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// 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
// +build !ios
package usbwallet
import (
"fmt"
"sync"
"time"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/event"
"github.com/karalabe/gousb/usb"
)
// LedgerScheme is the protocol scheme prefixing account and wallet URLs.
var LedgerScheme = "ledger"
// ledgerDeviceIDs are the known device IDs that Ledger wallets use.
var ledgerDeviceIDs = []deviceID{
{Vendor: 0x2c97, Product: 0x0000}, // Ledger Blue
{Vendor: 0x2c97, Product: 0x0001}, // Ledger Nano S
}
// Maximum time between wallet refreshes (if USB hotplug notifications don't work).
const ledgerRefreshCycle = time.Second
// Minimum time between wallet refreshes to avoid USB trashing.
const ledgerRefreshThrottling = 500 * time.Millisecond
// LedgerHub is a accounts.Backend that can find and handle Ledger hardware wallets.
type LedgerHub struct {
ctx *usb.Context // Context interfacing with a libusb instance
refreshed time.Time // Time instance when the list of wallets was last refreshed
wallets []accounts.Wallet // List of Ledger devices currently tracking
updateFeed event.Feed // Event feed to notify wallet additions/removals
updateScope event.SubscriptionScope // Subscription scope tracking current live listeners
updating bool // Whether the event notification loop is running
quit chan chan error
lock sync.RWMutex
}
// NewLedgerHub creates a new hardware wallet manager for Ledger devices.
func NewLedgerHub() (*LedgerHub, error) {
// Initialize the USB library to access Ledgers through
ctx, err := usb.NewContext()
if err != nil {
return nil, err
}
// Create the USB hub, start and return it
hub := &LedgerHub{
ctx: ctx,
quit: make(chan chan error),
}
hub.refreshWallets()
return hub, nil
}
// Wallets implements accounts.Backend, returning all the currently tracked USB
// devices that appear to be Ledger hardware wallets.
func (hub *LedgerHub) Wallets() []accounts.Wallet {
// Make sure the list of wallets is up to date
hub.refreshWallets()
hub.lock.RLock()
defer hub.lock.RUnlock()
cpy := make([]accounts.Wallet, len(hub.wallets))
copy(cpy, hub.wallets)
return cpy
}
// refreshWallets scans the USB devices attached to the machine and updates the
// list of wallets based on the found devices.
func (hub *LedgerHub) refreshWallets() {
// Don't scan the USB like crazy it the user fetches wallets in a loop
hub.lock.RLock()
elapsed := time.Since(hub.refreshed)
hub.lock.RUnlock()
if elapsed < ledgerRefreshThrottling {
return
}
// Retrieve the current list of Ledger devices
var devIDs []deviceID
var busIDs []uint16
hub.ctx.ListDevices(func(desc *usb.Descriptor) bool {
// Gather Ledger devices, don't connect any just yet
for _, id := range ledgerDeviceIDs {
if desc.Vendor == id.Vendor && desc.Product == id.Product {
devIDs = append(devIDs, deviceID{Vendor: desc.Vendor, Product: desc.Product})
busIDs = append(busIDs, uint16(desc.Bus)<<8+uint16(desc.Address))
return false
}
}
// Not ledger, ignore and don't connect either
return false
})
// Transform the current list of wallets into the new one
hub.lock.Lock()
wallets := make([]accounts.Wallet, 0, len(devIDs))
events := []accounts.WalletEvent{}
for i := 0; i < len(devIDs); i++ {
devID, busID := devIDs[i], busIDs[i]
url := accounts.URL{Scheme: LedgerScheme, Path: fmt.Sprintf("%03d:%03d", busID>>8, busID&0xff)}
// Drop wallets while they were in front of the next account
for len(hub.wallets) > 0 && hub.wallets[0].URL().Cmp(url) < 0 {
events = append(events, accounts.WalletEvent{Wallet: hub.wallets[0], Arrive: false})
hub.wallets = hub.wallets[1:]
}
// If there are no more wallets or the account is before the next, wrap new wallet
if len(hub.wallets) == 0 || hub.wallets[0].URL().Cmp(url) > 0 {
wallet := &ledgerWallet{context: hub.ctx, hardwareID: devID, locationID: busID, url: &url}
events = append(events, accounts.WalletEvent{Wallet: wallet, Arrive: true})
wallets = append(wallets, wallet)
continue
}
// If the account is the same as the first wallet, keep it
if hub.wallets[0].URL().Cmp(url) == 0 {
wallets = append(wallets, hub.wallets[0])
hub.wallets = hub.wallets[1:]
continue
}
}
// Drop any leftover wallets and set the new batch
for _, wallet := range hub.wallets {
events = append(events, accounts.WalletEvent{Wallet: wallet, Arrive: false})
}
hub.refreshed = time.Now()
hub.wallets = wallets
hub.lock.Unlock()
// Fire all wallet events and return
for _, event := range events {
hub.updateFeed.Send(event)
}
}
// Subscribe implements accounts.Backend, creating an async subscription to
// receive notifications on the addition or removal of Ledger wallets.
func (hub *LedgerHub) Subscribe(sink chan<- accounts.WalletEvent) event.Subscription {
// We need the mutex to reliably start/stop the update loop
hub.lock.Lock()
defer hub.lock.Unlock()
// Subscribe the caller and track the subscriber count
sub := hub.updateScope.Track(hub.updateFeed.Subscribe(sink))
// Subscribers require an active notification loop, start it
if !hub.updating {
hub.updating = true
go hub.updater()
}
return sub
}
// updater is responsible for maintaining an up-to-date list of wallets stored in
// the keystore, and for firing wallet addition/removal events. It listens for
// account change events from the underlying account cache, and also periodically
// forces a manual refresh (only triggers for systems where the filesystem notifier
// is not running).
func (hub *LedgerHub) updater() {
for {
// Wait for a USB hotplug event (not supported yet) or a refresh timeout
select {
//case <-hub.changes: // reenable on hutplug implementation
case <-time.After(ledgerRefreshCycle):
}
// Run the wallet refresher
hub.refreshWallets()
// If all our subscribers left, stop the updater
hub.lock.Lock()
if hub.updateScope.Count() == 0 {
hub.updating = false
hub.lock.Unlock()
return
}
hub.lock.Unlock()
}
}
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