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chore: support adding dns hosts to tailnet.Conn #15419

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Merged
merged 1 commit into from
Nov 8, 2024
Merged

chore: support adding dns hosts to tailnet.Conn #15419

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66 changes: 62 additions & 4 deletions tailnet/configmaps.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,9 @@ import (
"encoding/json"
"errors"
"fmt"
"maps"
"net/netip"
"slices"
"sync"
"time"

Expand All @@ -14,9 +16,11 @@ import (
"tailscale.com/ipn/ipnstate"
"tailscale.com/net/dns"
"tailscale.com/tailcfg"
"tailscale.com/types/dnstype"
"tailscale.com/types/ipproto"
"tailscale.com/types/key"
"tailscale.com/types/netmap"
"tailscale.com/util/dnsname"
"tailscale.com/wgengine"
"tailscale.com/wgengine/filter"
"tailscale.com/wgengine/router"
Expand All @@ -30,6 +34,10 @@ import (

const lostTimeout = 15 * time.Minute

// CoderDNSSuffix is the default DNS suffix that we append to Coder DNS
// records.
const CoderDNSSuffix = "coder."

// engineConfigurable is the subset of wgengine.Engine that we use for configuration.
//
// This allows us to test configuration code without faking the whole interface.
Expand Down Expand Up @@ -63,6 +71,7 @@ type configMaps struct {

engine engineConfigurable
static netmap.NetworkMap
hosts map[dnsname.FQDN][]netip.Addr
peers map[uuid.UUID]*peerLifecycle
addresses []netip.Prefix
derpMap *tailcfg.DERPMap
Expand All @@ -79,6 +88,7 @@ func newConfigMaps(logger slog.Logger, engine engineConfigurable, nodeID tailcfg
phased: phased{Cond: *(sync.NewCond(&sync.Mutex{}))},
logger: logger,
engine: engine,
hosts: make(map[dnsname.FQDN][]netip.Addr),
static: netmap.NetworkMap{
SelfNode: &tailcfg.Node{
ID: nodeID,
Expand Down Expand Up @@ -153,10 +163,11 @@ func (c *configMaps) configLoop() {
}
if c.netmapDirty {
nm := c.netMapLocked()
hosts := c.hostsLocked()
actions = append(actions, func() {
c.logger.Debug(context.Background(), "updating engine network map", slog.F("network_map", nm))
c.engine.SetNetworkMap(nm)
c.reconfig(nm)
c.reconfig(nm, hosts)
})
}
if c.filterDirty {
Expand Down Expand Up @@ -212,6 +223,11 @@ func (c *configMaps) netMapLocked() *netmap.NetworkMap {
return nm
}

// hostsLocked returns the current DNS hosts mapping. c.L must be held.
func (c *configMaps) hostsLocked() map[dnsname.FQDN][]netip.Addr {
return maps.Clone(c.hosts)
}

// peerConfigLocked returns the set of peer nodes we have. c.L must be held.
func (c *configMaps) peerConfigLocked() []*tailcfg.Node {
out := make([]*tailcfg.Node, 0, len(c.peers))
Expand Down Expand Up @@ -261,6 +277,37 @@ func (c *configMaps) setAddresses(ips []netip.Prefix) {
c.Broadcast()
}

func (c *configMaps) addHosts(hosts map[dnsname.FQDN][]netip.Addr) {
c.L.Lock()
defer c.L.Unlock()
for name, addrs := range hosts {
c.hosts[name] = slices.Clone(addrs)
}
c.netmapDirty = true
c.Broadcast()
}

func (c *configMaps) setHosts(hosts map[dnsname.FQDN][]netip.Addr) {
c.L.Lock()
defer c.L.Unlock()
c.hosts = make(map[dnsname.FQDN][]netip.Addr)
for name, addrs := range hosts {
c.hosts[name] = slices.Clone(addrs)
}
c.netmapDirty = true
c.Broadcast()
}

func (c *configMaps) removeHosts(names []dnsname.FQDN) {
c.L.Lock()
defer c.L.Unlock()
for _, name := range names {
delete(c.hosts, name)
}
c.netmapDirty = true
c.Broadcast()
}

