addressdb.go

// Copyright (c) 2014 The btcsuite developers
// Copyright (c) 2015 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package udb

import (
	"crypto/sha256"
	"encoding/binary"
	"fmt"
	"time"

	"github.com/decred/dcrwallet/apperrors"
	"github.com/decred/dcrwallet/walletdb"
)

var (
	// latestMgrVersion is the most recent manager version as a variable so
	// the tests can change it to force errors.
	latestMgrVersion uint32 = 6
)

// ObtainUserInputFunc is a function that reads a user input and returns it as
// a byte stream. It is used to accept data required during upgrades, for e.g.
// wallet seed and private passphrase.
type ObtainUserInputFunc func() ([]byte, error)

// maybeConvertDbError converts the passed error to a ManagerError with an
// error code of ErrDatabase if it is not already a ManagerError.  This is
// useful for potential errors returned from managed transaction an other parts
// of the walletdb database.
func maybeConvertDbError(err error) error {
	// When the error is already a ManagerError, just return it.
	if _, ok := err.(apperrors.E); ok {
		return err
	}

	return managerError(apperrors.ErrDatabase, err.Error(), err)
}

// syncStatus represents a address synchronization status stored in the
// database.
type syncStatus uint8

// These constants define the various supported sync status types.
//
// NOTE: These are currently unused but are being defined for the possibility of
// supporting sync status on a per-address basis.
const (
	ssNone    syncStatus = 0 // not iota as they need to be stable for db
	ssPartial syncStatus = 1
	ssFull    syncStatus = 2
)

// addressType represents a type of address stored in the database.
type addressType uint8

// These constants define the various supported address types.
const (
	adtChain  addressType = 0 // not iota as they need to be stable for db
	adtImport addressType = 1
	adtScript addressType = 2
)

// accountType represents a type of address stored in the database.
type accountType uint8

// These constants define the various supported account types.
const (
	actBIP0044 accountType = 0 // not iota as they need to be stable for db
)

// dbAccountRow houses information stored about an account in the database.
type dbAccountRow struct {
	acctType accountType
	rawData  []byte // Varies based on account type field.
}

// dbBIP0044AccountRow houses additional information stored about a BIP0044
// account in the database.
type dbBIP0044AccountRow struct {
	dbAccountRow
	pubKeyEncrypted           []byte
	privKeyEncrypted          []byte
	nextExternalIndex         uint32 // Removed by version 2
	nextInternalIndex         uint32 // Removed by version 2
	lastUsedExternalIndex     uint32 // Added in version 2
	lastUsedInternalIndex     uint32 // Added in version 2
	lastReturnedExternalIndex uint32 // Added in version 5
	lastReturnedInternalIndex uint32 // Added in version 5
	name                      string
}

// dbAddressRow houses common information stored about an address in the
// database.
type dbAddressRow struct {
	addrType   addressType
	account    uint32
	addTime    uint64
	syncStatus syncStatus
	rawData    []byte // Varies based on address type field.
}

// dbChainAddressRow houses additional information stored about a chained
// address in the database.
type dbChainAddressRow struct {
	dbAddressRow
	branch uint32
	index  uint32
}

// dbImportedAddressRow houses additional information stored about an imported
// public key address in the database.
type dbImportedAddressRow struct {
	dbAddressRow
	encryptedPubKey  []byte
	encryptedPrivKey []byte
}

// dbImportedAddressRow houses additional information stored about a script
// address in the database.
type dbScriptAddressRow struct {
	dbAddressRow
	encryptedHash   []byte
	encryptedScript []byte
}

// Key names for various database fields.
var (
	// nullVall is null byte used as a flag value in a bucket entry
	nullVal = []byte{0}

	// Bucket names.
	acctBucketName = []byte("acct")
	addrBucketName = []byte("addr")

	// addrAcctIdxBucketName is used to index account addresses
	// Entries in this index may map:
	// * addr hash => account id
	// * account bucket -> addr hash => null
	// To fetch the account of an address, lookup the value using
	// the address hash.
	// To fetch all addresses of an account, fetch the account bucket, iterate
	// over the keys and fetch the address row from the addr bucket.
	// The index needs to be updated whenever an address is created e.g.
	// NewAddress
	addrAcctIdxBucketName = []byte("addracctidx")

	// acctNameIdxBucketName is used to create an index
	// mapping an account name string to the corresponding
	// account id.
	// The index needs to be updated whenever the account name
	// and id changes e.g. RenameAccount
	acctNameIdxBucketName = []byte("acctnameidx")

	// acctIDIdxBucketName is used to create an index
	// mapping an account id to the corresponding
	// account name string.
	// The index needs to be updated whenever the account name
	// and id changes e.g. RenameAccount
	acctIDIdxBucketName = []byte("acctididx")

	// meta is used to store meta-data about the address manager
	// e.g. last account number
	metaBucketName = []byte("meta")

	// addrPoolMetaKeyLen is the byte length of the address pool
	// prefixes. It is 11 bytes for the prefix and 4 bytes for
	// the account number.
	addrPoolMetaKeyLen = 15

	// addrPoolKeyPrefixExt is the prefix for keys mapping the
	// last used address pool index to a BIP0044 account. The
	// BIP0044 account is appended to this slice in order to
	// derive the key. This is the external branch.
	// e.g. in pseudocode:
	// key = append([]byte("addrpoolext"), []byte(account))
	//
	// This was removed by database version 2.
	addrPoolKeyPrefixExt = []byte("addrpoolext")

	// addrPoolKeyPrefixInt is the prefix for keys mapping the
	// last used address pool index to a BIP0044 account. The
	// BIP0044 account is appended to this slice in order to
	// derive the key. This is the internal branch.
	//
	// This was removed by database version 2.
	addrPoolKeyPrefixInt = []byte("addrpoolint")

	// lastAccountName is used to store the metadata - last account
	// in the manager
	lastAccountName = []byte("lastaccount")

	mainBucketName = []byte("main")

	// Db related key names (main bucket).
	mgrVersionName    = []byte("mgrver")
	mgrCreateDateName = []byte("mgrcreated")

	// Crypto related key names (main bucket).
	seedName            = []byte("seed")
	masterPrivKeyName   = []byte("mpriv")
	masterPubKeyName    = []byte("mpub")
	cryptoPrivKeyName   = []byte("cpriv")
	cryptoPubKeyName    = []byte("cpub")
	cryptoScriptKeyName = []byte("cscript")
	coinTypePrivKeyName = []byte("ctpriv")
	coinTypePubKeyName  = []byte("ctpub")
	watchingOnlyName    = []byte("watchonly")

	// Used addresses (used bucket).  This was removed by database version 2.
	usedAddrBucketName = []byte("usedaddrs")
)

