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cmd/evm: add difficulty calculation to t8n tool (#23353)
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This PR adds functionality to the evm t8n to calculate ethash difficulty. If the caller does not provide a currentDifficulty, but instead provides the parentTimestamp (well, semi-optional, will default to 0 if not given), and parentDifficulty, we can calculate it for him.

The caller can also provide a parentUncleHash. In most, but not all cases, the parent uncle hash also affects the formula. If no such hash is provided (or, if the empty all-zero hash is provided), it's assumed that there were no uncles.
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holiman authored Aug 25, 2021
1 parent efee853 commit 84c51bc
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Showing 8 changed files with 172 additions and 40 deletions.
70 changes: 49 additions & 21 deletions cmd/evm/internal/t8ntool/execution.go
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ import (

"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/consensus/ethash"
"github.com/ethereum/go-ethereum/consensus/misc"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/rawdb"
Expand All @@ -46,13 +47,14 @@ type Prestate struct {
// ExecutionResult contains the execution status after running a state test, any
// error that might have occurred and a dump of the final state if requested.
type ExecutionResult struct {
StateRoot common.Hash `json:"stateRoot"`
TxRoot common.Hash `json:"txRoot"`
ReceiptRoot common.Hash `json:"receiptRoot"`
LogsHash common.Hash `json:"logsHash"`
Bloom types.Bloom `json:"logsBloom" gencodec:"required"`
Receipts types.Receipts `json:"receipts"`
Rejected []*rejectedTx `json:"rejected,omitempty"`
StateRoot common.Hash `json:"stateRoot"`
TxRoot common.Hash `json:"txRoot"`
ReceiptRoot common.Hash `json:"receiptRoot"`
LogsHash common.Hash `json:"logsHash"`
Bloom types.Bloom `json:"logsBloom" gencodec:"required"`
Receipts types.Receipts `json:"receipts"`
Rejected []*rejectedTx `json:"rejected,omitempty"`
Difficulty *math.HexOrDecimal256 `json:"currentDifficulty" gencodec:"required"`
}

type ommer struct {
Expand All @@ -62,23 +64,28 @@ type ommer struct {

//go:generate gencodec -type stEnv -field-override stEnvMarshaling -out gen_stenv.go
type stEnv struct {
Coinbase common.Address `json:"currentCoinbase" gencodec:"required"`
Difficulty *big.Int `json:"currentDifficulty" gencodec:"required"`
GasLimit uint64 `json:"currentGasLimit" gencodec:"required"`
Number uint64 `json:"currentNumber" gencodec:"required"`
Timestamp uint64 `json:"currentTimestamp" gencodec:"required"`
BlockHashes map[math.HexOrDecimal64]common.Hash `json:"blockHashes,omitempty"`
Ommers []ommer `json:"ommers,omitempty"`
BaseFee *big.Int `json:"currentBaseFee,omitempty"`
Coinbase common.Address `json:"currentCoinbase" gencodec:"required"`
Difficulty *big.Int `json:"currentDifficulty"`
ParentDifficulty *big.Int `json:"parentDifficulty"`
GasLimit uint64 `json:"currentGasLimit" gencodec:"required"`
Number uint64 `json:"currentNumber" gencodec:"required"`
Timestamp uint64 `json:"currentTimestamp" gencodec:"required"`
ParentTimestamp uint64 `json:"parentTimestamp,omitempty"`
BlockHashes map[math.HexOrDecimal64]common.Hash `json:"blockHashes,omitempty"`
Ommers []ommer `json:"ommers,omitempty"`
BaseFee *big.Int `json:"currentBaseFee,omitempty"`
ParentUncleHash common.Hash `json:"parentUncleHash"`
}

type stEnvMarshaling struct {
Coinbase common.UnprefixedAddress
Difficulty *math.HexOrDecimal256
GasLimit math.HexOrDecimal64
Number math.HexOrDecimal64
Timestamp math.HexOrDecimal64
BaseFee *math.HexOrDecimal256
Coinbase common.UnprefixedAddress
Difficulty *math.HexOrDecimal256
ParentDifficulty *math.HexOrDecimal256
GasLimit math.HexOrDecimal64
Number math.HexOrDecimal64
Timestamp math.HexOrDecimal64
ParentTimestamp math.HexOrDecimal64
BaseFee *math.HexOrDecimal256
}

type rejectedTx struct {
Expand Down Expand Up @@ -247,6 +254,7 @@ func (pre *Prestate) Apply(vmConfig vm.Config, chainConfig *params.ChainConfig,
LogsHash: rlpHash(statedb.Logs()),
Receipts: receipts,
Rejected: rejectedTxs,
Difficulty: (*math.HexOrDecimal256)(vmContext.Difficulty),
}
return statedb, execRs, nil
}
Expand Down Expand Up @@ -274,3 +282,23 @@ func rlpHash(x interface{}) (h common.Hash) {
hw.Sum(h[:0])
return h
}

// calcDifficulty is based on ethash.CalcDifficulty. This method is used in case
// the caller does not provide an explicit difficulty, but instead provides only
// parent timestamp + difficulty.
// Note: this method only works for ethash engine.
func calcDifficulty(config *params.ChainConfig, number, currentTime, parentTime uint64,
parentDifficulty *big.Int, parentUncleHash common.Hash) *big.Int {
uncleHash := parentUncleHash
if uncleHash == (common.Hash{}) {
uncleHash = types.EmptyUncleHash
}
parent := &types.Header{
ParentHash: common.Hash{},
UncleHash: uncleHash,
Difficulty: parentDifficulty,
Number: new(big.Int).SetUint64(number - 1),
Time: parentTime,
}
return ethash.CalcDifficulty(config, currentTime, parent)
}
55 changes: 36 additions & 19 deletions cmd/evm/internal/t8ntool/gen_stenv.go

