plugeth/accounts/usbwallet/ledger_wallet.go

893 lines
32 KiB
Go

// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// This file contains the implementation for interacting with the Ledger hardware
// wallets. The wire protocol spec can be found in the Ledger Blue GitHub repo:
// https://raw.githubusercontent.com/LedgerHQ/blue-app-eth/master/doc/ethapp.asc
package usbwallet
import (
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"io"
"math/big"
"sync"
"time"
ethereum "github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/rlp"
"github.com/karalabe/hid"
"golang.org/x/net/context"
)
// Maximum time between wallet health checks to detect USB unplugs.
const ledgerHeartbeatCycle = time.Second
// Minimum time to wait between self derivation attempts, even it the user is
// requesting accounts like crazy.
const ledgerSelfDeriveThrottling = time.Second
// ledgerOpcode is an enumeration encoding the supported Ledger opcodes.
type ledgerOpcode byte
// ledgerParam1 is an enumeration encoding the supported Ledger parameters for
// specific opcodes. The same parameter values may be reused between opcodes.
type ledgerParam1 byte
// ledgerParam2 is an enumeration encoding the supported Ledger parameters for
// specific opcodes. The same parameter values may be reused between opcodes.
type ledgerParam2 byte
const (
ledgerOpRetrieveAddress ledgerOpcode = 0x02 // Returns the public key and Ethereum address for a given BIP 32 path
ledgerOpSignTransaction ledgerOpcode = 0x04 // Signs an Ethereum transaction after having the user validate the parameters
ledgerOpGetConfiguration ledgerOpcode = 0x06 // Returns specific wallet application configuration
ledgerP1DirectlyFetchAddress ledgerParam1 = 0x00 // Return address directly from the wallet
ledgerP1ConfirmFetchAddress ledgerParam1 = 0x01 // Require a user confirmation before returning the address
ledgerP1InitTransactionData ledgerParam1 = 0x00 // First transaction data block for signing
ledgerP1ContTransactionData ledgerParam1 = 0x80 // Subsequent transaction data block for signing
ledgerP2DiscardAddressChainCode ledgerParam2 = 0x00 // Do not return the chain code along with the address
ledgerP2ReturnAddressChainCode ledgerParam2 = 0x01 // Require a user confirmation before returning the address
)
// errReplyInvalidHeader is the error message returned by a Ledger data exchange
// if the device replies with a mismatching header. This usually means the device
// is in browser mode.
var errReplyInvalidHeader = errors.New("invalid reply header")
// errInvalidVersionReply is the error message returned by a Ledger version retrieval
// when a response does arrive, but it does not contain the expected data.
var errInvalidVersionReply = errors.New("invalid version reply")
// ledgerWallet represents a live USB Ledger hardware wallet.
type ledgerWallet struct {
url *accounts.URL // Textual URL uniquely identifying this wallet
info hid.DeviceInfo // Known USB device infos about the wallet
device *hid.Device // USB device advertising itself as a Ledger wallet
failure error // Any failure that would make the device unusable
version [3]byte // Current version of the Ledger Ethereum app (zero if app is offline)
browser bool // Flag whether the Ledger is in browser mode (reply channel mismatch)
accounts []accounts.Account // List of derive accounts pinned on the Ledger
paths map[common.Address]accounts.DerivationPath // Known derivation paths for signing operations
deriveNextPath accounts.DerivationPath // Next derivation path for account auto-discovery
deriveNextAddr common.Address // Next derived account address for auto-discovery
deriveChain ethereum.ChainStateReader // Blockchain state reader to discover used account with
deriveReq chan chan struct{} // Channel to request a self-derivation on
deriveQuit chan chan error // Channel to terminate the self-deriver with
healthQuit chan chan error
// Locking a hardware wallet is a bit special. Since hardware devices are lower
// performing, any communication with them might take a non negligible amount of
// time. Worse still, waiting for user confirmation can take arbitrarily long,
// but exclusive communication must be upheld during. Locking the entire wallet
// in the mean time however would stall any parts of the system that don't want
// to communicate, just read some state (e.g. list the accounts).
//
// As such, a hardware wallet needs two locks to function correctly. A state
// lock can be used to protect the wallet's software-side internal state, which
// must not be held exlusively during hardware communication. A communication
// lock can be used to achieve exclusive access to the device itself, this one
// however should allow "skipping" waiting for operations that might want to
// use the device, but can live without too (e.g. account self-derivation).