// setBlockEndpoints sets whether we should block configuring endpoints we learn
// from peers. It triggers a configuration of the engine if the value changes.
// nolint: revive
Expand Down Expand Up @@ -305,7 +352,15 @@ func (c *configMaps) derpMapLocked() *tailcfg.DERPMap {
// reconfig computes the correct wireguard config and calls the engine.Reconfig
// with the config we have. It is not intended for this to be called outside of
// the updateLoop()
func (c *configMaps) reconfig(nm *netmap.NetworkMap) {
func (c *configMaps) reconfig(nm *netmap.NetworkMap, hosts map[dnsname.FQDN][]netip.Addr) {
dnsCfg := &dns.Config{}
if len(hosts) > 0 {
dnsCfg.Hosts = hosts
dnsCfg.OnlyIPv6 = true
dnsCfg.Routes = map[dnsname.FQDN][]*dnstype.Resolver{
CoderDNSSuffix: nil,
}
}
cfg, err := nmcfg.WGCfg(nm, Logger(c.logger.Named("net.wgconfig")), netmap.AllowSingleHosts, "")
if err != nil {
// WGCfg never returns an error at the time this code was written. If it starts, returning
Expand All @@ -314,8 +369,11 @@ func (c *configMaps) reconfig(nm *netmap.NetworkMap) {
return
}

rc := &router.Config{LocalAddrs: nm.Addresses}
err = c.engine.Reconfig(cfg, rc, &dns.Config{}, &tailcfg.Debug{})
rc := &router.Config{
LocalAddrs: nm.Addresses,
Routes: []netip.Prefix{CoderServicePrefix.AsNetip()},
}
err = c.engine.Reconfig(cfg, rc, dnsCfg, &tailcfg.Debug{})
if err != nil {
if errors.Is(err, wgengine.ErrNoChanges) {
return
Expand Down
129 changes: 127 additions & 2 deletions tailnet/configmaps_internal_test.go
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,14 @@ import (
"github.com/google/uuid"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"golang.org/x/exp/maps"
"tailscale.com/ipn/ipnstate"
"tailscale.com/net/dns"
"tailscale.com/tailcfg"
"tailscale.com/types/dnstype"
"tailscale.com/types/key"
"tailscale.com/types/netmap"
"tailscale.com/util/dnsname"
"tailscale.com/wgengine/filter"
"tailscale.com/wgengine/router"
"tailscale.com/wgengine/wgcfg"
Expand Down Expand Up @@ -1157,6 +1160,127 @@ func TestConfigMaps_updatePeers_nonexist(t *testing.T) {
}
}

func TestConfigMaps_addRemoveHosts(t *testing.T) {
t.Parallel()

ctx := testutil.Context(t, testutil.WaitShort)
logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
fEng := newFakeEngineConfigurable()
nodePrivateKey := key.NewNode()
nodeID := tailcfg.NodeID(5)
discoKey := key.NewDisco()
uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
defer uut.close()

addr1 := CoderServicePrefix.AddrFromUUID(uuid.New())
addr2 := CoderServicePrefix.AddrFromUUID(uuid.New())
addr3 := CoderServicePrefix.AddrFromUUID(uuid.New())
addr4 := CoderServicePrefix.AddrFromUUID(uuid.New())

// WHEN: we add two hosts
uut.addHosts(map[dnsname.FQDN][]netip.Addr{
"agent.myws.me.coder.": {
addr1,
},
"dev.main.me.coder.": {
addr2,
addr3,
},
})

// THEN: the engine is reconfigured with those same hosts
_ = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)
req := testutil.RequireRecvCtx(ctx, t, fEng.reconfig)
require.Equal(t, req.dnsCfg, &dns.Config{
Routes: map[dnsname.FQDN][]*dnstype.Resolver{
CoderDNSSuffix: nil,
},
Hosts: map[dnsname.FQDN][]netip.Addr{
"agent.myws.me.coder.": {
addr1,
},
"dev.main.me.coder.": {
addr2,
addr3,
},
},
OnlyIPv6: true,
})

// WHEN: we add a new host
newHost := map[dnsname.FQDN][]netip.Addr{
"agent2.myws.me.coder.": {
addr4,
},
}
uut.addHosts(newHost)

// THEN: the engine is reconfigured with both the old and new hosts
_ = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)
req = testutil.RequireRecvCtx(ctx, t, fEng.reconfig)
require.Equal(t, req.dnsCfg, &dns.Config{
Routes: map[dnsname.FQDN][]*dnstype.Resolver{
CoderDNSSuffix: nil,
},
Hosts: map[dnsname.FQDN][]netip.Addr{
"agent.myws.me.coder.": {
addr1,
},
"dev.main.me.coder.": {
addr2,
addr3,
},
"agent2.myws.me.coder.": {
addr4,
},
},
OnlyIPv6: true,
})

// WHEN: We replace the hosts with a new set
uut.setHosts(map[dnsname.FQDN][]netip.Addr{
"newagent.myws.me.coder.": {
addr4,
},
"newagent2.main.me.coder.": {
addr1,
},
})

