derp: increase update frequency and harden on failures (#2741)

This commit is contained in:
Kristoffer Dalby
2025-08-22 10:40:38 +02:00
committed by GitHub
parent 51c6367bb1
commit b87567628a
10 changed files with 417 additions and 67 deletions

View File

@@ -1,16 +1,22 @@
package derp
import (
"cmp"
"context"
"encoding/json"
"hash/crc64"
"io"
"maps"
"math/rand"
"net/http"
"net/url"
"os"
"reflect"
"sync"
"time"
"github.com/juanfont/headscale/hscontrol/types"
"github.com/rs/zerolog/log"
"github.com/spf13/viper"
"gopkg.in/yaml.v3"
"tailscale.com/tailcfg"
)
@@ -79,26 +85,16 @@ func mergeDERPMaps(derpMaps []*tailcfg.DERPMap) *tailcfg.DERPMap {
return &result
}
func GetDERPMap(cfg types.DERPConfig) *tailcfg.DERPMap {
func GetDERPMap(cfg types.DERPConfig) (*tailcfg.DERPMap, error) {
var derpMaps []*tailcfg.DERPMap
if cfg.DERPMap != nil {
derpMaps = append(derpMaps, cfg.DERPMap)
}
for _, path := range cfg.Paths {
log.Debug().
Str("func", "GetDERPMap").
Str("path", path).
Msg("Loading DERPMap from path")
derpMap, err := loadDERPMapFromPath(path)
if err != nil {
log.Error().
Str("func", "GetDERPMap").
Str("path", path).
Err(err).
Msg("Could not load DERP map from path")
break
return nil, err
}
derpMaps = append(derpMaps, derpMap)
@@ -106,26 +102,59 @@ func GetDERPMap(cfg types.DERPConfig) *tailcfg.DERPMap {
for _, addr := range cfg.URLs {
derpMap, err := loadDERPMapFromURL(addr)
log.Debug().
Str("func", "GetDERPMap").
Str("url", addr.String()).
Msg("Loading DERPMap from path")
if err != nil {
log.Error().
Str("func", "GetDERPMap").
Str("url", addr.String()).
Err(err).
Msg("Could not load DERP map from path")
break
return nil, err
}
derpMaps = append(derpMaps, derpMap)
}
derpMap := mergeDERPMaps(derpMaps)
shuffleDERPMap(derpMap)
log.Trace().Interface("derpMap", derpMap).Msg("DERPMap loaded")
return derpMap
return derpMap, nil
}
func shuffleDERPMap(dm *tailcfg.DERPMap) {
if dm == nil || len(dm.Regions) == 0 {
return
}
for id, region := range dm.Regions {
if len(region.Nodes) == 0 {
continue
}
dm.Regions[id] = shuffleRegionNoClone(region)
}
}
var crc64Table = crc64.MakeTable(crc64.ISO)
var (
derpRandomOnce sync.Once
derpRandomInst *rand.Rand
derpRandomMu sync.RWMutex
)
func derpRandom() *rand.Rand {
derpRandomOnce.Do(func() {
seed := cmp.Or(viper.GetString("dns.base_domain"), time.Now().String())
rnd := rand.New(rand.NewSource(0))
rnd.Seed(int64(crc64.Checksum([]byte(seed), crc64Table)))
derpRandomInst = rnd
})
return derpRandomInst
}
func resetDerpRandomForTesting() {
derpRandomMu.Lock()
defer derpRandomMu.Unlock()
derpRandomOnce = sync.Once{}
derpRandomInst = nil
}
func shuffleRegionNoClone(r *tailcfg.DERPRegion) *tailcfg.DERPRegion {
derpRandom().Shuffle(len(r.Nodes), reflect.Swapper(r.Nodes))
return r
}