//
// Since we have two locks, it's important to know how to properly use them:
// - Communication requires the `device` to not change, so obtaining the
// commsLock should be done after having a stateLock.
// - Communication must not disable read access to the wallet state, so it
// must only ever hold a *read* lock to stateLock.
commsLock chan struct{} // Mutex (buf=1) for the USB comms without keeping the state locked
stateLock sync.RWMutex // Protects read and write access to the wallet struct fields
}
// URL implements accounts.Wallet, returning the URL of the Ledger device.
func (w *ledgerWallet) URL() accounts.URL {
return *w.url // Immutable, no need for a lock
}
// Status implements accounts.Wallet, always whether the Ledger is opened, closed
// or whether the Ethereum app was not started on it.
func (w *ledgerWallet) Status() string {
w.stateLock.RLock() // No device communication, state lock is enough
defer w.stateLock.RUnlock()
if w.failure != nil {
return fmt.Sprintf("Failed: %v", w.failure)
}
if w.device == nil {
return "Closed"
}
if w.browser {
return "Ethereum app in browser mode"
}
if w.offline() {
return "Ethereum app offline"
}
return fmt.Sprintf("Ethereum app v%d.%d.%d online", w.version[0], w.version[1], w.version[2])
}
// offline returns whether the wallet and the Ethereum app is offline or not.
//
// The method assumes that the state lock is held!
func (w *ledgerWallet) offline() bool {
return w.version == [3]byte{0, 0, 0}
}
// failed returns if the USB device wrapped by the wallet failed for some reason.
// This is used by the device scanner to report failed wallets as departed.
//
// The method assumes that the state lock is *not* held!
func (w *ledgerWallet) failed() bool {
w.stateLock.RLock() // No device communication, state lock is enough
defer w.stateLock.RUnlock()
return w.failure != nil
}
// Open implements accounts.Wallet, attempting to open a USB connection to the
// Ledger hardware wallet. The Ledger does not require a user passphrase, so that
// parameter is silently discarded.
func (w *ledgerWallet) Open(passphrase string) error {
w.stateLock.Lock() // State lock is enough since there's no connection yet at this point
defer w.stateLock.Unlock()
// If the wallet was already opened, don't try to open again
if w.device != nil {
return accounts.ErrWalletAlreadyOpen
}
// Otherwise iterate over all USB devices and find this again (no way to directly do this)
device, err := w.info.Open()
if err != nil {
return err
}
// Wallet seems to be successfully opened, guess if the Ethereum app is running
w.device = device
w.commsLock = make(chan struct{}, 1)
w.commsLock <- struct{}{} // Enable lock
w.paths = make(map[common.Address]accounts.DerivationPath)
w.deriveReq = make(chan chan struct{})
w.deriveQuit = make(chan chan error)
w.healthQuit = make(chan chan error)
defer func() {
go w.heartbeat()
go w.selfDerive()
}()
if _, err = w.ledgerDerive(accounts.DefaultBaseDerivationPath); err != nil {
// Ethereum app is not running or in browser mode, nothing more to do, return
if err == errReplyInvalidHeader {
w.browser = true
}
return nil
}
// Try to resolve the Ethereum app's version, will fail prior to v1.0.2
if w.version, err = w.ledgerVersion(); err != nil {
w.version = [3]byte{1, 0, 0} // Assume worst case, can't verify if v1.0.0 or v1.0.1
}
return nil
}
// heartbeat is a health check loop for the Ledger wallets to periodically verify
// whether they are still present or if they malfunctioned. It is needed because:
// - libusb on Windows doesn't support hotplug, so we can't detect USB unplugs
// - communication timeout on the Ledger requires a device power cycle to fix
func (w *ledgerWallet) heartbeat() {
glog.V(logger.Debug).Infof("%s health-check started", w.url.String())
defer glog.V(logger.Debug).Infof("%s health-check stopped", w.url.String())
// Execute heartbeat checks until termination or error
var (
errc chan error
err error
)
for errc == nil && err == nil {
// Wait until termination is requested or the heartbeat cycle arrives
select {
case errc = <-w.healthQuit:
// Termination requested
continue
case <-time.After(ledgerHeartbeatCycle):
// Heartbeat time
}
// Execute a tiny data exchange to see responsiveness
w.stateLock.RLock()
if w.device == nil {
// Terminated while waiting for the lock
w.stateLock.RUnlock()
continue
}
<-w.commsLock // Don't lock state while resolving version
_, err = w.ledgerVersion()
w.commsLock <- struct{}{}
w.stateLock.RUnlock()
if err != nil && err != errInvalidVersionReply {
w.stateLock.Lock() // Lock state to tear the wallet down
w.failure = err
w.close()
w.stateLock.Unlock()
}
// Ignore non hardware related errors
err = nil
}
// In case of error, wait for termination
if err != nil {
glog.V(logger.Debug).Infof("%s health-check failed: %v", w.url.String(), err)
errc = <-w.healthQuit
}
errc <- err
}
// Close implements accounts.Wallet, closing the USB connection to the Ledger.
