217 lines
7.6 KiB
Go
217 lines
7.6 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// This file contains the implementation for interacting with the Ledger hardware
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// wallets. The wire protocol spec can be found in the Ledger Blue GitHub repo:
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// https://raw.githubusercontent.com/LedgerHQ/blue-app-eth/master/doc/ethapp.asc
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package usbwallet
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import (
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"errors"
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"runtime"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/accounts"
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"github.com/ethereum/go-ethereum/event"
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"github.com/ethereum/go-ethereum/log"
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"github.com/karalabe/hid"
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)
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// LedgerScheme is the protocol scheme prefixing account and wallet URLs.
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var LedgerScheme = "ledger"
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// ledgerDeviceIDs are the known device IDs that Ledger wallets use.
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var ledgerDeviceIDs = []deviceID{
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{Vendor: 0x2c97, Product: 0x0000}, // Ledger Blue
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{Vendor: 0x2c97, Product: 0x0001}, // Ledger Nano S
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}
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// Maximum time between wallet refreshes (if USB hotplug notifications don't work).
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const ledgerRefreshCycle = time.Second
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// Minimum time between wallet refreshes to avoid USB trashing.
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const ledgerRefreshThrottling = 500 * time.Millisecond
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// LedgerHub is a accounts.Backend that can find and handle Ledger hardware wallets.
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type LedgerHub struct {
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refreshed time.Time // Time instance when the list of wallets was last refreshed
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wallets []accounts.Wallet // List of Ledger devices currently tracking
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updateFeed event.Feed // Event feed to notify wallet additions/removals
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updateScope event.SubscriptionScope // Subscription scope tracking current live listeners
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updating bool // Whether the event notification loop is running
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quit chan chan error
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stateLock sync.RWMutex // Protects the internals of the hub from racey access
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// TODO(karalabe): remove if hotplug lands on Windows
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commsPend int // Number of operations blocking enumeration
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commsLock sync.Mutex // Lock protecting the pending counter and enumeration
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}
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// NewLedgerHub creates a new hardware wallet manager for Ledger devices.
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func NewLedgerHub() (*LedgerHub, error) {
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if !hid.Supported() {
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return nil, errors.New("unsupported platform")
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}
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hub := &LedgerHub{
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quit: make(chan chan error),
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}
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hub.refreshWallets()
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return hub, nil
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}
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// Wallets implements accounts.Backend, returning all the currently tracked USB
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// devices that appear to be Ledger hardware wallets.
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func (hub *LedgerHub) Wallets() []accounts.Wallet {
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// Make sure the list of wallets is up to date
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hub.refreshWallets()
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hub.stateLock.RLock()
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defer hub.stateLock.RUnlock()
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cpy := make([]accounts.Wallet, len(hub.wallets))
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copy(cpy, hub.wallets)
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return cpy
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}
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// refreshWallets scans the USB devices attached to the machine and updates the
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// list of wallets based on the found devices.
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func (hub *LedgerHub) refreshWallets() {
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// Don't scan the USB like crazy it the user fetches wallets in a loop
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hub.stateLock.RLock()
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elapsed := time.Since(hub.refreshed)
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hub.stateLock.RUnlock()
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if elapsed < ledgerRefreshThrottling {
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return
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}
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// Retrieve the current list of Ledger devices
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var ledgers []hid.DeviceInfo
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if runtime.GOOS == "linux" {
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// hidapi on Linux opens the device during enumeration to retrieve some infos,
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// breaking the Ledger protocol if that is waiting for user confirmation. This
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// is a bug acknowledged at Ledger, but it won't be fixed on old devices so we
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// need to prevent concurrent comms ourselves. The more elegant solution would
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// be to ditch enumeration in favor of hutplug events, but that don't work yet
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// on Windows so if we need to hack it anyway, this is more elegant for now.
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hub.commsLock.Lock()
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if hub.commsPend > 0 { // A confirmation is pending, don't refresh
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hub.commsLock.Unlock()
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return
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}
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}
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for _, info := range hid.Enumerate(0, 0) { // Can't enumerate directly, one valid ID is the 0 wildcard
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for _, id := range ledgerDeviceIDs {
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if info.VendorID == id.Vendor && info.ProductID == id.Product {
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ledgers = append(ledgers, info)
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break
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}
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}
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}
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if runtime.GOOS == "linux" {
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// See rationale before the enumeration why this is needed and only on Linux.
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hub.commsLock.Unlock()
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}
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// Transform the current list of wallets into the new one
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hub.stateLock.Lock()
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wallets := make([]accounts.Wallet, 0, len(ledgers))
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events := []accounts.WalletEvent{}
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for _, ledger := range ledgers {
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url := accounts.URL{Scheme: LedgerScheme, Path: ledger.Path}
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// Drop wallets in front of the next device or those that failed for some reason
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for len(hub.wallets) > 0 && (hub.wallets[0].URL().Cmp(url) < 0 || hub.wallets[0].(*ledgerWallet).failed()) {
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events = append(events, accounts.WalletEvent{Wallet: hub.wallets[0], Arrive: false})
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hub.wallets = hub.wallets[1:]
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}
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// If there are no more wallets or the device is before the next, wrap new wallet
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if len(hub.wallets) == 0 || hub.wallets[0].URL().Cmp(url) > 0 {
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wallet := &ledgerWallet{hub: hub, url: &url, info: ledger, log: log.New("url", url)}
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events = append(events, accounts.WalletEvent{Wallet: wallet, Arrive: true})
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wallets = append(wallets, wallet)
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continue
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}
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// If the device is the same as the first wallet, keep it
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if hub.wallets[0].URL().Cmp(url) == 0 {
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wallets = append(wallets, hub.wallets[0])
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hub.wallets = hub.wallets[1:]
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continue
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}
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}
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// Drop any leftover wallets and set the new batch
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for _, wallet := range hub.wallets {
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events = append(events, accounts.WalletEvent{Wallet: wallet, Arrive: false})
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}
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hub.refreshed = time.Now()
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hub.wallets = wallets
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hub.stateLock.Unlock()
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// Fire all wallet events and return
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for _, event := range events {
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hub.updateFeed.Send(event)
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}
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}
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// Subscribe implements accounts.Backend, creating an async subscription to
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// receive notifications on the addition or removal of Ledger wallets.
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func (hub *LedgerHub) Subscribe(sink chan<- accounts.WalletEvent) event.Subscription {
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// We need the mutex to reliably start/stop the update loop
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hub.stateLock.Lock()
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defer hub.stateLock.Unlock()
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// Subscribe the caller and track the subscriber count
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sub := hub.updateScope.Track(hub.updateFeed.Subscribe(sink))
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// Subscribers require an active notification loop, start it
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if !hub.updating {
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hub.updating = true
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go hub.updater()
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}
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return sub
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}
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// updater is responsible for maintaining an up-to-date list of wallets stored in
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// the keystore, and for firing wallet addition/removal events. It listens for
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// account change events from the underlying account cache, and also periodically
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// forces a manual refresh (only triggers for systems where the filesystem notifier
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// is not running).
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func (hub *LedgerHub) updater() {
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for {
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// TODO: Wait for a USB hotplug event (not supported yet) or a refresh timeout
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// <-hub.changes
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time.Sleep(ledgerRefreshCycle)
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// Run the wallet refresher
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hub.refreshWallets()
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// If all our subscribers left, stop the updater
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hub.stateLock.Lock()
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if hub.updateScope.Count() == 0 {
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hub.updating = false
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hub.stateLock.Unlock()
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return
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}
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hub.stateLock.Unlock()
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}
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}
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