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 (
    "crypto/ecdsa"
    crand "crypto/rand"

    "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 AccountManager struct {
    keyStore   crypto.KeyStore2
    unlocked   map[string]*unlocked
    unlockTime time.Duration
    mutex      sync.RWMutex
}

type unlocked struct {
    addr  []byte
    abort chan struct{}

    *crypto.Key
}

func NewAccountManager(keyStore crypto.KeyStore2, unlockTime time.Duration) *AccountManager {
    return &AccountManager{
        keyStore:   keyStore,
        unlocked:   make(map[string]*unlocked),
        unlockTime: unlockTime,
    }
}

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

// MainAccount returns the primary account used for transactions.
func (am *AccountManager) Default() (Account, error) {
    // TODO: persist main account address on disk
    addr, err := am.firstAddr()
    return Account{Address: addr}, err
}

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

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

func (am *AccountManager) 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
}

func (am *AccountManager) SignLocked(a Account, keyAuth string, toSign []byte) (signature []byte, err error) {
    key, err := am.keyStore.GetKey(a.Address, keyAuth)
    if err != nil {
        return nil, err
    }
    u := am.addUnlocked(a.Address, key)
    go am.dropLater(u)
    signature, err = crypto.Sign(toSign, key.PrivateKey)
    return signature, err
}

func (am *AccountManager) 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 *AccountManager) Accounts() ([]Account, error) {
    addresses, err := am.keyStore.GetKeyAddresses()
    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 *AccountManager) addUnlocked(addr []byte, key *crypto.Key) *unlocked {
    u := &unlocked{addr: addr, abort: make(chan struct{}), Key: key}
    am.mutex.Lock()
    prev, found := am.unlocked[string(addr)]
    if found {
        // terminate dropLater for this key to avoid unexpected drops.
        close(prev.abort)
        zeroKey(prev.PrivateKey)
    }
    am.unlocked[string(addr)] = u
    am.mutex.Unlock()
    return u
}

func (am *AccountManager) dropLater(u *unlocked) {
    t := time.NewTimer(am.unlockTime)
    defer t.Stop()
    select {
    case <-u.abort:
        // just quit
    case <-t.C:
        am.mutex.Lock()
        if am.unlocked[string(u.addr)] == u {
            zeroKey(u.PrivateKey)
            delete(am.unlocked, string(u.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
    }
}