mirror of
https://github.com/juanfont/headscale.git
synced 2025-09-25 17:51:11 +02:00
derp: shuffle nodes per region
Avoid that all headscale clients picks the same first node in a region. Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
This commit is contained in:
Kristoffer Dalby
parent
e82b001ce6
commit
0c8765c5a2
@ -1,13 +1,19 @@
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package derp
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import (
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"cmp"
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"context"
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"encoding/json"
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"hash/crc64"
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"io"
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"maps"
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"math/rand"
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"net/http"
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"net/url"
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"os"
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"reflect"
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"sync"
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"time"
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"github.com/juanfont/headscale/hscontrol/types"
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"github.com/spf13/viper"
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@ -104,6 +110,51 @@ func GetDERPMap(cfg types.DERPConfig) (*tailcfg.DERPMap, error) {
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}
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derpMap := mergeDERPMaps(derpMaps)
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shuffleDERPMap(derpMap)
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return derpMap, nil
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}
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func shuffleDERPMap(dm *tailcfg.DERPMap) {
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if dm == nil || len(dm.Regions) == 0 {
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return
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}
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for id, region := range dm.Regions {
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if len(region.Nodes) == 0 {
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continue
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}
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dm.Regions[id] = shuffleRegionNoClone(region)
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}
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}
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var crc64Table = crc64.MakeTable(crc64.ISO)
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var (
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derpRandomOnce sync.Once
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derpRandomInst *rand.Rand
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derpRandomMu sync.RWMutex
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)
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func derpRandom() *rand.Rand {
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derpRandomOnce.Do(func() {
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seed := cmp.Or(viper.GetString("dns.base_domain"), time.Now().String())
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rnd := rand.New(rand.NewSource(0))
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rnd.Seed(int64(crc64.Checksum([]byte(seed), crc64Table)))
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derpRandomInst = rnd
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})
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return derpRandomInst
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}
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func resetDerpRandomForTesting() {
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derpRandomMu.Lock()
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defer derpRandomMu.Unlock()
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derpRandomOnce = sync.Once{}
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derpRandomInst = nil
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}
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func shuffleRegionNoClone(r *tailcfg.DERPRegion) *tailcfg.DERPRegion {
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derpRandom().Shuffle(len(r.Nodes), reflect.Swapper(r.Nodes))
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return r
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}
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284
hscontrol/derp/derp_test.go
Normal file
284
hscontrol/derp/derp_test.go
Normal file
@ -0,0 +1,284 @@
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package derp
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import (
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"testing"
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"github.com/google/go-cmp/cmp"
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"github.com/spf13/viper"
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"tailscale.com/tailcfg"
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)
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func TestShuffleDERPMapDeterministic(t *testing.T) {
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tests := []struct {
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name string
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baseDomain string
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derpMap *tailcfg.DERPMap
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expected *tailcfg.DERPMap
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}{
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{
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name: "single region with 4 nodes",
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baseDomain: "test1.example.com",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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1: {
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RegionID: 1,
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RegionCode: "nyc",
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RegionName: "New York City",
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Nodes: []*tailcfg.DERPNode{
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{Name: "1f", RegionID: 1, HostName: "derp1f.tailscale.com"},
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{Name: "1g", RegionID: 1, HostName: "derp1g.tailscale.com"},
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{Name: "1h", RegionID: 1, HostName: "derp1h.tailscale.com"},
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{Name: "1i", RegionID: 1, HostName: "derp1i.tailscale.com"},
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},
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},
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},
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},
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expected: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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1: {
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RegionID: 1,
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RegionCode: "nyc",
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RegionName: "New York City",
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Nodes: []*tailcfg.DERPNode{
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{Name: "1g", RegionID: 1, HostName: "derp1g.tailscale.com"},
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{Name: "1f", RegionID: 1, HostName: "derp1f.tailscale.com"},
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{Name: "1i", RegionID: 1, HostName: "derp1i.tailscale.com"},
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{Name: "1h", RegionID: 1, HostName: "derp1h.tailscale.com"},
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},
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},
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},
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},
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},
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{
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name: "multiple regions with nodes",
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baseDomain: "test2.example.com",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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10: {
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RegionID: 10,
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RegionCode: "sea",
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RegionName: "Seattle",
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Nodes: []*tailcfg.DERPNode{
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{Name: "10b", RegionID: 10, HostName: "derp10b.tailscale.com"},
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{Name: "10c", RegionID: 10, HostName: "derp10c.tailscale.com"},
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{Name: "10d", RegionID: 10, HostName: "derp10d.tailscale.com"},
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},
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},
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2: {
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RegionID: 2,
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RegionCode: "sfo",
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RegionName: "San Francisco",
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Nodes: []*tailcfg.DERPNode{
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{Name: "2d", RegionID: 2, HostName: "derp2d.tailscale.com"},
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{Name: "2e", RegionID: 2, HostName: "derp2e.tailscale.com"},
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{Name: "2f", RegionID: 2, HostName: "derp2f.tailscale.com"},
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},
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},
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},
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},
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expected: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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10: {
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RegionID: 10,
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RegionCode: "sea",
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RegionName: "Seattle",
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Nodes: []*tailcfg.DERPNode{
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{Name: "10b", RegionID: 10, HostName: "derp10b.tailscale.com"},
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{Name: "10c", RegionID: 10, HostName: "derp10c.tailscale.com"},
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{Name: "10d", RegionID: 10, HostName: "derp10d.tailscale.com"},
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},
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},
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2: {
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RegionID: 2,
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RegionCode: "sfo",
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RegionName: "San Francisco",
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Nodes: []*tailcfg.DERPNode{
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{Name: "2f", RegionID: 2, HostName: "derp2f.tailscale.com"},
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{Name: "2e", RegionID: 2, HostName: "derp2e.tailscale.com"},
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{Name: "2d", RegionID: 2, HostName: "derp2d.tailscale.com"},
