diff --git a/tools/build/build.go b/tools/build/build.go
index 7a334b5a..1f6799be 100644
--- a/tools/build/build.go
+++ b/tools/build/build.go
@@ -3,130 +3,26 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"runtime"
-	"strings"
-	"time"
+
+	"github.com/v2ray/v2ray-core/tools/git"
 )
 
 var (
 	targetOS   = flag.String("os", runtime.GOOS, "Target OS of this build.")
 	targetArch = flag.String("arch", runtime.GOARCH, "Target CPU arch of this build.")
 	archive    = flag.Bool("zip", false, "Whether to make an archive of files or not.")
-
-	GOPATH   string
-	repoRoot string
-)
-
-type OS string
-
-const (
-	Windows = OS("windows")
-	MacOS   = OS("darwin")
-	Linux   = OS("linux")
-)
-
-type Architecture string
-
-const (
-	X86   = Architecture("386")
-	Amd64 = Architecture("amd64")
-	Arm   = Architecture("arm")
-	Arm64 = Architecture("arm64")
 )
 
-func getRepoVersion() (string, error) {
-	revHead, err := exec.Command("git", "rev-parse", "HEAD").Output()
-	if err != nil {
-		return "", err
-	}
-	version, err := exec.Command("git", "name-rev", "--tags", "--name-only", strings.TrimSpace(string(revHead))).Output()
-	if err != nil {
-		return "", err
-	}
-	verStr := strings.TrimSpace(string(version))
-	if strings.HasSuffix(verStr, "^0") {
-		verStr = verStr[:len(verStr)-2]
-	}
-	if verStr == "undefined" {
-		verStr = "custom"
-	}
-	return verStr, nil
-}
-
-func getOS() OS {
-	if targetOS == nil {
-		panic("OS is not specified.")
-	}
-	osStr := strings.ToLower(*targetOS)
-	if osStr == "windows" || osStr == "win" {
-		return Windows
-	}
-	if osStr == "darwin" || osStr == "mac" || osStr == "macos" || osStr == "osx" {
-		return MacOS
-	}
-	if osStr == "linux" || osStr == "debian" || osStr == "ubuntu" || osStr == "redhat" || osStr == "centos" {
-		return Linux
-	}
-	panic("Unknown OS " + *targetOS)
-}
-
-func getArch() Architecture {
-	if targetArch == nil {
-		panic("Arch is not specified.")
-	}
-	archStr := strings.ToLower(*targetArch)
-	if archStr == "x86" || archStr == "386" || archStr == "i386" {
-		return X86
-	}
-	if archStr == "amd64" || archStr == "x86-64" || archStr == "x64" {
-		return Amd64
-	}
-	if archStr == "arm" {
-		return Arm
-	}
-	if archStr == "arm64" {
-		return Arm64
-	}
-	panic("Unknown Arch " + *targetArch)
-}
-
-func getSuffix(vos OS, arch Architecture) string {
-	suffix := "-custom"
-	switch vos {
-	case Windows:
-		switch arch {
-		case X86:
-			suffix = "-windows-32"
-		case Amd64:
-			suffix = "-windows-64"
-		}
-	case MacOS:
-		suffix = "-macos"
-	case Linux:
-		switch arch {
-		case X86:
-			suffix = "-linux-32"
-		case Amd64:
-			suffix = "-linux-64"
-		case Arm:
-			suffix = "-linux-arm"
-		case Arm64:
-			suffix = "-linux-arm64"
-		}
-
-	}
-	return suffix
-}
-
-func createTargetDirectory(version string, vos OS, arch Architecture) (string, error) {
+func createTargetDirectory(version string, goOS GoOS, goArch GoArch) (string, error) {
 	suffix := "-custom"
 	if version != "custom" {
-		suffix = getSuffix(vos, arch)
+		suffix = getSuffix(goOS, goArch)
 	}
+	GOPATH := os.Getenv("GOPATH")
+
 	targetDir := filepath.Join(GOPATH, "bin", "v2ray"+suffix)
 	if version != "custom" {
 		os.RemoveAll(targetDir)
@@ -135,104 +31,45 @@ func createTargetDirectory(version string, vos OS, arch Architecture) (string, e
 	return targetDir, err
 }
 
