Merge 4999fd5b7b into ab5d7cf3d2

2025-04-04 06:13:35 +03:00 · 2025-03-31 16:35:03 +03:30 · 2025-03-31 16:35:03 +03:30 · ed3eeccb10
commit ed3eeccb10
parent ab5d7cf3d2 4999fd5b7b
8 changed files with 311 additions and 36 deletions
--- a/go.mod
+++ b/go.mod
@ -3,7 +3,7 @@ module github.com/xtls/xray-core
 go 1.24

 require (
-	github.com/OmarTariq612/goech v0.0.0-20240405204721-8e2e1dafd3a0
+	github.com/OmarTariq612/goech v0.0.1
 	github.com/cloudflare/circl v1.6.0
 	github.com/ghodss/yaml v1.0.1-0.20220118164431-d8423dcdf344
 	github.com/golang/mock v1.7.0-rc.1
--- a/go.sum
+++ b/go.sum
@ -1,5 +1,5 @@
-github.com/OmarTariq612/goech v0.0.0-20240405204721-8e2e1dafd3a0 h1:Wo41lDOevRJSGpevP+8Pk5bANX7fJacO2w04aqLiC5I=
-github.com/OmarTariq612/goech v0.0.0-20240405204721-8e2e1dafd3a0/go.mod h1:FVGavL/QEBQDcBpr3fAojoK17xX5k9bicBphrOpP7uM=
+github.com/OmarTariq612/goech v0.0.1 h1:/0c918Bk1ik65GXDj2k7SOK78DyZr30Jmq9euy1/HXg=
+github.com/OmarTariq612/goech v0.0.1/go.mod h1:FVGavL/QEBQDcBpr3fAojoK17xX5k9bicBphrOpP7uM=
 github.com/andybalholm/brotli v1.1.0 h1:eLKJA0d02Lf0mVpIDgYnqXcUn0GqVmEFny3VuID1U3M=
 github.com/andybalholm/brotli v1.1.0/go.mod h1:sms7XGricyQI9K10gOSf56VKKWS4oLer58Q+mhRPtnY=
 github.com/cloudflare/circl v1.6.0 h1:cr5JKic4HI+LkINy2lg3W2jF8sHCVTBncJr5gIIq7qk=
--- a/infra/conf/transport_internet.go
+++ b/infra/conf/transport_internet.go
@ -412,6 +412,8 @@ type TLSConfig struct {
 	MasterKeyLog                         string           `json:"masterKeyLog"`
 	ServerNameToVerify                   string           `json:"serverNameToVerify"`
 	VerifyPeerCertInNames                []string         `json:"verifyPeerCertInNames"`
+	ECHConfigList                        string           `json:"echConfigList"`
+	EchKeySets                           string           `json:"echKeySets"`
 }

 // Build implements Buildable.
@ -483,6 +485,16 @@ func (c *TLSConfig) Build() (proto.Message, error) {
 	}
 	config.VerifyPeerCertInNames = c.VerifyPeerCertInNames

+	config.EchConfigList = c.ECHConfigList
+
+	if c.EchKeySets != "" {
+		EchPrivateKey, err := base64.StdEncoding.DecodeString(c.EchKeySets)
+		if err != nil {
+			return nil, errors.New("invalid ECH Config", c.EchKeySets)
+		}
+		config.EchKeySets = EchPrivateKey
+	}
+
 	return config, nil
 }

--- a/main/commands/all/tls/ech.go
+++ b/main/commands/all/tls/ech.go
@ -1,10 +1,8 @@
 package tls

 import (
-	"encoding/json"
 	"encoding/pem"
 	"os"
-	"strings"

 	"github.com/OmarTariq612/goech"
 	"github.com/cloudflare/circl/hpke"
@ -13,13 +11,13 @@ import (
 )

 var cmdECH = &base.Command{
-	UsageLine: `{{.Exec}} tls ech [--serverName (string)] [--json]`,
+	UsageLine: `{{.Exec}} tls ech [--serverName (string)] [--pem]`,
 	Short:     `Generate TLS-ECH certificates`,
 	Long: `
 Generate TLS-ECH certificates.

