refactor: move tunnel pkg down one level (#358)

* refactor: move tunnel pkg down one level

While there, reduce unnecessary dependency on external packages.

* file I forgot to commit

internal/engine/tunnel/tor.go

@@ -1,137 +0,0 @@
-package tunnel
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"io"
-	"net/url"
-	"os"
-	"path/filepath"
-	"strings"
-	"time"
-
-	"github.com/cretz/bine/tor"
-)
-
-// torProcess is a running tor process.
-type torProcess interface {
-	io.Closer
-}
-
-// torTunnel is the Tor tunnel
-type torTunnel struct {
-	// bootstrapTime is the duration of the bootstrap
-	bootstrapTime time.Duration
-
-	// instance is the running tor instance
-	instance torProcess
-
-	// proxy is the SOCKS5 proxy URL
-	proxy *url.URL
-}
-
-// BootstrapTime returns the bootstrap time
-func (tt *torTunnel) BootstrapTime() time.Duration {
-	return tt.bootstrapTime
-}
-
-// SOCKS5ProxyURL returns the URL of the SOCKS5 proxy
-func (tt *torTunnel) SOCKS5ProxyURL() *url.URL {
-	return tt.proxy
-}
-
-// Stop stops the Tor tunnel
-func (tt *torTunnel) Stop() {
-	tt.instance.Close()
-}
-
-// ErrTorUnableToGetSOCKSProxyAddress indicates that we could not
-// get the SOCKS proxy address via the control port.
-var ErrTorUnableToGetSOCKSProxyAddress = errors.New(
-	"unable to get socks proxy address")
-
-// ErrTorReturnedUnsupportedProxy indicates that tor returned to
-// us the address of a proxy that we don't support.
-var ErrTorReturnedUnsupportedProxy = errors.New(
-	"tor returned unsupported proxy")
-
-// torStart starts the tor tunnel.
-func torStart(ctx context.Context, config *Config) (Tunnel, error) {
-	select {
-	case <-ctx.Done():
-		return nil, ctx.Err() // allows to write unit tests using this code
-	default:
-	}
-	if config.TunnelDir == "" {
-		return nil, ErrEmptyTunnelDir
-	}
-	stateDir := filepath.Join(config.TunnelDir, "tor")
-	logfile := filepath.Join(stateDir, "tor.log")
-	maybeCleanupTunnelDir(stateDir, logfile)
-	extraArgs := append([]string{}, config.TorArgs...)
-	extraArgs = append(extraArgs, "Log")
-	extraArgs = append(extraArgs, "notice stderr")
-	extraArgs = append(extraArgs, "Log")
-	extraArgs = append(extraArgs, fmt.Sprintf(`notice file %s`, logfile))
-	// Implementation note: here we make sure that we're not going to
-	// execute a binary called "tor" in the current directory on Windows
-	// as documented in https://blog.golang.org/path-security.
-	exePath, err := config.execabsLookPath(config.torBinary())
-	if err != nil {
-		return nil, err
-	}
-	config.logger().Infof("tunnel: exec: %s %+v", exePath, extraArgs)
-	instance, err := config.torStart(ctx, &tor.StartConf{
-		DataDir:   stateDir,
-		ExtraArgs: extraArgs,
-		ExePath:   exePath,
-		NoHush:    true,
-	})
-	if err != nil {
-		return nil, err
-	}
-	instance.StopProcessOnClose = true
-	start := time.Now()
-	if err := config.torEnableNetwork(ctx, instance, true); err != nil {
-		instance.Close()
-		return nil, err
-	}
-	stop := time.Now()
-	// Adapted from <https://git.io/Jfc7N>
-	info, err := config.torGetInfo(instance.Control, "net/listeners/socks")
-	if err != nil {
-		instance.Close()
-		return nil, err
-	}
-	if len(info) != 1 || info[0].Key != "net/listeners/socks" {
-		instance.Close()
-		return nil, ErrTorUnableToGetSOCKSProxyAddress
-	}
-	proxyAddress := info[0].Val
-	if strings.HasPrefix(proxyAddress, "unix:") {
-		instance.Close()
-		return nil, ErrTorReturnedUnsupportedProxy
-	}
-	return &torTunnel{
-		bootstrapTime: stop.Sub(start),
-		instance:      instance,
-		proxy:         &url.URL{Scheme: "socks5", Host: proxyAddress},
-	}, nil
-}
-
-// maybeCleanupTunnelDir removes stale files inside
-// of the tunnel directory.
-func maybeCleanupTunnelDir(dir, logfile string) {
-	os.Remove(logfile)
-	removeWithGlob(filepath.Join(dir, "torrc-*"))
-	removeWithGlob(filepath.Join(dir, "control-port-*"))
-}
-
-// removeWithGlob globs and removes files.
-func removeWithGlob(pattern string) {
-	files, _ := filepath.Glob(pattern)
-	for _, file := range files {
-		os.Remove(file)
-	}
-}