-func getTargetFile(vos OS, arch Architecture) string {
-	suffix := getSuffix(vos, arch)
-	if vos == "Windows" {
+func getTargetFile(goOS GoOS) string {
+	suffix := ""
+	if goOS == "Windows" {
 		suffix += ".exe"
 	}
 	return "v2ray" + suffix
 }
 
-func normalizedContent(content []byte, vos OS) []byte {
-	str := strings.Replace(string(content), "\r\n", "\n", -1)
-	if vos == Windows {
-		str = strings.Replace(str, "\n", "\r\n", -1)
-	}
-	return []byte(str)
-}
-
-func copyConfigFiles(dir string, version string, vos OS, arch Architecture) error {
-	clientConfig, err := ioutil.ReadFile(filepath.Join(repoRoot, "release", "config", "vpoint_socks_vmess.json"))
-	if err != nil {
-		return err
-	}
-	clientConfig = normalizedContent(clientConfig, vos)
-	clientConfigName := "vpoint_socks_vmess.json"
-	if vos == Windows || vos == MacOS {
-		clientConfigName = "config.json"
-	}
-	err = ioutil.WriteFile(filepath.Join(dir, clientConfigName), clientConfig, 0777)
-	if err != nil {
-		return err
-	}
-
-	if vos == Windows || vos == MacOS {
-		return nil
-	}
-
-	serverConfig, err := ioutil.ReadFile(filepath.Join(repoRoot, "release", "config", "vpoint_vmess_freedom.json"))
-	if err != nil {
-		return err
-	}
-	serverConfig = normalizedContent(serverConfig, vos)
-	err = ioutil.WriteFile(filepath.Join(dir, "vpoint_vmess_freedom.json"), serverConfig, 0777)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
-func buildV2Ray(targetDir, targetFile string, version string, vos OS, arch Architecture) error {
-	ldFlags := "-s"
-	if version != "custom" {
-		year, month, day := time.Now().UTC().Date()
-		today := fmt.Sprintf("%04d%02d%02d", year, int(month), day)
-		ldFlags = ldFlags + " -X github.com/v2ray/v2ray-core.version=" + version + " -X github.com/v2ray/v2ray-core.build=" + today
-	}
-	target := filepath.Join(targetDir, targetFile)
-	fmt.Println("Building to " + target)
-	cmd := exec.Command("go", "build", "-o", target, "-compiler", "gc", "-ldflags", "\""+ldFlags+"\"", "github.com/v2ray/v2ray-core/release/server")
-	cmd.Env = append(cmd.Env, "GOOS="+string(vos), "GOARCH="+string(arch))
-	cmd.Env = append(cmd.Env, os.Environ()...)
-	_, err := cmd.Output()
-	return err
-}
-
 func main() {
 	flag.Parse()
+	fmt.Println(os.Args)
 
-	v2rayOS := getOS()
-	v2rayArch := getArch()
+	v2rayOS := parseOS(*targetOS)
+	v2rayArch := parseArch(*targetArch)
 
-	if err := os.Chdir(repoRoot); err != nil {
-		fmt.Println("Unable to switch to V2Ray repo: " + err.Error())
-		return
+	version, err := git.RepoVersionHead()
+	if version == git.VersionUndefined {
+		version = "custom"
 	}
-	version, err := getRepoVersion()
 	if err != nil {
 		fmt.Println("Unable to detect V2Ray version: " + err.Error())
 		return
 	}
 	fmt.Printf("Building V2Ray (%s) for %s %s\n", version, v2rayOS, v2rayArch)
+	version = "v1.0"
 
 	targetDir, err := createTargetDirectory(version, v2rayOS, v2rayArch)
 	if err != nil {
 		fmt.Println("Unable to create directory " + targetDir + ": " + err.Error())
 	}
 
-	targetFile := getTargetFile(v2rayOS, v2rayArch)
-	err = buildV2Ray(targetDir, targetFile, version, v2rayOS, v2rayArch)
+	targetFile := getTargetFile(v2rayOS)
+	err = buildV2Ray(filepath.Join(targetDir, targetFile), version, v2rayOS, v2rayArch)
 	if err != nil {
 		fmt.Println("Unable to build V2Ray: " + err.Error())
 	}
 