 Set serverName to your custom string: {{.Exec}} tls ech --serverName (string)
-Generate into json format: {{.Exec}} tls ech --json
+Generate into pem format: {{.Exec}} tls ech --pem
 `, // Enable PQ signature schemes: {{.Exec}} tls ech --pq-signature-schemes-enabled
 }

@ -29,7 +27,7 @@ func init() {

 var input_pqSignatureSchemesEnabled = cmdECH.Flag.Bool("pqSignatureSchemesEnabled", false, "")
 var input_serverName = cmdECH.Flag.String("serverName", "cloudflare-ech.com", "")
-var input_json = cmdECH.Flag.Bool("json", false, "True == turn on json output")
+var input_pem = cmdECH.Flag.Bool("pem", false, "True == turn on pem output")

 func executeECH(cmd *base.Command, args []string) {
 	var kem hpke.KEM
@ -40,30 +38,26 @@ func executeECH(cmd *base.Command, args []string) {
 		kem = hpke.KEM_X25519_HKDF_SHA256
 	}

-	echKeySet, err := goech.GenerateECHKeySet(0, *input_serverName, kem)
+	echKeySet, err := goech.GenerateECHKeySet(0, *input_serverName, kem, nil)
 	common.Must(err)

-	configBuffer, _ := echKeySet.ECHConfig.MarshalBinary()
-	keyBuffer, _ := echKeySet.MarshalBinary()
+	// Make single key set to a list with only one element
+	ECHConfigList := make(goech.ECHConfigList, 1)
+	ECHConfigList[0] = echKeySet.ECHConfig
+	ECHKeySetList := make(goech.ECHKeySetList, 1)
+	ECHKeySetList[0] = echKeySet
+	configBuffer, _ := ECHConfigList.MarshalBinary()
+	keyBuffer, _ := ECHKeySetList.MarshalBinary()
+	configStr, _ := ECHConfigList.ToBase64()
+	keySetStr, _ := ECHKeySetList.ToBase64()

 	configPEM := string(pem.EncodeToMemory(&pem.Block{Type: "ECH CONFIGS", Bytes: configBuffer}))
 	keyPEM := string(pem.EncodeToMemory(&pem.Block{Type: "ECH KEYS", Bytes: keyBuffer}))
-	if *input_json {
-		jECHConfigs := map[string]interface{}{
-			"configs": strings.Split(strings.TrimSpace(string(configPEM)), "\n"),
-		}
-		jECHKey := map[string]interface{}{
-			"key": strings.Split(strings.TrimSpace(string(keyPEM)), "\n"),
-		}
-
-		for _, i := range []map[string]interface{}{jECHConfigs, jECHKey} {
-			content, err := json.MarshalIndent(i, "", "  ")
-			common.Must(err)
-			os.Stdout.Write(content)
-			os.Stdout.WriteString("\n")
-		}
-	} else {
+	if *input_pem {
 		os.Stdout.WriteString(configPEM)
 		os.Stdout.WriteString(keyPEM)
+	} else {
+		os.Stdout.WriteString("ECH config list: \n" + configStr + "\n")
+		os.Stdout.WriteString("ECH Key sets: \n" + keySetStr + "\n")
 	}
 }
--- a/transport/internet/tls/config.go
+++ b/transport/internet/tls/config.go
@ -444,6 +444,12 @@ func (c *Config) GetTLSConfig(opts ...Option) *tls.Config {
 			config.KeyLogWriter = writer
 		}
 	}
+	if len(c.EchConfigList) > 0 || len(c.EchKeySets) > 0 {
+		err := ApplyECH(c, config)
+		if err != nil {
+			errors.LogError(context.Background(), err)
+		}
+	}

