path: root/accounts/backend.go

// 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 accounts

import (
    "math/big"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
)

// Backend is an "account provider" that can specify a batch of accounts it can
// sign transactions with and upon request, do so.
type Backend interface {
    // Accounts retrieves the list of signing accounts the backend is currently aware of.
    Accounts() []Account

    // HasAddress reports whether an account with the given address is present.
    HasAddress(addr common.Address) bool

    // SignHash requests the backend to sign the given hash.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    //
    // If the backend requires additional authentication to sign the request (e.g.
    // a password to decrypt the account, or a PIN code o verify the transaction),
    // an AuthNeededError instance will be returned, containing infos for the user
    // about which fields or actions are needed. The user may retry by providing
    // the needed details via SignHashWithPassphrase, or by other means (e.g. unlock
    // the account in a keystore).
    SignHash(acc Account, hash []byte) ([]byte, error)

    // SignTx requests the backend to sign the given transaction.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    //
    // If the backend requires additional authentication to sign the request (e.g.
    // a password to decrypt the account, or a PIN code o verify the transaction),
    // an AuthNeededError instance will be returned, containing infos for the user
    // about which fields or actions are needed. The user may retry by providing
    // the needed details via SignTxWithPassphrase, or by other means (e.g. unlock
    // the account in a keystore).
    SignTx(acc Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error)

    // SignHashWithPassphrase requests the backend to sign the given transaction with
    // the given passphrase as extra authentication information.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    SignHashWithPassphrase(acc Account, passphrase string, hash []byte) ([]byte, error)

    // SignTxWithPassphrase requests the backend to sign the given transaction, with the
    // given passphrase as extra authentication information.
    //
    // It looks up the account specified either solely via its address contained within,
    // or optionally with the aid of any location metadata from the embedded URL field.
    SignTxWithPassphrase(acc Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error)

    // TODO(karalabe,fjl): watching and caching needs the Go subscription system
    // Watch requests the backend to send a notification to the specified channel whenever
    // an new account appears or an existing one disappears.
    //Watch(chan AccountEvent) error

    // Unwatch requests the backend stop sending notifications to the given channel.
    //Unwatch(chan AccountEvent) error
}

// TODO(karalabe,fjl): watching and caching needs the Go subscription system
// type AccountEvent struct {
//  Account Account
//  Added   bool
// }