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netann: add new HostAnnouncer to support dynamic IPs via domains

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In this commit, we add a new sub-system, then `HostAnnouncer` which
allows a users without a static IP address to ensure that lnd always
announces the most up to date address based on a domain name. A new
command line flag `--external-hosts` has been added which allows a user
to specify one or most hosts that should be periodically resolved to
update any advertised IPs the node has.

Fixes #1624.
This commit is contained in:
Olaoluwa Osuntokun 2020-05-12 17:05:18 -07:00
parent f9c6a1b73f
commit ba3688c3b9
No known key found for this signature in database
GPG Key ID: BC13F65E2DC84465
4 changed files with 520 additions and 0 deletions
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10
config.go
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@ -80,6 +80,11 @@ const (
defaultAlias = ""
defaultColor = "#3399FF"
// defaultHostSampleInterval is the default amount of time that the
// HostAnnouncer will wait between DNS resolutions to check if the
// backing IP of a host has changed.
defaultHostSampleInterval = time.Minute * 5
)
var (
@ -157,6 +162,7 @@ type Config struct {
RawRESTListeners []string `long:"restlisten" description:"Add an interface/port/socket to listen for REST connections"`
RawListeners []string `long:"listen" description:"Add an interface/port to listen for peer connections"`
RawExternalIPs []string `long:"externalip" description:"Add an ip:port to the list of local addresses we claim to listen on to peers. If a port is not specified, the default (9735) will be used regardless of other parameters"`
ExternalHosts []string `long:"externalhosts" description:"A set of hosts that should be periodically resolved to announce IPs for"`
RPCListeners []net.Addr
RESTListeners []net.Addr
RestCORS []string `long:"restcors" description:"Add an ip:port/hostname to allow cross origin access from. To allow all origins, set as \"*\"."`
@ -659,6 +665,10 @@ func ValidateConfig(cfg Config, usageMessage string) (*Config, error) {
return nil, errors.New("NAT traversal cannot be used when " +
"listening is disabled")
}
if cfg.NAT && len(cfg.ExternalHosts) != 0 {
return nil, errors.New("NAT support and externalhosts are " +
"mutually exclusive, only one should be selected")
}
// Determine the active chain configuration and its parameters.
switch {

198
netann/host_ann.go Normal file
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@ -0,0 +1,198 @@
package netann
import (
"net"
"sync"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/ticker"
)
// HostAnnouncerConfig is the main config for the HostAnnouncer.
type HostAnnouncerConfig struct {
// Hosts is the set of hosts we should watch for IP changes.
Hosts []string
// RefreshTicker ticks each time we should check for any address
// changes.
RefreshTicker ticker.Ticker
// LookupHost performs DNS resolution on a given host and returns its
// addresses.
LookupHost func(string) (net.Addr, error)
// AdvertisedIPs is the set of IPs that we've already announced with
// our current NodeAnnouncement. This set will be constructed to avoid
// unnecessary node NodeAnnouncement updates.
AdvertisedIPs map[string]struct{}
// AnnounceNewIPs announces a new set of IP addresses for the backing
// Lightning node. The first set of addresses is the new set of
// addresses that we should advertise, while the other set are the
// stale addresses that we should no longer advertise.
AnnounceNewIPs func([]net.Addr, map[string]struct{}) error
}
// HostAnnouncer is a sub-system that allows a user to specify a set of hosts
// for lnd that will be continually resolved to notice any IP address changes.