func (w *ledgerWallet) Close() error {
// Ensure the wallet was opened
w.stateLock.RLock()
hQuit, dQuit := w.healthQuit, w.deriveQuit
w.stateLock.RUnlock()
// Terminate the health checks
var herr error
if hQuit != nil {
errc := make(chan error)
hQuit <- errc
herr = <-errc // Save for later, we *must* close the USB
}
// Terminate the self-derivations
var derr error
if dQuit != nil {
errc := make(chan error)
dQuit <- errc
derr = <-errc // Save for later, we *must* close the USB
}
// Terminate the device connection
w.stateLock.Lock()
defer w.stateLock.Unlock()
w.healthQuit = nil
w.deriveQuit = nil
w.deriveReq = nil
if err := w.close(); err != nil {
return err
}
if herr != nil {
return herr
}
return derr
}
// close is the internal wallet closer that terminates the USB connection and
// resets all the fields to their defaults.
//
// Note, close assumes the state lock is held!
func (w *ledgerWallet) close() error {
// Allow duplicate closes, especially for health-check failures
if w.device == nil {
return nil
}
// Close the device, clear everything, then return
w.device.Close()
w.device = nil
w.browser, w.version = false, [3]byte{}
w.accounts, w.paths = nil, nil
return nil
}
// Accounts implements accounts.Wallet, returning the list of accounts pinned to
// the Ledger hardware wallet. If self-derivation was enabled, the account list
// is periodically expanded based on current chain state.
func (w *ledgerWallet) Accounts() []accounts.Account {
// Attempt self-derivation if it's running
reqc := make(chan struct{}, 1)
select {
case w.deriveReq <- reqc:
// Self-derivation request accepted, wait for it
<-reqc
default:
// Self-derivation offline, throttled or busy, skip
}
// Return whatever account list we ended up with
w.stateLock.RLock()
defer w.stateLock.RUnlock()
cpy := make([]accounts.Account, len(w.accounts))
copy(cpy, w.accounts)
return cpy
}
// selfDerive is an account derivation loop that upon request attempts to find
// new non-zero accounts.
func (w *ledgerWallet) selfDerive() {
glog.V(logger.Debug).Infof("%s self-derivation started", w.url.String())
defer glog.V(logger.Debug).Infof("%s self-derivation stopped", w.url.String())
// Execute self-derivations until termination or error
var (
reqc chan struct{}
errc chan error
err error
)
for errc == nil && err == nil {
// Wait until either derivation or termination is requested
select {
case errc = <-w.deriveQuit:
// Termination requested
continue
case reqc = <-w.deriveReq:
// Account discovery requested
}
// Derivation needs a chain and device access, skip if either unavailable
w.stateLock.RLock()
if w.device == nil || w.deriveChain == nil || w.offline() {
w.stateLock.RUnlock()
reqc <- struct{}{}
continue
}
select {
case <-w.commsLock:
default:
w.stateLock.RUnlock()
reqc <- struct{}{}
continue
}
// Device lock obtained, derive the next batch of accounts
var (
accs []accounts.Account
paths []accounts.DerivationPath
nextAddr = w.deriveNextAddr
nextPath = w.deriveNextPath
context = context.Background()
)
for empty := false; !empty; {
// Retrieve the next derived Ethereum account
if nextAddr == (common.Address{}) {
if nextAddr, err = w.ledgerDerive(nextPath); err != nil {
glog.V(logger.Warn).Infof("%s self-derivation failed: %v", w.url.String(), err)
break
}
}
// Check the account's status against the current chain state
var (
balance *big.Int
nonce uint64
)
balance, err = w.deriveChain.BalanceAt(context, nextAddr, nil)
if err != nil {
glog.V(logger.Warn).Infof("%s self-derivation balance retrieval failed: %v", w.url.String(), err)
break
}
nonce, err = w.deriveChain.NonceAt(context, nextAddr, nil)
if err != nil {
glog.V(logger.Warn).Infof("%s self-derivation nonce retrieval failed: %v", w.url.String(), err)
