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cmd_onion.go
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cmd_onion.go
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package tor
import (
"errors"
"fmt"
"io/ioutil"
"os"
)
var (
// ErrNoPrivateKey is an error returned by the OnionStore.PrivateKey
// method when a private key hasn't yet been stored.
ErrNoPrivateKey = errors.New("private key not found")
)
// OnionType denotes the type of the onion service.
type OnionType int
const (
// V2 denotes that the onion service is V2.
V2 OnionType = iota
// V3 denotes that the onion service is V3.
V3
)
// OnionStore is a store containing information about a particular onion
// service.
type OnionStore interface {
// StorePrivateKey stores the private key according to the
// implementation of the OnionStore interface.
StorePrivateKey(OnionType, []byte) error
// PrivateKey retrieves a stored private key. If it is not found, then
// ErrNoPrivateKey should be returned.
PrivateKey(OnionType) ([]byte, error)
// DeletePrivateKey securely removes the private key from the store.
DeletePrivateKey(OnionType) error
}
// OnionFile is a file-based implementation of the OnionStore interface that
// stores an onion service's private key.
type OnionFile struct {
privateKeyPath string
privateKeyPerm os.FileMode
}
// A compile-time constraint to ensure OnionFile satisfies the OnionStore
// interface.
var _ OnionStore = (*OnionFile)(nil)
// NewOnionFile creates a file-based implementation of the OnionStore interface
// to store an onion service's private key.
func NewOnionFile(privateKeyPath string,
privateKeyPerm os.FileMode) *OnionFile {
return &OnionFile{
privateKeyPath: privateKeyPath,
privateKeyPerm: privateKeyPerm,
}
}
// StorePrivateKey stores the private key at its expected path.
func (f *OnionFile) StorePrivateKey(_ OnionType, privateKey []byte) error {
return ioutil.WriteFile(f.privateKeyPath, privateKey, f.privateKeyPerm)
}
// PrivateKey retrieves the private key from its expected path. If the file
// does not exist, then ErrNoPrivateKey is returned.
func (f *OnionFile) PrivateKey(_ OnionType) ([]byte, error) {
if _, err := os.Stat(f.privateKeyPath); os.IsNotExist(err) {
return nil, ErrNoPrivateKey
}
return ioutil.ReadFile(f.privateKeyPath)
}
// DeletePrivateKey removes the file containing the private key.
func (f *OnionFile) DeletePrivateKey(_ OnionType) error {
return os.Remove(f.privateKeyPath)
}
// AddOnionConfig houses all of the required parameters in order to
// successfully create a new onion service or restore an existing one.
type AddOnionConfig struct {
// Type denotes the type of the onion service that should be created.
Type OnionType
// VirtualPort is the externally reachable port of the onion address.
VirtualPort int
// TargetPorts is the set of ports that the service will be listening
// on locally. The Tor server will use choose a random port from this
// set to forward the traffic from the virtual port.
//
// NOTE: If nil/empty, the virtual port will be used as the only target
// port.
TargetPorts []int
// Store is responsible for storing all onion service related
// information.
//
// NOTE: If not specified, then nothing will be stored, making onion
// services unrecoverable after shutdown.
Store OnionStore
}
// prepareKeyparam takes a config and prepares the key param to be used inside
// ADD_ONION.
func (c *Controller) prepareKeyparam(cfg AddOnionConfig) (string, error) {
// We'll start off by checking if the store contains an existing
// private key. If it does not, then we should request the server to
// create a new onion service and return its private key. Otherwise,
// we'll request the server to recreate the onion server from our
// private key.
var keyParam string
switch cfg.Type {
// TODO(yy): drop support for v2.
case V2:
keyParam = "NEW:RSA1024"
case V3:
keyParam = "NEW:ED25519-V3"
}
if cfg.Store != nil {
privateKey, err := cfg.Store.PrivateKey(cfg.Type)
switch err {
// Proceed to request a new onion service.
case ErrNoPrivateKey:
// Recover the onion service with the private key found.
case nil:
keyParam = string(privateKey)
default:
return "", err
}
}
return keyParam, nil
}
// prepareAddOnion constructs a cmd command string based on the specified
// config.
func (c *Controller) prepareAddOnion(cfg AddOnionConfig) (string, error) {
// Create the keyParam.
keyParam, err := c.prepareKeyparam(cfg)
if err != nil {
return "", err
}
// Now, we'll create a mapping from the virtual port to each target
// port. If no target ports were specified, we'll use the virtual port
// to provide a one-to-one mapping.
var portParam string
// Helper function which appends the correct Port param depending on
// whether the user chose to use a custom target IP address or not.
