TCP client command (#1696)

* add cli commands

* add jwt cache test

* add tcptunnel test

* add stdin/stdout support

* use cryptutil hash function

* doc updates

* fix log timestamp

cmd/pomerium-cli/tcp.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net"
+	"net/url"
+	"os"
+	"os/signal"
+	"strings"
+	"syscall"
+
+	"github.com/rs/zerolog"
+	"github.com/spf13/cobra"
+
+	"github.com/pomerium/pomerium/internal/log"
+	"github.com/pomerium/pomerium/internal/tcptunnel"
+)
+
+var tcpCmdOptions struct {
+	listen      string
+	pomeriumURL string
+}
+
+func init() {
+	flags := tcpCmd.Flags()
+	flags.StringVar(&tcpCmdOptions.listen, "listen", "127.0.0.1:0",
+		"local address to start a listener on")
+	flags.StringVar(&tcpCmdOptions.pomeriumURL, "pomerium-url", "",
+		"the URL of the pomerium server to connect to")
+	rootCmd.AddCommand(tcpCmd)
+}
+
+var tcpCmd = &cobra.Command{
+	Use:  "tcp destination",
+	Args: cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		dstHost := args[0]
+		dstHostname, _, err := net.SplitHostPort(dstHost)
+		if err != nil {
+			return fmt.Errorf("invalid destination: %w", err)
+		}
+
+		pomeriumURL := &url.URL{
+			Scheme: "https",
+			Host:   net.JoinHostPort(dstHostname, "443"),
+		}
+		if tcpCmdOptions.pomeriumURL != "" {
+			pomeriumURL, err = url.Parse(tcpCmdOptions.pomeriumURL)
+			if err != nil {
+				return fmt.Errorf("invalid pomerium URL: %w", err)
+			}
+			if !strings.Contains(pomeriumURL.Host, ":") {
+				if pomeriumURL.Scheme == "https" {
+					pomeriumURL.Host = net.JoinHostPort(pomeriumURL.Hostname(), "443")
+				} else {
+					pomeriumURL.Host = net.JoinHostPort(pomeriumURL.Hostname(), "80")
+				}
+			}
+		}
+
+		var tlsConfig *tls.Config
+		if pomeriumURL.Scheme == "https" {
+			tlsConfig = new(tls.Config)
+		}
+
+		l := zerolog.New(zerolog.NewConsoleWriter(func(w *zerolog.ConsoleWriter) {
+			w.Out = os.Stderr
+		})).With().Timestamp().Logger()
+		log.SetLogger(&l)
+
+		c := make(chan os.Signal, 1)
+		signal.Notify(c, os.Interrupt, syscall.SIGTERM, syscall.SIGHUP)
+		ctx, cancel := context.WithCancel(context.Background())
+		go func() {
+			<-c
+			cancel()
+		}()
+
+		tun := tcptunnel.New(
+			tcptunnel.WithDestinationHost(dstHost),
+			tcptunnel.WithProxyHost(pomeriumURL.Host),
+			tcptunnel.WithTLSConfig(tlsConfig),
+		)
+
+		if tcpCmdOptions.listen == "-" {
+			err = tun.Run(ctx, readWriter{Reader: os.Stdin, Writer: os.Stdout})
+		} else {
+			err = tun.RunListener(ctx, tcpCmdOptions.listen)
+		}
+		if err != nil {
+			_, _ = fmt.Fprintf(os.Stderr, "%s\n", err.Error())
+			os.Exit(1)
+		}
+
+		return nil
+	},
+}
+
+type readWriter struct {
+	io.Reader
+	io.Writer
+}