// THEN: The engine is reconfigured with only the new hosts
_ = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)
req = testutil.RequireRecvCtx(ctx, t, fEng.reconfig)
require.Equal(t, req.dnsCfg, &dns.Config{
Routes: map[dnsname.FQDN][]*dnstype.Resolver{
CoderDNSSuffix: nil,
},
Hosts: map[dnsname.FQDN][]netip.Addr{
"newagent.myws.me.coder.": {
addr4,
},
"newagent2.main.me.coder.": {
addr1,
},
},
OnlyIPv6: true,
})

// WHEN: we remove all the hosts, and a bad host
uut.removeHosts(append(maps.Keys(req.dnsCfg.Hosts), "badhostname"))
_ = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)
req = testutil.RequireRecvCtx(ctx, t, fEng.reconfig)

// THEN: the engine is reconfigured with an empty config
require.Equal(t, req.dnsCfg, &dns.Config{})

done := make(chan struct{})
go func() {
defer close(done)
uut.close()
}()
_ = testutil.RequireRecvCtx(ctx, t, done)
}

func newTestNode(id int) *Node {
return &Node{
ID: tailcfg.NodeID(id),
Expand Down Expand Up @@ -1199,6 +1323,7 @@ func requireNeverConfigures(ctx context.Context, t *testing.T, uut *phased) {
type reconfigCall struct {
wg *wgcfg.Config
router *router.Config
dnsCfg *dns.Config
}

var _ engineConfigurable = &fakeEngineConfigurable{}
Expand Down Expand Up @@ -1235,8 +1360,8 @@ func (f fakeEngineConfigurable) SetNetworkMap(networkMap *netmap.NetworkMap) {
f.setNetworkMap <- networkMap
}

func (f fakeEngineConfigurable) Reconfig(wg *wgcfg.Config, r *router.Config, _ *dns.Config, _ *tailcfg.Debug) error {
f.reconfig <- reconfigCall{wg: wg, router: r}
func (f fakeEngineConfigurable) Reconfig(wg *wgcfg.Config, r *router.Config, dnsCfg *dns.Config, _ *tailcfg.Debug) error {
f.reconfig <- reconfigCall{wg: wg, router: r, dnsCfg: dnsCfg}
return nil
}

Expand Down
34 changes: 34 additions & 0 deletions tailnet/conn.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ import (
tslogger "tailscale.com/types/logger"
"tailscale.com/types/netlogtype"
"tailscale.com/types/netmap"
"tailscale.com/util/dnsname"
"tailscale.com/wgengine"
"tailscale.com/wgengine/capture"
"tailscale.com/wgengine/magicsock"
Expand Down Expand Up @@ -290,6 +291,7 @@ func NewConn(options *Options) (conn *Conn, err error) {
configMaps: cfgMaps,
nodeUpdater: nodeUp,
telemetrySink: options.TelemetrySink,
dnsConfigurator: options.DNSConfigurator,
telemetryStore: telemetryStore,
createdAt: time.Now(),
watchCtx: ctx,
Expand Down Expand Up @@ -379,6 +381,12 @@ func (p ServicePrefix) RandomPrefix() netip.Prefix {
return netip.PrefixFrom(p.RandomAddr(), 128)
}

func (p ServicePrefix) AsNetip() netip.Prefix {
out := [16]byte{}
copy(out[:], p[:])
return netip.PrefixFrom(netip.AddrFrom16(out), 48)
}

// Conn is an actively listening Wireguard connection.
type Conn struct {
// Unique ID used for telemetry.
Expand All @@ -396,6 +404,7 @@ type Conn struct {
wireguardMonitor *netmon.Monitor
wireguardRouter *router.Config
wireguardEngine wgengine.Engine
dnsConfigurator dns.OSConfigurator
listeners map[listenKey]*listener
clientType proto.TelemetryEvent_ClientType
createdAt time.Time
Expand Down Expand Up @@ -442,6 +451,31 @@ func (c *Conn) SetAddresses(ips []netip.Prefix) error {
return nil
}

func (c *Conn) AddDNSHosts(hosts map[dnsname.FQDN][]netip.Addr) error {
if c.dnsConfigurator == nil {
return xerrors.New("no DNSConfigurator set")
}
c.configMaps.addHosts(hosts)
return nil
}

func (c *Conn) RemoveDNSHosts(names []dnsname.FQDN) error {
if c.dnsConfigurator == nil {
return xerrors.New("no DNSConfigurator set")
}
c.configMaps.removeHosts(names)
return nil
}

// SetDNSHosts replaces the map of DNS hosts for the connection.
func (c *Conn) SetDNSHosts(hosts map[dnsname.FQDN][]netip.Addr) error {
if c.dnsConfigurator == nil {
return xerrors.New("no DNSConfigurator set")
}
c.configMaps.setHosts(hosts)
return nil
}

func (c *Conn) SetNodeCallback(callback func(node *Node)) {
c.nodeUpdater.setCallback(callback)
}
Expand Down
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