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},
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},
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},
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},
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},
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{
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name: "large region with many nodes",
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baseDomain: "test3.example.com",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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4: {
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RegionID: 4,
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RegionCode: "fra",
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RegionName: "Frankfurt",
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Nodes: []*tailcfg.DERPNode{
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{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
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{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
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{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
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{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
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},
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},
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},
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},
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expected: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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4: {
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RegionID: 4,
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RegionCode: "fra",
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RegionName: "Frankfurt",
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Nodes: []*tailcfg.DERPNode{
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{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
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{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
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{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
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{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
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},
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},
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},
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},
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},
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{
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name: "same region different base domain",
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baseDomain: "different.example.com",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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4: {
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RegionID: 4,
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RegionCode: "fra",
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RegionName: "Frankfurt",
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Nodes: []*tailcfg.DERPNode{
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{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
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{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
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{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
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{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
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},
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},
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},
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},
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expected: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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4: {
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RegionID: 4,
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RegionCode: "fra",
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RegionName: "Frankfurt",
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Nodes: []*tailcfg.DERPNode{
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{Name: "4g", RegionID: 4, HostName: "derp4g.tailscale.com"},
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{Name: "4i", RegionID: 4, HostName: "derp4i.tailscale.com"},
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{Name: "4f", RegionID: 4, HostName: "derp4f.tailscale.com"},
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{Name: "4h", RegionID: 4, HostName: "derp4h.tailscale.com"},
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},
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},
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},
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},
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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viper.Set("dns.base_domain", tt.baseDomain)
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defer viper.Reset()
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resetDerpRandomForTesting()
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testMap := tt.derpMap.View().AsStruct()
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shuffleDERPMap(testMap)
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if diff := cmp.Diff(tt.expected, testMap); diff != "" {
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t.Errorf("Shuffled DERP map doesn't match expected (-expected +actual):\n%s", diff)
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}
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})
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}
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}
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func TestShuffleDERPMapEdgeCases(t *testing.T) {
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tests := []struct {
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name string
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derpMap *tailcfg.DERPMap
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}{
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{
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name: "nil derp map",
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derpMap: nil,
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},
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{
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name: "empty derp map",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{},
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},
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},
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{
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name: "region with no nodes",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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1: {
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RegionID: 1,
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RegionCode: "empty",
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RegionName: "Empty Region",
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Nodes: []*tailcfg.DERPNode{},
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},
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},
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},
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},
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{
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name: "region with single node",
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derpMap: &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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1: {
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RegionID: 1,
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RegionCode: "single",
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RegionName: "Single Node Region",
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Nodes: []*tailcfg.DERPNode{
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{Name: "1a", RegionID: 1, HostName: "derp1a.tailscale.com"},
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},
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},
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},
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},
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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shuffleDERPMap(tt.derpMap)
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})
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}
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}
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func TestShuffleDERPMapWithoutBaseDomain(t *testing.T) {
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viper.Reset()
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resetDerpRandomForTesting()
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derpMap := &tailcfg.DERPMap{
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Regions: map[int]*tailcfg.DERPRegion{
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1: {
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RegionID: 1,
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RegionCode: "test",
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RegionName: "Test Region",
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Nodes: []*tailcfg.DERPNode{
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{Name: "1a", RegionID: 1, HostName: "derp1a.test.com"},
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{Name: "1b", RegionID: 1, HostName: "derp1b.test.com"},
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{Name: "1c", RegionID: 1, HostName: "derp1c.test.com"},
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{Name: "1d", RegionID: 1, HostName: "derp1d.test.com"},
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},
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},
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},
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}
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original := derpMap.View().AsStruct()
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shuffleDERPMap(derpMap)
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if len(derpMap.Regions) != 1 || len(derpMap.Regions[1].Nodes) != 4 {
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t.Error("Shuffle corrupted DERP map structure")
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}
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originalNodes := make(map[string]bool)
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for _, node := range original.Regions[1].Nodes {
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originalNodes[node.Name] = true
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}
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shuffledNodes := make(map[string]bool)
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for _, node := range derpMap.Regions[1].Nodes {
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shuffledNodes[node.Name] = true
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}
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if diff := cmp.Diff(originalNodes, shuffledNodes); diff != "" {
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t.Errorf("Shuffle changed node set (-original +shuffled):\n%s", diff)
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}
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}
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