1 files changed, 209 insertions, 0 deletions
diff --git a/accounts/usbwallet/ledger_hub.go b/accounts/usbwallet/ledger_hub.go
new file mode 100644
index 000000000..ad5940cd4
--- /dev/null
+++ b/accounts/usbwallet/ledger_hub.go
@@ -0,0 +1,209 @@
+// 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 in front of the next device or those that failed for some reason
+		for len(hub.wallets) > 0 && (hub.wallets[0].URL().Cmp(url) < 0 || hub.wallets[0].(*ledgerWallet).failed()) {
+			events = append(events, accounts.WalletEvent{Wallet: hub.wallets[0], Arrive: false})
+			hub.wallets = hub.wallets[1:]
+		}
+		// If there are no more wallets or the device 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 device 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()
+	}
+}