// Copyright 2014 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 vm import ( "fmt" "hash" "sync/atomic" "github.com/ava-labs/go-ethereum/common" "github.com/ava-labs/go-ethereum/common/math" "github.com/ava-labs/go-ethereum/log" ) var ( BuiltinAddr = common.Address{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, } ) // Config are the configuration options for the Interpreter type Config struct { Debug bool // Enables debugging Tracer Tracer // Opcode logger NoRecursion bool // Disables call, callcode, delegate call and create EnablePreimageRecording bool // Enables recording of SHA3/keccak preimages JumpTable [256]operation // EVM instruction table, automatically populated if unset EWASMInterpreter string // External EWASM interpreter options EVMInterpreter string // External EVM interpreter options ExtraEips []int // Additional EIPS that are to be enabled } // Interpreter is used to run Ethereum based contracts and will utilise the // passed environment to query external sources for state information. // The Interpreter will run the byte code VM based on the passed // configuration. type Interpreter interface { // Run loops and evaluates the contract's code with the given input data and returns // the return byte-slice and an error if one occurred. Run(contract *Contract, input []byte, static bool) ([]byte, error) // CanRun tells if the contract, passed as an argument, can be // run by the current interpreter. This is meant so that the // caller can do something like: // // ```golang // for _, interpreter := range interpreters { // if interpreter.CanRun(contract.code) { // interpreter.Run(contract.code, input) // } // } // ``` CanRun([]byte) bool } // keccakState wraps sha3.state. In addition to the usual hash methods, it also supports // Read to get a variable amount of data from the hash state. Read is faster than Sum // because it doesn't copy the internal state, but also modifies the internal state. type keccakState interface { hash.Hash Read([]byte) (int, error) } // EVMInterpreter represents an EVM interpreter type EVMInterpreter struct { evm *EVM cfg Config intPool *intPool hasher keccakState // Keccak256 hasher instance shared across opcodes hasherBuf common.Hash // Keccak256 hasher result array shared aross opcodes readOnly bool // Whether to throw on stateful modifications returnData []byte // Last CALL's return data for subsequent reuse } // NewEVMInterpreter returns a new instance of the Interpreter. func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter { // We use the STOP instruction whether to see // the jump table was initialised. If it was not // we'll set the default jump table. if !cfg.JumpTable[STOP].valid { var jt JumpTable switch { case evm.chainRules.IsIstanbul: jt = istanbulInstructionSet case evm.chainRules.IsConstantinople: jt = constantinopleInstructionSet case evm.chainRules.IsByzantium: jt = byzantiumInstructionSet case evm.chainRules.IsEIP158: jt = spuriousDragonInstructionSet case evm.chainRules.IsEIP150: jt = tangerineWhistleInstructionSet case evm.chainRules.IsHomestead: jt = homesteadInstructionSet default: jt = frontierInstructionSet } for i, eip := range cfg.ExtraEips { if err := EnableEIP(eip, &jt); err != nil { // Disable it, so caller can check if it's activated or not cfg.ExtraEips = append(cfg.ExtraEips[:i], cfg.ExtraEips[i+1:]...) log.Error("EIP activation failed", "eip", eip, "error", err) } } cfg.JumpTable = jt } return &EVMInterpreter{ evm: evm, cfg: cfg, } } // Run loops and evaluates the contract's code with the given input data and returns // the return byte-slice and an error if one occurred. // // It's important to note that any errors returned by the interpreter should be // considered a revert-and-consume-all-gas operation except for // errExecutionReverted which means revert-and-keep-gas-left. func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (ret []byte, err error) { if contract.Address() == BuiltinAddr { self := AccountRef(contract.Caller()) if _, ok := contract.caller.