break
}
// If the next account is empty, stop self-derivation, but add it nonetheless
if balance.BitLen() == 0 && nonce == 0 {
empty = true
}
// We've just self-derived a new account, start tracking it locally
path := make(accounts.DerivationPath, len(nextPath))
copy(path[:], nextPath[:])
paths = append(paths, path)
account := accounts.Account{
Address: nextAddr,
URL: accounts.URL{Scheme: w.url.Scheme, Path: fmt.Sprintf("%s/%s", w.url.Path, path)},
}
accs = append(accs, account)
// Display a log message to the user for new (or previously empty accounts)
if _, known := w.paths[nextAddr]; !known || (!empty && nextAddr == w.deriveNextAddr) {
glog.V(logger.Info).Infof("%s discovered %s (balance %22v, nonce %4d) at %s", w.url.String(), nextAddr.Hex(), balance, nonce, path)
}
// Fetch the next potential account
if !empty {
nextAddr = common.Address{}
nextPath[len(nextPath)-1]++
}
}
// Self derivation complete, release device lock
w.commsLock <- struct{}{}
w.stateLock.RUnlock()
// Insert any accounts successfully derived
w.stateLock.Lock()
for i := 0; i < len(accs); i++ {
if _, ok := w.paths[accs[i].Address]; !ok {
w.accounts = append(w.accounts, accs[i])
w.paths[accs[i].Address] = paths[i]
}
}
// Shift the self-derivation forward
// TODO(karalabe): don't overwrite changes from wallet.SelfDerive
w.deriveNextAddr = nextAddr
w.deriveNextPath = nextPath
w.stateLock.Unlock()
// Notify the user of termination and loop after a bit of time (to avoid trashing)
reqc <- struct{}{}
if err == nil {
select {
case errc = <-w.deriveQuit:
// Termination requested, abort
case <-time.After(ledgerSelfDeriveThrottling):
// Waited enough, willing to self-derive again
}
}
}
// In case of error, wait for termination
if err != nil {
glog.V(logger.Debug).Infof("%s self-derivation failed: %s", w.url.String(), err)
errc = <-w.deriveQuit
}
errc <- err
}
// Contains implements accounts.Wallet, returning whether a particular account is
// or is not pinned into this Ledger instance. Although we could attempt to resolve
// unpinned accounts, that would be an non-negligible hardware operation.
func (w *ledgerWallet) Contains(account accounts.Account) bool {
w.stateLock.RLock()
defer w.stateLock.RUnlock()
_, exists := w.paths[account.Address]
return exists
}
// Derive implements accounts.Wallet, deriving a new account at the specific
// derivation path. If pin is set to true, the account will be added to the list
// of tracked accounts.
func (w *ledgerWallet) Derive(path accounts.DerivationPath, pin bool) (accounts.Account, error) {
// Try to derive the actual account and update its URL if successful
w.stateLock.RLock() // Avoid device disappearing during derivation
if w.device == nil || w.offline() {
w.stateLock.RUnlock()
return accounts.Account{}, accounts.ErrWalletClosed
}
<-w.commsLock // Avoid concurrent hardware access
address, err := w.ledgerDerive(path)
w.commsLock <- struct{}{}
w.stateLock.RUnlock()
// If an error occurred or no pinning was requested, return
if err != nil {
return accounts.Account{}, err
}
account := accounts.Account{
Address: address,
URL: accounts.URL{Scheme: w.url.Scheme, Path: fmt.Sprintf("%s/%s", w.url.Path, path)},
}
if !pin {
return account, nil
}
// Pinning needs to modify the state
w.stateLock.Lock()
defer w.stateLock.Unlock()
if _, ok := w.paths[address]; !ok {
w.accounts = append(w.accounts, account)
w.paths[address] = path
}
return account, nil
}
// SelfDerive implements accounts.Wallet, trying to discover accounts that the
// user used previously (based on the chain state), but ones that he/she did not
// explicitly pin to the wallet manually. To avoid chain head monitoring, self
// derivation only runs during account listing (and even then throttled).