// uint32ToBytes converts a 32 bit unsigned integer into a 4-byte slice in
// little-endian order: 1 -> [1 0 0 0].
func uint32ToBytes(number uint32) []byte {
	buf := make([]byte, 4)
	binary.LittleEndian.PutUint32(buf, number)
	return buf
}

// stringToBytes converts a string into a variable length byte slice in
// little-endian order: "abc" -> [3 0 0 0 61 62 63]
func stringToBytes(s string) []byte {
	// The serialized format is:
	//   <size><string>
	//
	// 4 bytes string size + string
	size := len(s)
	buf := make([]byte, 4+size)
	copy(buf[0:4], uint32ToBytes(uint32(size)))
	copy(buf[4:4+size], s)
	return buf
}

// fetchManagerVersion fetches the current manager version from the database.
// Should only be called on managers in unmigrated DBs.
func fetchManagerVersion(ns walletdb.ReadBucket) (uint32, error) {
	mainBucket := ns.NestedReadBucket(mainBucketName)
	verBytes := mainBucket.Get(mgrVersionName)
	if verBytes == nil {
		str := "required version number not stored in database"
		return 0, managerError(apperrors.ErrDatabase, str, nil)
	}
	version := binary.LittleEndian.Uint32(verBytes)
	return version, nil
}

// putManagerVersion stores the provided version to the database.  Should only
// be called on managers in unmigrated DBs.
func putManagerVersion(ns walletdb.ReadWriteBucket, version uint32) error {
	bucket := ns.NestedReadWriteBucket(mainBucketName)

	verBytes := uint32ToBytes(version)
	err := bucket.Put(mgrVersionName, verBytes)
	if err != nil {
		str := "failed to store version"
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// fetchMasterKeyParams loads the master key parameters needed to derive them
// (when given the correct user-supplied passphrase) from the database.  Either
// returned value can be nil, but in practice only the private key params will
// be nil for a watching-only database.
func fetchMasterKeyParams(ns walletdb.ReadBucket) ([]byte, []byte, error) {
	bucket := ns.NestedReadBucket(mainBucketName)

	// Load the master public key parameters.  Required.
	val := bucket.Get(masterPubKeyName)
	if val == nil {
		str := "required master public key parameters not stored in " +
			"database"
		return nil, nil, managerError(apperrors.ErrDatabase, str, nil)
	}
	pubParams := make([]byte, len(val))
	copy(pubParams, val)

	// Load the master private key parameters if they were stored.
	var privParams []byte
	val = bucket.Get(masterPrivKeyName)
	if val != nil {
		privParams = make([]byte, len(val))
		copy(privParams, val)
	}

	return pubParams, privParams, nil
}

// putMasterKeyParams stores the master key parameters needed to derive them
// to the database.  Either parameter can be nil in which case no value is
// written for the parameter.
func putMasterKeyParams(ns walletdb.ReadWriteBucket, pubParams, privParams []byte) error {
	bucket := ns.NestedReadWriteBucket(mainBucketName)

	if privParams != nil {
		err := bucket.Put(masterPrivKeyName, privParams)
		if err != nil {
			str := "failed to store master private key parameters"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	if pubParams != nil {
		err := bucket.Put(masterPubKeyName, pubParams)
		if err != nil {
			str := "failed to store master public key parameters"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	return nil
}

// fetchCoinTypeKeys loads the encrypted cointype keys which are in turn used to
// derive the extended keys for all accounts.
func fetchCoinTypeKeys(ns walletdb.ReadBucket) ([]byte, []byte, error) {
	bucket := ns.NestedReadBucket(mainBucketName)

	coinTypePubKeyEnc := bucket.Get(coinTypePubKeyName)
	if coinTypePubKeyEnc == nil {
		str := "required encrypted cointype public key not stored in database"
		return nil, nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	coinTypePrivKeyEnc := bucket.Get(coinTypePrivKeyName)
	if coinTypePrivKeyEnc == nil {
		str := "required encrypted cointype private key not stored in database"
		return nil, nil, managerError(apperrors.ErrDatabase, str, nil)
	}
	return coinTypePubKeyEnc, coinTypePrivKeyEnc, nil
}

// putCoinTypeKeys stores the encrypted cointype keys which are in turn used to
// derive the extended keys for all accounts.  Either parameter can be nil in which
// case no value is written for the parameter.
func putCoinTypeKeys(ns walletdb.ReadWriteBucket, coinTypePubKeyEnc []byte, coinTypePrivKeyEnc []byte) error {
	bucket := ns.NestedReadWriteBucket(mainBucketName)

	if coinTypePubKeyEnc != nil {
		err := bucket.Put(coinTypePubKeyName, coinTypePubKeyEnc)
		if err != nil {
			str := "failed to store encrypted cointype public key"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	if coinTypePrivKeyEnc != nil {
		err := bucket.Put(coinTypePrivKeyName, coinTypePrivKeyEnc)
		if err != nil {
			str := "failed to store encrypted cointype private key"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	return nil
}

// fetchCryptoKeys loads the encrypted crypto keys which are in turn used to
// protect the extended keys, imported keys, and scripts.  Any of the returned
// values can be nil, but in practice only the crypto private and script keys
// will be nil for a watching-only database.
func fetchCryptoKeys(ns walletdb.ReadBucket) ([]byte, []byte, []byte, error) {
	bucket := ns.NestedReadBucket(mainBucketName)

	// Load the crypto public key parameters.  Required.
	val := bucket.Get(cryptoPubKeyName)
	if val == nil {
		str := "required encrypted crypto public not stored in database"
		return nil, nil, nil, managerError(apperrors.ErrDatabase, str, nil)
	}
	pubKey := make([]byte, len(val))
	copy(pubKey, val)

	// Load the crypto private key parameters if they were stored.
	var privKey []byte
	val = bucket.Get(cryptoPrivKeyName)
	if val != nil {
		privKey = make([]byte, len(val))
		copy(privKey, val)
	}

