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>
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>
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>
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>
fixestailscale/corp#25612
We now keep track of any dns configurations which we could not
compile. This gives RecompileDNSConfig a configuration to
attempt to recompile and apply when the OS pokes us to indicate
that the interface dns servers have changed/updated. The manager config
will remain unset until we have the required information to compile
it correctly which should eliminate the problematic SERVFAIL
responses (especially on macOS 15).
This also removes the missingUpstreamRecovery func in the forwarder
which is no longer required now that we have proper error handling
and recovery manager and the client.
Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
As per the docstring, (*forwarder).forwardWithDestChan should either send to responseChan
and returns nil, or returns a non-nil error (without sending to the channel).
However, this does not hold when all upstream DNS servers replied with an error.
We've been handling this special error path in (*Resolver).Query but not in (*Resolver).HandlePeerDNSQuery.
As a result, SERVFAIL responses from upstream servers were being converted into HTTP 503 responses,
instead of being properly forwarded as SERVFAIL within a successful HTTP response, as per RFC 8484, section 4.2.1:
A successful HTTP response with a 2xx status code (see Section 6.3 of [RFC7231]) is used for any valid DNS response,
regardless of the DNS response code. For example, a successful 2xx HTTP status code is used even with a DNS message
whose DNS response code indicates failure, such as SERVFAIL or NXDOMAIN.
In this PR we fix (*forwarder).forwardWithDestChan to no longer return an error when it sends a response to responseChan,
and remove the special handling in (*Resolver).Query, as it is no longer necessary.
Updates #13571
Signed-off-by: Nick Hill <mykola.khyl@gmail.com>
Updates tailscale/tailscale#13326
Adds a CLI subcommand to perform DNS queries using the internal DNS forwarder and observe its internals (namely, which upstream resolvers are being used).
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
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>
And some misc doc tweaks for idiomatic Go style.
Updates #cleanup
Change-Id: I3ca45f78aaca037f433538b847fd6a9571a2d918
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Fixestailscale/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>
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>
Updates https://github.com/tailscale/corp/issues/15802.
On iOS exclusively, this PR adds logic to use a split DNS configuration in more cases, with the goal of improving battery life. Acting as the global DNS resolver on iOS should be avoided, as it leads to frequent wakes of IPNExtension.
We try to determine if we can have Tailscale only handle DNS queries for resources inside the tailnet, that is, all routes in the DNS configuration do not require a custom resolver (this is the case for app connectors, for instance).
If so, we set all Routes as MatchDomains. This enables a split DNS configuration which will help preserve battery life. Effectively, for the average Tailscale user who only relies on MagicDNS to resolve *.ts.net domains, this means that Tailscale DNS will only be used for those domains.
This PR doesn't affect users with Override Local DNS enabled. For these users, there should be no difference and Tailscale will continue acting as a global DNS resolver.
Signed-off-by: Andrea Gottardo <andrea@tailscale.com>
The goal is to move more network state accessors to netmon.Monitor
where they can be cheaper/cached. But first (this change and others)
we need to make sure the one netmon.Monitor is plumbed everywhere.
Some notable bits:
* tsdial.NewDialer is added, taking a now-required netmon
* because a tsdial.Dialer always has a netmon, anything taking both
a Dialer and a NetMon is now redundant; take only the Dialer and
get the NetMon from that if/when needed.
* netmon.NewStatic is added, primarily for tests
Updates tailscale/corp#10910
Updates tailscale/corp#18960
Updates #7967
Updates #3299
Change-Id: I877f9cb87618c4eb037cee098241d18da9c01691
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
An EmbeddedAppConnector is added that when configured observes DNS
responses from the PeerAPI. If a response is found matching a configured
domain, routes are advertised when necessary.
The wiring from a configuration in the netmap capmap is not yet done, so
while the connector can be enabled, no domains can yet be added.
Updates tailscale/corp#15437
Signed-off-by: James Tucker <james@tailscale.com>
Advertise it on Android (it looks like it already works once advertised).
And both advertise & likely fix it on iOS. Yet untested.
Updates #9672
Change-Id: If3b7e97f011dea61e7e75aff23dcc178b6cf9123
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We weren't correctly retrying truncated requests to an upstream DNS
server with TCP. Instead, we'd return a truncated request to the user,
even if the user was querying us over TCP and thus able to handle a
large response.
Also, add an envknob and controlknob to allow users/us to disable this
behaviour if it turns out to be buggy (✨ DNS ✨).
Updates #9264
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ifb04b563839a9614c0ba03e9c564e8924c1a2bfd
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>
Add the envknob TS_DEBUG_EXIT_NODE_DNS_NET_PKG, which enables more
verbose debug logging when calling the handleExitNodeDNSQueryWithNetPkg
function. This function is currently only called on Windows and Android.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ieb3ca7b98837d7dc69cd9ca47609c1c52e3afd7b
This updates all source files to use a new standard header for copyright
and license declaration. Notably, copyright no longer includes a date,
and we now use the standard SPDX-License-Identifier header.
This commit was done almost entirely mechanically with perl, and then
some minimal manual fixes.
Updates #6865
Signed-off-by: Will Norris <will@tailscale.com>
And remove the GCP special-casing from ipn/ipnlocal; do it only in the
forwarder for *.internal.
Fixes#4980Fixes#4981
Change-Id: I5c481e96d91f3d51d274a80fbd37c38f16dfa5cb
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Currently we only support "via-<site-id>.<IPv4>", however that does not
work with Google Chrome which parses `http://via-1.10.0.0.1` as a search
string and not as a URL. This commit introduces "<IPv4>.via-<site-id>"
(`http://10.0.0.1.via-1`) which is parsed correctly by Chrome.
Updates #3616
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Fixes https://github.com/tailscale/corp/issues/5198
The upstream forwarder will block indefinitely on `udpconn.ReadFrom` if no
reply is recieved, due to the lack of deadline on the connection object.
There still isn't a deadline on the connection object, but the automatic closing
of the context on deadline expiry will close the connection via `closeOnCtxDone`,
unblocking the read and resulting in a normal teardown.
Signed-off-by: Tom DNetto <tom@tailscale.com>
Moves magicDNS-specific handling out of Resolver & into dns.Manager. This
greatly simplifies the Resolver to solely issuing queries and returning
responses, without channels.
Enforcement of max number of in-flight magicDNS queries, assembly of
synthetic UDP datagrams, and integration with wgengine for
recieving/responding to magicDNS traffic is now entirely in Manager.
This path is being kept around, but ultimately aims to be deleted and
replaced with a netstack-based path.
This commit is part of a series to implement magicDNS using netstack.
Signed-off-by: Tom DNetto <tom@tailscale.com>
Updates #2067
This should help us determine if more robust control of edns parameters
+ implementing answer truncation is warranted, given its likely complexity.
Signed-off-by: Tom DNetto <tom@tailscale.com>
* net/dns, net/dns/resolver, wgengine: refactor DNS request path
Previously, method calls into the DNS manager/resolver types handled DNS
requests rather than DNS packets. This is fine for UDP as one packet
corresponds to one request or response, however will not suit an
implementation that supports DNS over TCP.
To support PRs implementing this in the future, wgengine delegates
all handling/construction of packets to the magic DNS endpoint, to
the DNS types themselves. Handling IP packets at this level enables
future support for both UDP and TCP.
Signed-off-by: Tom DNetto <tom@tailscale.com>
Brad Fitzpatrick
Jonathan Nobels
Brendan Creane
Fernando Serboncini
Will Norris
Nahum Shalman
Nick Hill
Andrea Gottardo
Nick Khyl
Andrew Lytvynov
James Tucker
Andrew Dunham
Mihai Parparita
Josh Soref
Maisem Ali
Tom DNetto
Tom
Josh Bleecher Snyder