func (w *ledgerWallet) SelfDerive(base accounts.DerivationPath, chain ethereum.ChainStateReader) {
w.stateLock.Lock()
defer w.stateLock.Unlock()
w.deriveNextPath = make(accounts.DerivationPath, len(base))
copy(w.deriveNextPath[:], base[:])
w.deriveNextAddr = common.Address{}
w.deriveChain = chain
}
// SignHash implements accounts.Wallet, however signing arbitrary data is not
// supported for Ledger wallets, so this method will always return an error.
func (w *ledgerWallet) SignHash(acc accounts.Account, hash []byte) ([]byte, error) {
return nil, accounts.ErrNotSupported
}
// SignTx implements accounts.Wallet. It sends the transaction over to the Ledger
// wallet to request a confirmation from the user. It returns either the signed
// transaction or a failure if the user denied the transaction.
//
// Note, if the version of the Ethereum application running on the Ledger wallet is
// too old to sign EIP-155 transactions, but such is requested nonetheless, an error
// will be returned opposed to silently signing in Homestead mode.
func (w *ledgerWallet) SignTx(account accounts.Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
w.stateLock.RLock() // Comms have own mutex, this is for the state fields
defer w.stateLock.RUnlock()
// If the wallet is closed, or the Ethereum app doesn't run, abort
if w.device == nil || w.offline() {
return nil, accounts.ErrWalletClosed
}
// Make sure the requested account is contained within
path, ok := w.paths[account.Address]
if !ok {
return nil, accounts.ErrUnknownAccount
}
// Ensure the wallet is capable of signing the given transaction
if chainID != nil && w.version[0] <= 1 && w.version[1] <= 0 && w.version[2] <= 2 {
return nil, fmt.Errorf("Ledger v%d.%d.%d doesn't support signing this transaction, please update to v1.0.3 at least", w.version[0], w.version[1], w.version[2])
}
// All infos gathered and metadata checks out, request signing
<-w.commsLock
defer func() { w.commsLock <- struct{}{} }()
return w.ledgerSign(path, account.Address, tx, chainID)
}
// SignHashWithPassphrase implements accounts.Wallet, however signing arbitrary
// data is not supported for Ledger wallets, so this method will always return
// an error.
func (w *ledgerWallet) SignHashWithPassphrase(account accounts.Account, passphrase string, hash []byte) ([]byte, error) {
return nil, accounts.ErrNotSupported
}
// SignTxWithPassphrase implements accounts.Wallet, attempting to sign the given
// transaction with the given account using passphrase as extra authentication.
// Since the Ledger does not support extra passphrases, it is silently ignored.
func (w *ledgerWallet) SignTxWithPassphrase(account accounts.Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
return w.SignTx(account, tx, chainID)
}
// ledgerVersion retrieves the current version of the Ethereum wallet app running
// on the Ledger wallet.
//
// The version retrieval protocol is defined as follows:
//
// CLA | INS | P1 | P2 | Lc | Le
// ----+-----+----+----+----+---
// E0 | 06 | 00 | 00 | 00 | 04
//
// With no input data, and the output data being:
//
// Description | Length
// ---------------------------------------------------+--------
// Flags 01: arbitrary data signature enabled by user | 1 byte
// Application major version | 1 byte
// Application minor version | 1 byte
// Application patch version | 1 byte
func (w *ledgerWallet) ledgerVersion() ([3]byte, error) {
// Send the request and wait for the response
reply, err := w.ledgerExchange(ledgerOpGetConfiguration, 0, 0, nil)
if err != nil {
return [3]byte{}, err
}
if len(reply) != 4 {
return [3]byte{}, errInvalidVersionReply
}
// Cache the version for future reference
var version [3]byte
copy(version[:], reply[1:])
return version, nil
}
// ledgerDerive retrieves the currently active Ethereum address from a Ledger
// wallet at the specified derivation path.