 	return config
 }
--- a/transport/internet/tls/config.pb.go
+++ b/transport/internet/tls/config.pb.go
@ -217,6 +217,8 @@ type Config struct {
 	// @Document After allow_insecure (automatically), if the server's cert can't be verified by any of these names, pinned_peer_certificate_chain_sha256 will be tried.
 	// @Critical
 	VerifyPeerCertInNames []string `protobuf:"bytes,17,rep,name=verify_peer_cert_in_names,json=verifyPeerCertInNames,proto3" json:"verify_peer_cert_in_names,omitempty"`
+	EchConfigList         string   `protobuf:"bytes,18,opt,name=ech_config_list,json=echConfigList,proto3" json:"ech_config_list,omitempty"`
+	EchKeySets            []byte   `protobuf:"bytes,19,opt,name=ech_key_sets,json=echKeySets,proto3" json:"ech_key_sets,omitempty"`
 }

 func (x *Config) Reset() {
@ -361,6 +363,20 @@ func (x *Config) GetVerifyPeerCertInNames() []string {
 	return nil
 }

+func (x *Config) GetEchConfigList() string {
+	if x != nil {
+		return x.EchConfigList
+	}
+	return ""
+}
+
+func (x *Config) GetEchKeySets() []byte {
+	if x != nil {
+		return x.EchKeySets
+	}
+	return nil
+}
+
 var File_transport_internet_tls_config_proto protoreflect.FileDescriptor

