main.go

// mkonion: create a Tor onion service for existing Docker containers
// Copyright (C) 2016 Aleksa Sarai <cyphar@cyphar.com>

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"strconv"
	"strings"

	log "github.com/Sirupsen/logrus"
	"github.com/docker/engine-api/client"
)

func IsInteger(s string) bool {
	_, err := strconv.Atoi(s)
	return err == nil
}

func mkonion() (err error) {
	var (
		oMappings   *flagList = new(flagList)
		oPrivateKey string
	)

	flag.Var(oMappings, "p", "specify a list of port mappings of the form '[onion:]container'")
	flag.StringVar(&oPrivateKey, "k", "", "specify a private_key to use for the hidden service")

	flag.Parse()
	oTargetContainer := flag.Arg(0)

	if flag.NArg() != 1 || oTargetContainer == "" {
		flag.Usage()
		return fmt.Errorf("must specify a container to create an onion service for")
	}

	// Load the private key.
	var privatekey []byte
	if oPrivateKey != "" {
		pk, err := ioutil.ReadFile(oPrivateKey)
		if err != nil {
			return fmt.Errorf("reading private key: %s", err)
		}

		// -k is technically unsafe if you don't know what it does
		log.WithFields(log.Fields{
			"keypath": oPrivateKey,
		}).Warn("using the -k option results in your private key being embedded in the resulting image: do not share the image or any images derived from it with anybody")

		privatekey = pk
	}

	// Check the validity of arguments here.
	for _, arg := range *oMappings {
		ports := strings.SplitN(arg, ":", 2)
		if len(ports) == 0 || len(ports) > 2 {
			return fmt.Errorf("port mappings must be of the form '[onion:]container'")
		}

		for _, port := range ports {
			if !IsInteger(port) {
				return fmt.Errorf("port mappings must be integers")
			}
		}
	}

	cli, err := client.NewEnvClient()
	if err != nil {
		return fmt.Errorf("connecting to client: %s", err)
	}

	ident := generateIdentifier()
	networkID, err := CreateOnionNetwork(cli, ident)
	if err != nil {
		return fmt.Errorf("creating onion network: %s", err)
	}
	log.WithFields(log.Fields{
		"network": ident,
	}).Info("created onion network")
	defer func() {
		if err != nil {
			if err := PurgeOnionNetwork(cli, networkID); err != nil {
				log.Warnf("purge onion network: %s", err)
			}
		}
	}()

	if err := ConnectOnionNetwork(cli, oTargetContainer, networkID); err != nil {
		return fmt.Errorf("connecting target to onion network: %s", err)
	}
	log.WithFields(log.Fields{
		"network":   ident,
		"container": oTargetContainer,
	}).Info("attached container to onion network")

	ip, err := FindOnionIPAddress(cli, oTargetContainer, networkID)
	if err != nil {
		return fmt.Errorf("finding target onion ip: %s", err)
	}
	log.WithFields(log.Fields{
		"network":   ident,
		"container": oTargetContainer,
		"ip":        ip,
	}).Info("found target address")

	ports, err := FindTargetPorts(cli, oTargetContainer)
	if err != nil {
		return fmt.Errorf("finding target ports: %s", err)
	}

	// Add all exposed ports naively to mappings before parsing arguments.
	portMappings := map[string]string{}
	for _, port := range ports {
		log.Infof("forwarding port: %s", port)
		if port.Proto() != "tcp" {
			log.Warn("encountered non-TCP exposed port in container: %s", port)
		}
		portMappings[port.Port()] = port.Port()
	}

	// Now deal with arguments.
	for _, arg := range *oMappings {
		var onion, container string

		ports := strings.SplitN(arg, ":", 2)
		onion = ports[0]

		// The format is [onion:]container.
		switch len(ports) {
		case 2:
			container = ports[1]
		case 1:
			container = ports[0]
		default:
			return fmt.Errorf("port mappings must be of the form '[onion:]container'")
		}

		// Can't redefine external mappings.
		if _, ok := portMappings[onion]; ok {
			return fmt.Errorf("cannot have multiple definitons of onion port mappings")
		}

		portMappings[onion] = container
	}

	torrc, err := GenerateConfig(cli, GenerateTargetMappings(ip, portMappings))
	if err != nil {
		return fmt.Errorf("generating torrc: %s", err)
	}
	log.Info("generated torrc config")

	buildOptions := &FakeBuildOptions{
		ident:      ident,
		networkID:  networkID,
		torrc:      torrc,
		privatekey: privatekey,
	}

	containerID, err := FakeBuildRun(cli, buildOptions)
	if err != nil {
		return fmt.Errorf("starting tor daemon: %s", err)
	}
	log.WithFields(log.Fields{
		"container": containerID,
	}).Infof("tor daemon started")

	// XXX: This has issues because we need to wait for Tor to make a hostname.
	onionAddr, err := GetOnionHostname(cli, containerID)
	if err != nil {
		return fmt.Errorf("get onion hostname: %s", err)
	}
	log.WithFields(log.Fields{
		"onion": onionAddr,
	}).Infof("retrieved Tor onion address")
	return nil
}

func main() {
	if err := mkonion(); err != nil {
		log.Fatal(err)
	}
}