//
// The address derivation protocol is defined as follows:
//
// CLA | INS | P1 | P2 | Lc | Le
// ----+-----+----+----+-----+---
// E0 | 02 | 00 return address
// 01 display address and confirm before returning
// | 00: do not return the chain code
// | 01: return the chain code
// | var | 00
//
// Where the input data is:
//
// Description | Length
// -------------------------------------------------+--------
// Number of BIP 32 derivations to perform (max 10) | 1 byte
// First derivation index (big endian) | 4 bytes
// ... | 4 bytes
// Last derivation index (big endian) | 4 bytes
//
// And the output data is:
//
// Description | Length
// ------------------------+-------------------
// Public Key length | 1 byte
// Uncompressed Public Key | arbitrary
// Ethereum address length | 1 byte
// Ethereum address | 40 bytes hex ascii
// Chain code if requested | 32 bytes
func (w *ledgerWallet) ledgerDerive(derivationPath []uint32) (common.Address, error) {
// Flatten the derivation path into the Ledger request
path := make([]byte, 1+4*len(derivationPath))
path[0] = byte(len(derivationPath))
for i, component := range derivationPath {
binary.BigEndian.PutUint32(path[1+4*i:], component)
}
// Send the request and wait for the response
reply, err := w.ledgerExchange(ledgerOpRetrieveAddress, ledgerP1DirectlyFetchAddress, ledgerP2DiscardAddressChainCode, path)
if err != nil {
return common.Address{}, err
}
// Discard the public key, we don't need that for now
if len(reply) < 1 || len(reply) < 1+int(reply[0]) {
return common.Address{}, errors.New("reply lacks public key entry")
}
reply = reply[1+int(reply[0]):]
// Extract the Ethereum hex address string
if len(reply) < 1 || len(reply) < 1+int(reply[0]) {
return common.Address{}, errors.New("reply lacks address entry")
}
hexstr := reply[1 : 1+int(reply[0])]
// Decode the hex sting into an Ethereum address and return
var address common.Address
hex.Decode(address[:], hexstr)
return address, nil
}
// ledgerSign sends the transaction to the Ledger wallet, and waits for the user
// to confirm or deny the transaction.
//
// The transaction signing protocol is defined as follows:
//
// CLA | INS | P1 | P2 | Lc | Le
// ----+-----+----+----+-----+---
// E0 | 04 | 00: first transaction data block
// 80: subsequent transaction data block
// | 00 | variable | variable
//
// Where the input for the first transaction block (first 255 bytes) is:
//
// Description | Length
// -------------------------------------------------+----------
// Number of BIP 32 derivations to perform (max 10) | 1 byte
// First derivation index (big endian) | 4 bytes
// ... | 4 bytes
// Last derivation index (big endian) | 4 bytes
// RLP transaction chunk | arbitrary
//
// And the input for subsequent transaction blocks (first 255 bytes) are:
//
// Description | Length
// ----------------------+----------
// RLP transaction chunk | arbitrary
//
// And the output data is:
//
// Description | Length
// ------------+---------
// signature V | 1 byte
// signature R | 32 bytes
// signature S | 32 bytes
func (w *ledgerWallet) ledgerSign(derivationPath []uint32, address common.Address, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
// Flatten the derivation path into the Ledger request
path := make([]byte, 1+4*len(derivationPath))
path[0] = byte(len(derivationPath))
for i, component := range derivationPath {
binary.BigEndian.PutUint32(path[1+4*i:], component)
}
// Create the transaction RLP based on whether legacy or EIP155 signing was requeste
var (
txrlp []byte
err error
)
if chainID == nil {
if txrlp, err = rlp.EncodeToBytes([]interface{}{tx.Nonce(), tx.GasPrice(), tx.Gas(), tx.To(), tx.Value(), tx.Data()}); err != nil {
return nil, err
}
} else {
if txrlp, err = rlp.EncodeToBytes([]interface{}{tx.Nonce(), tx.GasPrice(), tx.Gas(), tx.To(), tx.Value(), tx.Data(), chainID, big.NewInt(0), big.NewInt(0)}); err != nil {
return nil, err
}
}
payload := append(path, txrlp...)
