...

1 files changed, 595 insertions, 0 deletions

diff --git a/accounts/usbwallet/wallet.go b/accounts/usbwallet/wallet.go
new file mode 100644
index 0000000..3622c92
--- /dev/null
+++ b/accounts/usbwallet/wallet.go
@@ -0,0 +1,595 @@
+// 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/>.
+
+// Package usbwallet implements support for USB hardware wallets.
+package usbwallet
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"math/big"
+	"sync"
+	"time"
+
+	"github.com/ava-labs/coreth/accounts"
+	"github.com/ava-labs/coreth/core/types"
+	ethereum "github.com/ava-labs/go-ethereum"
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/crypto"
+	"github.com/ava-labs/go-ethereum/log"
+	"github.com/karalabe/usb"
+)
+
+// Maximum time between wallet health checks to detect USB unplugs.
+const heartbeatCycle = time.Second
+
+// Minimum time to wait between self derivation attempts, even it the user is
+// requesting accounts like crazy.
+const selfDeriveThrottling = time.Second
+
+// driver defines the vendor specific functionality hardware wallets instances
+// must implement to allow using them with the wallet lifecycle management.
+type driver interface {
+	// Status returns a textual status to aid the user in the current state of the
+	// wallet. It also returns an error indicating any failure the wallet might have
+	// encountered.
+	Status() (string, error)
+
+	// Open initializes access to a wallet instance. The passphrase parameter may
+	// or may not be used by the implementation of a particular wallet instance.
+	Open(device io.ReadWriter, passphrase string) error
+
+	// Close releases any resources held by an open wallet instance.
+	Close() error
+
+	// Heartbeat performs a sanity check against the hardware wallet to see if it
+	// is still online and healthy.
+	Heartbeat() error
+
+	// Derive sends a derivation request to the USB device and returns the Ethereum
+	// address located on that path.
+	Derive(path accounts.DerivationPath) (common.Address, error)
+
+	// SignTx sends the transaction to the USB device and waits for the user to confirm
+	// or deny the transaction.
+	SignTx(path accounts.DerivationPath, tx *types.Transaction, chainID *big.Int) (common.Address, *types.Transaction, error)
+}
+
+// wallet represents the common functionality shared by all USB hardware
+// wallets to prevent reimplementing the same complex maintenance mechanisms
+// for different vendors.
+type wallet struct {
+	hub    *Hub          // USB hub scanning
+	driver driver        // Hardware implementation of the low level device operations
+	url    *accounts.URL // Textual URL uniquely identifying this wallet
+
+	info   usb.DeviceInfo // Known USB device infos about the wallet
+	device usb.Device     // USB device advertising itself as a hardware wallet
+
+	accounts []accounts.Account                         // List of derive accounts pinned on the hardware wallet
+	paths    map[common.Address]accounts.DerivationPath // Known derivation paths for signing operations
+
+	deriveNextPaths []accounts.DerivationPath // Next derivation paths for account auto-discovery (multiple bases supported)
+	deriveNextAddrs []common.Address          // Next derived account addresses for auto-discovery (multiple bases supported)
+	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 exclusively 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
+
+	log log.Logger // Contextual logger to tag the base with its id
+}
+
+// URL implements accounts.Wallet, returning the URL of the USB hardware device.
+func (w *wallet) URL() accounts.URL {
+	return *w.url // Immutable, no need for a lock
+}
+
+// Status implements accounts.Wallet, returning a custom status message from the
+// underlying vendor-specific hardware wallet implementation.
+func (w *wallet) Status() (string, error) {
+	w.stateLock.RLock() // No device communication, state lock is enough
+	defer w.stateLock.RUnlock()
+
+	status, failure := w.driver.Status()
+	if w.device == nil {
+		return "Closed", failure
+	}
+	return status, failure
+}
+
+// Open implements accounts.Wallet, attempting to open a USB connection to the
+// hardware wallet.
+func (w *wallet) 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 device was already opened once, refuse to try again
+	if w.paths != nil {
+		return accounts.ErrWalletAlreadyOpen
+	}
+	// Make sure the actual device connection is done only once
+	if w.device == nil {
+		device, err := w.info.Open()
+		if err != nil {
+			return err
+		}
+		w.device = device
+		w.commsLock = make(chan struct{}, 1)
+		w.commsLock <- struct{}{} // Enable lock
+	}
+	// Delegate device initialization to the underlying driver
+	if err := w.driver.Open(w.device, passphrase); err != nil {
+		return err
+	}
+	// Connection successful, start life-cycle management
+	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)
+
+	go w.heartbeat()
+	go w.selfDerive()
+
+	// Notify anyone listening for wallet events that a new device is accessible
+	go w.hub.updateFeed.Send(accounts.WalletEvent{Wallet: w, Kind: accounts.WalletOpened})
+
+	return nil
+}
+
+// heartbeat is a health check loop for the USB wallets to periodically verify
+// whether they are still present or if they malfunctioned.
