269 lines
12 KiB
Markdown
269 lines
12 KiB
Markdown
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## EVM state transition tool
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The `evm t8n` tool is a stateless state transition utility. It is a utility
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which can
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1. Take a prestate, including
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- Accounts,
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- Block context information,
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- Previous blockshashes (*optional)
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2. Apply a set of transactions,
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3. Apply a mining-reward (*optional),
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4. And generate a post-state, including
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- State root, transaction root, receipt root,
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- Information about rejected transactions,
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- Optionally: a full or partial post-state dump
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## Specification
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The idea is to specify the behaviour of this binary very _strict_, so that other
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node implementors can build replicas based on their own state-machines, and the
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state generators can swap between a `geth`-based implementation and a `parityvm`-based
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implementation.
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### Command line params
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Command line params that has to be supported are
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```
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--trace Output full trace logs to files <txhash>.jsonl
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--trace.nomemory Disable full memory dump in traces
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--trace.nostack Disable stack output in traces
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--output.alloc alloc Determines where to put the alloc of the post-state.
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`stdout` - into the stdout output
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`stderr` - into the stderr output
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--output.result result Determines where to put the result (stateroot, txroot etc) of the post-state.
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`stdout` - into the stdout output
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`stderr` - into the stderr output
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--state.fork value Name of ruleset to use.
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--state.chainid value ChainID to use (default: 1)
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--state.reward value Mining reward. Set to -1 to disable (default: 0)
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```
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### Error codes and output
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All logging should happen against the `stderr`.
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There are a few (not many) errors that can occur, those are defined below.
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#### EVM-based errors (`2` to `9`)
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- Other EVM error. Exit code `2`
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- Failed configuration: when a non-supported or invalid fork was specified. Exit code `3`.
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- Block history is not supplied, but needed for a `BLOCKHASH` operation. If `BLOCKHASH`
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is invoked targeting a block which history has not been provided for, the program will
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exit with code `4`.
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#### IO errors (`10`-`20`)
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- Invalid input json: the supplied data could not be marshalled.
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The program will exit with code `10`
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- IO problems: failure to load or save files, the program will exit with code `11`
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## Examples
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### Basic usage
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Invoking it with the provided example files
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```
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./evm t8n --input.alloc=./testdata/1/alloc.json --input.txs=./testdata/1/txs.json --input.env=./testdata/1/env.json
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```
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Two resulting files:
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`alloc.json`:
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```json
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{
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"0x8a8eafb1cf62bfbeb1741769dae1a9dd47996192": {
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"balance": "0xfeed1a9d",
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"nonce": "0x1"
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},
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"0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
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"balance": "0x5ffd4878be161d74",
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"nonce": "0xac"
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},
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"0xc94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
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"balance": "0xa410"
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}
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}
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```
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`result.json`:
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```json
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{
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"stateRoot": "0x84208a19bc2b46ada7445180c1db162be5b39b9abc8c0a54b05d32943eae4e13",
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"txRoot": "0xc4761fd7b87ff2364c7c60b6c5c8d02e522e815328aaea3f20e3b7b7ef52c42d",
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"receiptRoot": "0x056b23fbba480696b65fe5a59b8f2148a1299103c4f57df839233af2cf4ca2d2",
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"logsHash": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
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"logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
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"receipts": [
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{
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"root": "0x",
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"status": "0x1",
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"cumulativeGasUsed": "0x5208",
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"logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
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"logs": null,
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"transactionHash": "0x0557bacce3375c98d806609b8d5043072f0b6a8bae45ae5a67a00d3a1a18d673",
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"contractAddress": "0x0000000000000000000000000000000000000000",
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"gasUsed": "0x5208",
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"blockHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
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"transactionIndex": "0x0"
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}
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],
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"rejected": [
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1
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]
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}
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```
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We can make them spit out the data to e.g. `stdout` like this:
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```
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./evm t8n --input.alloc=./testdata/1/alloc.json --input.txs=./testdata/1/txs.json --input.env=./testdata/1/env.json --output.result=stdout --output.alloc=stdout
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```
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Output:
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```json
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{
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"alloc": {
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"0x8a8eafb1cf62bfbeb1741769dae1a9dd47996192": {
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"balance": "0xfeed1a9d",
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"nonce": "0x1"
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},
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"0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
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"balance": "0x5ffd4878be161d74",
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"nonce": "0xac"
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},
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"0xc94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
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"balance": "0xa410"
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}
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},
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"result": {
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"stateRoot": "0x84208a19bc2b46ada7445180c1db162be5b39b9abc8c0a54b05d32943eae4e13",
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"txRoot": "0xc4761fd7b87ff2364c7c60b6c5c8d02e522e815328aaea3f20e3b7b7ef52c42d",
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"receiptRoot": "0x056b23fbba480696b65fe5a59b8f2148a1299103c4f57df839233af2cf4ca2d2",
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"logsHash": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
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"logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
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"receipts": [
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{
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"root": "0x",
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"status": "0x1",
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"cumulativeGasUsed": "0x5208",
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"logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
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"logs": null,
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"transactionHash": "0x0557bacce3375c98d806609b8d5043072f0b6a8bae45ae5a67a00d3a1a18d673",
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"contractAddress": "0x0000000000000000000000000000000000000000",
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"gasUsed": "0x5208",
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"blockHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
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"transactionIndex": "0x0"
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}
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],
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"rejected": [
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1
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]
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}
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}
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```
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## About Ommers
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Mining rewards and ommer rewards might need to be added. This is how those are applied:
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- `block_reward` is the block mining reward for the miner (`0xaa`), of a block at height `N`.
