refactor: merge psiphonx and torx into tunnel (#287)

* refactor: merge psiphonx and torx into tunnel

This is a case where it seems that merging these three packages into
a single package will enable us to better the implementation.

The goal is still https://github.com/ooni/probe/issues/985.

The roadblock I'm trying to overcome is
https://github.com/ooni/probe-cli/pull/286#pullrequestreview-627460104.

* avoid duplicating logger for now

internal/engine/internal/psiphonx/psiphonx.go

@@ -1,131 +0,0 @@
-// Package psiphonx is a wrapper around the psiphon-tunnel-core.
-package psiphonx
-
-import (
-	"context"
-	"fmt"
-	"net"
-	"net/url"
-	"os"
-	"path/filepath"
-	"time"
-
-	"github.com/ooni/psiphon/oopsi/github.com/Psiphon-Labs/psiphon-tunnel-core/ClientLibrary/clientlib"
-)
-
-// Session is the way in which this package sees a Session.
-type Session interface {
-	FetchPsiphonConfig(ctx context.Context) ([]byte, error)
-	TempDir() string
-}
-
-// Dependencies contains dependencies for Start
-type Dependencies interface {
-	MkdirAll(path string, perm os.FileMode) error
-	RemoveAll(path string) error
-	Start(ctx context.Context, config []byte,
-		workdir string) (*clientlib.PsiphonTunnel, error)
-}
-
-type defaultDependencies struct{}
-
-func (defaultDependencies) MkdirAll(path string, perm os.FileMode) error {
-	return os.MkdirAll(path, perm)
-}
-
-func (defaultDependencies) RemoveAll(path string) error {
-	return os.RemoveAll(path)
-}
-
-func (defaultDependencies) Start(
-	ctx context.Context, config []byte, workdir string) (*clientlib.PsiphonTunnel, error) {
-	return clientlib.StartTunnel(ctx, config, "", clientlib.Parameters{
-		DataRootDirectory: &workdir}, nil, nil)
-}
-
-// Config contains the settings for Start. The empty config object implies
-// that we will be using default settings for starting the tunnel.
-type Config struct {
-	// Dependencies contains dependencies for Start.
-	Dependencies Dependencies
-
-	// WorkDir is the directory where Psiphon should store
-	// its configuration database.
-	WorkDir string
-}
-
-// Tunnel is a psiphon tunnel
-type Tunnel struct {
-	tunnel   *clientlib.PsiphonTunnel
-	duration time.Duration
-}
-
-func makeworkingdir(config Config) (string, error) {
-	const testdirname = "oonipsiphon"
-	workdir := filepath.Join(config.WorkDir, testdirname)
-	if err := config.Dependencies.RemoveAll(workdir); err != nil {
-		return "", err
-	}
-	if err := config.Dependencies.MkdirAll(workdir, 0700); err != nil {
-		return "", err
-	}
-	return workdir, nil
-}
-
-// Start starts the psiphon tunnel.
-func Start(
-	ctx context.Context, sess Session, config Config) (*Tunnel, error) {
-	select {
-	case <-ctx.Done():
-		return nil, ctx.Err() // simplifies unit testing this code
-	default:
-	}
-	if config.Dependencies == nil {
-		config.Dependencies = defaultDependencies{}
-	}
-	if config.WorkDir == "" {
-		config.WorkDir = sess.TempDir()
-	}
-	configJSON, err := sess.FetchPsiphonConfig(ctx)
-	if err != nil {
-		return nil, err
-	}
-	workdir, err := makeworkingdir(config)
-	if err != nil {
-		return nil, err
-	}
-	start := time.Now()
-	tunnel, err := config.Dependencies.Start(ctx, configJSON, workdir)
-	if err != nil {
-		return nil, err
-	}
-	stop := time.Now()
-	return &Tunnel{tunnel: tunnel, duration: stop.Sub(start)}, nil
-}
-
-// Stop is an idempotent method that shuts down the tunnel
-func (t *Tunnel) Stop() {
-	if t != nil {
-		t.tunnel.Stop()
-	}
-}
-
-// SOCKS5ProxyURL returns the SOCKS5 proxy URL.
-func (t *Tunnel) SOCKS5ProxyURL() (proxyURL *url.URL) {
-	if t != nil {
-		proxyURL = &url.URL{
-			Scheme: "socks5",
-			Host: net.JoinHostPort(
-				"127.0.0.1", fmt.Sprintf("%d", t.tunnel.SOCKSProxyPort)),
-		}
-	}
-	return
-}
-
-// BootstrapTime returns the bootstrap time
-func (t *Tunnel) BootstrapTime() (duration time.Duration) {
-	if t != nil {
-		duration = t.duration
-	}
-	return
-}