Merge branch 'multi-coin'

1 files changed, 302 insertions, 0 deletions

diff --git a/accounts/scwallet/hub.go b/accounts/scwallet/hub.go
new file mode 100644
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--- /dev/null
+++ b/accounts/scwallet/hub.go
@@ -0,0 +1,302 @@
+// Copyright 2018 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 package implements support for smartcard-based hardware wallets such as
+// the one written by Status: https://github.com/status-im/hardware-wallet
+//
+// This implementation of smartcard wallets have a different interaction process
+// to other types of hardware wallet. The process works like this:
+//
+// 1. (First use with a given client) Establish a pairing between hardware
+//    wallet and client. This requires a secret value called a 'pairing password'.
+//    You can pair with an unpaired wallet with `personal.openWallet(URI, pairing password)`.
+// 2. (First use only) Initialize the wallet, which generates a keypair, stores
+//    it on the wallet, and returns it so the user can back it up. You can
+//    initialize a wallet with `personal.initializeWallet(URI)`.
+// 3. Connect to the wallet using the pairing information established in step 1.
+//    You can connect to a paired wallet with `personal.openWallet(URI, PIN)`.
+// 4. Interact with the wallet as normal.
+
+package scwallet
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"sync"
+	"time"
+
+	"github.com/ava-labs/coreth/accounts"
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/event"
+	"github.com/ava-labs/go-ethereum/log"
+	pcsc "github.com/gballet/go-libpcsclite"
+)
+
+// Scheme is the URI prefix for smartcard wallets.
+const Scheme = "keycard"
+
+// refreshCycle is the maximum time between wallet refreshes (if USB hotplug
+// notifications don't work).
+const refreshCycle = time.Second
+
+// refreshThrottling is the minimum time between wallet refreshes to avoid thrashing.
+const refreshThrottling = 500 * time.Millisecond
+
+// smartcardPairing contains information about a smart card we have paired with
+// or might pair with the hub.
+type smartcardPairing struct {
+	PublicKey    []byte                                     `json:"publicKey"`
+	PairingIndex uint8                                      `json:"pairingIndex"`
+	PairingKey   []byte                                     `json:"pairingKey"`
+	Accounts     map[common.Address]accounts.DerivationPath `json:"accounts"`
+}
+
+// Hub is a accounts.Backend that can find and handle generic PC/SC hardware wallets.
+type Hub struct {
+	scheme string // Protocol scheme prefixing account and wallet URLs.
+
+	context  *pcsc.Client
+	datadir  string
+	pairings map[string]smartcardPairing
+
+	refreshed   time.Time               // Time instance when the list of wallets was last refreshed
+	wallets     map[string]*Wallet      // Mapping from reader names to wallet instances
+	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
+
+	stateLock sync.RWMutex // Protects the internals of the hub from racey access
+}
+
+func (hub *Hub) readPairings() error {
+	hub.pairings = make(map[string]smartcardPairing)
+	pairingFile, err := os.Open(filepath.Join(hub.datadir, "smartcards.json"))
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	pairingData, err := ioutil.ReadAll(pairingFile)
+	if err != nil {
+		return err
+	}
+	var pairings []smartcardPairing
+	if err := json.Unmarshal(pairingData, &pairings); err != nil {
+		return err
+	}
+
+	for _, pairing := range pairings {
+		hub.pairings[string(pairing.PublicKey)] = pairing
+	}
+	return nil
+}
+
+func (hub *Hub) writePairings() error {
+	pairingFile, err := os.OpenFile(filepath.Join(hub.datadir, "smartcards.json"), os.O_RDWR|os.O_CREATE, 0755)
+	if err != nil {
+		return err
+	}
+	defer pairingFile.Close()
+
+	pairings := make([]smartcardPairing, 0, len(hub.pairings))
+	for _, pairing := range hub.pairings {
+		pairings = append(pairings, pairing)
+	}
+
+	pairingData, err := json.Marshal(pairings)
+	if err != nil {
+		return err
+	}
+
+	if _, err := pairingFile.Write(pairingData); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (hub *Hub) pairing(wallet *Wallet) *smartcardPairing {
+	if pairing, ok := hub.pairings[string(wallet.PublicKey)]; ok {
+		return &pairing
+	}
+	return nil
+}
+
+func (hub *Hub) setPairing(wallet *Wallet, pairing *smartcardPairing) error {
+	if pairing == nil {
+		delete(hub.pairings, string(wallet.PublicKey))
+	} else {
+		hub.pairings[string(wallet.PublicKey)] = *pairing
+	}
+	return hub.writePairings()
+}
+
+// NewHub creates a new hardware wallet manager for smartcards.
