313 lines
11 KiB
Go
313 lines
11 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"hash"
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"sync/atomic"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/math"
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"github.com/ethereum/go-ethereum/log"
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)
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// Config are the configuration options for the Interpreter
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type Config struct {
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Debug bool // Enables debugging
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Tracer Tracer // Opcode logger
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NoRecursion bool // Disables call, callcode, delegate call and create
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EnablePreimageRecording bool // Enables recording of SHA3/keccak preimages
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JumpTable [256]*operation // EVM instruction table, automatically populated if unset
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EWASMInterpreter string // External EWASM interpreter options
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EVMInterpreter string // External EVM interpreter options
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ExtraEips []int // Additional EIPS that are to be enabled
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}
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// Interpreter is used to run Ethereum based contracts and will utilise the
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// passed environment to query external sources for state information.
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// The Interpreter will run the byte code VM based on the passed
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// configuration.
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type Interpreter interface {
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// Run loops and evaluates the contract's code with the given input data and returns
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// the return byte-slice and an error if one occurred.
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Run(contract *Contract, input []byte, static bool) ([]byte, error)
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// CanRun tells if the contract, passed as an argument, can be
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// run by the current interpreter. This is meant so that the
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// caller can do something like:
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//
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// ```golang
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// for _, interpreter := range interpreters {
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// if interpreter.CanRun(contract.code) {
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// interpreter.Run(contract.code, input)
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// }
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// }
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// ```
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CanRun([]byte) bool
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}
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// callCtx contains the things that are per-call, such as stack and memory,
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// but not transients like pc and gas
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type callCtx struct {
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memory *Memory
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stack *Stack
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rstack *ReturnStack
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contract *Contract
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}
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// keccakState wraps sha3.state. In addition to the usual hash methods, it also supports
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// Read to get a variable amount of data from the hash state. Read is faster than Sum
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// because it doesn't copy the internal state, but also modifies the internal state.
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type keccakState interface {
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hash.Hash
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Read([]byte) (int, error)
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}
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// EVMInterpreter represents an EVM interpreter
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type EVMInterpreter struct {
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evm *EVM
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cfg Config
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hasher keccakState // Keccak256 hasher instance shared across opcodes
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hasherBuf common.Hash // Keccak256 hasher result array shared aross opcodes
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readOnly bool // Whether to throw on stateful modifications
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returnData []byte // Last CALL's return data for subsequent reuse
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}
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// NewEVMInterpreter returns a new instance of the Interpreter.
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func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter {
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// We use the STOP instruction whether to see
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// the jump table was initialised. If it was not
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// we'll set the default jump table.
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if cfg.JumpTable[STOP] == nil {
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var jt JumpTable
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switch {
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case evm.chainRules.IsBerlin:
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jt = berlinInstructionSet
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case evm.chainRules.IsIstanbul:
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jt = istanbulInstructionSet
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case evm.chainRules.IsConstantinople:
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jt = constantinopleInstructionSet
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case evm.chainRules.IsByzantium:
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jt = byzantiumInstructionSet
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case evm.chainRules.IsEIP158:
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jt = spuriousDragonInstructionSet
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case evm.chainRules.IsEIP150:
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jt = tangerineWhistleInstructionSet
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case evm.chainRules.IsHomestead:
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jt = homesteadInstructionSet
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default:
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jt = frontierInstructionSet
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}
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for i, eip := range cfg.ExtraEips {
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if err := EnableEIP(eip, &jt); err != nil {
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// Disable it, so caller can check if it's activated or not
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cfg.ExtraEips = append(cfg.ExtraEips[:i], cfg.ExtraEips[i+1:]...)
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log.Error("EIP activation failed", "eip", eip, "error", err)
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}
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}
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cfg.JumpTable = jt
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}
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return &EVMInterpreter{
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evm: evm,
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cfg: cfg,
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}
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}
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// Run loops and evaluates the contract's code with the given input data and returns
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// the return byte-slice and an error if one occurred.
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//
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// It's important to note that any errors returned by the interpreter should be
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// considered a revert-and-consume-all-gas operation except for
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// ErrExecutionReverted which means revert-and-keep-gas-left.
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func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (ret []byte, err error) {
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// Increment the call depth which is restricted to 1024
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in.evm.depth++
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defer func() { in.evm.depth-- }()
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// Make sure the readOnly is only set if we aren't in readOnly yet.
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// This makes also sure that the readOnly flag isn't removed for child calls.
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if readOnly && !in.readOnly {
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in.readOnly = true
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defer func() { in.readOnly = false }()
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}
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// Reset the previous call's return data. It's unimportant to preserve the old buffer
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// as every returning call will return new data anyway.
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in.returnData = nil
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// Don't bother with the execution if there's no code.
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if len(contract.Code) == 0 {
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return nil, nil
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}
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var (
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op OpCode // current opcode
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mem = NewMemory() // bound memory
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stack = newstack() // local stack
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returns = newReturnStack() // local returns stack
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callContext = &callCtx{
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memory: mem,
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stack: stack,
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rstack: returns,
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contract: contract,
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}
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// For optimisation reason we're using uint64 as the program counter.