 var file_transport_internet_tls_config_proto_rawDesc = []byte{
@ -392,7 +408,7 @@ var file_transport_internet_tls_config_proto_rawDesc = []byte{
 	0x4e, 0x43, 0x49, 0x50, 0x48, 0x45, 0x52, 0x4d, 0x45, 0x4e, 0x54, 0x10, 0x00, 0x12, 0x14, 0x0a,
 	0x10, 0x41, 0x55, 0x54, 0x48, 0x4f, 0x52, 0x49, 0x54, 0x59, 0x5f, 0x56, 0x45, 0x52, 0x49, 0x46,
 	0x59, 0x10, 0x01, 0x12, 0x13, 0x0a, 0x0f, 0x41, 0x55, 0x54, 0x48, 0x4f, 0x52, 0x49, 0x54, 0x59,
-	0x5f, 0x49, 0x53, 0x53, 0x55, 0x45, 0x10, 0x02, 0x22, 0x9a, 0x06, 0x0a, 0x06, 0x43, 0x6f, 0x6e,
+	0x5f, 0x49, 0x53, 0x53, 0x55, 0x45, 0x10, 0x02, 0x22, 0xe4, 0x06, 0x0a, 0x06, 0x43, 0x6f, 0x6e,
 	0x66, 0x69, 0x67, 0x12, 0x25, 0x0a, 0x0e, 0x61, 0x6c, 0x6c, 0x6f, 0x77, 0x5f, 0x69, 0x6e, 0x73,
 	0x65, 0x63, 0x75, 0x72, 0x65, 0x18, 0x01, 0x20, 0x01, 0x28, 0x08, 0x52, 0x0d, 0x61, 0x6c, 0x6c,
 	0x6f, 0x77, 0x49, 0x6e, 0x73, 0x65, 0x63, 0x75, 0x72, 0x65, 0x12, 0x4a, 0x0a, 0x0b, 0x63, 0x65,
@ -442,15 +458,19 @@ var file_transport_internet_tls_config_proto_rawDesc = []byte{
 	0x65, 0x72, 0x69, 0x66, 0x79, 0x5f, 0x70, 0x65, 0x65, 0x72, 0x5f, 0x63, 0x65, 0x72, 0x74, 0x5f,
 	0x69, 0x6e, 0x5f, 0x6e, 0x61, 0x6d, 0x65, 0x73, 0x18, 0x11, 0x20, 0x03, 0x28, 0x09, 0x52, 0x15,
 	0x76, 0x65, 0x72, 0x69, 0x66, 0x79, 0x50, 0x65, 0x65, 0x72, 0x43, 0x65, 0x72, 0x74, 0x49, 0x6e,
-	0x4e, 0x61, 0x6d, 0x65, 0x73, 0x42, 0x73, 0x0a, 0x1f, 0x63, 0x6f, 0x6d, 0x2e, 0x78, 0x72, 0x61,
-	0x79, 0x2e, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x2e, 0x69, 0x6e, 0x74, 0x65,
-	0x72, 0x6e, 0x65, 0x74, 0x2e, 0x74, 0x6c, 0x73, 0x50, 0x01, 0x5a, 0x30, 0x67, 0x69, 0x74, 0x68,
-	0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x78, 0x74, 0x6c, 0x73, 0x2f, 0x78, 0x72, 0x61, 0x79,
-	0x2d, 0x63, 0x6f, 0x72, 0x65, 0x2f, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x2f,
-	0x69, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2f, 0x74, 0x6c, 0x73, 0xaa, 0x02, 0x1b, 0x58,
-	0x72, 0x61, 0x79, 0x2e, 0x54, 0x72, 0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x2e, 0x49, 0x6e,
-	0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2e, 0x54, 0x6c, 0x73, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74,
-	0x6f, 0x33,
+	0x4e, 0x61, 0x6d, 0x65, 0x73, 0x12, 0x26, 0x0a, 0x0f, 0x65, 0x63, 0x68, 0x5f, 0x63, 0x6f, 0x6e,
+	0x66, 0x69, 0x67, 0x5f, 0x6c, 0x69, 0x73, 0x74, 0x18, 0x12, 0x20, 0x01, 0x28, 0x09, 0x52, 0x0d,
+	0x65, 0x63, 0x68, 0x43, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x4c, 0x69, 0x73, 0x74, 0x12, 0x20, 0x0a,
+	0x0c, 0x65, 0x63, 0x68, 0x5f, 0x6b, 0x65, 0x79, 0x5f, 0x73, 0x65, 0x74, 0x73, 0x18, 0x13, 0x20,
+	0x01, 0x28, 0x0c, 0x52, 0x0a, 0x65, 0x63, 0x68, 0x4b, 0x65, 0x79, 0x53, 0x65, 0x74, 0x73, 0x42,
+	0x73, 0x0a, 0x1f, 0x63, 0x6f, 0x6d, 0x2e, 0x78, 0x72, 0x61, 0x79, 0x2e, 0x74, 0x72, 0x61, 0x6e,
+	0x73, 0x70, 0x6f, 0x72, 0x74, 0x2e, 0x69, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2e, 0x74,
+	0x6c, 0x73, 0x50, 0x01, 0x5a, 0x30, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d,
+	0x2f, 0x78, 0x74, 0x6c, 0x73, 0x2f, 0x78, 0x72, 0x61, 0x79, 0x2d, 0x63, 0x6f, 0x72, 0x65, 0x2f,
+	0x74, 0x72, 0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x2f, 0x69, 0x6e, 0x74, 0x65, 0x72, 0x6e,
+	0x65, 0x74, 0x2f, 0x74, 0x6c, 0x73, 0xaa, 0x02, 0x1b, 0x58, 0x72, 0x61, 0x79, 0x2e, 0x54, 0x72,
+	0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x2e, 0x49, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74,
+	0x2e, 0x54, 0x6c, 0x73, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }

 var (
--- a/transport/internet/tls/config.proto
+++ b/transport/internet/tls/config.proto
@ -91,4 +91,8 @@ message Config {
     @Critical
  */
  repeated string verify_peer_cert_in_names = 17;
+
+  string ech_config_list = 18;
+
+  bytes ech_key_sets = 19;
 }
--- a/transport/internet/tls/ech.go
+++ b/transport/internet/tls/ech.go
@ -0,0 +1,239 @@
+package tls
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"io"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/OmarTariq612/goech"
+	"github.com/miekg/dns"
+	"github.com/xtls/xray-core/common/errors"
+	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/transport/internet"
+)
+
+func ApplyECH(c *Config, config *tls.Config) error {
+	var ECHConfig []byte
+	var err error
+
+	nameToQuery := c.ServerName
+	var DNSServer string
+
+	// for client
+	if len(c.EchConfigList) != 0 {
+		// direct base64 config
+		if strings.HasPrefix(c.EchConfigList, "base64") {
+			Base64ECHConfigList := c.EchConfigList[len("base64://"):]
+			ECHConfigList, err := goech.ECHConfigListFromBase64(Base64ECHConfigList)
+			if err != nil {
+				return errors.New("Failed to unmarshal ECHConfigList: ", err)
+			}
+			ECHConfig, _ = ECHConfigList.MarshalBinary()
+		} else { // query config from dns
+			parts := strings.Split(c.EchConfigList, "+")
+			if len(parts) == 2 {
+				// parse ECH DNS server in format of "example.com+https://1.1.1.1/dns-query"
+				nameToQuery = parts[0]
+				DNSServer = parts[1]
+			} else if len(parts) == 1 {
+				// normal format
+				DNSServer = parts[0]
+			} else {
+				return errors.New("Invalid ECH DNS server format: ", c.EchConfigList)
+			}
+			if nameToQuery == "" {
+				return errors.New("Using DNS for ECH Config needs serverName or use Server format example.com+https://1.1.1.1/dns-query")
+			}
+			ECHConfig, err = QueryRecord(nameToQuery, DNSServer)
+			if err != nil {
+				return err
+			}
+		}
+
+		config.EncryptedClientHelloConfigList = ECHConfig
+	}
+
+	// for server
+	if len(c.EchKeySets) != 0 {
+		var keys []tls.EncryptedClientHelloKey
+		KeySets, err := goech.UnmarshalECHKeySetList(c.EchKeySets)
+		if err != nil {
+			return errors.New("Failed to unmarshal ECHKeySetList: ", err)
+		}
+		for idx, keySet := range KeySets {
+			ECHConfig, err := keySet.ECHConfig.MarshalBinary()
+			ECHPrivateKey, err := keySet.PrivateKey.MarshalBinary()
+			if err != nil {
+				return errors.New("Failed to marshal ECHKey in index: ", idx, "with err: ", err)
+			}
+			keys = append(keys, tls.EncryptedClientHelloKey{
+				Config:     ECHConfig,
+				PrivateKey: ECHPrivateKey})
+		}
+		config.EncryptedClientHelloKeys = keys
+	}
+	
+	return nil
+}
+
+type record struct {
+	echConfig []byte
+	expire    time.Time
+}
+
+var (
+	dnsCache sync.Map
+	// global Lock? I'm not sure if this needs finer grained locks.
+	// If we do this, we will need to nest another layer of struct
+	updating sync.Mutex
+)
+
+// QueryRecord returns the ECH config for given domain.
+// If the record is not in cache or expired, it will query the DNS server and update the cache.
+func QueryRecord(domain string, server string) ([]byte, error) {
+	val, found := dnsCache.Load(domain)
+	rec, _ := val.(record)
+	if found && rec.expire.After(time.Now()) {
+		errors.LogDebug(context.Background(), "Cache hit for domain: ", domain)
+		return rec.echConfig, nil
+	}
+
+	updating.Lock()
+	defer updating.Unlock()
+	// Try to get cache again after lock, in case another goroutine has updated it
+	// This might happen when the core tring is just stared and multiple goroutines are trying to query the same domain
+	val, found = dnsCache.Load(domain)
+	rec, _ = val.(record)
+	if found && rec.expire.After(time.Now()) {
+		errors.LogDebug(context.Background(), "ECH Config cache hit for domain: ", domain, " after trying to get update lock")