// If the target IP address for a host changes, then we'll generate a new
// NodeAnnouncement that includes these new IPs.
type HostAnnouncer struct {
cfg HostAnnouncerConfig
quit chan struct{}
wg sync.WaitGroup
startOnce sync.Once
stopOnce sync.Once
}
// NewHostAnnouncer returns a new instance of the HostAnnouncer.
func NewHostAnnouncer(cfg HostAnnouncerConfig) *HostAnnouncer {
return &HostAnnouncer{
cfg: cfg,
quit: make(chan struct{}),
}
}
// Start starts the HostAnnouncer.
func (h *HostAnnouncer) Start() error {
h.startOnce.Do(func() {
h.wg.Add(1)
go h.hostWatcher()
})
return nil
}
// Stop signals the HostAnnouncer for a graceful stop.
func (h *HostAnnouncer) Stop() error {
h.stopOnce.Do(func() {
close(h.quit)
h.wg.Wait()
})
return nil
}
// hostWatcher periodically attempts to resolve the IP for each host, updating
// them if they change within the interval.
func (h *HostAnnouncer) hostWatcher() {
defer h.wg.Done()
ipMapping := make(map[string]net.Addr)
refreshHosts := func() {
// We'll now run through each of our hosts to check if they had
// their backing IPs changed. If so, we'll want to re-announce
// them.
var addrsToUpdate []net.Addr
addrsToRemove := make(map[string]struct{})
for _, host := range h.cfg.Hosts {
newAddr, err := h.cfg.LookupHost(host)
if err != nil {
log.Warnf("unable to resolve IP for "+
"host %v: %v", host, err)
continue
}
// If nothing has changed since the last time we
// checked, then we don't need to do any updates.
oldAddr, oldAddrFound := ipMapping[host]
if oldAddrFound && oldAddr.String() == newAddr.String() {
continue
}
// Update the IP mapping now, as if this is the first
// time then we don't need to send a new announcement.
ipMapping[host] = newAddr
// If this IP has already been announced, then we'll
// skip it to avoid triggering an unnecessary node
// announcement update.
_, ipAnnounced := h.cfg.AdvertisedIPs[newAddr.String()]
if ipAnnounced {
continue
}
// If we've reached this point, then the old address
// was found, and the new address we just looked up
// differs from the old one.
log.Debugf("IP change detected! %v: %v -> %v", host,
oldAddr, newAddr)
// If we had already advertised an addr for this host,
// then we'll need to remove that old stale address.
if oldAddr != nil {
addrsToRemove[oldAddr.String()] = struct{}{}
}
addrsToUpdate = append(addrsToUpdate, newAddr)
}
// If we don't have any addresses to update, then we can skip
// things around until the next round.
if len(addrsToUpdate) == 0 {
log.Debugf("No IP changes detected for hosts: %v",
h.cfg.Hosts)
return
}
// Now that we know the set of IPs we need to update, we'll do
// them all in a single batch.
err := h.cfg.AnnounceNewIPs(addrsToUpdate, addrsToRemove)
if err != nil {
log.Warnf("unable to announce new IPs: %v", err)
}
}
refreshHosts()
h.cfg.RefreshTicker.Resume()
for {
select {
case <-h.cfg.RefreshTicker.Ticks():
log.Debugf("HostAnnouncer checking for any IP " +
"changes...")
refreshHosts()
case <-h.quit:
return
}
}
}
// NodeAnnUpdater describes a function that's able to update our current node
// announcement on disk. It returns the updated node announcement given a set
// of updates to be applied to the current node announcement.
type NodeAnnUpdater func(refresh bool, modifier ...NodeAnnModifier,
) (lnwire.NodeAnnouncement, error)
// IPAnnouncer is a factory function that generates a new function that uses
// the passed annUpdater function to to announce new IP changes for a given
// host.
func IPAnnouncer(annUpdater NodeAnnUpdater) func([]net.Addr, map[string]struct{}) error {
return func(newAddrs []net.Addr, oldAddrs map[string]struct{}) error {
_, err := annUpdater(true, func(currentNodeAnn *lnwire.NodeAnnouncement) {
// To ensure we don't duplicate any addresses, we'll
// filter out the same of addresses we should no longer
// advertise.
