path: root/accounts/account_manager.go

/*
    This file is part of go-ethereum

    go-ethereum 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.

    go-ethereum 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 General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with go-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @authors
 *  Gustav Simonsson <gustav.simonsson@gmail.com>
 * @date 2015
 *
 */
/*

This abstracts part of a user's interaction with an account she controls.
It's not an abstraction of core Ethereum accounts data type / logic -
for that see the core processing code of blocks / txs.

Currently this is pretty much a passthrough to the KeyStore2 interface,
and accounts persistence is derived from stored keys' addresses

*/
package accounts

import (
    "bytes"
    "crypto/ecdsa"
    crand "crypto/rand"
    "os"

    "errors"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/crypto"
)

var (
    ErrLocked = errors.New("account is locked")
    ErrNoKeys = errors.New("no keys in store")
)

type Account struct {
    Address []byte
}

type Manager struct {
    keyStore crypto.KeyStore2
    unlocked map[string]*unlocked
    mutex    sync.RWMutex
}

type unlocked struct {
    *crypto.Key
    abort chan struct{}
}

func NewManager(keyStore crypto.KeyStore2) *Manager {
    return &Manager{
        keyStore: keyStore,
        unlocked: make(map[string]*unlocked),
    }
}

func (am *Manager) HasAccount(addr []byte) bool {
    accounts, _ := am.Accounts()
    for _, acct := range accounts {
        if bytes.Compare(acct.Address, addr) == 0 {
            return true
        }
    }
    return false
}

// Coinbase returns the account address that mining rewards are sent to.
func (am *Manager) Coinbase() (addr []byte, err error) {
    // TODO: persist coinbase address on disk
    return am.firstAddr()
}

func (am *Manager) firstAddr() ([]byte, error) {
    addrs, err := am.keyStore.GetKeyAddresses()
    if os.IsNotExist(err) {
        return nil, ErrNoKeys
    } else if err != nil {
        return nil, err
    }
    if len(addrs) == 0 {
        return nil, ErrNoKeys
    }
    return addrs[0], nil
}

func (am *Manager) DeleteAccount(address []byte, auth string) error {
    return am.keyStore.DeleteKey(address, auth)
}

func (am *Manager) Sign(a Account, toSign []byte) (signature []byte, err error) {
    am.mutex.RLock()
    unlockedKey, found := am.unlocked[string(a.Address)]
    am.mutex.RUnlock()
    if !found {
        return nil, ErrLocked
    }
    signature, err = crypto.Sign(toSign, unlockedKey.PrivateKey)
    return signature, err
}

// TimedUnlock unlocks the account with the given address.
// When timeout has passed, the account will be locked again.
func (am *Manager) TimedUnlock(addr []byte, keyAuth string, timeout time.Duration) error {
    key, err := am.keyStore.GetKey(addr, keyAuth)
    if err != nil {
        return err
    }
    u := am.addUnlocked(addr, key)
    go am.dropLater(addr, u, timeout)
    return nil
}

// Unlock unlocks the account with the given address. The account
// stays unlocked until the program exits or until a TimedUnlock
// timeout (started after the call to Unlock) expires.
func (am *Manager) Unlock(addr []byte, keyAuth string) error {
    key, err := am.keyStore.GetKey(addr, keyAuth)
    if err != nil {
        return err
    }
    am.addUnlocked(addr, key)
    return nil
}

func (am *Manager) NewAccount(auth string) (Account, error) {
    key, err := am.keyStore.GenerateNewKey(crand.Reader, auth)
    if err != nil {
        return Account{}, err
    }
    return Account{Address: key.Address}, nil
}

func (am *Manager) Accounts() ([]Account, error) {
    addresses, err := am.keyStore.GetKeyAddresses()
    if os.IsNotExist(err) {
        return nil, ErrNoKeys
    } else if err != nil {
        return nil, err
    }
    accounts := make([]Account, len(addresses))
    for i, addr := range addresses {
        accounts[i] = Account{
            Address: addr,
        }
    }
    return accounts, err
}

func (am *Manager) addUnlocked(addr []byte, key *crypto.Key) *unlocked {
    u := &unlocked{Key: key, abort: make(chan struct{})}
    am.mutex.Lock()
    prev, found := am.unlocked[string(addr)]
    if found {
        // terminate dropLater for this key to avoid unexpected drops.
        close(prev.abort)
        // the key is zeroed here instead of in dropLater because
        // there might not actually be a dropLater running for this
        // key, i.e. when Unlock was used.
        zeroKey(prev.PrivateKey)
    }
    am.unlocked[string(addr)] = u
    am.mutex.Unlock()
    return u
}

func (am *Manager) dropLater(addr []byte, u *unlocked, timeout time.Duration) {
    t := time.NewTimer(timeout)
    defer t.Stop()
    select {
    case <-u.abort:
        // just quit
    case <-t.C:
        am.mutex.Lock()
        // only drop if it's still the same key instance that dropLater
        // was launched with. we can check that using pointer equality
        // because the map stores a new pointer every time the key is
        // unlocked.
        if am.unlocked[string(addr)] == u {
            zeroKey(u.PrivateKey)
            delete(am.unlocked, string(addr))
        }
        am.mutex.Unlock()
    }
}

// zeroKey zeroes a private key in memory.
func zeroKey(k *ecdsa.PrivateKey) {
    b := k.D.Bits()
    for i := range b {
        b[i] = 0
    }
}