+func NewHub(daemonPath string, scheme string, datadir string) (*Hub, error) {
+	context, err := pcsc.EstablishContext(daemonPath, pcsc.ScopeSystem)
+	if err != nil {
+		return nil, err
+	}
+	hub := &Hub{
+		scheme:  scheme,
+		context: context,
+		datadir: datadir,
+		wallets: make(map[string]*Wallet),
+		quit:    make(chan chan error),
+	}
+	if err := hub.readPairings(); err != nil {
+		return nil, err
+	}
+	hub.refreshWallets()
+	return hub, nil
+}
+
+// Wallets implements accounts.Backend, returning all the currently tracked smart
+// cards that appear to be hardware wallets.
+func (hub *Hub) Wallets() []accounts.Wallet {
+	// Make sure the list of wallets is up to date
+	hub.refreshWallets()
+
+	hub.stateLock.RLock()
+	defer hub.stateLock.RUnlock()
+
+	cpy := make([]accounts.Wallet, 0, len(hub.wallets))
+	for _, wallet := range hub.wallets {
+		cpy = append(cpy, wallet)
+	}
+	sort.Sort(accounts.WalletsByURL(cpy))
+	return cpy
+}
+
+// refreshWallets scans the devices attached to the machine and updates the
+// list of wallets based on the found devices.
+func (hub *Hub) refreshWallets() {
+	// Don't scan the USB like crazy it the user fetches wallets in a loop
+	hub.stateLock.RLock()
+	elapsed := time.Since(hub.refreshed)
+	hub.stateLock.RUnlock()
+
+	if elapsed < refreshThrottling {
+		return
+	}
+	// Retrieve all the smart card reader to check for cards
+	readers, err := hub.context.ListReaders()
+	if err != nil {
+		// This is a perverted hack, the scard library returns an error if no card
+		// readers are present instead of simply returning an empty list. We don't
+		// want to fill the user's log with errors, so filter those out.
+		if err.Error() != "scard: Cannot find a smart card reader." {
+			log.Error("Failed to enumerate smart card readers", "err", err)
+			return
+		}
+	}
+	// Transform the current list of wallets into the new one
+	hub.stateLock.Lock()
+
+	events := []accounts.WalletEvent{}
+	seen := make(map[string]struct{})
+
+	for _, reader := range readers {
+		// Mark the reader as present
+		seen[reader] = struct{}{}
+
+		// If we alreay know about this card, skip to the next reader, otherwise clean up
+		if wallet, ok := hub.wallets[reader]; ok {
+			if err := wallet.ping(); err == nil {
+				continue
+			}
+			wallet.Close()
+			events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletDropped})
+			delete(hub.wallets, reader)
+		}
+		// New card detected, try to connect to it
+		card, err := hub.context.Connect(reader, pcsc.ShareShared, pcsc.ProtocolAny)
+		if err != nil {
+			log.Debug("Failed to open smart card", "reader", reader, "err", err)
+			continue
+		}
+		wallet := NewWallet(hub, card)
+		if err = wallet.connect(); err != nil {
+			log.Debug("Failed to connect to smart card", "reader", reader, "err", err)
+			card.Disconnect(pcsc.LeaveCard)
+			continue
+		}
+		// Card connected, start tracking in amongs the wallets
+		hub.wallets[reader] = wallet
+		events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletArrived})
+	}
+	// Remove any wallets no longer present
+	for reader, wallet := range hub.wallets {
+		if _, ok := seen[reader]; !ok {
+			wallet.Close()
+			events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletDropped})
+			delete(hub.wallets, reader)
+		}
+	}
+	hub.refreshed = time.Now()
+	hub.stateLock.Unlock()
+
+	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 smart card wallets.
+func (hub *Hub) Subscribe(sink chan<- accounts.WalletEvent) event.Subscription {
+	// We need the mutex to reliably start/stop the update loop
+	hub.stateLock.Lock()
+	defer hub.stateLock.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 managed
+// by the smart card hub, and for firing wallet addition/removal events.
+func (hub *Hub) updater() {
+	for {
+		// TODO: Wait for a USB hotplug event (not supported yet) or a refresh timeout
+		// <-hub.changes
+		time.Sleep(refreshCycle)
+
+		// Run the wallet refresher
+		hub.refreshWallets()
+
+		// If all our subscribers left, stop the updater
+		hub.stateLock.Lock()
+		if hub.updateScope.Count() == 0 {
+			hub.updating = false
+			hub.stateLock.Unlock()
+			return
+		}
+		hub.stateLock.Unlock()
+	}
+}