pushPortParam := func(targetPort int) {
if c.targetIPAddress == "" {
portParam += fmt.Sprintf("Port=%d,%d ", cfg.VirtualPort,
targetPort)
} else {
portParam += fmt.Sprintf("Port=%d,%s:%d ",
cfg.VirtualPort, c.targetIPAddress, targetPort)
}
}
if len(cfg.TargetPorts) == 0 {
pushPortParam(cfg.VirtualPort)
} else {
for _, targetPort := range cfg.TargetPorts {
pushPortParam(targetPort)
}
}
// Send the command to create the onion service to the Tor server and
// await its response.
cmd := fmt.Sprintf("ADD_ONION %s %s", keyParam, portParam)
return cmd, nil
}
// AddOnion creates an ephemeral onion service and returns its onion address.
// Once created, the new onion service will remain active until either,
// - the onion service is removed via `DEL_ONION`.
// - the Tor daemon terminates.
// - the controller connection that originated the `ADD_ONION` is closed.
//
// Each connection can only see its own ephemeral services. If a service needs
// to survive beyond current controller connection, use the "Detach" flag when
// creating new service via `ADD_ONION`.
func (c *Controller) AddOnion(cfg AddOnionConfig) (*OnionAddr, error) {
// Before sending the request to create an onion service to the Tor
// server, we'll make sure that it supports V3 onion services if that
// was the type requested.
// TODO(yy): drop support for v2.
if cfg.Type == V3 {
if err := supportsV3(c.version); err != nil {
return nil, err
}
}
// Construct the cmd command.
cmd, err := c.prepareAddOnion(cfg)
if err != nil {
return nil, err
}
// Send the command to create the onion service to the Tor server and
// await its response.
_, reply, err := c.sendCommand(cmd)
if err != nil {
return nil, err
}
// If successful, the reply from the server should be of the following
// format, depending on whether a private key has been requested:
//
// C: ADD_ONION RSA1024:[Blob Redacted] Port=80,8080
// S: 250-ServiceID=testonion1234567
// S: 250 OK
//
// C: ADD_ONION NEW:RSA1024 Port=80,8080
// S: 250-ServiceID=testonion1234567
// S: 250-PrivateKey=RSA1024:[Blob Redacted]
// S: 250 OK
//
// We're interested in retrieving the service ID, which is the public
// name of the service, and the private key if requested.
replyParams := parseTorReply(reply)
serviceID, ok := replyParams["ServiceID"]
if !ok {
return nil, errors.New("service id not found in reply")
}
// If a new onion service was created and an onion store was provided,
// we'll store its private key to disk in the event that it needs to be
// recreated later on.
if privateKey, ok := replyParams["PrivateKey"]; cfg.Store != nil && ok {
err := cfg.Store.StorePrivateKey(cfg.Type, []byte(privateKey))
if err != nil {
return nil, fmt.Errorf("unable to write private key "+
"to file: %v", err)
}
}
c.activeServiceID = serviceID
log.Debugf("serviceID:%s added to tor controller", serviceID)
// Finally, we'll return the onion address composed of the service ID,
// along with the onion suffix, and the port this onion service can be
// reached at externally.
return &OnionAddr{
OnionService: serviceID + ".onion",
Port: cfg.VirtualPort,
}, nil
}
// DelOnion tells the Tor daemon to remove an onion service, which satisfies
// either,
// - the onion service was created on the same control connection as the
// "DEL_ONION" command.
// - the onion service was created using the "Detach" flag.
func (c *Controller) DelOnion(serviceID string) error {
log.Debugf("removing serviceID:%s from tor controller", serviceID)
cmd := fmt.Sprintf("DEL_ONION %s", serviceID)
// Send the command to create the onion service to the Tor server and
// await its response.
code, _, err := c.sendCommand(cmd)
// Tor replies with "250 OK" on success, or a 512 if there are an
// invalid number of arguments, or a 552 if it doesn't recognize the
// ServiceID.
switch code {
// Replied 250 OK.
case success:
return nil
// Replied 512 for invalid arguments. This is most likely that the
// serviceID is not set(empty string).
case invalidNumOfArguments:
return fmt.Errorf("invalid arguments: %w", err)
// Replied 552, which means either,
// - the serviceID is invalid.
// - the onion service is not owned by the current control connection
// and,
// - the onion service is not a detached service.
// In either case, we will ignore the error and log a warning as there
// not much we can do from the controller side.
case serviceIDNotRecognized:
log.Warnf("removing serviceID:%v not found", serviceID)
return nil
default:
return fmt.Errorf("undefined response code: %v, err: %w",
code, err)
}
}