284
hscontrol/derp/derp_test.go Normal file
View File

@@ -0,0 +1,284 @@
package derp
import (
"testing"
"github.com/google/go-cmp/cmp"
"github.com/spf13/viper"
"tailscale.com/tailcfg"
)
func TestShuffleDERPMapDeterministic(t *testing.T) {
tests := []struct {
name string
baseDomain string
derpMap *tailcfg.DERPMap
expected *tailcfg.DERPMap
}{
{
name: "single region with 4 nodes",
baseDomain: "test1.example.com",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: {
RegionID: 1,
RegionCode: "nyc",
RegionName: "New York City",
Nodes: []*tailcfg.DERPNode{
{Name: "1f", RegionID: 1, HostName: "derp1f.tailscale.com"},
{Name: "1g", RegionID: 1, HostName: "derp1g.tailscale.com"},
{Name: "1h", RegionID: 1, HostName: "derp1h.tailscale.com"},
{Name: "1i", RegionID: 1, HostName: "derp1i.tailscale.com"},
},
},
},
},
expected: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: {
RegionID: 1,
RegionCode: "nyc",
RegionName: "New York City",
Nodes: []*tailcfg.DERPNode{
{Name: "1g", RegionID: 1, HostName: "derp1g.tailscale.com"},
{Name: "1f", RegionID: 1, HostName: "derp1f.tailscale.com"},
{Name: "1i", RegionID: 1, HostName: "derp1i.tailscale.com"},
{Name: "1h", RegionID: 1, HostName: "derp1h.tailscale.com"},
},
},
},
},
},
{
name: "multiple regions with nodes",
baseDomain: "test2.example.com",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
10: {
RegionID: 10,
RegionCode: "sea",
RegionName: "Seattle",
Nodes: []*tailcfg.DERPNode{
{Name: "10b", RegionID: 10, HostName: "derp10b.tailscale.com"},
{Name: "10c", RegionID: 10, HostName: "derp10c.tailscale.com"},
{Name: "10d", RegionID: 10, HostName: "derp10d.tailscale.com"},
},
},
2: {
RegionID: 2,
RegionCode: "sfo",
RegionName: "San Francisco",
Nodes: []*tailcfg.DERPNode{
{Name: "2d", RegionID: 2, HostName: "derp2d.tailscale.com"},
{Name: "2e", RegionID: 2, HostName: "derp2e.tailscale.com"},
{Name: "2f", RegionID: 2, HostName: "derp2f.tailscale.com"},
},
},
},
},
expected: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
10: {
RegionID: 10,
RegionCode: "sea",
RegionName: "Seattle",
Nodes: []*tailcfg.DERPNode{
{Name: "10b", RegionID: 10, HostName: "derp10b.tailscale.com"},
{Name: "10c", RegionID: 10, HostName: "derp10c.tailscale.com"},
{Name: "10d", RegionID: 10, HostName: "derp10d.tailscale.com"},
},
},
2: {
RegionID: 2,
RegionCode: "sfo",
RegionName: "San Francisco",
Nodes: []*tailcfg.DERPNode{
{Name: "2f", RegionID: 2, HostName: "derp2f.tailscale.com"},
{Name: "2e", RegionID: 2, HostName: "derp2e.tailscale.com"},
{Name: "2d", RegionID: 2, HostName: "derp2d.tailscale.com"},
},
},
},
},
},
{
name: "large region with many nodes",
baseDomain: "test3.example.com",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
4: {
RegionID: 4,
RegionCode: "fra",
RegionName: "Frankfurt",
Nodes: []*tailcfg.DERPNode{
{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
},
},
},
},
expected: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
4: {
RegionID: 4,
RegionCode: "fra",
RegionName: "Frankfurt",
Nodes: []*tailcfg.DERPNode{
{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
},
},
},
},
},
{
name: "same region different base domain",
baseDomain: "different.example.com",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
4: {
RegionID: 4,
RegionCode: "fra",
RegionName: "Frankfurt",
Nodes: []*tailcfg.DERPNode{
{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
},
},
},
},
expected: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
4: {
RegionID: 4,
RegionCode: "fra",
RegionName: "Frankfurt",
Nodes: []*tailcfg.DERPNode{
{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
},
},
},
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
viper.Set("dns.base_domain", tt.baseDomain)
defer viper.Reset()
resetDerpRandomForTesting()
testMap := tt.derpMap.View().AsStruct()
shuffleDERPMap(testMap)
if diff := cmp.Diff(tt.expected, testMap); diff != "" {
t.Errorf("Shuffled DERP map doesn't match expected (-expected +actual):\n%s", diff)
}
})
}
}
func TestShuffleDERPMapEdgeCases(t *testing.T) {
tests := []struct {
name string
derpMap *tailcfg.DERPMap
}{
{
name: "nil derp map",
derpMap: nil,
},
{
name: "empty derp map",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{},
},
},
{
name: "region with no nodes",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: {
RegionID: 1,
RegionCode: "empty",
RegionName: "Empty Region",
Nodes: []*tailcfg.DERPNode{},
},
},
},
},
{
name: "region with single node",
derpMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: {
RegionID: 1,
RegionCode: "single",
RegionName: "Single Node Region",
Nodes: []*tailcfg.DERPNode{
{Name: "1a", RegionID: 1, HostName: "derp1a.tailscale.com"},
},
},
},
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
shuffleDERPMap(tt.derpMap)
})
}
}
func TestShuffleDERPMapWithoutBaseDomain(t *testing.T) {
viper.Reset()
resetDerpRandomForTesting()
derpMap := &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: {
RegionID: 1,
RegionCode: "test",
RegionName: "Test Region",
Nodes: []*tailcfg.DERPNode{
{Name: "1a", RegionID: 1, HostName: "derp1a.test.com"},
{Name: "1b", RegionID: 1, HostName: "derp1b.test.com"},
{Name: "1c", RegionID: 1, HostName: "derp1c.test.com"},
{Name: "1d", RegionID: 1, HostName: "derp1d.test.com"},
},
},
},
}
original := derpMap.View().AsStruct()
shuffleDERPMap(derpMap)
if len(derpMap.Regions) != 1 || len(derpMap.Regions[1].Nodes) != 4 {
t.Error("Shuffle corrupted DERP map structure")
}
originalNodes := make(map[string]bool)
for _, node := range original.Regions[1].Nodes {
originalNodes[node.Name] = true
}
shuffledNodes := make(map[string]bool)
for _, node := range derpMap.Regions[1].Nodes {
shuffledNodes[node.Name] = true
}
if diff := cmp.Diff(originalNodes, shuffledNodes); diff != "" {
t.Errorf("Shuffle changed node set (-original +shuffled):\n%s", diff)
}
}

