add serial port(COM) listener and handler

listener/com/conn.go

@@ -0,0 +1,63 @@
+package com
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net"
+	"time"
+)
+
+type conn struct {
+	port   io.ReadWriteCloser
+	laddr  net.Addr
+	raddr  net.Addr
+	cancel context.CancelFunc
+}
+
+func (c *conn) Read(b []byte) (n int, err error) {
+	return c.port.Read(b)
+}
+
+func (c *conn) Write(b []byte) (n int, err error) {
+	return c.port.Write(b)
+}
+
+func (c *conn) LocalAddr() net.Addr {
+	return c.laddr
+}
+
+func (c *conn) RemoteAddr() net.Addr {
+	return c.raddr
+}
+
+func (c *conn) SetDeadline(t time.Time) error {
+	return &net.OpError{Op: "set", Net: "com", Source: nil, Addr: nil, Err: errors.New("deadline not supported")}
+}
+
+func (c *conn) SetReadDeadline(t time.Time) error {
+	return &net.OpError{Op: "set", Net: "com", Source: nil, Addr: nil, Err: errors.New("deadline not supported")}
+}
+
+func (c *conn) SetWriteDeadline(t time.Time) error {
+	return &net.OpError{Op: "set", Net: "com", Source: nil, Addr: nil, Err: errors.New("deadline not supported")}
+}
+
+func (c *conn) Close() (err error) {
+	if c.cancel != nil {
+		c.cancel()
+	}
+	return c.port.Close()
+}
+
+type comAddr struct {
+	port string
+}
+
+func (a *comAddr) Network() string {
+	return "com"
+}
+
+func (a *comAddr) String() string {
+	return a.port
+}

listener/com/listener.go

@@ -0,0 +1,142 @@
+package com
+
+import (
+	"context"
+	"net"
+	"strings"
+	"time"
+
+	"github.com/go-gost/core/listener"
+	"github.com/go-gost/core/logger"
+	md "github.com/go-gost/core/metadata"
+	limiter "github.com/go-gost/x/limiter/traffic/wrapper"
+	metrics "github.com/go-gost/x/metrics/wrapper"
+	"github.com/go-gost/x/registry"
+	goserial "github.com/tarm/serial"
+)
+
+func init() {
+	registry.ListenerRegistry().Register("com", NewListener)
+}
+
+type comListener struct {
+	cqueue  chan net.Conn
+	closed  chan struct{}
+	addr    net.Addr
+	logger  logger.Logger
+	md      metadata
+	options listener.Options
+}
+
+func NewListener(opts ...listener.Option) listener.Listener {
+	options := listener.Options{}
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	if options.Addr == "" {
+		options.Addr = defaultPort
+	}
+
+	return &comListener{
+		logger:  options.Logger,
+		options: options,
+	}
+}
+
+func (l *comListener) Init(md md.Metadata) (err error) {
+	if err = l.parseMetadata(md); err != nil {
+		return
+	}
+
+	l.addr = &comAddr{port: l.options.Addr}
+
+	l.cqueue = make(chan net.Conn)
+	l.closed = make(chan struct{})
+
+	go l.listenLoop()
+
+	return
+}
+
+func (l *comListener) Accept() (conn net.Conn, err error) {
+	select {
+	case conn := <-l.cqueue:
+		return conn, nil
+	case <-l.closed:
+	}
+
+	return nil, listener.ErrClosed
+}
+
+func (l *comListener) Addr() net.Addr {
+	return l.addr
+}
+
+func (l *comListener) Close() error {
+	select {
+	case <-l.closed:
+		return net.ErrClosed
+	default:
+		close(l.closed)
+	}
+	return nil
+}
+
+func (l *comListener) listenLoop() {
+	for {
+		ctx, cancel := context.WithCancel(context.Background())
+		err := func() error {
+			port, err := goserial.OpenPort(&goserial.Config{
+				Name:        l.options.Addr,
+				Baud:        l.md.baudRate,
+				Parity:      parseParity(l.md.parity),
+				ReadTimeout: l.md.timeout,
+			})
+			if err != nil {
+				return err
+			}
+
+			var c net.Conn
+			c = &conn{
+				port:   port,
+				laddr:  l.addr,
+				raddr:  l.addr,
+				cancel: cancel,
+			}
+			c = metrics.WrapConn(l.options.Service, c)
+			c = limiter.WrapConn(l.options.TrafficLimiter, c)
+
+			l.cqueue <- c
+
+			return nil
+		}()
+		if err != nil {
+			l.logger.Error(err)
+			cancel()
+		}
+
+		select {
+		case <-ctx.Done():
+		case <-l.closed:
+			return
+		}
+
+		time.Sleep(time.Second)
+	}
+}
+
+func parseParity(s string) goserial.Parity {
+	switch strings.ToLower(s) {
+	case "o", "odd":
+		return goserial.ParityOdd
+	case "e", "even":
+		return goserial.ParityEven
+	case "m", "mark":
+		return goserial.ParityMark
+	case "s", "space":
+		return goserial.ParitySpace
+	default:
+		return goserial.ParityNone
+	}
+}

listener/com/metadata.go

@@ -0,0 +1,33 @@
+package com
+
+import (
+	"time"
+
+	md "github.com/go-gost/core/metadata"
+	mdutil "github.com/go-gost/core/metadata/util"
+)
+
+const (
+	defaultPort     = "COM1"
+	defaultBaudRate = 9600
+	defaultParity   = "odd"
+)
+
+type metadata struct {
+	baudRate int
+	parity   string
+	timeout  time.Duration
+}
+
+func (l *comListener) parseMetadata(md md.Metadata) (err error) {
+	l.md.baudRate = mdutil.GetInt(md, "baud", "com.baud", "listener.com.baud")
+	if l.md.baudRate <= 0 {
+		l.md.baudRate = defaultBaudRate
+	}
+	l.md.parity = mdutil.GetString(md, "parity", "com.parity", "listener.com.parity")
+	if l.md.parity == "" {
+		l.md.parity = defaultParity
+	}
+	l.md.timeout = mdutil.GetDuration(md, "timeout", "com.timeout", "listener.com.timeout")
+	return
+}