Commit Graph

84 Commits (7b1c764088673cfe17e2a8695170cdec8cfc47fd)

Author SHA1 Message Date
Brad Fitzpatrick c37af58ea4 net/tsdial: move more weirdo dialing into new tsdial package, plumb
Not done yet, but this move more of the outbound dial special casing
from random packages into tsdial, which aspires to be the one unified
place for all outbound dialing shenanigans.

Then this plumbs it all around, so everybody is ultimately
holding on to the same dialer.

As of this commit, macOS/iOS using an exit node should be able to
reach to the exit node's DoH DNS proxy over peerapi, doing the sockopt
to stay within the Network Extension.

A number of steps remain, including but limited to:

* move a bunch more random dialing stuff

* make netstack-mode tailscaled be able to use exit node's DNS proxy,
  teaching tsdial's resolver to use it when an exit node is in use.

Updates #1713

Change-Id: I1e8ee378f125421c2b816f47bc2c6d913ddcd2f5
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 3ae6f898cf ipn/ipnlocal, net/dns/resolver: use exit node's DoH proxy when available
Updates #1713

Change-Id: I3695a40ec12d2b4e6dac41cf4559daca6dddd68e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 135580a5a8 tailcfg, ipn/ipnlocal, net/dns: forward exit node DNS on Unix to system DNS
Updates #1713

Change-Id: I4c073fec0992d9e01a9a4ce97087d5af0efdc68d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 78b0bd2957 net/dns/resolver: add clientmetrics for DNS
Fixes tailscale/corp#1811

Change-Id: I864d11e0332a177e8c5ff403591bff6fec548f5a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 25525b7754 net/dns/resolver, ipn/ipnlocal: wire up peerapi DoH server to DNS forwarder
Updates #1713

Change-Id: Ia4ed9d8c9cef0e70aa6d30f2852eaab80f5f695a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Josh Bleecher Snyder 758c37b83d net/netns: thread logf into control functions
So that darwin can log there without panicking during tests.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
3 years ago
Maisem Ali 7817ab6b20 net/dns/resolver: set maxDoHInFlight to 1000 on iOS 15+.
Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
David Crawshaw 77696579f5 net/dns/resolver: drop dropping log
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
3 years ago
Smitty b382161fe5 tsdns: don't forward transient DNS errors
When a DNS server claims to be unable or unwilling to handle a request,
instead of passing that refusal along to the client, just treat it as
any other error trying to connect to the DNS server. This prevents DNS
requests from failing based on if a server can respond with a transient
error before another server is able to give an actual response. DNS
requests only failing *sometimes* is really hard to find the cause of
(#1033).

Signed-off-by: Smitty <me@smitop.com>
3 years ago
Denton Gentry d883747d8b net/dns/resolver: don't forward DNS-SD on all platforms
We added the initial handling only for macOS and iOS.
With 1.16.0 now released, suppress forwarding DNS-SD
on all platforms to test it through the 1.17.x cycle.

Updates #2442

Signed-off-by: Denton Gentry <dgentry@tailscale.com>
3 years ago
Brad Fitzpatrick 297d1b7cb6 net/dns/resolver: don't forward DNS-SD queries
Updates #2442
Fixes tailscale/corp#2820

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 7634af5c6f all: gofmt
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Filippo Valsorda d7ce2be5f4 net/dns/resolver: add unsecured Quad9 resolvers
DNSSEC is an availability issue, as recently demonstrated by the
Slack issue, with limited security advantage. DoH on the other hand
is a critical security upgrade. This change adds DoH support for the
non-DNSSEC endpoints of Quad9.

https://www.quad9.net/service/service-addresses-and-features#unsec
Signed-off-by: Filippo Valsorda <hi@filippo.io>
3 years ago
David Crawshaw 9502b515f1 net/dns: replace resolver IPs with type for DoH
We currently plumb full URLs for DNS resolvers from the control server
down to the client. But when we pass the values into the net/dns
package, we throw away any URL that isn't a bare IP. This commit
continues the plumbing, and gets the URL all the way to the built in
forwarder. (It stops before plumbing URLs into the OS configurations
that can handle them.)

For #2596

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
3 years ago
Adrian Dewhurst 8bdf878832 net/dns/resolver: use forwarded dns txid directly
Previously, we hashed the question and combined it with the original
txid which was useful when concurrent queries were multiplexed on a
single local source port. We encountered some situations where the DNS
server canonicalizes the question in the response (uppercase converted
to lowercase in this case), which resulted in responses that we couldn't
match to the original request due to hash mismatches. This includes a
new test to cover that situation.

