1// Copyright 2016 The go-ethereum Authors
2// This file is part of the go-ethereum library.
3//
4// The go-ethereum library is free software: you can redistribute it and/or modify
5// it under the terms of the GNU Lesser General Public License as published by
6// the Free Software Foundation, either version 3 of the License, or
7// (at your option) any later version.
8//
9// The go-ethereum library is distributed in the hope that it will be useful,
10// but WITHOUT ANY WARRANTY; without even the implied warranty of
11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12// GNU Lesser General Public License for more details.
13//
14// You should have received a copy of the GNU Lesser General Public License
15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
16
17package misc
18
19import (
20	"bytes"
21	"errors"
22	"math/big"
23
24	"github.com/ethereum/go-ethereum/core/state"
25	"github.com/ethereum/go-ethereum/core/types"
26	"github.com/ethereum/go-ethereum/params"
27)
28
29var (
30	// ErrBadProDAOExtra is returned if a header doesn't support the DAO fork on a
31	// pro-fork client.
32	ErrBadProDAOExtra = errors.New("bad DAO pro-fork extra-data")
33
34	// ErrBadNoDAOExtra is returned if a header does support the DAO fork on a no-
35	// fork client.
36	ErrBadNoDAOExtra = errors.New("bad DAO no-fork extra-data")
37)
38
39// VerifyDAOHeaderExtraData validates the extra-data field of a block header to
40// ensure it conforms to DAO hard-fork rules.
41//
42// DAO hard-fork extension to the header validity:
43//   a) if the node is no-fork, do not accept blocks in the [fork, fork+10) range
44//      with the fork specific extra-data set
45//   b) if the node is pro-fork, require blocks in the specific range to have the
46//      unique extra-data set.
47func VerifyDAOHeaderExtraData(config *params.ChainConfig, header *types.Header) error {
48	// Short circuit validation if the node doesn't care about the DAO fork
49	if config.DAOForkBlock == nil {
50		return nil
51	}
52	// Make sure the block is within the fork's modified extra-data range
53	limit := new(big.Int).Add(config.DAOForkBlock, params.DAOForkExtraRange)
54	if header.Number.Cmp(config.DAOForkBlock) < 0 || header.Number.Cmp(limit) >= 0 {
55		return nil
56	}
57	// Depending on whether we support or oppose the fork, validate the extra-data contents
58	if config.DAOForkSupport {
59		if !bytes.Equal(header.Extra, params.DAOForkBlockExtra) {
60			return ErrBadProDAOExtra
61		}
62	} else {
63		if bytes.Equal(header.Extra, params.DAOForkBlockExtra) {
64			return ErrBadNoDAOExtra
65		}
66	}
67	// All ok, header has the same extra-data we expect
68	return nil
69}
70
71// ApplyDAOHardFork modifies the state database according to the DAO hard-fork
72// rules, transferring all balances of a set of DAO accounts to a single refund
73// contract.
74func ApplyDAOHardFork(statedb *state.StateDB) {
75	// Retrieve the contract to refund balances into
76	if !statedb.Exist(params.DAORefundContract) {
77		statedb.CreateAccount(params.DAORefundContract)
78	}
79
80	// Move every DAO account and extra-balance account funds into the refund contract
81	for _, addr := range params.DAODrainList() {
82		statedb.AddBalance(params.DAORefundContract, statedb.GetBalance(addr))
83		statedb.SetBalance(addr, new(big.Int))
84	}
85}
86