	// Load the crypto script key parameters if they were stored.
	var scriptKey []byte
	val = bucket.Get(cryptoScriptKeyName)
	if val != nil {
		scriptKey = make([]byte, len(val))
		copy(scriptKey, val)
	}

	return pubKey, privKey, scriptKey, nil
}

// putCryptoKeys stores the encrypted crypto keys which are in turn used to
// protect the extended and imported keys.  Either parameter can be nil in which
// case no value is written for the parameter.
func putCryptoKeys(ns walletdb.ReadWriteBucket, pubKeyEncrypted, privKeyEncrypted, scriptKeyEncrypted []byte) error {
	bucket := ns.NestedReadWriteBucket(mainBucketName)

	if pubKeyEncrypted != nil {
		err := bucket.Put(cryptoPubKeyName, pubKeyEncrypted)
		if err != nil {
			str := "failed to store encrypted crypto public key"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	if privKeyEncrypted != nil {
		err := bucket.Put(cryptoPrivKeyName, privKeyEncrypted)
		if err != nil {
			str := "failed to store encrypted crypto private key"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	if scriptKeyEncrypted != nil {
		err := bucket.Put(cryptoScriptKeyName, scriptKeyEncrypted)
		if err != nil {
			str := "failed to store encrypted crypto script key"
			return managerError(apperrors.ErrDatabase, str, err)
		}
	}

	return nil
}

// fetchWatchingOnly loads the watching-only flag from the database.
func fetchWatchingOnly(ns walletdb.ReadBucket) (bool, error) {
	bucket := ns.NestedReadBucket(mainBucketName)

	buf := bucket.Get(watchingOnlyName)
	if len(buf) != 1 {
		str := "malformed watching-only flag stored in database"
		return false, managerError(apperrors.ErrDatabase, str, nil)
	}

	return buf[0] != 0, nil
}

// putWatchingOnly stores the watching-only flag to the database.
func putWatchingOnly(ns walletdb.ReadWriteBucket, watchingOnly bool) error {
	bucket := ns.NestedReadWriteBucket(mainBucketName)

	var encoded byte
	if watchingOnly {
		encoded = 1
	}

	if err := bucket.Put(watchingOnlyName, []byte{encoded}); err != nil {
		str := "failed to store watching only flag"
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// deserializeAccountRow deserializes the passed serialized account information.
// This is used as a common base for the various account types to deserialize
// the common parts.
func deserializeAccountRow(accountID []byte, serializedAccount []byte) (*dbAccountRow, error) {
	// The serialized account format is:
	//   <acctType><rdlen><rawdata>
	//
	// 1 byte acctType + 4 bytes raw data length + raw data

	// Given the above, the length of the entry must be at a minimum
	// the constant value sizes.
	if len(serializedAccount) < 5 {
		str := fmt.Sprintf("malformed serialized account for key %x",
			accountID)
		return nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	row := dbAccountRow{}
	row.acctType = accountType(serializedAccount[0])
	rdlen := binary.LittleEndian.Uint32(serializedAccount[1:5])
	row.rawData = make([]byte, rdlen)
	copy(row.rawData, serializedAccount[5:5+rdlen])

	return &row, nil
}

// serializeAccountRow returns the serialization of the passed account row.
func serializeAccountRow(row *dbAccountRow) []byte {
	// The serialized account format is:
	//   <acctType><rdlen><rawdata>
	//
	// 1 byte acctType + 4 bytes raw data length + raw data
	rdlen := len(row.rawData)
	buf := make([]byte, 5+rdlen)
	buf[0] = byte(row.acctType)
	binary.LittleEndian.PutUint32(buf[1:5], uint32(rdlen))
	copy(buf[5:5+rdlen], row.rawData)
	return buf
}

// deserializeBIP0044AccountRow deserializes the raw data from the passed
// account row as a BIP0044 account.
func deserializeBIP0044AccountRow(accountID []byte, row *dbAccountRow, dbVersion uint32) (*dbBIP0044AccountRow, error) {
	// The serialized BIP0044 account raw data format is:
	//   <encpubkeylen><encpubkey><encprivkeylen><encprivkey><lastusedext>
	//   <lastusedint><lastretext><lastretint><namelen><name>
	//
	// 4 bytes encrypted pubkey len + encrypted pubkey + 4 bytes encrypted
	// privkey len + encrypted privkey + 4 bytes last used external index +
	// 4 bytes last used internal index + 4 bytes last returned external +
	// 4 bytes last returned internal + 4 bytes name len + name

	// Given the above, the length of the entry must be at a minimum
	// the constant value sizes.
	switch {
	case dbVersion < 5 && len(row.rawData) < 20:
		fallthrough
	case dbVersion >= 5 && len(row.rawData) < 28:
		str := fmt.Sprintf("malformed serialized bip0044 account for "+
			"key %x", accountID)
		return nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	retRow := dbBIP0044AccountRow{
		dbAccountRow: *row,
	}

	pubLen := binary.LittleEndian.Uint32(row.rawData[0:4])
	retRow.pubKeyEncrypted = make([]byte, pubLen)
	copy(retRow.pubKeyEncrypted, row.rawData[4:4+pubLen])
	offset := 4 + pubLen
	privLen := binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
	offset += 4
	retRow.privKeyEncrypted = make([]byte, privLen)
	copy(retRow.privKeyEncrypted, row.rawData[offset:offset+privLen])
	offset += privLen
	switch {
	case dbVersion == 1:
		retRow.nextExternalIndex = binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
		offset += 4
		retRow.nextInternalIndex = binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
		offset += 4
	case dbVersion >= 2:
		retRow.lastUsedExternalIndex = binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
		retRow.lastUsedInternalIndex = binary.LittleEndian.Uint32(row.rawData[offset+4 : offset+8])
		offset += 8
	}
	switch {
	case dbVersion >= 5:
		retRow.lastReturnedExternalIndex = binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
		retRow.lastReturnedInternalIndex = binary.LittleEndian.Uint32(row.rawData[offset+4 : offset+8])
		offset += 8
	}
	nameLen := binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
	offset += 4
	retRow.name = string(row.rawData[offset : offset+nameLen])

