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tailscale/net
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>
1 year ago
..
art all: fix new lint warnings from bumping staticcheck 1 year ago
captivedetection net/captivedetection: mark TestAllEndpointsAreUpAndReturnExpectedResponse flaky (#13021) 1 year ago
connstats all: use Go 1.22 range-over-int 2 years ago
dns net/dns/resolver: fix dns-sd NXDOMAIN responses from quad-100 1 year ago
dnscache net/dnscache: use parent context to perform lookup 1 year ago
dnsfallback {control,net}: close idle connections of custom transports 1 year ago
flowtrack net/flowtrack: fix, test String method 1 year ago
ipset go.mod: bump bart 1 year ago
ktimeout net/ktimeout: add a package to set TCP user timeout 2 years ago
memnet net/memnet: export the network name (#9111) 2 years ago
netaddr all: update copyright and license headers 3 years ago
netcheck net/netcheck,wgengine/magicsock: plumb OnlyTCP443 controlknob through netcheck (#13491) 1 year ago
neterror net/neterror, wgengine/magicsock: use UDP GSO and GRO on Linux (#7791) 3 years ago
netkernelconf ipn/{ipnlocal,localapi},net/netkernelconf,client/tailscale,cmd/containerboot: optionally enable UDP GRO forwarding for containers (#12410) 2 years ago
netknob all: update copyright and license headers 3 years ago
netmon all: fix new lint warnings from bumping staticcheck 1 year ago
netns net/netns: remove some logspam by avoiding logging parse errors due to unspecified addresses 1 year ago
netstat all: add test for package comments, fix, add comments as needed 1 year ago
netutil all: add test for package comments, fix, add comments as needed 1 year ago
packet wgengine/magicsock: actually use AF_PACKET socket for raw disco 1 year ago
ping net/ping: fix ICMP echo code field to 0 2 years ago
portmapper all: use math/rand/v2 more 2 years ago
proxymux all: cleanup unused code, part 1 (#10661) 2 years ago
routetable net/{interfaces,netmon}, all: merge net/interfaces package into net/netmon 2 years ago
socks5 net/socks5: support UDP 1 year ago
sockstats net/{interfaces,netmon}, all: merge net/interfaces package into net/netmon 2 years ago
speedtest all: update copyright and license headers 3 years ago
stun ci: enable checklocks workflow for specific packages 1 year ago
stunserver all: use Go 1.22 range-over-int 2 years ago
tcpinfo all: use Go 1.22 range-over-int 2 years ago
tlsdial cmd/tta, vnet: add host firewall, env var support, more tests 1 year ago
tsaddr net/ipset, wgengine/filter/filtertype: add split-out packages 1 year ago
tsdial {control,net}: close idle connections of custom transports 1 year ago
tshttpproxy all: use Go 1.22 range-over-int 2 years ago
tstun net/tstun: probe TCP GRO (#13376) 1 year ago
wsconn go.{mod,sum}: migrate from nhooyr.io/websocket to github.com/coder/websocket 1 year ago