+func (w *wallet) heartbeat() {
+	w.log.Debug("USB wallet health-check started")
+	defer w.log.Debug("USB wallet health-check stopped")
+
+	// 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(heartbeatCycle):
+			// 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.driver.Heartbeat()
+		w.commsLock <- struct{}{}
+		w.stateLock.RUnlock()
+
+		if err != nil {
+			w.stateLock.Lock() // Lock state to tear the wallet down
+			w.close()
+			w.stateLock.Unlock()
+		}
+		// Ignore non hardware related errors
+		err = nil
+	}
+	// In case of error, wait for termination
+	if err != nil {
+		w.log.Debug("USB wallet health-check failed", "err", err)
+		errc = <-w.healthQuit
+	}
+	errc <- err
+}
+
+// Close implements accounts.Wallet, closing the USB connection to the device.
+func (w *wallet) 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 *wallet) 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.accounts, w.paths = nil, nil
+	return w.driver.Close()
+}
+
+// Accounts implements accounts.Wallet, returning the list of accounts pinned to
+// the USB hardware wallet. If self-derivation was enabled, the account list is
+// periodically expanded based on current chain state.
+func (w *wallet) 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 *wallet) selfDerive() {
+	w.log.Debug("USB wallet self-derivation started")
+	defer w.log.Debug("USB wallet self-derivation stopped")
+
+	// 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.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
+
+			nextPaths = append([]accounts.DerivationPath{}, w.deriveNextPaths...)
+			nextAddrs = append([]common.Address{}, w.deriveNextAddrs...)
+
+			context = context.Background()
+		)
+		for i := 0; i < len(nextAddrs); i++ {
+			for empty := false; !empty; {
+				// Retrieve the next derived Ethereum account
+				if nextAddrs[i] == (common.Address{}) {
+					if nextAddrs[i], err = w.driver.Derive(nextPaths[i]); err != nil {
+						w.log.Warn("USB wallet account derivation failed", "err", err)
+						break
+					}
+				}
+				// Check the account's status against the current chain state
+				var (
+					balance *big.Int
+					nonce   uint64
+				)
+				balance, err = w.deriveChain.BalanceAt(context, nextAddrs[i], nil)
+				if err != nil {
+					w.log.Warn("USB wallet balance retrieval failed", "err", err)
+					break
+				}
+				nonce, err = w.deriveChain.NonceAt(context, nextAddrs[i], nil)
+				if err != nil {
+					w.log.Warn("USB wallet nonce retrieval failed", "err", err)
+					break
+				}
+				// If the next account is empty, stop self-derivation, but add for the last base path
+				if balance.Sign() == 0 && nonce == 0 {
+					empty = true
+					if i < len(nextAddrs)-1 {
+						break
+					}
+				}
+				// We've just self-derived a new account, start tracking it locally
+				path := make(accounts.DerivationPath, len(nextPaths[i]))
+				copy(path[:], nextPaths[i][:])
+				paths = append(paths, path)
+
+				account := accounts.Account{
+					Address: nextAddrs[i],
+					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[nextAddrs[i]]; !known || (!empty && nextAddrs[i] == w.deriveNextAddrs[i]) {
+					w.log.Info("USB wallet discovered new account", "address", nextAddrs[i], "path", path, "balance", balance, "nonce", nonce)
+				}
+				// Fetch the next potential account
+				if !empty {
+					nextAddrs[i] = common.Address{}
+					nextPaths[i][len(nextPaths[i])-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.deriveNextAddrs = nextAddrs
+		w.deriveNextPaths = nextPaths
+		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(selfDeriveThrottling):
+				// Waited enough, willing to self-derive again
+			}
+		}
+	}
+	// In case of error, wait for termination
+	if err != nil {
+		w.log.Debug("USB wallet self-derivation failed", "err", err)
+		errc = <-w.deriveQuit
+	}
+	errc <- err
+}
+
+// Contains implements accounts.Wallet, returning whether a particular account is
+// or is not pinned into this wallet instance. Although we could attempt to resolve
+// unpinned accounts, that would be an non-negligible hardware operation.