filteredAddrs := make(
[]net.Addr, 0, len(currentNodeAnn.Addresses),
)
for _, addr := range currentNodeAnn.Addresses {
if _, ok := oldAddrs[addr.String()]; ok {
continue
}
filteredAddrs = append(filteredAddrs, addr)
}
filteredAddrs = append(filteredAddrs, newAddrs...)
currentNodeAnn.Addresses = filteredAddrs
})
return err
}
}

276
netann/host_ann_test.go Normal file
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@ -0,0 +1,276 @@
package netann
import (
"net"
"testing"
"time"
"github.com/lightningnetwork/lnd/ticker"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
// TestHostAnnouncerUpdates tests that the HostAnnouncer will properly announce
// a new set of addresses each time a target host changes and will noop if not
// change happens during an interval.
func TestHostAnnouncerUpdates(t *testing.T) {
t.Parallel()
hosts := []string{"test.com", "example.com"}
startingAddrs := []net.Addr{
&net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
&net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
}
ticker := ticker.NewForce(time.Hour * 24)
testTimeout := time.Millisecond * 200
type annReq struct {
newAddrs []net.Addr
removedAddrs map[string]struct{}
}
testCases := []struct {
preAdvertisedIPs map[string]struct{}
startingAddrs []net.Addr
preTickHosts map[string]net.Addr
postTickHosts map[string]net.Addr
updateTriggered bool
newAddrs []net.Addr
removedAddrs map[string]struct{}
}{
// The set of addresses are the same before and after a tick we
// expect no change.
{
preTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
startingAddrs: startingAddrs,
postTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
updateTriggered: false,
},
// Half of the addresses are changed out, the new one should be
// added with the old one forgotten.
{
preTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
startingAddrs: startingAddrs,
postTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("9.9.9.9"),
},
},
updateTriggered: true,
newAddrs: []net.Addr{
&net.TCPAddr{
IP: net.ParseIP("9.9.9.9"),
},
},
removedAddrs: map[string]struct{}{
"8.8.8.8:0": {},
},
},
// All addresses change, they should all be refreshed.
{
preTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
startingAddrs: startingAddrs,
postTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("2.2.2.2"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("9.9.9.9"),
},
},
updateTriggered: true,
newAddrs: []net.Addr{
&net.TCPAddr{
IP: net.ParseIP("2.2.2.2"),
},
&net.TCPAddr{
IP: net.ParseIP("9.9.9.9"),
},
},
removedAddrs: map[string]struct{}{
"8.8.8.8:0": {},
"1.1.1.1:0": {},
},
},
// Two addresses, one has already been advertised on start up,
// so we only expect one of them to be announced again. After
// the tick we don't expect an update trigger since nothing.
// changed.
{
preAdvertisedIPs: map[string]struct{}{
"1.1.1.1:0": {},
},
startingAddrs: []net.Addr{
&net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
preTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
postTickHosts: map[string]net.Addr{
"test.com": &net.TCPAddr{
IP: net.ParseIP("1.1.1.1"),
},
"example.com": &net.TCPAddr{
IP: net.ParseIP("8.8.8.8"),
},
},
updateTriggered: false,
},
}
for idx, testCase := range testCases {
hostResps := make(chan net.Addr)
annReqs := make(chan annReq)
hostAnncer := NewHostAnnouncer(HostAnnouncerConfig{
Hosts: hosts,
AdvertisedIPs: testCase.preAdvertisedIPs,
RefreshTicker: ticker,
LookupHost: func(str string) (net.Addr, error) {
return <-hostResps, nil
},
AnnounceNewIPs: func(newAddrs []net.Addr,
removeAddrs map[string]struct{}) error {
annReqs <- annReq{
newAddrs: newAddrs,
removedAddrs: removeAddrs,
}
return nil
},
})
if err := hostAnncer.Start(); err != nil {
t.Fatalf("unable to start announcer: %v", err)
}
// As soon as the announcer starts, it'll try to query for the
// state of the hosts. We'll return the preTick state for all
// hosts.