	return &retRow, nil
}

// serializeBIP0044AccountRow returns the serialization of the raw data field
// for a BIP0044 account.
func serializeBIP0044AccountRow(row *dbBIP0044AccountRow, dbVersion uint32) []byte {
	// The serialized BIP0044 account raw data format is:
	//   <encpubkeylen><encpubkey><encprivkeylen><encprivkey><lastusedext>
	//   <lastusedint><lastretext><lastretint><namelen><name>
	//
	// 4 bytes encrypted pubkey len + encrypted pubkey + 4 bytes encrypted
	// privkey len + encrypted privkey + 4 bytes last used external index +
	// 4 bytes last used internal index + 4 bytes last returned external +
	// 4 bytes last returned internal + 4 bytes name len + name
	pubLen := uint32(len(row.pubKeyEncrypted))
	privLen := uint32(len(row.privKeyEncrypted))
	nameLen := uint32(len(row.name))
	rowSize := 28 + pubLen + privLen + nameLen
	switch {
	case dbVersion < 5:
		rowSize -= 8
	}
	rawData := make([]byte, rowSize)
	binary.LittleEndian.PutUint32(rawData[0:4], pubLen)
	copy(rawData[4:4+pubLen], row.pubKeyEncrypted)
	offset := 4 + pubLen
	binary.LittleEndian.PutUint32(rawData[offset:offset+4], privLen)
	offset += 4
	copy(rawData[offset:offset+privLen], row.privKeyEncrypted)
	offset += privLen
	switch {
	case dbVersion == 1:
		binary.LittleEndian.PutUint32(rawData[offset:offset+4], row.nextExternalIndex)
		offset += 4
		binary.LittleEndian.PutUint32(rawData[offset:offset+4], row.nextInternalIndex)
		offset += 4
	case dbVersion >= 2:
		binary.LittleEndian.PutUint32(rawData[offset:offset+4], row.lastUsedExternalIndex)
		binary.LittleEndian.PutUint32(rawData[offset+4:offset+8], row.lastUsedInternalIndex)
		offset += 8
	}
	switch {
	case dbVersion >= 5:
		binary.LittleEndian.PutUint32(rawData[offset:offset+4], row.lastReturnedExternalIndex)
		binary.LittleEndian.PutUint32(rawData[offset+4:offset+8], row.lastReturnedInternalIndex)
		offset += 8
	}
	binary.LittleEndian.PutUint32(rawData[offset:offset+4], nameLen)
	offset += 4
	copy(rawData[offset:offset+nameLen], row.name)
	return rawData
}

func bip0044AccountInfo(pubKeyEnc, privKeyEnc []byte, nextExtIndex, nextIntIndex,
	lastUsedExtIndex, lastUsedIntIndex, lastRetExtIndex, lastRetIntIndex uint32,
	name string, dbVersion uint32) *dbBIP0044AccountRow {

	row := &dbBIP0044AccountRow{
		dbAccountRow: dbAccountRow{
			acctType: actBIP0044,
			rawData:  nil,
		},
		pubKeyEncrypted:           pubKeyEnc,
		privKeyEncrypted:          privKeyEnc,
		nextExternalIndex:         0,
		nextInternalIndex:         0,
		lastUsedExternalIndex:     0,
		lastUsedInternalIndex:     0,
		lastReturnedExternalIndex: 0,
		lastReturnedInternalIndex: 0,
		name: name,
	}
	switch {
	case dbVersion == 1:
		row.nextExternalIndex = nextExtIndex
		row.nextInternalIndex = nextIntIndex
	case dbVersion >= 2:
		row.lastUsedExternalIndex = lastUsedExtIndex
		row.lastUsedInternalIndex = lastUsedIntIndex
	}
	switch {
	case dbVersion >= 5:
		row.lastReturnedExternalIndex = lastRetExtIndex
		row.lastReturnedInternalIndex = lastRetIntIndex
	}
	row.rawData = serializeBIP0044AccountRow(row, dbVersion)
	return row
}

// forEachAccount calls the given function with each account stored in
// the manager, breaking early on error.
func forEachAccount(ns walletdb.ReadBucket, fn func(account uint32) error) error {
	bucket := ns.NestedReadBucket(acctBucketName)

	return bucket.ForEach(func(k, v []byte) error {
		// Skip buckets.
		if v == nil {
			return nil
		}
		return fn(binary.LittleEndian.Uint32(k))
	})
}

// fetchLastAccount retreives the last account from the database.
func fetchLastAccount(ns walletdb.ReadBucket) (uint32, error) {
	bucket := ns.NestedReadBucket(metaBucketName)

	val := bucket.Get(lastAccountName)
	if len(val) != 4 {
		str := fmt.Sprintf("malformed metadata '%s' stored in database",
			lastAccountName)
		return 0, managerError(apperrors.ErrDatabase, str, nil)
	}
	account := binary.LittleEndian.Uint32(val[0:4])
	return account, nil
}

// fetchAccountName retreives the account name given an account number from
// the database.
func fetchAccountName(ns walletdb.ReadBucket, account uint32) (string, error) {
	bucket := ns.NestedReadBucket(acctIDIdxBucketName)

	val := bucket.Get(uint32ToBytes(account))
	if val == nil {
		str := fmt.Sprintf("account %d not found", account)
		return "", managerError(apperrors.ErrAccountNotFound, str, nil)
	}
	offset := uint32(0)
	nameLen := binary.LittleEndian.Uint32(val[offset : offset+4])
	offset += 4
	acctName := string(val[offset : offset+nameLen])
	return acctName, nil
}

// fetchAccountByName retreives the account number given an account name
// from the database.
func fetchAccountByName(ns walletdb.ReadBucket, name string) (uint32, error) {
	bucket := ns.NestedReadBucket(acctNameIdxBucketName)

	val := bucket.Get(stringToBytes(name))
	if val == nil {
		str := fmt.Sprintf("account name '%s' not found", name)
		return 0, managerError(apperrors.ErrAccountNotFound, str, nil)
	}

	return binary.LittleEndian.Uint32(val), nil
}

// fetchAccountInfo loads information about the passed account from the
// database.
func fetchAccountInfo(ns walletdb.ReadBucket, account uint32, dbVersion uint32) (*dbBIP0044AccountRow, error) {
	bucket := ns.NestedReadBucket(acctBucketName)

	accountID := uint32ToBytes(account)
	serializedRow := bucket.Get(accountID)
	if serializedRow == nil {
		str := fmt.Sprintf("account %d not found", account)
		return nil, managerError(apperrors.ErrAccountNotFound, str, nil)
	}

	row, err := deserializeAccountRow(accountID, serializedRow)
	if err != nil {
		return nil, err
	}

	switch row.acctType {
	case actBIP0044:
		return deserializeBIP0044AccountRow(accountID, row, dbVersion)
	}

	str := fmt.Sprintf("unsupported account type '%d'", row.acctType)
	return nil, managerError(apperrors.ErrDatabase, str, nil)
}

// deleteAccountNameIndex deletes the given key from the account name index of the database.
func deleteAccountNameIndex(ns walletdb.ReadWriteBucket, name string) error {
	bucket := ns.NestedReadWriteBucket(acctNameIdxBucketName)

	// Delete the account name key
	err := bucket.Delete(stringToBytes(name))
	if err != nil {
		str := fmt.Sprintf("failed to delete account name index key %s", name)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// deleteAccounIdIndex deletes the given key from the account id index of the database.
func deleteAccountIDIndex(ns walletdb.ReadWriteBucket, account uint32) error {
	bucket := ns.NestedReadWriteBucket(acctIDIdxBucketName)

	// Delete the account id key
	err := bucket.Delete(uint32ToBytes(account))
	if err != nil {
		str := fmt.Sprintf("failed to delete account id index key %d", account)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// putAccountNameIndex stores the given key to the account name index of the database.
func putAccountNameIndex(ns walletdb.ReadWriteBucket, account uint32, name string) error {
	bucket := ns.NestedReadWriteBucket(acctNameIdxBucketName)

