path: root/accounts/addrcache.go

// Copyright 2016 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 accounts

import (
    "bufio"
    "encoding/json"
    "fmt"
    "io/ioutil"
    "os"
    "path/filepath"
    "sort"
    "strings"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
)

// Minimum amount of time between cache reloads. This limit applies if the platform does
// not support change notifications. It also applies if the keystore directory does not
// exist yet, the code will attempt to create a watcher at most this often.
const minReloadInterval = 2 * time.Second

type accountsByFile []Account

func (s accountsByFile) Len() int           { return len(s) }
func (s accountsByFile) Less(i, j int) bool { return s[i].File < s[j].File }
func (s accountsByFile) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

// AmbiguousAddrError is returned when attempting to unlock
// an address for which more than one file exists.
type AmbiguousAddrError struct {
    Addr    common.Address
    Matches []Account
}

func (err *AmbiguousAddrError) Error() string {
    files := ""
    for i, a := range err.Matches {
        files += a.File
        if i < len(err.Matches)-1 {
            files += ", "
        }
    }
    return fmt.Sprintf("multiple keys match address (%s)", files)
}

// addrCache is a live index of all accounts in the keystore.
type addrCache struct {
    keydir   string
    watcher  *watcher
    mu       sync.Mutex
    all      accountsByFile
    byAddr   map[common.Address][]Account
    throttle *time.Timer
}

func newAddrCache(keydir string) *addrCache {
    ac := &addrCache{
        keydir: keydir,
        byAddr: make(map[common.Address][]Account),
    }
    ac.watcher = newWatcher(ac)
    return ac
}

func (ac *addrCache) accounts() []Account {
    ac.maybeReload()
    ac.mu.Lock()
    defer ac.mu.Unlock()
    cpy := make([]Account, len(ac.all))
    copy(cpy, ac.all)
    return cpy
}

func (ac *addrCache) hasAddress(addr common.Address) bool {
    ac.maybeReload()
    ac.mu.Lock()
    defer ac.mu.Unlock()
    return len(ac.byAddr[addr]) > 0
}

func (ac *addrCache) add(newAccount Account) {
    ac.mu.Lock()
    defer ac.mu.Unlock()

    i := sort.Search(len(ac.all), func(i int) bool { return ac.all[i].File >= newAccount.File })
    if i < len(ac.all) && ac.all[i] == newAccount {
        return
    }
    // newAccount is not in the cache.
    ac.all = append(ac.all, Account{})
    copy(ac.all[i+1:], ac.all[i:])
    ac.all[i] = newAccount
    ac.byAddr[newAccount.Address] = append(ac.byAddr[newAccount.Address], newAccount)
}

// note: removed needs to be unique here (i.e. both File and Address must be set).
func (ac *addrCache) delete(removed Account) {
    ac.mu.Lock()
    defer ac.mu.Unlock()
    ac.all = removeAccount(ac.all, removed)
    if ba := removeAccount(ac.byAddr[removed.Address], removed); len(ba) == 0 {
        delete(ac.byAddr, removed.Address)
    } else {
        ac.byAddr[removed.Address] = ba
    }
}

func removeAccount(slice []Account, elem Account) []Account {
    for i := range slice {
        if slice[i] == elem {
            return append(slice[:i], slice[i+1:]...)
        }
    }
    return slice
}

// find returns the cached account for address if there is a unique match.
// The exact matching rules are explained by the documentation of Account.
// Callers must hold ac.mu.
func (ac *addrCache) find(a Account) (Account, error) {
    // Limit search to address candidates if possible.
    matches := ac.all
    if (a.Address != common.Address{}) {
        matches = ac.byAddr[a.Address]
    }
    if a.File != "" {
        // If only the basename is specified, complete the path.
        if !strings.ContainsRune(a.File, filepath.Separator) {
            a.File = filepath.Join(ac.keydir, a.File)
        }
        for i := range matches {
            if matches[i].File == a.File {
                return matches[i], nil
            }
        }
        if (a.Address == common.Address{}) {
            return Account{}, ErrNoMatch
        }
    }
    switch len(matches) {
    case 1:
        return matches[0], nil
    case 0:
        return Account{}, ErrNoMatch
    default:
        err := &AmbiguousAddrError{Addr: a.Address, Matches: make([]Account, len(matches))}
        copy(err.Matches, matches)
        return Account{}, err
    }
}

func (ac *addrCache) maybeReload() {
    ac.mu.Lock()
    defer ac.mu.Unlock()
    if ac.watcher.running {
        return // A watcher is running and will keep the cache up-to-date.
    }
    if ac.throttle == nil {
        ac.throttle = time.NewTimer(0)
    } else {
        select {
        case <-ac.throttle.C:
        default:
            return // The cache was reloaded recently.
        }
    }
    ac.watcher.start()
    ac.reload()
    ac.throttle.Reset(minReloadInterval)
}

func (ac *addrCache) close() {
    ac.mu.Lock()
    ac.watcher.close()
    if ac.throttle != nil {
        ac.throttle.Stop()
    }
    ac.mu.Unlock()
}

// reload caches addresses of existing accounts.
// Callers must hold ac.mu.
func (ac *addrCache) reload() {
    accounts, err := ac.scan()
    if err != nil && glog.V(logger.Debug) {
        glog.Errorf("can't load keys: %v", err)
    }
    ac.all = accounts
    sort.Sort(ac.all)
    for k := range ac.byAddr {
        delete(ac.byAddr, k)
    }
    for _, a := range accounts {
        ac.byAddr[a.Address] = append(ac.byAddr[a.Address], a)
    }
    glog.V(logger.Debug).Infof("reloaded keys, cache has %d accounts", len(ac.all))
}

func (ac *addrCache) scan() ([]Account, error) {
    files, err := ioutil.ReadDir(ac.keydir)
    if err != nil {
        return nil, err
    }

    var (
        buf     = new(bufio.Reader)
        addrs   []Account
        keyJSON struct {
            Address common.Address `json:"address"`
        }
    )
    for _, fi := range files {
        path := filepath.Join(ac.keydir, fi.Name())
        if skipKeyFile(fi) {
            glog.V(logger.Detail).Infof("ignoring file %s", path)
            continue
        }
        fd, err := os.Open(path)
        if err != nil {
            glog.V(logger.Detail).Infoln(err)
            continue
        }
        buf.Reset(fd)
        // Parse the address.
        keyJSON.Address = common.Address{}
        err = json.NewDecoder(buf).Decode(&keyJSON)
        switch {
        case err != nil:
            glog.V(logger.Debug).Infof("can't decode key %s: %v", path, err)
        case (keyJSON.Address == common.Address{}):
            glog.V(logger.Debug).Infof("can't decode key %s: missing or zero address", path)
        default:
            addrs = append(addrs, Account{Address: keyJSON.Address, File: path})
        }
        fd.Close()
    }
    return addrs, err
}

func skipKeyFile(fi os.FileInfo) bool {
    // Skip editor backups and UNIX-style hidden files.
    if strings.HasSuffix(fi.Name(), "~") || strings.HasPrefix(fi.Name(), ".") {
        return true
    }
    // Skip misc special files, directories (yes, symlinks too).
    if fi.IsDir() || fi.Mode()&os.ModeType != 0 {
        return true
    }
    return false
}