tailscale/net
Brad Fitzpatrick 7e609b2581 ipn/ipnlocal,net/dns/resolver: serve MagicDNS names from live indexes
Every netmap change, including an incremental delta of a single peer,
rebuilt the full MagicDNS state twice: dnsConfigForNetmap walked all
peers to build the dns.Config.Hosts map, and resolver.SetConfig then
walked that map again to build its reverse (PTR) index. On a tailnet
with 10k peers that is a lot of garbage per delta.

Instead, add a resolver.MagicDNSHosts hook, installed once by
LocalBackend, that the quad-100 resolver consults on demand at query
time. It is backed by nodeBackend's nodeByName, nodeByAddr, and peers
indexes, which are already maintained incrementally as netmap deltas
arrive. The subdomain-resolve capability check also moves to the hook
(checking the node's CapMap at query time), so dns.Config's
SubdomainHosts is no longer populated.

dns.Config.Hosts remains for control's DNS.ExtraRecords, which are
few and which feed the split-DNS decisions in dns.Manager's
compileConfig, and on Windows it still carries every node's records
because the hosts-file fallback path (compileHostEntries) needs the
complete enumerable set. Those compileConfig decisions also consulted
the per-node Hosts entries (hasHostsWithoutSplitDNSRoutes), so a new
Config.MagicDNSHostsUnrouted bit preserves that signal now that node
records are not listed: with MagicDNS names present but MagicDNS
domain routing off, quad-100 stays in the OS resolver path.

One small behavior change: reverse (PTR) lookups now also answer for
node addresses whose forward records are filtered out by the
IPv6-suppression rule (issue #1152), since nodeByAddr indexes all node
addresses. Previously such addresses were absent from the pushed
Hosts map and thus from the reverse index.

Updates #12542
Updates tailscale/corp#43949

Change-Id: I63b99199c2b3b124c08cb8bbaea1f63165095294
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-07-14 07:26:41 -07:00
..
ace all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
art all: apply go fix 2026-07-10 17:39:16 -07:00
bakedroots all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
batching net/batching: reset Buffers len in WriteBatchTo 2026-05-31 06:12:53 -07:00
captivedetection all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
connectproxy all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
dns ipn/ipnlocal,net/dns/resolver: serve MagicDNS names from live indexes 2026-07-14 07:26:41 -07:00
dnscache net/tsdial: run happy eyeballs across A and AAAA in UserDial 2026-05-20 18:35:55 -07:00
dnsfallback net/netutil: add NewDefaultTransport to avoid http.DefaultTransport panics 2026-06-01 12:28:36 -07:00
flowtrack all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
ipset all: use bart.Lite instead of bart.Table where appropriate 2026-03-24 14:45:23 +00:00
ktimeout all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
memnet all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netaddr all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netcheck net/netcheck: don't mutate Client.TimeNow in AddReportHistoryForTest 2026-07-13 15:20:36 -07:00
neterror all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
netkernelconf all: make this spelling mistake non-existant 2026-06-11 10:37:50 +01:00
netknob all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netmon all: fix typos where we repeat repeat ourselves 2026-07-03 16:09:03 +01:00
netns all: don't repeat the the word "the" unnecessarily 2026-06-18 16:32:08 +01:00
netstat all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netutil cmd/{containerboot,k8s-operator}: add 4via6 support in singleton egress (#19983) 2026-06-18 16:13:10 +01:00
netx net/tsdial: run happy eyeballs across A and AAAA in UserDial 2026-05-20 18:35:55 -07:00
packet all: fix typos where we repeat repeat ourselves 2026-07-03 16:09:03 +01:00
ping wgengine/netstack, net/ping: stop using pro-bing and use our net/ping instead 2026-05-04 14:05:24 -07:00
portmapper all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
porttrack net/porttrack: change magic listen address format for Go 1.26 2026-03-04 21:57:05 -08:00
proxymux all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
routecheck ipn/ipnlocal: use routecheck reports to make exit node suggestions 2026-07-02 20:26:27 -07:00
routemanager ipn/ipnlocal,net/routemanager: keep a routemanager.RouteManager updated per node 2026-07-13 10:20:54 -07:00
routetable netns,wgengine: add OpenBSD support to netns via an rtable 2026-02-25 12:44:32 -08:00
sockopts all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
socks5 all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
sockstats all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
speedtest cmd/vet: add subtestnames analyzer; fix all existing violations 2026-04-05 15:52:51 -07:00
stun all: fix more typos caused by unnecessary repetition 2026-07-06 10:36:17 +01:00
stunserver all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
tcpinfo all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
tlsdial tsd, all: add Sys.ExtraRootCAs, plumb through TLS dial paths 2026-04-07 18:10:54 -07:00
traffic net/traffic: add fuzz test for sorting nodes by traffic score (#19893) 2026-05-29 11:55:49 -07:00
tsaddr all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
tsdial net/tsdial, ipn/ipnlocal: stop using netmap.NetworkMap in Dialer 2026-06-24 13:14:45 -07:00
tshttpproxy cmd/vet: add subtestnames analyzer; fix all existing violations 2026-04-05 15:52:51 -07:00
tstun net/tstun: invoke conn25 app connector hook on injected reads 2026-06-24 16:59:58 -04:00
udprelay control/controlknobs,net/{batching,tstun},wgengine: add nodecaps to disable UDP & TUN GRO/GSO 2026-05-27 17:10:14 -07:00
wsconn all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00