// Send the request and wait for the response
var (
op = ledgerP1InitTransactionData
reply []byte
)
for len(payload) > 0 {
// Calculate the size of the next data chunk
chunk := 255
if chunk > len(payload) {
chunk = len(payload)
}
// Send the chunk over, ensuring it's processed correctly
reply, err = w.ledgerExchange(ledgerOpSignTransaction, op, 0, payload[:chunk])
if err != nil {
return nil, err
}
// Shift the payload and ensure subsequent chunks are marked as such
payload = payload[chunk:]
op = ledgerP1ContTransactionData
}
// Extract the Ethereum signature and do a sanity validation
if len(reply) != 65 {
return nil, errors.New("reply lacks signature")
}
signature := append(reply[1:], reply[0])
// Create the correct signer and signature transform based on the chain ID
var signer types.Signer
if chainID == nil {
signer = new(types.HomesteadSigner)
} else {
signer = types.NewEIP155Signer(chainID)
signature[64] = signature[64] - byte(chainID.Uint64()*2+35)
}
// Inject the final signature into the transaction and sanity check the sender
signed, err := tx.WithSignature(signer, signature)
if err != nil {
return nil, err
}
sender, err := types.Sender(signer, signed)
if err != nil {
return nil, err
}
if sender != address {
return nil, fmt.Errorf("signer mismatch: expected %s, got %s", address.Hex(), sender.Hex())
}
return signed, nil
}
// ledgerExchange performs a data exchange with the Ledger wallet, sending it a
// message and retrieving the response.
//
// The common transport header is defined as follows:
//
// Description | Length
// --------------------------------------+----------
// Communication channel ID (big endian) | 2 bytes
// Command tag | 1 byte
// Packet sequence index (big endian) | 2 bytes
// Payload | arbitrary
//
// The Communication channel ID allows commands multiplexing over the same
// physical link. It is not used for the time being, and should be set to 0101
// to avoid compatibility issues with implementations ignoring a leading 00 byte.
//
// The Command tag describes the message content. Use TAG_APDU (0x05) for standard
// APDU payloads, or TAG_PING (0x02) for a simple link test.
//
// The Packet sequence index describes the current sequence for fragmented payloads.
// The first fragment index is 0x00.
//
// APDU Command payloads are encoded as follows:
//
// Description | Length
// -----------------------------------
// APDU length (big endian) | 2 bytes
// APDU CLA | 1 byte
// APDU INS | 1 byte
// APDU P1 | 1 byte
// APDU P2 | 1 byte
// APDU length | 1 byte
// Optional APDU data | arbitrary
func (w *ledgerWallet) ledgerExchange(opcode ledgerOpcode, p1 ledgerParam1, p2 ledgerParam2, data []byte) ([]byte, error) {
// Construct the message payload, possibly split into multiple chunks
apdu := make([]byte, 2, 7+len(data))
binary.BigEndian.PutUint16(apdu, uint16(5+len(data)))
apdu = append(apdu, []byte{0xe0, byte(opcode), byte(p1), byte(p2), byte(len(data))}...)
apdu = append(apdu, data...)
// Stream all the chunks to the device
header := []byte{0x01, 0x01, 0x05, 0x00, 0x00} // Channel ID and command tag appended
chunk := make([]byte, 64)
space := len(chunk) - len(header)
for i := 0; len(apdu) > 0; i++ {
// Construct the new message to stream
chunk = append(chunk[:0], header...)
binary.BigEndian.PutUint16(chunk[3:], uint16(i))
if len(apdu) > space {
chunk = append(chunk, apdu[:space]...)
apdu = apdu[space:]
} else {
chunk = append(chunk, apdu...)
apdu = nil
}
// Send over to the device
if glog.V(logger.Detail) {
glog.Infof("-> %s: %x", w.device.Path, chunk)
}
if _, err := w.device.Write(chunk); err != nil {
return nil, err
}
}
// Stream the reply back from the wallet in 64 byte chunks
var reply []byte
chunk = chunk[:64] // Yeah, we surely have enough space
for {
// Read the next chunk from the Ledger wallet
if _, err := io.ReadFull(w.device, chunk); err != nil {
return nil, err
}
if glog.V(logger.Detail) {
glog.Infof("<- %s: %x", w.device.Path, chunk)
}
// Make sure the transport header matches
if chunk[0] != 0x01 || chunk[1] != 0x01 || chunk[2] != 0x05 {
return nil, errReplyInvalidHeader
}
// If it's the first chunk, retrieve the total message length
var payload []byte
if chunk[3] == 0x00 && chunk[4] == 0x00 {
reply = make([]byte, 0, int(binary.BigEndian.Uint16(chunk[5:7])))
payload = chunk[7:]
} else {
payload = chunk[5:]
}
// Append to the reply and stop when filled up
if left := cap(reply) - len(reply); left > len(payload) {
reply = append(reply, payload...)
} else {
reply = append(reply, payload[:left]...)
break
}
}
return reply[:len(reply)-2], nil
}