add go-tun2socks code

common/lsof/lsof_unix.go

@@ -0,0 +1,45 @@
+// +build darwin,!ios linux,!android
+
+package lsof
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+func GetCommandNameBySocket(network string, addr string, port uint16) (string, error) {
+	pattern := ""
+	switch network {
+	case "tcp":
+		pattern = fmt.Sprintf("-i%s@%s:%d", network, addr, port)
+	case "udp":
+		// The current approach isn't quite accurate for
+		// udp sockets, as more than one processes can
+		// listen on the same udp port. Moreover, if
+		// the application closes the socket immediately
+		// after sending out the packet (e.g. it just
+		// uploading data but not receving any data),
+		// we may not be able to find it.
+		pattern = fmt.Sprintf("-i%s:%d", network, port)
+	default:
+	}
+	out, err := exec.Command("lsof", "-n", "-Fc", pattern).Output()
+	if err != nil {
+		if len(out) != 0 {
+			return "", errors.New(fmt.Sprintf("%v, output: %s", err, out))
+		}
+		return "", err
+	}
+	lines := strings.Split(string(out), "\n")
+	for _, line := range lines {
+		// There may be multiple candidate
+		// sockets in the list, just take
+		// the first one for simplicity.
+		if strings.HasPrefix(line, "c") {
+			return line[1:len(line)], nil
+		}
+	}
+	return "", errors.New("not found")
+}