View File

@@ -276,7 +276,7 @@ func DERPProbeHandler(
// An example implementation is found here https://derp.tailscale.com/bootstrap-dns
// Coordination server is included automatically, since local DERP is using the same DNS Name in d.serverURL.
func DERPBootstrapDNSHandler(
derpMap *tailcfg.DERPMap,
derpMap tailcfg.DERPMapView,
) func(http.ResponseWriter, *http.Request) {
return func(
writer http.ResponseWriter,
@@ -287,18 +287,18 @@ func DERPBootstrapDNSHandler(
resolvCtx, cancel := context.WithTimeout(req.Context(), time.Minute)
defer cancel()
var resolver net.Resolver
for _, region := range derpMap.Regions {
for _, node := range region.Nodes { // we don't care if we override some nodes
addrs, err := resolver.LookupIP(resolvCtx, "ip", node.HostName)
for _, region := range derpMap.Regions().All() {
for _, node := range region.Nodes().All() { // we don't care if we override some nodes
addrs, err := resolver.LookupIP(resolvCtx, "ip", node.HostName())
if err != nil {
log.Trace().
Caller().
Err(err).
Msgf("bootstrap DNS lookup failed %q", node.HostName)
Msgf("bootstrap DNS lookup failed %q", node.HostName())
continue
}
dnsEntries[node.HostName] = addrs
dnsEntries[node.HostName()] = addrs
}
}
writer.Header().Set("Content-Type", "application/json")