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tailscale/net/dns
James Tucker af5a845a87 net/dns/resolver: fix dns-sd NXDOMAIN responses from quad-100
mdnsResponder at least as of macOS Sequoia does not find NXDOMAIN
responses to these dns-sd PTR queries acceptable unless they include the
question section in the response. This was found debugging #13511, once
we turned on additional diagnostic reporting from mdnsResponder we
witnessed:

```
Received unacceptable 12-byte response from 100.100.100.100 over UDP via utun6/27 -- id: 0x7F41 (32577), flags: 0x8183 (R/Query, RD, RA, NXDomain), counts: 0/0/0/0,
```

If the response includes a question section, the resposnes are
acceptable, e.g.:

```
Received acceptable 59-byte response from 8.8.8.8 over UDP via en0/17 -- id: 0x2E55 (11861), flags: 0x8183 (R/Query, RD, RA, NXDomain), counts: 1/0/0/0,
```

This may be contributing to an issue under diagnosis in #13511 wherein
some combination of conditions results in mdnsResponder no longer
answering DNS queries correctly to applications on the system for
extended periods of time (multiple minutes), while dig against quad-100
provides correct responses for those same domains. If additional debug
logging is enabled in mdnsResponder we see it reporting:

```
Penalizing server 100.100.100.100 for 60 seconds
```

It is also possible that the reason that macOS & iOS never "stopped
spamming" these queries is that they have never been replied to with
acceptable responses. It is not clear if this special case handling of
dns-sd PTR queries was ever beneficial, and given this evidence may have
always been harmful. If we subsequently observe that the queries settle
down now that they have acceptable responses, we should remove these
special cases - making upstream queries very occasionally isn't a lot of
battery, so we should be better off having to maintain less special
cases and avoid bugs of this class.

Updates #2442
Updates #3025
Updates #3363
Updates #3594
Updates #13511

Signed-off-by: James Tucker <james@tailscale.com>
2 months ago
..
publicdns net/dns/publicdns: remove additional information in DOH URL passed to IPv6 address generation for controlD. 5 months ago
recursive all: use Go 1.22 range-over-int 8 months ago
resolvconffile clientupdate, net/dns: fix some "tailsacle" typos 8 months ago
resolver net/dns/resolver: fix dns-sd NXDOMAIN responses from quad-100 2 months ago
config.go all: add test for package comments, fix, add comments as needed 5 months ago
debian_resolvconf.go all: update copyright and license headers 2 years ago
direct.go net/dns: ensure /etc/resolv.conf is world-readable even with a umask 5 months ago
direct_linux.go net/dns: updated gonotify dependency to v2 that supports closable context 3 months ago
direct_notlinux.go all: update copyright and license headers 2 years ago
direct_test.go clientupdate, net/dns: fix some "tailsacle" typos 8 months ago
direct_unix_test.go net/dns: ensure /etc/resolv.conf is world-readable even with a umask 5 months ago
flush_default.go all: update copyright and license headers 2 years ago
flush_windows.go cmd/tailscaled, net/dns, wgengine/router: start Windows child processes with DETACHED_PROCESS when I/O is being piped 6 months ago
ini.go all: update copyright and license headers 2 years ago
ini_test.go all: update copyright and license headers 2 years ago
manager.go cli: implement `tailscale dns status` (#13353) 3 months ago
manager_darwin.go net/dns: support GetBaseConfig on Darwin OSS tailscaled (#13351) 3 months ago
manager_default.go various: create a catch-all NRPT rule when "Override local DNS" is enabled on Windows 6 months ago
manager_freebsd.go various: create a catch-all NRPT rule when "Override local DNS" is enabled on Windows 6 months ago
manager_linux.go various: create a catch-all NRPT rule when "Override local DNS" is enabled on Windows 6 months ago
manager_linux_test.go net/dns: ensure /etc/resolv.conf is world-readable even with a umask 5 months ago
manager_openbsd.go various: create a catch-all NRPT rule when "Override local DNS" is enabled on Windows 6 months ago
manager_tcp_test.go net/dns, health: raise health warning for failing forwarded DNS queries (#12888) 4 months ago
manager_test.go net/dns: ensure multiple hosts with the same IP address are combined into a single HostEntry 5 months ago
manager_windows.go net/dns: disable DNS registration for Tailscale interface on Windows 3 months ago
manager_windows_test.go util/winutil/gp, net/dns: add package for Group Policy API 5 months ago
nm.go all: cleanup unused code, part 2 (#10670) 11 months ago
noop.go all: update copyright and license headers 2 years ago
nrpt_windows.go util/winutil/gp, net/dns: add package for Group Policy API 5 months ago
openresolv.go net/dns: log more info when openresolv commands fail 10 months ago
osconfig.go net/dns: fix IsZero and Equal methods on OSConfig 3 months ago
osconfig_test.go net/dns: fix IsZero and Equal methods on OSConfig 3 months ago
resolvconf-workaround.sh all: update copyright and license headers 2 years ago
resolvconf.go net/dns: properly detect newer debian resolvconf 1 year ago
resolvconfpath_default.go net/dns: overwrite /tmp/resolv.conf on gokrazy 1 year ago
resolvconfpath_gokrazy.go net/dns: overwrite /tmp/resolv.conf on gokrazy 1 year ago
resolvd.go all: update copyright and license headers 2 years ago
resolved.go health, all: remove health.Global, finish plumbing health.Tracker 7 months ago
utf.go all: update copyright and license headers 2 years ago
utf_test.go all: update copyright and license headers 2 years ago
wsl_windows.go net/dns: ensure /etc/resolv.conf is world-readable even with a umask 5 months ago