	// Write the account number keyed by the account name.
	err := bucket.Put(stringToBytes(name), uint32ToBytes(account))
	if err != nil {
		str := fmt.Sprintf("failed to store account name index key %s", name)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// putAccountIDIndex stores the given key to the account id index of the database.
func putAccountIDIndex(ns walletdb.ReadWriteBucket, account uint32, name string) error {
	bucket := ns.NestedReadWriteBucket(acctIDIdxBucketName)

	// Write the account number keyed by the account id.
	err := bucket.Put(uint32ToBytes(account), stringToBytes(name))
	if err != nil {
		str := fmt.Sprintf("failed to store account id index key %s", name)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// putAddrAccountIndex stores the given key to the address account index of the database.
func putAddrAccountIndex(ns walletdb.ReadWriteBucket, account uint32, addrHash []byte) error {
	bucket := ns.NestedReadWriteBucket(addrAcctIdxBucketName)

	// Write account keyed by address hash
	err := bucket.Put(addrHash, uint32ToBytes(account))
	if err != nil {
		return nil
	}

	bucket, err = bucket.CreateBucketIfNotExists(uint32ToBytes(account))
	if err != nil {
		return err
	}
	// In account bucket, write a null value keyed by the address hash
	err = bucket.Put(addrHash, nullVal)
	if err != nil {
		str := fmt.Sprintf("failed to store address account index key %s", addrHash)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// putAccountRow stores the provided account information to the database.  This
// is used a common base for storing the various account types.
func putAccountRow(ns walletdb.ReadWriteBucket, account uint32, row *dbAccountRow) error {
	bucket := ns.NestedReadWriteBucket(acctBucketName)

	// Write the serialized value keyed by the account number.
	err := bucket.Put(uint32ToBytes(account), serializeAccountRow(row))
	if err != nil {
		str := fmt.Sprintf("failed to store account %d", account)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// putAccountInfo stores the provided account information to the database.
func putAccountInfo(ns walletdb.ReadWriteBucket, account uint32, row *dbBIP0044AccountRow) error {
	if err := putAccountRow(ns, account, &row.dbAccountRow); err != nil {
		return err
	}
	// Update account id index
	if err := putAccountIDIndex(ns, account, row.name); err != nil {
		return err
	}
	// Update account name index
	return putAccountNameIndex(ns, account, row.name)
}

// putLastAccount stores the provided metadata - last account - to the database.
func putLastAccount(ns walletdb.ReadWriteBucket, account uint32) error {
	bucket := ns.NestedReadWriteBucket(metaBucketName)

	err := bucket.Put(lastAccountName, uint32ToBytes(account))
	if err != nil {
		str := fmt.Sprintf("failed to update metadata '%s'", lastAccountName)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	return nil
}

// deserializeAddressRow deserializes the passed serialized address information.
// This is used as a common base for the various address types to deserialize
// the common parts.
func deserializeAddressRow(serializedAddress []byte) (*dbAddressRow, error) {
	// The serialized address format is:
	//   <addrType><account><addedTime><syncStatus><rawdata>
	//
	// 1 byte addrType + 4 bytes account + 8 bytes addTime + 1 byte
	// syncStatus + 4 bytes raw data length + raw data

	// Given the above, the length of the entry must be at a minimum
	// the constant value sizes.
	if len(serializedAddress) < 18 {
		str := "malformed serialized address"
		return nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	row := dbAddressRow{}
	row.addrType = addressType(serializedAddress[0])
	row.account = binary.LittleEndian.Uint32(serializedAddress[1:5])
	row.addTime = binary.LittleEndian.Uint64(serializedAddress[5:13])
	row.syncStatus = syncStatus(serializedAddress[13])
	rdlen := binary.LittleEndian.Uint32(serializedAddress[14:18])
	row.rawData = make([]byte, rdlen)
	copy(row.rawData, serializedAddress[18:18+rdlen])

	return &row, nil
}

// serializeAddressRow returns the serialization of the passed address row.
func serializeAddressRow(row *dbAddressRow) []byte {
	// The serialized address format is:
	//   <addrType><account><addedTime><syncStatus><commentlen><comment>
	//   <rawdata>
	//
	// 1 byte addrType + 4 bytes account + 8 bytes addTime + 1 byte
	// syncStatus + 4 bytes raw data length + raw data
	rdlen := len(row.rawData)
	buf := make([]byte, 18+rdlen)
	buf[0] = byte(row.addrType)
	binary.LittleEndian.PutUint32(buf[1:5], row.account)
	binary.LittleEndian.PutUint64(buf[5:13], row.addTime)
	buf[13] = byte(row.syncStatus)
	binary.LittleEndian.PutUint32(buf[14:18], uint32(rdlen))
	copy(buf[18:18+rdlen], row.rawData)
	return buf
}

// deserializeChainedAddress deserializes the raw data from the passed address
// row as a chained address.
func deserializeChainedAddress(row *dbAddressRow) (*dbChainAddressRow, error) {
	// The serialized chain address raw data format is:
	//   <branch><index>
	//
	// 4 bytes branch + 4 bytes address index
	if len(row.rawData) != 8 {
		str := "malformed serialized chained address"
		return nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	retRow := dbChainAddressRow{
		dbAddressRow: *row,
	}

	retRow.branch = binary.LittleEndian.Uint32(row.rawData[0:4])
	retRow.index = binary.LittleEndian.Uint32(row.rawData[4:8])

	return &retRow, nil
}

// serializeChainedAddress returns the serialization of the raw data field for
// a chained address.
func serializeChainedAddress(branch, index uint32) []byte {
	// The serialized chain address raw data format is:
	//   <branch><index>
	//
	// 4 bytes branch + 4 bytes address index
	rawData := make([]byte, 8)
	binary.LittleEndian.PutUint32(rawData[0:4], branch)
	binary.LittleEndian.PutUint32(rawData[4:8], index)
	return rawData
}

// deserializeImportedAddress deserializes the raw data from the passed address
// row as an imported address.
func deserializeImportedAddress(row *dbAddressRow) (*dbImportedAddressRow, error) {
	// The serialized imported address raw data format is:
	//   <encpubkeylen><encpubkey><encprivkeylen><encprivkey>
	//
	// 4 bytes encrypted pubkey len + encrypted pubkey + 4 bytes encrypted
	// privkey len + encrypted privkey

