/hashx, both with unsafe code.
It can actually be more efficient to not use deephash, as you don't
have to walk all bytes of all fields recursively to answer that two
things are not equal. Instead, you can just return false at the first
difference you see. And then with views (as we use ~everywhere
nowadays), the cloning the old value isn't expensive, as it's just a
pointer under the hood.
Updates #12614
Change-Id: I7b08616b8a09b3ade454bb5e0ac5672086fe8aec
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Saves 262 KB so far. I'm sure I missed some places, but shotizam says
these were the low hanging fruit.
Updates #12614
Change-Id: Ia31c01b454f627e6d0470229aae4e19d615e45e3
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
The callback itself is not removed as it is used in other repos, making
it simpler for those to slowly transition to the eventbus.
Updates #15160
Signed-off-by: Claus Lensbøl <claus@tailscale.com>
Saves 328 KB (2.5%) off the minimal binary.
For IoT devices that don't need MagicDNS (e.g. they don't make
outbound connections), this provides a knob to disable all the DNS
functionality.
Rather than a massive refactor today, this uses constant false values
as a deadcode sledgehammer, guided by shotizam to find the largest DNS
functions which survived deadcode.
A future refactor could make it so that the net/dns/resolver and
publicdns packages don't even show up in the import graph (along with
their imports) but really it's already pretty good looking with just
these consts, so it's not at the top of my list to refactor it more
soon.
Also do the same in a few places with the ACME (cert) functionality,
as I saw those while searching for DNS stuff.
Updates #12614
Change-Id: I8e459f595c2fde68ca16503ff61c8ab339871f97
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
