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// Copyright 2018 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package core
import (
"bytes"
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common"
)
// The validation package contains validation checks for transactions
// - ABI-data validation
// - Transaction semantics validation
// The package provides warnings for typical pitfalls
func (vs *ValidationMessages) crit(msg string) {
vs.Messages = append(vs.Messages, ValidationInfo{"CRITICAL", msg})
}
func (vs *ValidationMessages) warn(msg string) {
vs.Messages = append(vs.Messages, ValidationInfo{"WARNING", msg})
}
func (vs *ValidationMessages) info(msg string) {
vs.Messages = append(vs.Messages, ValidationInfo{"Info", msg})
}
type Validator struct {
db *AbiDb
}
func NewValidator(db *AbiDb) *Validator {
return &Validator{db}
}
func testSelector(selector string, data []byte) (*decodedCallData, error) {
if selector == "" {
return nil, fmt.Errorf("selector not found")
}
abiData, err := MethodSelectorToAbi(selector)
if err != nil {
return nil, err
}
info, err := parseCallData(data, string(abiData))
if err != nil {
return nil, err
}
return info, nil
}
// validateCallData checks if the ABI-data + methodselector (if given) can be parsed and seems to match
func (v *Validator) validateCallData(msgs *ValidationMessages, data []byte, methodSelector *string) {
if len(data) == 0 {
return
}
if len(data) < 4 {
msgs.warn("Tx contains data which is not valid ABI")
return
}
var (
info *decodedCallData
err error
)
// Check the provided one
if methodSelector != nil {
info, err = testSelector(*methodSelector, data)
if err != nil {
msgs.warn(fmt.Sprintf("Tx contains data, but provided ABI signature could not be matched: %v", err))
} else {
msgs.info(info.String())
//Successfull match. add to db if not there already (ignore errors there)
v.db.AddSignature(*methodSelector, data[:4])
}
return
}
// Check the db
selector, err := v.db.LookupMethodSelector(data[:4])
if err != nil {
msgs.warn(fmt.Sprintf("Tx contains data, but the ABI signature could not be found: %v", err))
return
}
info, err = testSelector(selector, data)
if err != nil {
msgs.warn(fmt.Sprintf("Tx contains data, but provided ABI signature could not be matched: %v", err))
} else {
msgs.info(info.String())
}
}
// validateSemantics checks if the transactions 'makes sense', and generate warnings for a couple of typical scenarios
func (v *Validator) validate(msgs *ValidationMessages, txargs *SendTxArgs, methodSelector *string) error {
// Prevent accidental erroneous usage of both 'input' and 'data'
if txargs.Data != nil && txargs.Input != nil && !bytes.Equal(*txargs.Data, *txargs.Input) {
// This is a showstopper
return errors.New(`Ambiguous request: both "data" and "input" are set and are not identical`)
}
var (
data []byte
)
// Place data on 'data', and nil 'input'
if txargs.Input != nil {
txargs.Data = txargs.Input
txargs.Input = nil
}
if txargs.Data != nil {
data = *txargs.Data
}
if txargs.To == nil {
//Contract creation should contain sufficient data to deploy a contract
// A typical error is omitting sender due to some quirk in the javascript call
// e.g. https://github.com/ethereum/go-ethereum/issues/16106
if len(data) == 0 {
if txargs.Value.ToInt().Cmp(big.NewInt(0)) > 0 {
// Sending ether into black hole
return errors.New("Tx will create contract with value but empty code!")
}
// No value submitted at least
msgs.crit("Tx will create contract with empty code!")
} else if len(data) < 40 { //Arbitrary limit
msgs.warn(fmt.Sprintf("Tx will will create contract, but payload is suspiciously small (%d b)", len(data)))
}
// methodSelector should be nil for contract creation
if methodSelector != nil {
msgs.warn("Tx will create contract, but method selector supplied; indicating intent to call a method.")
}
} else {
if !txargs.To.ValidChecksum() {
msgs.warn("Invalid checksum on to-address")
}
// Normal transaction
if bytes.Equal(txargs.To.Address().Bytes(), common.Address{}.Bytes()) {
// Sending to 0
msgs.crit("Tx destination is the zero address!")
}
// Validate calldata
v.validateCallData(msgs, data, methodSelector)
}
return nil
}
// ValidateTransaction does a number of checks on the supplied transaction, and returns either a list of warnings,
// or an error, indicating that the transaction should be immediately rejected
func (v *Validator) ValidateTransaction(txArgs *SendTxArgs, methodSelector *string) (*ValidationMessages, error) {
msgs := &ValidationMessages{}
return msgs, v.validate(msgs, txArgs, methodSelector)
}
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