	// Given the above, the length of the entry must be at a minimum
	// the constant value sizes.
	if len(row.rawData) < 8 {
		str := "malformed serialized imported address"
		return nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	retRow := dbImportedAddressRow{
		dbAddressRow: *row,
	}

	pubLen := binary.LittleEndian.Uint32(row.rawData[0:4])
	retRow.encryptedPubKey = make([]byte, pubLen)
	copy(retRow.encryptedPubKey, row.rawData[4:4+pubLen])
	offset := 4 + pubLen
	privLen := binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
	offset += 4
	retRow.encryptedPrivKey = make([]byte, privLen)
	copy(retRow.encryptedPrivKey, row.rawData[offset:offset+privLen])

	return &retRow, nil
}

// serializeImportedAddress returns the serialization of the raw data field for
// an imported address.
func serializeImportedAddress(encryptedPubKey, encryptedPrivKey []byte) []byte {
	// The serialized imported address raw data format is:
	//   <encpubkeylen><encpubkey><encprivkeylen><encprivkey>
	//
	// 4 bytes encrypted pubkey len + encrypted pubkey + 4 bytes encrypted
	// privkey len + encrypted privkey
	pubLen := uint32(len(encryptedPubKey))
	privLen := uint32(len(encryptedPrivKey))
	rawData := make([]byte, 8+pubLen+privLen)
	binary.LittleEndian.PutUint32(rawData[0:4], pubLen)
	copy(rawData[4:4+pubLen], encryptedPubKey)
	offset := 4 + pubLen
	binary.LittleEndian.PutUint32(rawData[offset:offset+4], privLen)
	offset += 4
	copy(rawData[offset:offset+privLen], encryptedPrivKey)
	return rawData
}

// deserializeScriptAddress deserializes the raw data from the passed address
// row as a script address.
func deserializeScriptAddress(row *dbAddressRow) (*dbScriptAddressRow, error) {
	// The serialized script address raw data format is:
	//   <encscripthashlen><encscripthash><encscriptlen><encscript>
	//
	// 4 bytes encrypted script hash len + encrypted script hash + 4 bytes
	// encrypted script len + encrypted script

	// Given the above, the length of the entry must be at a minimum
	// the constant value sizes.
	if len(row.rawData) < 8 {
		str := "malformed serialized script address"
		return nil, managerError(apperrors.ErrDatabase, str, nil)
	}

	retRow := dbScriptAddressRow{
		dbAddressRow: *row,
	}

	hashLen := binary.LittleEndian.Uint32(row.rawData[0:4])
	retRow.encryptedHash = make([]byte, hashLen)
	copy(retRow.encryptedHash, row.rawData[4:4+hashLen])
	offset := 4 + hashLen
	scriptLen := binary.LittleEndian.Uint32(row.rawData[offset : offset+4])
	offset += 4
	retRow.encryptedScript = make([]byte, scriptLen)
	copy(retRow.encryptedScript, row.rawData[offset:offset+scriptLen])

	return &retRow, nil
}

// serializeScriptAddress returns the serialization of the raw data field for
// a script address.
func serializeScriptAddress(encryptedHash, encryptedScript []byte) []byte {
	// The serialized script address raw data format is:
	//   <encscripthashlen><encscripthash><encscriptlen><encscript>
	//
	// 4 bytes encrypted script hash len + encrypted script hash + 4 bytes
	// encrypted script len + encrypted script

	hashLen := uint32(len(encryptedHash))
	scriptLen := uint32(len(encryptedScript))
	rawData := make([]byte, 8+hashLen+scriptLen)
	binary.LittleEndian.PutUint32(rawData[0:4], hashLen)
	copy(rawData[4:4+hashLen], encryptedHash)
	offset := 4 + hashLen
	binary.LittleEndian.PutUint32(rawData[offset:offset+4], scriptLen)
	offset += 4
	copy(rawData[offset:offset+scriptLen], encryptedScript)
	return rawData
}

// fetchAddressByHash loads address information for the provided address hash
// from the database.  The returned value is one of the address rows for the
// specific address type.  The caller should use type assertions to ascertain
// the type.  The caller should prefix the error message with the address hash
// which caused the failure.
func fetchAddressByHash(ns walletdb.ReadBucket, addrHash []byte) (interface{}, error) {
	bucket := ns.NestedReadBucket(addrBucketName)

	serializedRow := bucket.Get(addrHash[:])
	if serializedRow == nil {
		str := "address not found"
		return nil, managerError(apperrors.ErrAddressNotFound, str, nil)
	}

	row, err := deserializeAddressRow(serializedRow)
	if err != nil {
		return nil, err
	}

	switch row.addrType {
	case adtChain:
		return deserializeChainedAddress(row)
	case adtImport:
		return deserializeImportedAddress(row)
	case adtScript:
		return deserializeScriptAddress(row)
	}

	str := fmt.Sprintf("unsupported address type '%d'", row.addrType)
	return nil, managerError(apperrors.ErrDatabase, str, nil)
}

// fetchAddress loads address information for the provided address id from the
// database.  The returned value is one of the address rows for the specific
// address type.  The caller should use type assertions to ascertain the type.
// The caller should prefix the error message with the address which caused the
// failure.
func fetchAddress(ns walletdb.ReadBucket, addressID []byte) (interface{}, error) {
	addrHash := sha256.Sum256(addressID)
	return fetchAddressByHash(ns, addrHash[:])
}

// putAddress stores the provided address information to the database.  This
// is used a common base for storing the various address types.
func putAddress(ns walletdb.ReadWriteBucket, addressID []byte, row *dbAddressRow) error {
	bucket := ns.NestedReadWriteBucket(addrBucketName)

	// Write the serialized value keyed by the hash of the address.  The
	// additional hash is used to conceal the actual address while still
	// allowed keyed lookups.
	addrHash := sha256.Sum256(addressID)
	err := bucket.Put(addrHash[:], serializeAddressRow(row))
	if err != nil {
		str := fmt.Sprintf("failed to store address %x", addressID)
		return managerError(apperrors.ErrDatabase, str, err)
	}
	// Update address account index
	return putAddrAccountIndex(ns, row.account, addrHash[:])
}

// putChainedAddress stores the provided chained address information to the
// database.
func putChainedAddress(ns walletdb.ReadWriteBucket, addressID []byte, account uint32,
	status syncStatus, branch, index uint32) error {

	addrRow := dbAddressRow{
		addrType:   adtChain,
		account:    account,
		addTime:    uint64(time.Now().Unix()),
		syncStatus: status,
		rawData:    serializeChainedAddress(branch, index),
	}
	return putAddress(ns, addressID, &addrRow)
}