+		return rec.echConfig, nil
+	}
+
+	// Query ECH config from DNS server
+	errors.LogDebug(context.Background(), "Trying to query ECH config for domain: ", domain, " with ECH server: ", server)
+	echConfig, ttl, err := dnsQuery(server, domain)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	// Set minimum TTL to 600 seconds
+	if ttl < 600 {
+		ttl = 600
+	}
+
+	// Update cache
+	newRecored := record{
+		echConfig: echConfig,
+		expire:    time.Now().Add(time.Second * time.Duration(ttl)),
+	}
+	dnsCache.Store(domain, newRecored)
+	return echConfig, nil
+}
+
+// dnsQuery is the real func for sending type65 query for given domain to given DNS server.
+// return ECH config, TTL and error
+func dnsQuery(server string, domain string) ([]byte, uint32, error) {
+	m := new(dns.Msg)
+	var dnsResolve []byte
+	m.SetQuestion(dns.Fqdn(domain), dns.TypeHTTPS)
+	// for DOH server
+	if strings.HasPrefix(server, "https://") {
+		// always 0 in DOH
+		m.Id = 0
+		msg, err := m.Pack()
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		// All traffic sent by core should via xray's internet.DialSystem
+		// This involves the behavior of some Android VPN GUI clients
+		tr := &http.Transport{
+			IdleConnTimeout:   90 * time.Second,
+			ForceAttemptHTTP2: true,
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				dest, err := net.ParseDestination(network + ":" + addr)
+				if err != nil {
+					return nil, err
+				}
+				conn, err := internet.DialSystem(ctx, dest, nil)
+				if err != nil {
+					return nil, err
+				}
+				return conn, nil
+			},
+		}
+		client := &http.Client{
+			Timeout:   5 * time.Second,
+			Transport: tr,
+		}
+		req, err := http.NewRequest("POST", server, bytes.NewReader(msg))
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		req.Header.Set("Content-Type", "application/dns-message")
+		resp, err := client.Do(req)
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		defer resp.Body.Close()
+		respBody, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		if resp.StatusCode != http.StatusOK {
+			return []byte{}, 0, errors.New("query failed with response code:", resp.StatusCode)
+		}
+		dnsResolve = respBody
+	} else if strings.HasPrefix(server, "udp://") { // for classic udp dns server
+		udpServerAddr := server[len("udp://"):]
+		// default port 53 if not specified
+		if !strings.Contains(udpServerAddr, ":") {
+			udpServerAddr = udpServerAddr + ":53"
+		}
+		dest, err := net.ParseDestination("udp" + ":" + udpServerAddr)
+		if err != nil {
+			return nil, 0, errors.New("failed to parse udp dns server ", udpServerAddr, " for ECH: ", err)
+		}
+		dnsTimeoutCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		// use xray's internet.DialSystem as mentioned above
+		conn, err := internet.DialSystem(dnsTimeoutCtx, dest, nil)
+		defer conn.Close()
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		msg, err := m.Pack()
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		conn.Write(msg)
+		udpResponse := make([]byte, 512)
+		_, err = conn.Read(udpResponse)
+		if err != nil {
+			return []byte{}, 0, err
+		}
+		dnsResolve = udpResponse
+	}
+	respMsg := new(dns.Msg)
+	err := respMsg.Unpack(dnsResolve)
+	if err != nil {
+		return []byte{}, 0, errors.New("failed to unpack dns response for ECH: ", err)
+	}
+	if len(respMsg.Answer) > 0 {
+		for _, answer := range respMsg.Answer {
+			if https, ok := answer.(*dns.HTTPS); ok && https.Hdr.Name == dns.Fqdn(domain) {
+				for _, v := range https.Value {
+					if echConfig, ok := v.(*dns.SVCBECHConfig); ok {
+						errors.LogDebug(context.Background(), "Get ECH config:", echConfig.String(), " TTL:", respMsg.Answer[0].Header().Ttl)
+						return echConfig.ECH, answer.Header().Ttl, nil
+					}
+				}
+			}
+		}
+	}
+	return []byte{}, 0, errors.New("no ech record found")
+}