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14 changes: 14 additions & 0 deletions cmd/evm/internal/t8ntool/transition.go
Original file line number Diff line number Diff line change
Expand Up @@ -252,6 +252,20 @@ func Main(ctx *cli.Context) error {
return NewError(ErrorVMConfig, errors.New("EIP-1559 config but missing 'currentBaseFee' in env section"))
}
}
if env := prestate.Env; env.Difficulty == nil {
// If difficulty was not provided by caller, we need to calculate it.
switch {
case env.ParentDifficulty == nil:
return NewError(ErrorVMConfig, errors.New("currentDifficulty was not provided, and cannot be calculated due to missing parentDifficulty"))
case env.Number == 0:
return NewError(ErrorVMConfig, errors.New("currentDifficulty needs to be provided for block number 0"))
case env.Timestamp <= env.ParentTimestamp:
return NewError(ErrorVMConfig, fmt.Errorf("currentDifficulty cannot be calculated -- currentTime (%d) needs to be after parent time (%d)",
env.Timestamp, env.ParentTimestamp))
}
prestate.Env.Difficulty = calcDifficulty(chainConfig, env.Number, env.Timestamp,
env.ParentTimestamp, env.ParentDifficulty, env.ParentUncleHash)
}
// Run the test and aggregate the result
s, result, err := prestate.Apply(vmConfig, chainConfig, txs, ctx.Int64(RewardFlag.Name), getTracer)
if err != nil {
Expand Down
12 changes: 12 additions & 0 deletions cmd/evm/testdata/14/alloc.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
{
"a94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
"balance": "0x5ffd4878be161d74",
"code": "0x",
"nonce": "0xac",
"storage": {}
},
"0x8a8eafb1cf62bfbeb1741769dae1a9dd47996192":{
"balance": "0xfeedbead",
"nonce" : "0x00"
}
}
9 changes: 9 additions & 0 deletions cmd/evm/testdata/14/env.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
{
"currentCoinbase": "0xc94f5374fce5edbc8e2a8697c15331677e6ebf0b",
"currentGasLimit": "0x750a163df65e8a",
"currentBaseFee": "0x500",
"currentNumber": "12800000",
"currentTimestamp": "10015",
"parentTimestamp" : "99999",
"parentDifficulty" : "0x2000000000000"
}
10 changes: 10 additions & 0 deletions cmd/evm/testdata/14/env.uncles.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
{
"currentCoinbase": "0xc94f5374fce5edbc8e2a8697c15331677e6ebf0b",
"currentGasLimit": "0x750a163df65e8a",
"currentBaseFee": "0x500",
"currentNumber": "12800000",
"currentTimestamp": "10035",
"parentTimestamp" : "99999",
"parentDifficulty" : "0x2000000000000",
"parentUncleHash" : "0x000000000000000000000000000000000000000000000000000000000000beef"
}
41 changes: 41 additions & 0 deletions cmd/evm/testdata/14/readme.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,41 @@
## Difficulty calculation

This test shows how the `evm t8n` can be used to calculate the (ethash) difficulty, if none is provided by the caller.

Calculating it (with an empty set of txs) using `London` rules (and no provided unclehash for the parent block):
```
[user@work evm]$ ./evm t8n --input.alloc=./testdata/14/alloc.json --input.txs=./testdata/14/txs.json --input.env=./testdata/14/env.json --output.result=stdout --state.fork=London
INFO [08-08|17:35:46.876] Trie dumping started root=6f0588..7f4bdc
INFO [08-08|17:35:46.876] Trie dumping complete accounts=2 elapsed="89.313µs"
INFO [08-08|17:35:46.877] Wrote file file=alloc.json
{
"result": {
"stateRoot": "0x6f058887ca01549716789c380ede95aecc510e6d1fdc4dbf67d053c7c07f4bdc",
"txRoot": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
"receiptRoot": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
"logsHash": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
"logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
"receipts": [],
"currentDifficulty": 3311729559732224
}
}
```
Same thing, but this time providing a non-empty (and non-`emptyKeccak`) unclehash, which leads to a slightly different result:
```
[user@work evm]$ ./evm t8n --input.alloc=./testdata/14/alloc.json --input.txs=./testdata/14/txs.json --input.env=./testdata/14/env.uncles.json --output.result=stdout --state.fork=London
INFO [08-08|17:35:49.232] Trie dumping started root=6f0588..7f4bdc
INFO [08-08|17:35:49.232] Trie dumping complete accounts=2 elapsed="83.069µs"
INFO [08-08|17:35:49.233] Wrote file file=alloc.json
{
"result": {
"stateRoot": "0x6f058887ca01549716789c380ede95aecc510e6d1fdc4dbf67d053c7c07f4bdc",
"txRoot": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
"receiptRoot": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
"logsHash": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
"logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
"receipts": [],
"currentDifficulty": 3311179803918336
}
}
```

1 change: 1 addition & 0 deletions cmd/evm/testdata/14/txs.json
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
[]

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