Commit Graph

20 Commits

Author SHA1 Message Date
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>
2022-02-14 14:28:08 -08:00
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>
2022-02-14 10:47:48 -08:00
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>
2022-01-24 11:51:23 -08:00
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>
2022-01-13 23:01:29 +00:00
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>
2022-01-13 23:01:29 +00:00
Brad Fitzpatrick
aaf2df7ab1 net/{dnscache,interfaces}: use netaddr.IP.IsPrivate, delete copied code
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2021-07-26 20:30:28 -07:00
Brad Fitzpatrick
c17d743886 net/dnscache: update a comment
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2021-07-26 16:16:08 -07:00
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>
2021-07-26 15:44:32 -07:00
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>
2021-07-26 12:27:46 -07:00
Brad Fitzpatrick
9df4185c94 control/controlclient, net/{dnscache,dnsfallback}: add DNS fallback mechanism
Updates 
Updates 

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2021-03-01 18:42:03 -08:00
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>
2021-01-06 19:53:13 -08:00
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>
2020-11-11 12:50:04 -08:00
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
2020-11-11 09:17:04 -08:00
David Anderson
657f331e8b net/dnscache: remove unnecessary lint warning. 2020-04-30 20:31:44 -07:00
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>
2020-04-27 12:04:39 -07:00
Brad Fitzpatrick
bd0e20f351 net/dnscache: ignore annoying staticcheck check 2020-03-09 22:12:22 -07:00
Brad Fitzpatrick
d44325295e net/dnscache: initialize the single Resolver more directly 2020-03-09 21:05:01 -07:00
David Crawshaw
cac68fe102 net/dnscache: do not PreferGo on macOS/iOS
With this commit my iPhone can now DERP.
2020-03-09 14:20:09 -04:00
David Crawshaw
5a1ce4adae net/dnscache: parse passed CIDR
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
2020-03-09 13:11:35 -04:00
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  (can be better later, of course)
2020-03-05 12:23:37 -08:00