Skip if not go1.23

go.mod

@@ -1,6 +1,6 @@
 module github.com/xtls/xray-core
 
-go 1.23
+go 1.21.4
 
 require (
 	github.com/OmarTariq612/goech v0.0.0-20240405204721-8e2e1dafd3a0

transport/internet/tls/config.go

@@ -391,11 +391,10 @@ func (c *Config) GetTLSConfig(opts ...Option) *tls.Config {
 		}
 	}
 	if len(c.EchConfig) > 0 {
-		ECHConfig, err := base64.StdEncoding.DecodeString(c.EchConfig)
+		err := ApplyECH(c, config)
 		if err != nil {
-			errors.LogError(context.Background(), "invalid ECH config")
+			errors.LogError(context.Background(), err)
 		}
-		config.EncryptedClientHelloConfigList = ECHConfig
 	}
 
 	return config

transport/internet/tls/ech.go

@@ -0,0 +1,21 @@
+//go:build go1.23
+// +build go1.23
+
+package tls
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/base64"
+
+	"github.com/xtls/xray-core/common/errors"
+)
+
+func ApplyECH(c *Config, config *tls.Config) error {
+	ECHConfig, err := base64.StdEncoding.DecodeString(c.EchConfig)
+	if err != nil {
+		errors.LogError(context.Background(), "invalid ECH config")
+	}
+	config.EncryptedClientHelloConfigList = ECHConfig
+	return nil
+}

transport/internet/tls/ech_go121.go

@@ -0,0 +1,14 @@
+//go:build !go1.23
+// +build !go1.23
+
+package tls
+
+import (
+	"crypto/tls"
+
+	"github.com/xtls/xray-core/common/errors"
+)
+
+func ApplyECH(c *Config, config *tls.Config) error {
+	return errors.New("Win7 does not support ECH")
+}