TUN-4063: Cleanup dependencies between packages.

- Move packages the provide generic functionality (such as config) from `cmd` subtree to top level.
- Remove all dependencies on `cmd` subtree from top level packages.
- Consolidate all code dealing with token generation and transfer to a single cohesive package.

tunneldns/tunnel.go

@@ -2,22 +2,14 @@ package tunneldns
 
 import (
 	"net"
-	"os"
-	"os/signal"
 	"strconv"
 	"sync"
-	"syscall"
-
-	"github.com/cloudflare/cloudflared/cmd/cloudflared/cliutil"
-	"github.com/cloudflare/cloudflared/logger"
-	"github.com/cloudflare/cloudflared/metrics"
 
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/cache"
 	"github.com/pkg/errors"
 	"github.com/rs/zerolog"
-	"github.com/urfave/cli/v2"
 )
 
 const (
@@ -33,104 +25,6 @@ type Listener struct {
 	log    *zerolog.Logger
 }
 
-func Command(hidden bool) *cli.Command {
-	return &cli.Command{
-		Name:   "proxy-dns",
-		Action: cliutil.ErrorHandler(Run),
-		Usage:  "Run a DNS over HTTPS proxy server.",
-		Flags: []cli.Flag{
-			&cli.StringFlag{
-				Name:    "metrics",
-				Value:   "localhost:",
-				Usage:   "Listen address for metrics reporting.",
-				EnvVars: []string{"TUNNEL_METRICS"},
-			},
-			&cli.StringFlag{
-				Name:    "address",
-				Usage:   "Listen address for the DNS over HTTPS proxy server.",
-				Value:   "localhost",
-				EnvVars: []string{"TUNNEL_DNS_ADDRESS"},
-			},
-			// Note TUN-3758 , we use Int because UInt is not supported with altsrc
-			&cli.IntFlag{
-				Name:    "port",
-				Usage:   "Listen on given port for the DNS over HTTPS proxy server.",
-				Value:   53,
-				EnvVars: []string{"TUNNEL_DNS_PORT"},
-			},
-			&cli.StringSliceFlag{
-				Name:    "upstream",
-				Usage:   "Upstream endpoint URL, you can specify multiple endpoints for redundancy.",
-				Value:   cli.NewStringSlice("https://1.1.1.1/dns-query", "https://1.0.0.1/dns-query"),
-				EnvVars: []string{"TUNNEL_DNS_UPSTREAM"},
-			},
-			&cli.StringSliceFlag{
-				Name:    "bootstrap",
-				Usage:   "bootstrap endpoint URL, you can specify multiple endpoints for redundancy.",
-				Value:   cli.NewStringSlice("https://162.159.36.1/dns-query", "https://162.159.46.1/dns-query", "https://[2606:4700:4700::1111]/dns-query", "https://[2606:4700:4700::1001]/dns-query"),
-				EnvVars: []string{"TUNNEL_DNS_BOOTSTRAP"},
-			},
-			&cli.IntFlag{
-				Name:    "max-upstream-conns",
-				Usage:   "Maximum concurrent connections to upstream. Setting to 0 means unlimited.",
-				Value:   MaxUpstreamConnsDefault,
-				EnvVars: []string{"TUNNEL_DNS_MAX_UPSTREAM_CONNS"},
-			},
-		},
-		ArgsUsage: " ", // can't be the empty string or we get the default output
-		Hidden:    hidden,
-	}
-}
-
-// Run implements a foreground runner
-func Run(c *cli.Context) error {
-	log := logger.CreateLoggerFromContext(c, logger.EnableTerminalLog)
-
-	metricsListener, err := net.Listen("tcp", c.String("metrics"))
-	if err != nil {
-		log.Fatal().Err(err).Msg("Failed to open the metrics listener")
-	}
-
-	go metrics.ServeMetrics(metricsListener, nil, nil, log)
-
-	listener, err := CreateListener(
-		c.String("address"),
-		// Note TUN-3758 , we use Int because UInt is not supported with altsrc
-		uint16(c.Int("port")),
-		c.StringSlice("upstream"),
-		c.StringSlice("bootstrap"),
-		c.Int("max-upstream-conns"),
-		log,
-	)
-
-	if err != nil {
-		log.Err(err).Msg("Failed to create the listeners")
-		return err
-	}
-
-	// Try to start the server
-	readySignal := make(chan struct{})
-	err = listener.Start(readySignal)
-	if err != nil {
-		log.Err(err).Msg("Failed to start the listeners")
-		return listener.Stop()
-	}
-	<-readySignal
-
-	// Wait for signal
-	signals := make(chan os.Signal, 10)
-	signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)
-	defer signal.Stop(signals)
-	<-signals
-
-	// Shut down server
-	err = listener.Stop()
-	if err != nil {
-		log.Err(err).Msg("failed to stop")
-	}
-	return err
-}
-
 // Create a CoreDNS server plugin from configuration
 func createConfig(address string, port uint16, p plugin.Handler) *dnsserver.Config {
 	c := &dnsserver.Config{