for i := 0; i < len(hosts); i++ {
hostResps <- testCase.preTickHosts[hosts[i]]
}
// Since this is the first time the announcer is starting up,
// we expect it to advertise the hosts as they exist before any
// updates.
select {
case addrUpdate := <-annReqs:
assert.Equal(
t, testCase.startingAddrs, addrUpdate.newAddrs,
"addresses should match",
)
assert.Empty(
t, addrUpdate.removedAddrs,
"removed addrs should match",
)
case <-time.After(testTimeout):
t.Fatalf("#%v: no addr update sent", idx)
}
// We'll now force a tick which'll force another query. This
// time we'll respond with the set of the hosts as they should
// be post-tick.
ticker.Force <- time.Time{}
for i := 0; i < len(hosts); i++ {
hostResps <- testCase.postTickHosts[hosts[i]]
}
// If we expect an update, then we'll assert that we received
// the proper set of modified addresses.
if testCase.updateTriggered {
select {
// The receive update should match exactly what the
// test case dictates.
case addrUpdate := <-annReqs:
require.Equal(
t, testCase.newAddrs, addrUpdate.newAddrs,
"addresses should match",
)
require.Equal(
t, testCase.removedAddrs, addrUpdate.removedAddrs,
"removed addrs should match",
)
case <-time.After(testTimeout):
t.Fatalf("#%v: no addr update set", idx)
}
if err := hostAnncer.Stop(); err != nil {
t.Fatalf("unable to stop announcer: %v", err)
}
continue
}
// Otherwise, no updates should be sent since nothing changed.
select {
case <-annReqs:
t.Fatalf("#%v: expected no call to AnnounceNewIPs", idx)
case <-time.After(testTimeout):
}
if err := hostAnncer.Stop(); err != nil {
t.Fatalf("unable to stop announcer: %v", err)
}
}
}

36
server.go
View File

@ -271,6 +271,8 @@ type server struct {
// provide insights into their health and performance.
chanEventStore *chanfitness.ChannelEventStore
hostAnn *netann.HostAnnouncer
quit chan struct{}
wg sync.WaitGroup
@ -1231,6 +1233,26 @@ func newServer(cfg *Config, listenAddrs []net.Addr, chanDB *channeldb.DB,
}
}
if len(cfg.ExternalHosts) != 0 {
advertisedIPs := make(map[string]struct{})
for _, addr := range s.currentNodeAnn.Addresses {
advertisedIPs[addr.String()] = struct{}{}
}
s.hostAnn = netann.NewHostAnnouncer(netann.HostAnnouncerConfig{
Hosts: cfg.ExternalHosts,
RefreshTicker: ticker.New(defaultHostSampleInterval),
LookupHost: func(host string) (net.Addr, error) {
return lncfg.ParseAddressString(
host, strconv.Itoa(defaultPeerPort),
cfg.net.ResolveTCPAddr,
)
},
AdvertisedIPs: advertisedIPs,
AnnounceNewIPs: netann.IPAnnouncer(s.genNodeAnnouncement),
})
}
// Create the connection manager which will be responsible for
// maintaining persistent outbound connections and also accepting new
// incoming connections
@ -1274,6 +1296,13 @@ func (s *server) Start() error {
go s.watchExternalIP()
}
if s.hostAnn != nil {
if err := s.hostAnn.Start(); err != nil {
startErr = err
return
}
}
// Start the notification server. This is used so channel
// management goroutines can be notified when a funding
// transaction reaches a sufficient number of confirmations, or
@ -1492,6 +1521,13 @@ func (s *server) Stop() error {
s.towerClient.Stop()
}
if s.hostAnn != nil {
if err := s.hostAnn.Stop(); err != nil {
srvrLog.Warnf("unable to shut down host "+
"annoucner: %v", err)
}
}
// Wait for all lingering goroutines to quit.
s.wg.Wait()