-	err = copyConfigFiles(targetDir, version, v2rayOS, v2rayArch)
+	err = copyConfigFiles(targetDir, v2rayOS)
 	if err != nil {
 		fmt.Println("Unable to copy config files: " + err.Error())
 	}
 }
-
-func init() {
-	GOPATH = os.Getenv("GOPATH")
-	repoRoot = filepath.Join(GOPATH, "src", "github.com", "v2ray", "v2ray-core")
-}
diff --git a/tools/build/config.go b/tools/build/config.go
new file mode 100644
index 00000000..067ec418
--- /dev/null
+++ b/tools/build/config.go
@@ -0,0 +1,43 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func copyConfigFile(src, dest string, goOS GoOS) error {
+	content, err := ioutil.ReadFile(src)
+	if err != nil {
+		return err
+	}
+	str := string(content)
+	str = strings.Replace(str, "\r\n", "\n", -1)
+	if goOS == Windows {
+		str = strings.Replace(str, "\n", "\r\n", -1)
+	}
+	return ioutil.WriteFile(dest, []byte(str), 0777)
+}
+
+func copyConfigFiles(dir string, goOS GoOS) error {
+	GOPATH := os.Getenv("GOPATH")
+	srcDir := filepath.Join(GOPATH, "src", "github.com", "v2ray", "v2ray-core", "release", "config")
+	src := filepath.Join(srcDir, "vpoint_socks_vmess.json")
+	dest := filepath.Join(dir, "vpoint_socks_vmess.json")
+	if goOS == Windows || goOS == MacOS {
+		dest = filepath.Join(dir, "config.json")
+	}
+	err := copyConfigFile(src, dest, goOS)
+	if err != nil {
+		return err
+	}
+
+	if goOS == Windows || goOS == MacOS {
+		return nil
+	}
+
+	src = filepath.Join(srcDir, "vpoint_vmess_freedom.json")
+	dest = filepath.Join(dir, "vpoint_vmess_freedom.json")
+	return copyConfigFile(src, dest, goOS)
+}
diff --git a/tools/build/env.go b/tools/build/env.go
new file mode 100644
index 00000000..a557b3d1
--- /dev/null
+++ b/tools/build/env.go
@@ -0,0 +1,83 @@
+package main
+
+import (
+	"strings"
+)
+
+type GoOS string
+
+const (
+	Windows   = GoOS("windows")
+	MacOS     = GoOS("darwin")
+	Linux     = GoOS("linux")
+	UnknownOS = GoOS("unknown")
+)
+
+type GoArch string
+
+const (
+	X86         = GoArch("386")
+	Amd64       = GoArch("amd64")
+	Arm         = GoArch("arm")
+	Arm64       = GoArch("arm64")
+	UnknownArch = GoArch("unknown")
+)
+
+func parseOS(rawOS string) GoOS {
+	osStr := strings.ToLower(rawOS)
+	if osStr == "windows" || osStr == "win" {
+		return Windows
+	}
+	if osStr == "darwin" || osStr == "mac" || osStr == "macos" || osStr == "osx" {
+		return MacOS
+	}
+	if osStr == "linux" || osStr == "debian" || osStr == "ubuntu" || osStr == "redhat" || osStr == "centos" {
+		return Linux
+	}
+	return UnknownOS
+}
+
+func parseArch(rawArch string) GoArch {
+	archStr := strings.ToLower(rawArch)
+	if archStr == "x86" || archStr == "386" || archStr == "i386" {
+		return X86
+	}
+	if archStr == "amd64" || archStr == "x86-64" || archStr == "x64" {
+		return Amd64
+	}
+	if archStr == "arm" {
+		return Arm
+	}
+	if archStr == "arm64" {
+		return Arm64
+	}
+	return UnknownArch
+}
+
+func getSuffix(os GoOS, arch GoArch) string {
+	suffix := "-custom"
+	switch os {
+	case Windows:
+		switch arch {
+		case X86:
+			suffix = "-windows-32"
+		case Amd64:
+			suffix = "-windows-64"
+		}
+	case MacOS:
+		suffix = "-macos"
+	case Linux:
+		switch arch {
+		case X86:
+			suffix = "-linux-32"
+		case Amd64:
+			suffix = "-linux-64"
+		case Arm:
+			suffix = "-linux-arm"
+		case Arm64:
+			suffix = "-linux-arm64"
+		}
+
+	}
+	return suffix
+}
diff --git a/tools/build/env_test.go b/tools/build/env_test.go
new file mode 100644
index 00000000..45c22e60
--- /dev/null
+++ b/tools/build/env_test.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/v2ray/v2ray-core/testing/unit"
+)
+
+func TestParseOS(t *testing.T) {
+	assert := unit.Assert(t)
+
+	assert.Pointer(parseOS("windows")).Equals(Windows)
+	assert.Pointer(parseOS("macos")).Equals(MacOS)
+	assert.Pointer(parseOS("linux")).Equals(Linux)
+	assert.Pointer(parseOS("test")).Equals(UnknownOS)
+}
+
+func TestParseArch(t *testing.T) {
+	assert := unit.Assert(t)
+
+	assert.Pointer(parseArch("x86")).Equals(X86)
+	assert.Pointer(parseArch("x64")).Equals(Amd64)
+	assert.Pointer(parseArch("arm")).Equals(Arm)
+	assert.Pointer(parseArch("arm64")).Equals(Arm64)
+	assert.Pointer(parseArch("test")).Equals(UnknownArch)
+}
diff --git a/tools/build/go.go b/tools/build/go.go
new file mode 100644
index 00000000..017d2ba9
--- /dev/null
+++ b/tools/build/go.go
@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"time"
+)
+
+func buildV2Ray(targetFile string, version string, goOS GoOS, goArch GoArch) error {
+	ldFlags := "-s"
+	if version != "" {
+		year, month, day := time.Now().UTC().Date()
+		today := fmt.Sprintf("%04d%02d%02d", year, int(month), day)
+		ldFlags = ldFlags + " -X github.com/v2ray/v2ray-core.version=" + version + " -X github.com/v2ray/v2ray-core.build=" + today
+	}
+	cmd := exec.Command("go", "build", "-o", targetFile, "-compiler", "gc", "-ldflags", ldFlags, "github.com/v2ray/v2ray-core/release/server")
+	cmd.Env = append(cmd.Env, "GOOS="+string(goOS), "GOARCH="+string(goArch))
+	cmd.Env = append(cmd.Env, os.Environ()...)
+	_, err := cmd.Output()
+	return err
+}
diff --git a/tools/build/go_test.go b/tools/build/go_test.go
new file mode 100644
index 00000000..65785ae0
--- /dev/null
+++ b/tools/build/go_test.go
@@ -0,0 +1,46 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/v2ray/v2ray-core/testing/unit"
+)
+
+func TestBuildAndRun(t *testing.T) {
+	assert := unit.Assert(t)
+
+	gopath := os.Getenv("GOPATH")
+	target := filepath.Join(gopath, "src", "v2ray_test")
+	fmt.Println(target)
+	goOS := parseOS(runtime.GOOS)
+	goArch := parseArch(runtime.GOARCH)
+	err := buildV2Ray(target, "v1.0", goOS, goArch)
+	assert.Error(err).IsNil()
+
+	outBuffer := bytes.NewBuffer(make([]byte, 0, 1024))
+	errBuffer := bytes.NewBuffer(make([]byte, 0, 1024))
+	configFile := filepath.Join(gopath, "src", "github.com", "v2ray", "v2ray-core", "release", "config", "vpoint_socks_vmess.json")
+	cmd := exec.Command(target, "--config="+configFile)
+	cmd.Stdout = outBuffer
+	cmd.Stderr = errBuffer
+	cmd.Start()
+
+	<-time.After(1 * time.Second)
+	cmd.Process.Kill()
+
+	outStr := string(outBuffer.Bytes())
+	errStr := string(errBuffer.Bytes())
+
+	assert.Bool(strings.Contains(outStr, "v1.0")).IsTrue()
+	assert.Int(len(errStr)).Equals(0)
+
+	os.Remove(target)
+}