From d235e2c6a5788ec4a6cff15a16f56b38a3876a0d Mon Sep 17 00:00:00 2001 From: Determinant Date: Sun, 28 Jun 2020 14:47:41 -0400 Subject: ... --- core/vm/contract.go | 184 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 184 insertions(+) create mode 100644 core/vm/contract.go (limited to 'core/vm/contract.go') diff --git a/core/vm/contract.go b/core/vm/contract.go new file mode 100644 index 0000000..ed17402 --- /dev/null +++ b/core/vm/contract.go @@ -0,0 +1,184 @@ +// Copyright 2015 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 . + +package vm + +import ( + "math/big" + + "github.com/ava-labs/go-ethereum/common" +) + +// ContractRef is a reference to the contract's backing object +type ContractRef interface { + Address() common.Address +} + +// AccountRef implements ContractRef. +// +// Account references are used during EVM initialisation and +// it's primary use is to fetch addresses. Removing this object +// proves difficult because of the cached jump destinations which +// are fetched from the parent contract (i.e. the caller), which +// is a ContractRef. +type AccountRef common.Address + +// Address casts AccountRef to a Address +func (ar AccountRef) Address() common.Address { return (common.Address)(ar) } + +// Contract represents an ethereum contract in the state database. It contains +// the contract code, calling arguments. Contract implements ContractRef +type Contract struct { + // CallerAddress is the result of the caller which initialised this + // contract. However when the "call method" is delegated this value + // needs to be initialised to that of the caller's caller. + CallerAddress common.Address + caller ContractRef + self ContractRef + + jumpdests map[common.Hash]bitvec // Aggregated result of JUMPDEST analysis. + analysis bitvec // Locally cached result of JUMPDEST analysis + + Code []byte + CodeHash common.Hash + CodeAddr *common.Address + Input []byte + + Gas uint64 + value *big.Int +} + +// NewContract returns a new contract environment for the execution of EVM. +func NewContract(caller ContractRef, object ContractRef, value *big.Int, gas uint64) *Contract { + c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object} + + if parent, ok := caller.(*Contract); ok { + // Reuse JUMPDEST analysis from parent context if available. + c.jumpdests = parent.jumpdests + } else { + c.jumpdests = make(map[common.Hash]bitvec) + } + + // Gas should be a pointer so it can safely be reduced through the run + // This pointer will be off the state transition + c.Gas = gas + // ensures a value is set + c.value = value + + return c +} + +func (c *Contract) validJumpdest(dest *big.Int) bool { + udest := dest.Uint64() + // PC cannot go beyond len(code) and certainly can't be bigger than 63bits. + // Don't bother checking for JUMPDEST in that case. + if dest.BitLen() >= 63 || udest >= uint64(len(c.Code)) { + return false + } + // Only JUMPDESTs allowed for destinations + if OpCode(c.Code[udest]) != JUMPDEST { + return false + } + // Do we have a contract hash already? + if c.CodeHash != (common.Hash{}) { + // Does parent context have the analysis? + analysis, exist := c.jumpdests[c.CodeHash] + if !exist { + // Do the analysis and save in parent context + // We do not need to store it in c.analysis + analysis = codeBitmap(c.Code) + c.jumpdests[c.CodeHash] = analysis + } + return analysis.codeSegment(udest) + } + // We don't have the code hash, most likely a piece of initcode not already + // in state trie. In that case, we do an analysis, and save it locally, so + // we don't have to recalculate it for every JUMP instruction in the execution + // However, we don't save it within the parent context + if c.analysis == nil { + c.analysis = codeBitmap(c.Code) + } + return c.analysis.codeSegment(udest) +} + +// AsDelegate sets the contract to be a delegate call and returns the current +// contract (for chaining calls) +func (c *Contract) AsDelegate() *Contract { + // NOTE: caller must, at all times be a contract. It should never happen + // that caller is something other than a Contract. + parent := c.caller.(*Contract) + c.CallerAddress = parent.CallerAddress + c.value = parent.value + + return c +} + +// GetOp returns the n'th element in the contract's byte array +func (c *Contract) GetOp(n uint64) OpCode { + return OpCode(c.GetByte(n)) +} + +// GetByte returns the n'th byte in the contract's byte array +func (c *Contract) GetByte(n uint64) byte { + if n < uint64(len(c.Code)) { + return c.Code[n] + } + + return 0 +} + +// Caller returns the caller of the contract. +// +// Caller will recursively call caller when the contract is a delegate +// call, including that of caller's caller. +func (c *Contract) Caller() common.Address { + return c.CallerAddress +} + +// UseGas attempts the use gas and subtracts it and returns true on success +func (c *Contract) UseGas(gas uint64) (ok bool) { + if c.Gas < gas { + return false + } + c.Gas -= gas + return true +} + +// Address returns the contracts address +func (c *Contract) Address() common.Address { + return c.self.Address() +} + +// Value returns the contract's value (sent to it from it's caller) +func (c *Contract) Value() *big.Int { + return c.value +} + +// SetCallCode sets the code of the contract and address of the backing data +// object +func (c *Contract) SetCallCode(addr *common.Address, hash common.Hash, code []byte) { + c.Code = code + c.CodeHash = hash + c.CodeAddr = addr +} + +// SetCodeOptionalHash can be used to provide code, but it's optional to provide hash. +// In case hash is not provided, the jumpdest analysis will not be saved to the parent context +func (c *Contract) SetCodeOptionalHash(addr *common.Address, codeAndHash *codeAndHash) { + c.Code = codeAndHash.code + c.CodeHash = codeAndHash.hash + c.CodeAddr = addr +} -- cgit v1.2.3