118 lines
4.7 KiB
Go
118 lines
4.7 KiB
Go
// Copyright 2019 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 fourbyte
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import (
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"bytes"
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"errors"
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"fmt"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/signer/core"
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)
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// ValidateTransaction does a number of checks on the supplied transaction, and
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// returns either a list of warnings, or an error (indicating that the transaction
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// should be immediately rejected).
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func (db *Database) ValidateTransaction(selector *string, tx *core.SendTxArgs) (*core.ValidationMessages, error) {
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messages := new(core.ValidationMessages)
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// Prevent accidental erroneous usage of both 'input' and 'data' (show stopper)
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if tx.Data != nil && tx.Input != nil && !bytes.Equal(*tx.Data, *tx.Input) {
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return nil, errors.New(`ambiguous request: both "data" and "input" are set and are not identical`)
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}
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// Place data on 'data', and nil 'input'
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var data []byte
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if tx.Input != nil {
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tx.Data = tx.Input
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tx.Input = nil
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}
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if tx.Data != nil {
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data = *tx.Data
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}
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// Contract creation doesn't validate call data, handle first
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if tx.To == nil {
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// Contract creation should contain sufficient data to deploy a contract. A
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// typical error is omitting sender due to some quirk in the javascript call
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// e.g. https://github.com/ethereum/go-ethereum/issues/16106.
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if len(data) == 0 {
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// Prevent sending ether into black hole (show stopper)
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if tx.Value.ToInt().Cmp(big.NewInt(0)) > 0 {
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return nil, errors.New("transaction will create a contract with value but empty code")
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}
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// No value submitted at least, critically Warn, but don't blow up
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messages.Crit("Transaction will create a contract with empty code")
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} else if len(data) < 40 { // arbitrary heuristic limit
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messages.Warn(fmt.Sprintf("Transaction will create a contract, but the payload is suspiciously small (%d bytes)", len(data)))
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}
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// Method selector should be nil for contract creation
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if selector != nil {
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messages.Warn("Transaction will create a contract, but method selector supplied, indicating an intent to call a method")
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}
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return messages, nil
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}
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// Not a contract creation, validate as a plain transaction
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if !tx.To.ValidChecksum() {
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messages.Warn("Invalid checksum on recipient address")
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}
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if bytes.Equal(tx.To.Address().Bytes(), common.Address{}.Bytes()) {
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messages.Crit("Transaction recipient is the zero address")
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}
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// Semantic fields validated, try to make heads or tails of the call data
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db.ValidateCallData(selector, data, messages)
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return messages, nil
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}
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// ValidateCallData checks if the ABI call-data + method selector (if given) can
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// be parsed and seems to match.
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func (db *Database) ValidateCallData(selector *string, data []byte, messages *core.ValidationMessages) {
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// If the data is empty, we have a plain value transfer, nothing more to do
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if len(data) == 0 {
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return
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}
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// Validate the call data that it has the 4byte prefix and the rest divisible by 32 bytes
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if len(data) < 4 {
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messages.Warn("Transaction data is not valid ABI (missing the 4 byte call prefix)")
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return
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}
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if n := len(data) - 4; n%32 != 0 {
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messages.Warn(fmt.Sprintf("Transaction data is not valid ABI (length should be a multiple of 32 (was %d))", n))
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}
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// If a custom method selector was provided, validate with that
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if selector != nil {
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if info, err := verifySelector(*selector, data); err != nil {
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messages.Warn(fmt.Sprintf("Transaction contains data, but provided ABI signature could not be matched: %v", err))
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} else {
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messages.Info(info.String())
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db.AddSelector(*selector, data[:4])
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}
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return
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}
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// No method selector was provided, check the database for embedded ones
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embedded, err := db.Selector(data[:4])
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if err != nil {
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messages.Warn(fmt.Sprintf("Transaction contains data, but the ABI signature could not be found: %v", err))
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return
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}
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if info, err := verifySelector(embedded, data); err != nil {
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messages.Warn(fmt.Sprintf("Transaction contains data, but provided ABI signature could not be verified: %v", err))
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} else {
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messages.Info(info.String())
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}
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}
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