// putImportedAddress stores the provided imported address information to the
// database.
func putImportedAddress(ns walletdb.ReadWriteBucket, addressID []byte, account uint32,
	status syncStatus, encryptedPubKey, encryptedPrivKey []byte) error {

	rawData := serializeImportedAddress(encryptedPubKey, encryptedPrivKey)
	addrRow := dbAddressRow{
		addrType:   adtImport,
		account:    account,
		addTime:    uint64(time.Now().Unix()),
		syncStatus: status,
		rawData:    rawData,
	}
	return putAddress(ns, addressID, &addrRow)
}

// putScriptAddress stores the provided script address information to the
// database.
func putScriptAddress(ns walletdb.ReadWriteBucket, addressID []byte, account uint32,
	status syncStatus, encryptedHash, encryptedScript []byte) error {

	rawData := serializeScriptAddress(encryptedHash, encryptedScript)
	addrRow := dbAddressRow{
		addrType:   adtScript,
		account:    account,
		addTime:    uint64(time.Now().Unix()),
		syncStatus: status,
		rawData:    rawData,
	}
	return putAddress(ns, addressID, &addrRow)
}

// existsAddress returns whether or not the address id exists in the database.
func existsAddress(ns walletdb.ReadBucket, addressID []byte) bool {
	bucket := ns.NestedReadBucket(addrBucketName)

	addrHash := sha256.Sum256(addressID)
	return bucket.Get(addrHash[:]) != nil
}

// fetchAddrAccount returns the account to which the given address belongs to.
// It looks up the account using the addracctidx index which maps the address
// hash to its corresponding account id.
func fetchAddrAccount(ns walletdb.ReadBucket, addressID []byte) (uint32, error) {
	bucket := ns.NestedReadBucket(addrAcctIdxBucketName)

	addrHash := sha256.Sum256(addressID)
	val := bucket.Get(addrHash[:])
	if val == nil {
		str := "address not found"
		return 0, managerError(apperrors.ErrAddressNotFound, str, nil)
	}
	return binary.LittleEndian.Uint32(val), nil
}

// forEachAccountAddress calls the given function with each address of
// the given account stored in the manager, breaking early on error.
func forEachAccountAddress(ns walletdb.ReadBucket, account uint32, fn func(rowInterface interface{}) error) error {
	bucket := ns.NestedReadBucket(addrAcctIdxBucketName).
		NestedReadBucket(uint32ToBytes(account))
	// if index bucket is missing the account, there hasn't been any address
	// entries yet
	if bucket == nil {
		return nil
	}

	err := bucket.ForEach(func(k, v []byte) error {
		// Skip buckets.
		if v == nil {
			return nil
		}
		addrRow, err := fetchAddressByHash(ns, k)
		if err != nil {
			if merr, ok := err.(apperrors.E); ok {
				desc := fmt.Sprintf("failed to fetch address hash '%x': %v",
					k, merr.Description)
				merr.Description = desc
				return merr
			}
			return err
		}

		return fn(addrRow)
	})
	if err != nil {
		return maybeConvertDbError(err)
	}
	return nil
}

// forEachActiveAddress calls the given function with each active address
// stored in the manager, breaking early on error.
func forEachActiveAddress(ns walletdb.ReadBucket, fn func(rowInterface interface{}) error) error {
	bucket := ns.NestedReadBucket(addrBucketName)

	err := bucket.ForEach(func(k, v []byte) error {
		// Skip buckets.
		if v == nil {
			return nil
		}

		// Deserialize the address row first to determine the field
		// values.
		addrRow, err := fetchAddressByHash(ns, k)
		if merr, ok := err.(apperrors.E); ok {
			desc := fmt.Sprintf("failed to fetch address hash '%x': %v",
				k, merr.Description)
			merr.Description = desc
			return merr
		}
		if err != nil {
			return err
		}

		return fn(addrRow)
	})
	if err != nil {
		return maybeConvertDbError(err)
	}
	return nil
}

// deletePrivateKeys removes all private key material from the database.
//
// NOTE: Care should be taken when calling this function.  It is primarily
// intended for use in converting to a watching-only copy.  Removing the private
// keys from the main database without also marking it watching-only will result
// in an unusable database.  It will also make any imported scripts and private
// keys unrecoverable unless there is a backup copy available.
func deletePrivateKeys(ns walletdb.ReadWriteBucket, dbVersion uint32) error {
	bucket := ns.NestedReadWriteBucket(mainBucketName)

	// Delete the master private key params and the crypto private and
	// script keys.
	if err := bucket.Delete(masterPrivKeyName); err != nil {
		str := "failed to delete master private key parameters"
		return managerError(apperrors.ErrDatabase, str, err)
	}
	if err := bucket.Delete(cryptoPrivKeyName); err != nil {
		str := "failed to delete crypto private key"
		return managerError(apperrors.ErrDatabase, str, err)
	}
	if err := bucket.Delete(cryptoScriptKeyName); err != nil {
		str := "failed to delete crypto script key"
		return managerError(apperrors.ErrDatabase, str, err)
	}
	if err := bucket.Delete(coinTypePrivKeyName); err != nil {
		str := "failed to delete cointype private key"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	// Delete the account extended private key for all accounts.
	bucket = ns.NestedReadWriteBucket(acctBucketName)
	err := bucket.ForEach(func(k, v []byte) error {
		// Skip buckets.
		if v == nil {
			return nil
		}

		// Deserialize the account row first to determine the type.
		row, err := deserializeAccountRow(k, v)
		if err != nil {
			return err
		}

		switch row.acctType {
		case actBIP0044:
			arow, err := deserializeBIP0044AccountRow(k, row, dbVersion)
			if err != nil {
				return err
			}

			// Reserialize the account without the private key and
			// store it.
			row := bip0044AccountInfo(arow.pubKeyEncrypted, nil,
				arow.nextExternalIndex, arow.nextInternalIndex,
				arow.lastUsedExternalIndex, arow.lastUsedInternalIndex,
				arow.lastReturnedExternalIndex, arow.lastReturnedInternalIndex,
				arow.name, dbVersion)
			err = bucket.Put(k, serializeAccountRow(&row.dbAccountRow))
			if err != nil {
				str := "failed to delete account private key"
				return managerError(apperrors.ErrDatabase, str, err)
			}
		}

		return nil
	})
	if err != nil {
		return maybeConvertDbError(err)
	}

	// Delete the private key for all imported addresses.
	bucket = ns.NestedReadWriteBucket(addrBucketName)
	err = bucket.ForEach(func(k, v []byte) error {
		// Skip buckets.
		if v == nil {
			return nil
		}

		// Deserialize the address row first to determine the field
		// values.
		row, err := deserializeAddressRow(v)
		if err != nil {
			return err
		}

		switch row.addrType {
		case adtImport:
			irow, err := deserializeImportedAddress(row)
			if err != nil {
				return err
			}

