Refactoring modules

modules/gps/gps.go

@@ -0,0 +1,153 @@
+package gps
+
+import (
+	"fmt"
+	"io"
+	"time"
+
+	"github.com/bettercap/bettercap/log"
+	"github.com/bettercap/bettercap/session"
+
+	"github.com/adrianmo/go-nmea"
+	"github.com/tarm/serial"
+
+	"github.com/evilsocket/islazy/str"
+)
+
+type GPS struct {
+	session.SessionModule
+
+	serialPort string
+	baudRate   int
+	serial     *serial.Port
+}
+
+func NewGPS(s *session.Session) *GPS {
+	gps := &GPS{
+		SessionModule: session.NewSessionModule("http.server", s),
+		serialPort:    "/dev/ttyUSB0",
+		baudRate:      19200,
+	}
+
+	gps.AddParam(session.NewStringParameter("gps.device",
+		gps.serialPort,
+		"",
+		"Serial device of the GPS hardware."))
+
+	gps.AddParam(session.NewIntParameter("gps.baudrate",
+		fmt.Sprintf("%d", gps.baudRate),
+		"Baud rate of the GPS serial device."))
+
+	gps.AddHandler(session.NewModuleHandler("gps on", "",
+		"Start acquiring from the GPS hardware.",
+		func(args []string) error {
+			return gps.Start()
+		}))
+
+	gps.AddHandler(session.NewModuleHandler("gps off", "",
+		"Stop acquiring from the GPS hardware.",
+		func(args []string) error {
+			return gps.Stop()
+		}))
+
+	gps.AddHandler(session.NewModuleHandler("gps.show", "",
+		"Show the last coordinates returned by the GPS hardware.",
+		func(args []string) error {
+			return gps.Show()
+		}))
+
+	return gps
+}
+
+func (gps *GPS) Name() string {
+	return "gps"
+}
+
+func (gps *GPS) Description() string {
+	return "A module talking with GPS hardware on a serial interface."
+}
+
+func (gps *GPS) Author() string {
+	return "Simone Margaritelli <evilsocket@protonmail.com>"
+}
+
+func (gps *GPS) Configure() (err error) {
+	if gps.Running() {
+		return session.ErrAlreadyStarted
+	} else if err, gps.serialPort = gps.StringParam("gps.device"); err != nil {
+		return err
+	} else if err, gps.baudRate = gps.IntParam("gps.baudrate"); err != nil {
+		return err
+	}
+
+	gps.serial, err = serial.OpenPort(&serial.Config{
+		Name:        gps.serialPort,
+		Baud:        gps.baudRate,
+		ReadTimeout: time.Second * 1,
+	})
+
+	return
+}
+
+func (gps *GPS) readLine() (line string, err error) {
+	var n int
+
+	b := make([]byte, 1)
+	for {
+		if n, err = gps.serial.Read(b); err != nil {
+			return
+		} else if n == 1 {
+			if b[0] == '\n' {
+				return str.Trim(line), nil
+			} else {
+				line += string(b[0])
+			}
+		}
+	}
+}
+
+func (gps *GPS) Show() error {
+	fmt.Printf("latitude:%f longitude:%f quality:%s satellites:%d altitude:%f\n",
+		gps.Session.GPS.Latitude,
+		gps.Session.GPS.Longitude,
+		gps.Session.GPS.FixQuality,
+		gps.Session.GPS.NumSatellites,
+		gps.Session.GPS.Altitude)
+
+	gps.Session.Refresh()
+
+	return nil
+}
+
+func (gps *GPS) Start() error {
+	if err := gps.Configure(); err != nil {
+		return err
+	}
+
+	return gps.SetRunning(true, func() {
+
+		defer gps.serial.Close()
+
+		for gps.Running() {
+			if line, err := gps.readLine(); err == nil {
+				if s, err := nmea.Parse(line); err == nil {
+					// http://aprs.gids.nl/nmea/#gga
+					if m, ok := s.(nmea.GNGGA); ok {
+						gps.Session.GPS = m
+					}
+				} else {
+					log.Debug("Error parsing line '%s': %s", line, err)
+				}
+			} else if err != io.EOF {
+				log.Warning("Error while reading serial port: %s", err)
+			}
+		}
+	})
+}
+
+func (gps *GPS) Stop() error {
+	return gps.SetRunning(false, func() {
+		// let the read fail and exit
+		gps.serial.Close()
+	})
+}