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// It's theoretically possible to go above 2^64. The YP defines the PC
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// to be uint256. Practically much less so feasible.
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pc = uint64(0) // program counter
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cost uint64
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// copies used by tracer
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pcCopy uint64 // needed for the deferred Tracer
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gasCopy uint64 // for Tracer to log gas remaining before execution
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logged bool // deferred Tracer should ignore already logged steps
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res []byte // result of the opcode execution function
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)
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// Don't move this deferrred function, it's placed before the capturestate-deferred method,
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// so that it get's executed _after_: the capturestate needs the stacks before
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// they are returned to the pools
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defer func() {
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returnStack(stack)
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returnRStack(returns)
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}()
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contract.Input = input
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if in.cfg.Debug {
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defer func() {
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if err != nil {
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if !logged {
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in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stack, returns, in.returnData, contract, in.evm.depth, err)
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} else {
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in.cfg.Tracer.CaptureFault(in.evm, pcCopy, op, gasCopy, cost, mem, stack, returns, contract, in.evm.depth, err)
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}
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}
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}()
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}
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// The Interpreter main run loop (contextual). This loop runs until either an
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// explicit STOP, RETURN or SELFDESTRUCT is executed, an error occurred during
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// the execution of one of the operations or until the done flag is set by the
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// parent context.
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steps := 0
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for {
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steps++
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if steps%1000 == 0 && atomic.LoadInt32(&in.evm.abort) != 0 {
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break
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}
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if in.cfg.Debug {
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// Capture pre-execution values for tracing.
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logged, pcCopy, gasCopy = false, pc, contract.Gas
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}
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// Get the operation from the jump table and validate the stack to ensure there are
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// enough stack items available to perform the operation.
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op = contract.GetOp(pc)
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operation := in.cfg.JumpTable[op]
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if operation == nil {
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return nil, &ErrInvalidOpCode{opcode: op}
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}
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// Validate stack
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if sLen := stack.len(); sLen < operation.minStack {
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return nil, &ErrStackUnderflow{stackLen: sLen, required: operation.minStack}
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} else if sLen > operation.maxStack {
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return nil, &ErrStackOverflow{stackLen: sLen, limit: operation.maxStack}
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}
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// If the operation is valid, enforce and write restrictions
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if in.readOnly && in.evm.chainRules.IsByzantium {
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// If the interpreter is operating in readonly mode, make sure no
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// state-modifying operation is performed. The 3rd stack item
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// for a call operation is the value. Transferring value from one
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// account to the others means the state is modified and should also
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// return with an error.
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if operation.writes || (op == CALL && stack.Back(2).Sign() != 0) {
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return nil, ErrWriteProtection
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}
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}
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// Static portion of gas
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cost = operation.constantGas // For tracing
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if !contract.UseGas(operation.constantGas) {
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return nil, ErrOutOfGas
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}
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var memorySize uint64
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// calculate the new memory size and expand the memory to fit
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// the operation
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// Memory check needs to be done prior to evaluating the dynamic gas portion,
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// to detect calculation overflows
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if operation.memorySize != nil {
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memSize, overflow := operation.memorySize(stack)
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if overflow {
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return nil, ErrGasUintOverflow
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}
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// memory is expanded in words of 32 bytes. Gas
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// is also calculated in words.
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if memorySize, overflow = math.SafeMul(toWordSize(memSize), 32); overflow {
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return nil, ErrGasUintOverflow
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}
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}
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// Dynamic portion of gas
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// consume the gas and return an error if not enough gas is available.
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// cost is explicitly set so that the capture state defer method can get the proper cost
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if operation.dynamicGas != nil {
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var dynamicCost uint64
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dynamicCost, err = operation.dynamicGas(in.evm, contract, stack, mem, memorySize)
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cost += dynamicCost // total cost, for debug tracing
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if err != nil || !contract.UseGas(dynamicCost) {
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return nil, ErrOutOfGas
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}
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}
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if memorySize > 0 {
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mem.Resize(memorySize)
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}
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if in.cfg.Debug {
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in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stack, returns, in.returnData, contract, in.evm.depth, err)
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logged = true
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}
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// execute the operation
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res, err = operation.execute(&pc, in, callContext)
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// if the operation clears the return data (e.g. it has returning data)
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// set the last return to the result of the operation.
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if operation.returns {
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in.returnData = common.CopyBytes(res)
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}
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switch {
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case err != nil:
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return nil, err
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case operation.reverts:
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return res, ErrExecutionReverted
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case operation.halts:
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return res, nil
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case !operation.jumps:
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pc++
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}
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}
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return nil, nil
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}
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// CanRun tells if the contract, passed as an argument, can be
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// run by the current interpreter.
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func (in *EVMInterpreter) CanRun(code []byte) bool {
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return true
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}
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