(*Contract); ok { contract = contract.AsDelegate() } contract.self = self } if in.intPool == nil { in.intPool = poolOfIntPools.get() defer func() { poolOfIntPools.put(in.intPool) in.intPool = nil }() } // Increment the call depth which is restricted to 1024 in.evm.depth++ defer func() { in.evm.depth-- }() // Make sure the readOnly is only set if we aren't in readOnly yet. // This makes also sure that the readOnly flag isn't removed for child calls. if readOnly && !in.readOnly { in.readOnly = true defer func() { in.readOnly = false }() } // Reset the previous call's return data. It's unimportant to preserve the old buffer // as every returning call will return new data anyway. in.returnData = nil // Don't bother with the execution if there's no code. if len(contract.Code) == 0 { return nil, nil } var ( op OpCode // current opcode mem = NewMemory() // bound memory stack = newstack() // local stack // For optimisation reason we're using uint64 as the program counter. // It's theoretically possible to go above 2^64. The YP defines the PC // to be uint256. Practically much less so feasible. pc = uint64(0) // program counter cost uint64 // copies used by tracer pcCopy uint64 // needed for the deferred Tracer gasCopy uint64 // for Tracer to log gas remaining before execution logged bool // deferred Tracer should ignore already logged steps res []byte // result of the opcode execution function ) contract.Input = input // Reclaim the stack as an int pool when the execution stops defer func() { in.intPool.put(stack.data...) }() if in.cfg.Debug { defer func() { if err != nil { if !logged { in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err) } else { in.cfg.Tracer.CaptureFault(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err) } } }() } // The Interpreter main run loop (contextual). This loop runs until either an // explicit STOP, RETURN or SELFDESTRUCT is executed, an error occurred during // the execution of one of the operations or until the done flag is set by the // parent context. for atomic.LoadInt32(&in.evm.abort) == 0 { if in.cfg.Debug { // Capture pre-execution values for tracing. logged, pcCopy, gasCopy = false, pc, contract.Gas } // Get the operation from the jump table and validate the stack to ensure there are // enough stack items available to perform the operation. op = contract.GetOp(pc) operation := in.cfg.JumpTable[op] if !operation.valid { return nil, fmt.Errorf("invalid opcode 0x%x", int(op)) } // Validate stack if sLen := stack.len(); sLen < operation.minStack { return nil, fmt.Errorf("stack underflow (%d <=> %d)", sLen, operation.minStack) } else if sLen > operation.maxStack { return nil, fmt.Errorf("stack limit reached %d (%d)", sLen, operation.maxStack) } // If the operation is valid, enforce and write restrictions if in.readOnly && in.evm.chainRules.IsByzantium { // If the interpreter is operating in readonly mode, make sure no // state-modifying operation is performed. The 3rd stack item // for a call operation is the value. Transferring value from one // account to the others means the state is modified and should also // return with an error. if operation.writes || ((op == CALL || op == CALLEX) && stack.Back(2).Sign() != 0) { return nil, errWriteProtection } } // Static portion of gas cost = operation.constantGas // For tracing if !contract.UseGas(operation.constantGas) { return nil, ErrOutOfGas } var memorySize uint64 // calculate the new memory size and expand the memory to fit // the operation // Memory check needs to be done prior to evaluating the dynamic gas portion, // to detect calculation overflows if operation.memorySize != nil { memSize, overflow := operation.memorySize(stack) if overflow { return nil, errGasUintOverflow } // memory is expanded in words of 32 bytes. Gas // is also calculated in words. if memorySize, overflow = math.SafeMul(toWordSize(memSize), 32); overflow { return nil, errGasUintOverflow } } // Dynamic portion of gas // consume the gas and return an error if not enough gas is available. // cost is explicitly set so that the capture state defer method can get the proper cost if operation.dynamicGas != nil { var dynamicCost uint64 dynamicCost, err = operation.dynamicGas(in.evm, contract, stack, mem, memorySize) cost += dynamicCost // total cost, for debug tracing if err != nil || !contract.UseGas(dynamicCost) { return nil, ErrOutOfGas } } if memorySize > 0 { mem.Resize(memorySize) } if in.cfg.Debug { in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err) logged = true } // execute the operation res, err = operation.execute(&pc, in, contract, mem, stack) // verifyPool is a build flag. Pool verification makes sure the integrity // of the integer pool by comparing values to a default value. if verifyPool { verifyIntegerPool(in.intPool) } // if the operation clears the return data (e.g. it has returning data) // set the last return to the result of the operation. if operation.returns { in.returnData = res } switch { case err != nil: return nil, err case operation.reverts: return res, errExecutionReverted case operation.halts: return res, nil case !operation.jumps: pc++ } } return nil, nil } // CanRun tells if the contract, passed as an argument, can be // run by the current interpreter. func (in *EVMInterpreter) CanRun(code []byte) bool { return true }