Add Version Output Support to Snowflake

From now on, there will be a file at common/version/version.go that includes current version number.

common/utls/client_hello_id.go

@@ -36,3 +36,11 @@ func NameToUTLSID(name string) (utls.ClientHelloID, error) {
 	}
 	return utls.ClientHelloID{}, errNameNotFound
 }
+
+func ListAllNames() []string {
+	var names []string
+	for k, _ := range clientHelloIDMap {
+		names = append(names, k)
+	}
+	return names
+}

common/utls/client_hello_id_version.go

@@ -0,0 +1,24 @@
+package utls
+
+import (
+	"git.torproject.org/pluggable-transports/snowflake.git/v2/common/version"
+	"strings"
+)
+
+func generateVersionOutput() string {
+	var versionOutputBuilder strings.Builder
+
+	versionOutputBuilder.WriteString(`Known utls-imitate values:
+(empty)
+`)
+
+	for _, name := range ListAllNames() {
+		versionOutputBuilder.WriteString(name)
+		versionOutputBuilder.WriteRune('\n')
+	}
+	return versionOutputBuilder.String()
+}
+
+func init() {
+	version.AddVersionDetail(generateVersionOutput())
+}

common/version/combined.go

@@ -0,0 +1,5 @@
+package version
+
+func ConstructResult() string {
+	return GetVersion() + "\n" + GetVersionDetail()
+}

common/version/detail.go

@@ -0,0 +1,13 @@
+package version
+
+import "strings"
+
+var detailBuilder strings.Builder
+
+func AddVersionDetail(detail string) {
+	detailBuilder.WriteString(detail)
+}
+
+func GetVersionDetail() string {
+	return detailBuilder.String()
+}

common/version/version.go

@@ -0,0 +1,7 @@
+package version
+
+func GetVersion() string {
+	return version
+}
+
+var version = "2.3.1"