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- For each ommer (mined by `0xbb`), with blocknumber `N-delta`
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- (where `delta` is the difference between the current block and the ommer)
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- The account `0xbb` (ommer miner) is awarded `(8-delta)/ 8 * block_reward`
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- The account `0xaa` (block miner) is awarded `block_reward / 32`
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To make `state_t8n` apply these, the following inputs are required:
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- `state.reward`
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- For ethash, it is `5000000000000000000` `wei`,
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- If this is not defined, mining rewards are not applied,
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- A value of `0` is valid, and causes accounts to be 'touched'.
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- For each ommer, the tool needs to be given an `address` and a `delta`. This
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is done via the `env`.
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Note: the tool does not verify that e.g. the normal uncle rules apply,
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and allows e.g two uncles at the same height, or the uncle-distance. This means that
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the tool allows for negative uncle reward (distance > 8)
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Example:
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`./testdata/5/env.json`:
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```json
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{
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"currentCoinbase": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
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"currentDifficulty": "0x20000",
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"currentGasLimit": "0x750a163df65e8a",
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"currentNumber": "1",
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"currentTimestamp": "1000",
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"ommers": [
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{"delta": 1, "address": "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb" },
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{"delta": 2, "address": "0xcccccccccccccccccccccccccccccccccccccccc" }
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]
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}
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```
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When applying this, using a reward of `0x08`
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Output:
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```json
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{
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"alloc": {
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"0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa": {
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"balance": "0x88"
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},
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"0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb": {
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"balance": "0x70"
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},
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"0xcccccccccccccccccccccccccccccccccccccccc": {
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"balance": "0x60"
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}
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}
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}
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```
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### Future EIPS
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It is also possible to experiment with future eips that are not yet defined in a hard fork.
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Example, putting EIP-1344 into Frontier:
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```
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./evm t8n --state.fork=Frontier+1344 --input.pre=./testdata/1/pre.json --input.txs=./testdata/1/txs.json --input.env=/testdata/1/env.json
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```
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### Block history
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The `BLOCKHASH` opcode requires blockhashes to be provided by the caller, inside the `env`.
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If a required blockhash is not provided, the exit code should be `4`:
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Example where blockhashes are provided:
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```
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./evm t8n --input.alloc=./testdata/3/alloc.json --input.txs=./testdata/3/txs.json --input.env=./testdata/3/env.json --trace
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```
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```
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cat trace-0.jsonl | grep BLOCKHASH -C2
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```
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```
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{"pc":0,"op":96,"gas":"0x5f58ef8","gasCost":"0x3","memory":"0x","memSize":0,"stack":[],"returnStack":[],"depth":1,"refund":0,"opName":"PUSH1","error":""}
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{"pc":2,"op":64,"gas":"0x5f58ef5","gasCost":"0x14","memory":"0x","memSize":0,"stack":["0x1"],"returnStack":[],"depth":1,"refund":0,"opName":"BLOCKHASH","error":""}
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{"pc":3,"op":0,"gas":"0x5f58ee1","gasCost":"0x0","memory":"0x","memSize":0,"stack":["0xdac58aa524e50956d0c0bae7f3f8bb9d35381365d07804dd5b48a5a297c06af4"],"returnStack":[],"depth":1,"refund":0,"opName":"STOP","error":""}
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{"output":"","gasUsed":"0x17","time":155861}
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```
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In this example, the caller has not provided the required blockhash:
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```
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./evm t8n --input.alloc=./testdata/4/alloc.json --input.txs=./testdata/4/txs.json --input.env=./testdata/4/env.json --trace
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```
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```
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ERROR(4): getHash(3) invoked, blockhash for that block not provided
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```
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Error code: 4
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### Chaining
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Another thing that can be done, is to chain invocations:
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```
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./evm t8n --input.alloc=./testdata/1/alloc.json --input.txs=./testdata/1/txs.json --input.env=./testdata/1/env.json --output.alloc=stdout | ./evm t8n --input.alloc=stdin --input.env=./testdata/1/env.json --input.txs=./testdata/1/txs.json
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INFO [06-29|11:52:04.934] rejected tx index=1 hash="0557ba…18d673" from=0x8A8eAFb1cf62BfBeb1741769DAE1a9dd47996192 error="nonce too low"
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INFO [06-29|11:52:04.936] rejected tx index=0 hash="0557ba…18d673" from=0x8A8eAFb1cf62BfBeb1741769DAE1a9dd47996192 error="nonce too low"
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INFO [06-29|11:52:04.936] rejected tx index=1 hash="0557ba…18d673" from=0x8A8eAFb1cf62BfBeb1741769DAE1a9dd47996192 error="nonce too low"
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```
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What happened here, is that we first applied two identical transactions, so the second one was rejected.
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Then, taking the poststate alloc as the input for the next state, we tried again to include
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the same two transactions: this time, both failed due to too low nonce.
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In order to meaningfully chain invocations, one would need to provide meaningful new `env`, otherwise the
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actual blocknumber (exposed to the EVM) would not increase.
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