Commit Graph

66 Commits (f7a7957a118c071cab3f86cdb3e786ed0756538c)

Author SHA1 Message Date
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>
3 years ago
David Anderson 1a371b93be util/dnsname: add FQDN type, use throughout codebase.
Signed-off-by: David Anderson <danderson@tailscale.com>
3 years ago
David Anderson 6def647514 net/dns/resolver: don't avoid tailscale routes for DNS forwarding.
Signed-off-by: David Anderson <danderson@tailscale.com>
3 years ago
David Anderson c4530971db net/dns/resolver: remove leftover debug print.
Signed-off-by: David Anderson <danderson@tailscale.com>
3 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>
3 years ago
David Anderson f185d62dc8 net/dns/resolver: unexport Packet, only use it internally.
Signed-off-by: David Anderson <danderson@tailscale.com>
3 years ago
David Anderson d99f5b1596 net/dns/resolver: factor the resolver out into a sub-package.
Signed-off-by: David Anderson <danderson@tailscale.com>
3 years ago