Fixes #2597

Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
3 years ago
David Crawshaw f414a9cc01 net/dns/resolver: EDNS OPT record off-by-one
I don't know how to get access to a real packet. Basing this commit
entirely off:

       +------------+--------------+------------------------------+
       | Field Name | Field Type   | Description                  |
       +------------+--------------+------------------------------+
       | NAME       | domain name  | MUST be 0 (root domain)      |
       | TYPE       | u_int16_t    | OPT (41)                     |
       | CLASS      | u_int16_t    | requestor's UDP payload size |
       | TTL        | u_int32_t    | extended RCODE and flags     |
       | RDLEN      | u_int16_t    | length of all RDATA          |
       | RDATA      | octet stream | {attribute,value} pairs      |
       +------------+--------------+------------------------------+

From https://datatracker.ietf.org/doc/html/rfc6891#section-6.1.2

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
3 years ago
Brad Fitzpatrick 53a2f63658 net/dns/resolver: race well-known resolvers less aggressively
Instead of blasting away at all upstream resolvers at the same time,
make a timing plan upon reconfiguration and have each upstream have an
associated start delay, depending on the overall forwarding config.

So now if you have two or four upstream Google or Cloudflare DNS
servers (e.g. two IPv4 and two IPv6), we now usually only send a
query, not four.

This is especially nice on iOS where we start fewer DoH queries and
thus fewer HTTP/1 requests (because we still disable HTTP/2 on iOS),
fewer sockets, fewer goroutines, and fewer associated HTTP buffers,
etc, saving overall memory burstiness.

Fixes #2436
Updates tailscale/corp#2250
Updates tailscale/corp#2238

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick e94ec448a7 net/dns/resolver: add forwardQuery type as race work prep
Add a place to hang state in a future change for #2436.
For now this just simplifies the send signature without
any functional change.

Updates #2436

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 064b916b1a net/dns/resolver: fix func used as netaddr.IP in printf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 2968893add net/dns/resolver: bound DoH usage on iOS
Updates tailscale/corp#2238

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 3daf27eaad net/dns/resolver: fall back to IPv6 for well-known DoH servers if v4 fails
Should help with IPv6-only environments when the tailnet admin
only specified IPv4 DNS IPs.

See https://github.com/tailscale/tailscale/issues/2447#issuecomment-884188562

Co-Author: Adrian Dewhurst <adrian@tailscale.com>
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 74eee4de1c net/dns/resolver: use correct Cloudflare DoH hostnames
We were using the wrong ones for the malware & adult content
variants. Docs:

https://developers.cloudflare.com/1.1.1.1/1.1.1.1-for-families/setup-instructions/dns-over-https

Earlier commit which added them:
236eb4d04d

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 236eb4d04d net/dns/resolver: upgrade forwarded MagicDNS queries to DoH when IP known
Recognize Cloudflare, Google, Quad9 which are by far the
majority of upstream DNS servers that people use.

RELNOTE=MagicDNS now uses DNS-over-HTTPS when querying popular upstream resolvers,
so DNS queries aren't sent in the clear over the Internet.

Updates #915 (might fix it?)
Updates #988 (gets us closer, if it fixes Android)
Updates #74 (not yet configurable, but progress)
Updates #2056 (not yet configurable, dup of #74?)

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Adrian Dewhurst bcaae3e074 net/dns/resolver: clamp EDNS size
This change (subject to some limitations) looks for the EDNS OPT record
in queries and responses, clamping the size field to fit within our DNS
receive buffer. If the size field is smaller than the DNS receive buffer
then it is left unchanged.

I think we will eventually need to transition to fully processing the
DNS queries to handle all situations, but this should cover the most
common case.

Mostly fixes #2066

Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
3 years ago
Brad Fitzpatrick 45e64f2e1a net/dns{,/resolver}: refactor DNS forwarder, send out of right link on macOS/iOS
Fixes #2224
Fixes tailscale/corp#2045

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Adrian Dewhurst 8b11937eaf net/dns/resolver: permit larger max responses, signal truncation
This raises the maximum DNS response message size from 512 to 4095. This
should be large enough for almost all situations that do not need TCP.
We still do not recognize EDNS, so we will still forward requests that
claim support for a larger response size than 4095 (that will be solved
later). For now, when a response comes back that is too large to fit in
our receive buffer, we now set the truncation flag in the DNS header,
which is an improvement from before but will prompt attempts to use TCP
which isn't supported yet.

On Windows, WSARecvFrom into a buffer that's too small returns an error
in addition to the data. On other OSes, the extra data is silently
discarded. In this case, we prefer the latter so need to catch the error
on Windows.

Partially addresses #1123

Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
3 years ago
David Anderson 7fab244614 net/dns/resolver: don't spam logs on EHOSTUNREACH.
Fixes #1719.

Signed-off-by: David Anderson <danderson@tailscale.com>
3 years ago
David Anderson 30f5d706a1 net/dns/resolver: remove unnecessary/racy WaitGroup.
Fixes #1663

Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson 1a371b93be util/dnsname: add FQDN type, use throughout codebase.
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson 6def647514 net/dns/resolver: don't avoid tailscale routes for DNS forwarding.
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson c4530971db net/dns/resolver: remove leftover debug print.
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson 9f105d3968 net/dns/resolver: teach the forwarder to do per-domain routing.
Given a DNS route map, the forwarder selects the right set of
upstreams for a given name.

Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson f185d62dc8 net/dns/resolver: unexport Packet, only use it internally.
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson d99f5b1596 net/dns/resolver: factor the resolver out into a sub-package.
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago