tunnel: add localproxy command

tunnel/cmd/localproxy/.gitignore

@@ -0,0 +1 @@
+localproxy

tunnel/cmd/localproxy/main.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"net"
+
+	"github.com/seqsense/aws-iot-device-sdk-go/v4/tunnel"
+)
+
+var (
+	accessToken     = flag.String("access-token", "", "Client access token")
+	proxyEndpoint   = flag.String("proxy-endpoint", "", "Endpoint of proxy server (e.g. data.tunneling.iot.ap-northeast-1.amazonaws.com:443)")
+	region          = flag.String("region", "", "Endpoint region. Exclusive flag with -proxy-endpoint")
+	sourcePort      = flag.Int("source-listen-port", 0, "Assigns source mode and sets the port to listen")
+	destinationApp  = flag.String("destination-app", "", "Assigns destination mode and set the endpoint in address:port format")
+	noSSLHostVerify = flag.Bool("no-ssl-host-verify", false, "Turn off SSL host verification")
+	proxyScheme     = flag.String("proxy-scheme", "wss", "Proxy server protocol scheme")
+)
+
+func main() {
+	flag.Parse()
+
+	if *accessToken == "" {
+		log.Fatal("error: -access-token must be specified")
+	}
+
+	var endpoint string
+	switch {
+	case *proxyEndpoint != "" && *region == "":
+		endpoint = *proxyEndpoint
+	case *region != "" && *proxyEndpoint == "":
+		endpoint = fmt.Sprintf("data.tunneling.iot.%s.amazonaws.com", *region)
+	default:
+		log.Fatal("error: one of -proxy-endpoint or -region must be specified")
+	}
+
+	proxyOpt := func(opt *tunnel.ProxyOptions) error {
+		opt.NoTLS = *noSSLHostVerify
+		opt.Scheme = *proxyScheme
+		return nil
+	}
+
+	switch {
+	case *sourcePort > 0 && *destinationApp == "":
+		listener, err := net.Listen("tcp", fmt.Sprintf(":%d", *sourcePort))
+		if err != nil {
+			log.Fatalf("error: %v", err)
+		}
+		err = tunnel.ProxySource(listener, endpoint, *accessToken, proxyOpt)
+		if err != nil {
+			log.Fatalf("error: %v", err)
+		}
+
+	case *destinationApp != "" && *sourcePort == 0:
+		err := tunnel.ProxyDestination(func() (io.ReadWriteCloser, error) {
+			return net.Dial("tcp", *destinationApp)
+		}, endpoint, *accessToken, proxyOpt)
+		if err != nil {
+			log.Fatalf("error: %v", err)
+		}
+
+	default:
+		log.Fatal("error: one of -source-listen-port or -destination-app must be specified")
+	}
+}