			// Reserialize the imported address without the private
			// key and store it.
			row.rawData = serializeImportedAddress(
				irow.encryptedPubKey, nil)
			err = bucket.Put(k, serializeAddressRow(row))
			if err != nil {
				str := "failed to delete imported private key"
				return managerError(apperrors.ErrDatabase, str, err)
			}

		case adtScript:
			srow, err := deserializeScriptAddress(row)
			if err != nil {
				return err
			}

			// Reserialize the script address without the script
			// and store it.
			row.rawData = serializeScriptAddress(srow.encryptedHash,
				nil)
			err = bucket.Put(k, serializeAddressRow(row))
			if err != nil {
				str := "failed to delete imported script"
				return managerError(apperrors.ErrDatabase, str, err)
			}
		}

		return nil
	})
	if err != nil {
		return maybeConvertDbError(err)
	}

	return nil
}

// accountNumberToAddrPoolKey converts an account into a meta-bucket key for
// the storage of the next to use address index as the value.
func accountNumberToAddrPoolKey(isInternal bool, account uint32) []byte {
	k := make([]byte, addrPoolMetaKeyLen)
	if isInternal {
		copy(k, addrPoolKeyPrefixInt)
		binary.LittleEndian.PutUint32(k[addrPoolMetaKeyLen-4:], account)
	} else {
		copy(k, addrPoolKeyPrefixExt)
		binary.LittleEndian.PutUint32(k[addrPoolMetaKeyLen-4:], account)
	}

	return k
}

// putNextToUseAddrPoolIdx stores an address pool address index for a
// given account and branch in the meta bucket of the address manager
// database.
func putNextToUseAddrPoolIdx(ns walletdb.ReadWriteBucket, isInternal bool, account uint32, index uint32) error {
	bucket := ns.NestedReadWriteBucket(metaBucketName)
	k := accountNumberToAddrPoolKey(isInternal, account)
	v := make([]byte, 4)
	binary.LittleEndian.PutUint32(v, index)

	err := bucket.Put(k, v)
	if err != nil {
		str := "failed to store next to use idx"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	return nil
}

// managerExists returns whether or not the manager has already been created
// in the given database namespace.
func managerExists(ns walletdb.ReadBucket) bool {
	mainBucket := ns.NestedReadBucket(mainBucketName)
	return mainBucket != nil
}

// createManagerNS creates the initial namespace structure needed for all of the
// manager data.  This includes things such as all of the buckets as well as the
// version and creation date.
func createManagerNS(ns walletdb.ReadWriteBucket) error {
	mainBucket, err := ns.CreateBucket(mainBucketName)
	if err != nil {
		str := "failed to create main bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	_, err = ns.CreateBucket(addrBucketName)
	if err != nil {
		str := "failed to create address bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	_, err = ns.CreateBucket(acctBucketName)
	if err != nil {
		str := "failed to create account bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	_, err = ns.CreateBucket(addrAcctIdxBucketName)
	if err != nil {
		str := "failed to create address index bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	// usedAddrBucketName bucket was added after manager version 1 release
	_, err = ns.CreateBucket(usedAddrBucketName)
	if err != nil {
		str := "failed to create used addresses bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	_, err = ns.CreateBucket(acctNameIdxBucketName)
	if err != nil {
		str := "failed to create an account name index bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	_, err = ns.CreateBucket(acctIDIdxBucketName)
	if err != nil {
		str := "failed to create an account id index bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	_, err = ns.CreateBucket(metaBucketName)
	if err != nil {
		str := "failed to create a meta bucket"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	if err := putLastAccount(ns, DefaultAccountNum); err != nil {
		return err
	}

	if err := putManagerVersion(ns, latestMgrVersion); err != nil {
		return err
	}

	createDate := uint64(time.Now().Unix())
	var dateBytes [8]byte
	binary.LittleEndian.PutUint64(dateBytes[:], createDate)
	err = mainBucket.Put(mgrCreateDateName, dateBytes[:])
	if err != nil {
		str := "failed to store database creation time"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	return nil
}

// upgradeToVersion5 upgrades the database from version 4 to version 5.
// Version 5 uses the metadata bucket to store the address pool indexes,
// so lastAddrs can be removed from the db.
func upgradeToVersion5(ns walletdb.ReadWriteBucket) error {
	lastDefaultAddsrName := []byte("lastaddrs")

	bucket := ns.NestedReadWriteBucket(mainBucketName)
	err := bucket.Delete(lastDefaultAddsrName)
	if err != nil {
		return err
	}

	return putManagerVersion(ns, 5)
}

// upgradeToVersion6 upgrades the database from version 5 to 6.  Version 6
// removes the synchronization buckets that were no longer updated after
// switching the wallet to storing all block headers.
func upgradeToVersion6(ns walletdb.ReadWriteBucket) error {
	syncBucketName := []byte("sync")
	err := ns.DeleteNestedBucket(syncBucketName)
	if err != nil {
		return err
	}
	return putManagerVersion(ns, 6)
}

// upgradeManager upgrades the data in the provided manager namespace to newer
// versions as neeeded.
func upgradeManager(ns walletdb.ReadWriteBucket) error {
	version, err := fetchManagerVersion(ns)
	if err != nil {
		str := "failed to fetch version for update"
		return managerError(apperrors.ErrDatabase, str, err)
	}

	// Below is some example code on how to properly perform DB
	// upgrades. Use it as a model for future upgrades.
	//
	// Upgrade one version at a time so it is possible to upgrade across
	// an aribtary number of versions without needing to write a bunch of
	// additional code to go directly from version X to Y.
	// if version < 2 {
	// 	// Upgrade from version 1 to 2.
	//	if err := upgradeToVersion2(namespace); err != nil {
	//		return err
	//	}
	//
	//	// The manager is now at version 2.
	//	version = 2
	// }
	// if version < 3 {
	// 	// Upgrade from version 2 to 3.
	//	if err := upgradeToVersion3(namespace); err != nil {
	//		return err
	//	}
	//
	//	// The manager is now at version 3.
	//	version = 3
	// }

	if version < 5 {
		err := upgradeToVersion5(ns)
		if err != nil {
			return err
		}

		// The manager is now at version 5.
		version = 5
	}

	if version < 6 {
		err := upgradeToVersion6(ns)
		if err != nil {
			return err
		}

		// The manager is now at version 6.
		version = 6
	}

	// Ensure the manager version is equal to the version used by the code.
	// This causes failures if the database was not upgraded to the latest
	// version or the there is a newer version that this code does not
	// understand.
	if version != latestMgrVersion {
		str := fmt.Sprintf("the latest address manager db version %d does "+
			"not equal the expected version %d", version, latestMgrVersion)
		return managerError(apperrors.ErrUpgrade, str, nil)
	}

	return nil
}