+func (w *wallet) 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 *wallet) 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.stateLock.RUnlock()
+		return accounts.Account{}, accounts.ErrWalletClosed
+	}
+	<-w.commsLock // Avoid concurrent hardware access
+	address, err := w.driver.Derive(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] = make(accounts.DerivationPath, len(path))
+		copy(w.paths[address], path)
+	}
+	return account, nil
+}
+
+// SelfDerive sets a base account derivation path from which the wallet attempts
+// to discover non zero accounts and automatically add them to list of tracked
+// accounts.
+//
+// Note, self derivaton will increment the last component of the specified path
+// opposed to decending into a child path to allow discovering accounts starting
+// from non zero components.
+//
+// Some hardware wallets switched derivation paths through their evolution, so
+// this method supports providing multiple bases to discover old user accounts
+// too. Only the last base will be used to derive the next empty account.
+//
+// You can disable automatic account discovery by calling SelfDerive with a nil
+// chain state reader.
+func (w *wallet) SelfDerive(bases []accounts.DerivationPath, chain ethereum.ChainStateReader) {
+	w.stateLock.Lock()
+	defer w.stateLock.Unlock()
+
+	w.deriveNextPaths = make([]accounts.DerivationPath, len(bases))
+	for i, base := range bases {
+		w.deriveNextPaths[i] = make(accounts.DerivationPath, len(base))
+		copy(w.deriveNextPaths[i][:], base[:])
+	}
+	w.deriveNextAddrs = make([]common.Address, len(bases))
+	w.deriveChain = chain
+}
+
+// signHash implements accounts.Wallet, however signing arbitrary data is not
+// supported for hardware wallets, so this method will always return an error.
+func (w *wallet) signHash(account accounts.Account, hash []byte) ([]byte, error) {
+	return nil, accounts.ErrNotSupported
+}
+
+// SignData signs keccak256(data). The mimetype parameter describes the type of data being signed
+func (w *wallet) SignData(account accounts.Account, mimeType string, data []byte) ([]byte, error) {
+	return w.signHash(account, crypto.Keccak256(data))
+}
+
+// SignDataWithPassphrase implements accounts.Wallet, attempting to sign the given
+// data with the given account using passphrase as extra authentication.
+// Since USB wallets don't rely on passphrases, these are silently ignored.
+func (w *wallet) SignDataWithPassphrase(account accounts.Account, passphrase, mimeType string, data []byte) ([]byte, error) {
+	return w.SignData(account, mimeType, data)
+}
+
+func (w *wallet) SignText(account accounts.Account, text []byte) ([]byte, error) {
+	return w.signHash(account, accounts.TextHash(text))
+}
+
+// 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 *wallet) 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, abort
+	if w.device == nil {
+		return nil, accounts.ErrWalletClosed
+	}
+	// Make sure the requested account is contained within
+	path, ok := w.paths[account.Address]
+	if !ok {
+		return nil, accounts.ErrUnknownAccount
+	}
+	// All infos gathered and metadata checks out, request signing
+	<-w.commsLock
+	defer func() { w.commsLock <- struct{}{} }()
+
+	// Ensure the device isn't screwed with while user confirmation is pending
+	// TODO(karalabe): remove if hotplug lands on Windows
+	w.hub.commsLock.Lock()
+	w.hub.commsPend++
+	w.hub.commsLock.Unlock()
+
+	defer func() {
+		w.hub.commsLock.Lock()
+		w.hub.commsPend--
+		w.hub.commsLock.Unlock()
+	}()
+	// Sign the transaction and verify the sender to avoid hardware fault surprises
+	sender, signed, err := w.driver.SignTx(path, tx, chainID)
+	if err != nil {
+		return nil, err
+	}
+	if sender != account.Address {
+		return nil, fmt.Errorf("signer mismatch: expected %s, got %s", account.Address.Hex(), sender.Hex())
+	}
+	return signed, nil
+}
+
+// SignHashWithPassphrase implements accounts.Wallet, however signing arbitrary
+// data is not supported for Ledger wallets, so this method will always return
+// an error.
+func (w *wallet) SignTextWithPassphrase(account accounts.Account, passphrase string, text []byte) ([]byte, error) {
+	return w.SignText(account, accounts.TextHash(text))
+}
+
+// SignTxWithPassphrase implements accounts.Wallet, attempting to sign the given
+// transaction with the given account using passphrase as extra authentication.
+// Since USB wallets don't rely on passphrases, these are silently ignored.
+func (w *wallet) SignTxWithPassphrase(account accounts.Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
+	return w.SignTx(account, tx, chainID)
+}