Commit Graph

26 Commits (88133c361e8cc267b9e45c90f357f96084c60a0c)

Author SHA1 Message Date
Brad Fitzpatrick 13d0b8e6a4 control/controlclient, net/dnscache: use typed singleflight fork
Change-Id: I12be4c5a91ae3a812fe88d9b2d15526fdbb5a921
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick ecea6cb994 net/dns/resolver: make DoH dialer use existing dnscache happy eyeball dialer
Simplify the ability to reason about the DoH dialing code by reusing the
dnscache's dialer we already have.

Also, reduce the scope of the "ip" variable we don't want to close over.

This necessarily adds a new field to dnscache.Resolver:
SingleHostStaticResult, for when the caller already knows the IPs to be
returned.

Change-Id: I9f2aef7926f649137a5a3e63eebad6a3fffa48c0
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Maisem Ali b45bb577a0 net/dnscache: do not call LookupIPFallback if the context was canceled.
When the context is canceled, dc.dialOne returns an error from line 345.
This causes the defer on line 312 to try to resolve the host again, which
triggers a dns lookup of "127.0.0.1" from derp.

Updates tailscale/corp#4475

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Josh Bleecher Snyder 0868329936 all: use any instead of interface{}
My favorite part of generics.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2 years ago
Brad Fitzpatrick 8d6cf14456 net/dnscache: don't do bootstrap DNS lookup after most failed dials
If we've already connected to a certain name's IP in the past, don't
assume the problem was DNS related. That just puts unnecessarily load
on our bootstrap DNS servers during regular restarts of Tailscale
infrastructure components.

Also, if we do do a bootstrap DNS lookup and it gives the same IP(s)
that we already tried, don't try them again.

Change-Id: I743e8991a7f957381b8e4c1508b8e9d0df1782fe
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick 903988b392 net/dnscache: refactor from func-y closure-y state to types & methods
No behavior changes (intended, at least).

This is in prep for future changes to this package, which would get
too complicated in the current style.

Change-Id: Ic260f8e34ae2f64f34819d4a56e38bee8d8ac5ce
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick 41fd4eab5c envknob: add new package for all the strconv.ParseBool(os.Getenv(..))
A new package can also later record/report which knobs are checked and
set. It also makes the code cleaner & easier to grep for env knobs.

Change-Id: Id8a123ab7539f1fadbd27e0cbeac79c2e4f09751
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
David Anderson 463b3e8f62 net/dnscache: use tls.Conn.HandshakeContext.
Go 1.17 added a HandshakeContext func to take care of timeouts during
TLS handshaking, so switch from our homegrown goroutine implementation
to the standard way.

Signed-off-by: David Anderson <danderson@tailscale.com>
2 years ago
David Anderson a9da6b73a8 net/dnscache: don't cancel the TLS context before writing to the result channel.
Cancelling the context makes the timeout goroutine race with the write that
reports a successful TLS handshake, so you can end up with a successful TLS
handshake that mysteriously reports that it timed out after ~0s in flight.

The context is always canceled and cleaned up as the function exits, which
happens mere microseconds later, so just let function exit clean up and
thereby avoid races.

Signed-off-by: David Anderson <danderson@tailscale.com>
2 years ago
Brad Fitzpatrick 39ffa16853 net/dnscache, net/tsdial: add DNS caching to tsdial UserDial
This is enough to handle the DNS queries as generated by Go's
net package (which our HTTP/SOCKS client uses), and the responses
generated by the ExitDNS DoH server.

This isn't yet suitable for putting on 100.100.100.100 where a number
of different DNS clients would hit it, as this doesn't yet do
EDNS0. It might work, but it's untested and likely incomplete.

Likewise, this doesn't handle anything about truncation, as the
exchanges are entirely in memory between Go or DoH. That would also
need to be handled later, if/when it's hooked up to 100.100.100.100.

Updates #3507

Change-Id: I1736b0ad31eea85ea853b310c52c5e6bf65c6e2a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick aaf2df7ab1 net/{dnscache,interfaces}: use netaddr.IP.IsPrivate, delete copied code
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick c17d743886 net/dnscache: update a comment
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 281d503626 net/dnscache: make Dialer try all resolved IPs
Tested manually with:

$ go test -v ./net/dnscache/ -dial-test=bogusplane.dev.tailscale.com:80

Where bogusplane has three A records, only one of which works.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick e299300b48 net/dnscache: cache all IPs per hostname
Not yet used in the dialer, but plumbed around.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 9df4185c94 control/controlclient, net/{dnscache,dnsfallback}: add DNS fallback mechanism
Updates #1405
Updates #1403

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 66be052a70 net/dnscache: work on IPv6-only hosts (again)
This fixes the regression where we had stopped working on IPv6-only
hosts.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick a2d78b4d3e net/dnscache, control/controlclient: use DNS cache when dialing control
Cache DNS results of earlier login.tailscale.com control dials, and use
them for future dials if DNS is slow or broken.

Fixes various issues with trickier setups with the domain's DNS server
behind a subnet router.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
Brad Fitzpatrick 19b0cfe89e all: prepare for GOOS=ios in Go 1.16
Work with either way for now on iOS (darwin/arm64 vs ios/arm64).

In February when Go 1.16 comes out we'll have a universal binary for
darwin/arm64 (macOS) and will drop support for Go 1.15 and its
darwin/amd64 meaning iOS. (it'll mean macOS).

Context:

* https://tip.golang.org/doc/go1.16#darwin
* https://github.com/golang/go/issues/38485
* https://github.com/golang/go/issues/42100
4 years ago
David Anderson 657f331e8b net/dnscache: remove unnecessary lint warning. 4 years ago
Elias Naur ad0795efc2 net/dnscache: don't use the Go resolver on Android
The local resolver is not available for apps on Android.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
4 years ago
Brad Fitzpatrick bd0e20f351 net/dnscache: ignore annoying staticcheck check 4 years ago
Brad Fitzpatrick d44325295e net/dnscache: initialize the single Resolver more directly 4 years ago
David Crawshaw cac68fe102 net/dnscache: do not PreferGo on macOS/iOS
With this commit my iPhone can now DERP.
4 years ago
Brad Fitzpatrick 8f0fd01efd net/dnscache: add copyright header to test 4 years ago
David Crawshaw 5a1ce4adae net/dnscache: parse passed CIDR
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
4 years ago
Brad Fitzpatrick 2cff9016e4 net/dnscache: add overly simplistic DNS cache package for selective use
I started to write a full DNS caching resolver and I realized it was
overkill and wouldn't work on Windows even in Go 1.14 yet, so I'm
doing this tiny one instead for now, just for all our netcheck STUN
derp lookups, and connections to DERP servers. (This will be caching a
exactly 8 DNS entries, all ours.)

Fixes #145 (can be better later, of course)
4 years ago