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Diffstat (limited to 'accounts/usbwallet/hub.go')
| -rw-r--r-- | accounts/usbwallet/hub.go | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/accounts/usbwallet/hub.go b/accounts/usbwallet/hub.go new file mode 100644 index 000000000..7069d2531 --- /dev/null +++ b/accounts/usbwallet/hub.go @@ -0,0 +1,234 @@ +// 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 + +import ( + "errors" + "runtime" + "sync" + "time" + + "github.com/ethereum/go-ethereum/accounts" + "github.com/ethereum/go-ethereum/event" + "github.com/ethereum/go-ethereum/log" + "github.com/karalabe/hid" +) + +// LedgerScheme is the protocol scheme prefixing account and wallet URLs. +const LedgerScheme = "ledger" + +// TrezorScheme is the protocol scheme prefixing account and wallet URLs. +const TrezorScheme = "trezor" + +// 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 USB +// trashing. +const refreshThrottling = 500 * time.Millisecond + +// Hub is a accounts.Backend that can find and handle generic USB hardware wallets. +type Hub struct { + scheme string // Protocol scheme prefixing account and wallet URLs. + vendorID uint16 // USB vendor identifier used for device discovery + productIDs []uint16 // USB product identifiers used for device discovery + makeDriver func(log.Logger) driver // Factory method to construct a vendor specific driver + + refreshed time.Time // Time instance when the list of wallets was last refreshed + wallets []accounts.Wallet // List of USB wallet 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 + + stateLock sync.RWMutex // Protects the internals of the hub from racey access + + // TODO(karalabe): remove if hotplug lands on Windows + commsPend int // Number of operations blocking enumeration + commsLock sync.Mutex // Lock protecting the pending counter and enumeration +} + +// NewLedgerHub creates a new hardware wallet manager for Ledger devices. +func NewLedgerHub() (*Hub, error) { + return newHub(LedgerScheme, 0x2c97, []uint16{0x0000 /* Ledger Blue */, 0x0001 /* Ledger Nano S */}, newLedgerDriver) +} + +// NewTrezorHub creates a new hardware wallet manager for Trezor devices. +func NewTrezorHub() (*Hub, error) { + return newHub(TrezorScheme, 0x534c, []uint16{0x0001 /* Trezor 1 */}, newTrezorDriver) +} + +// newHub creates a new hardware wallet manager for generic USB devices. +func newHub(scheme string, vendorID uint16, productIDs []uint16, makeDriver func(log.Logger) driver) (*Hub, error) { + if !hid.Supported() { + return nil, errors.New("unsupported platform") + } + hub := &Hub{ + scheme: scheme, + vendorID: vendorID, + productIDs: productIDs, + makeDriver: makeDriver, + 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 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, 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 *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 the current list of USB wallet devices + var devices []hid.DeviceInfo + + if runtime.GOOS == "linux" { + // hidapi on Linux opens the device during enumeration to retrieve some infos, + // breaking the Ledger protocol if that is waiting for user confirmation. This + // is a bug acknowledged at Ledger, but it won't be fixed on old devices so we + // need to prevent concurrent comms ourselves. The more elegant solution would + // be to ditch enumeration in favor of hutplug events, but that don't work yet + // on Windows so if we need to hack it anyway, this is more elegant for now. + hub.commsLock.Lock() + if hub.commsPend > 0 { // A confirmation is pending, don't refresh + hub.commsLock.Unlock() + return + } + } + for _, info := range hid.Enumerate(hub.vendorID, 0) { + for _, id := range hub.productIDs { + if info.ProductID == id && info.Interface == 0 { + devices = append(devices, info) + break + } + } + } + if runtime.GOOS == "linux" { + // See rationale before the enumeration why this is needed and only on Linux. + hub.commsLock.Unlock() + } + // Transform the current list of wallets into the new one + hub.stateLock.Lock() + + wallets := make([]accounts.Wallet, 0, len(devices)) + events := []accounts.WalletEvent{} + + for _, device := range devices { + url := accounts.URL{Scheme: hub.scheme, Path: device.Path} + + // Drop wallets in front of the next device or those that failed for some reason + for len(hub.wallets) > 0 { + // Abort if we're past the current device and found an operational one + _, failure := hub.wallets[0].Status() + if hub.wallets[0].URL().Cmp(url) >= 0 || failure == nil { + break + } + // Drop the stale and failed devices + events = append(events, accounts.WalletEvent{Wallet: hub.wallets[0], Kind: accounts.WalletDropped}) + 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 { + logger := log.New("url", url) + wallet := &wallet{hub: hub, driver: hub.makeDriver(logger), url: &url, info: device, log: logger} + + events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletArrived}) + 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, Kind: accounts.WalletDropped}) + } + hub.refreshed = time.Now() + hub.wallets = wallets + hub.stateLock.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 USB 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 USB 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() + } +} |