// 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 (
"encoding/json"
"fmt"
"io/ioutil"
"strings"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"bytes"
"os"
"regexp"
)
type decodedArgument struct {
soltype abi.Argument
value interface{}
}
type decodedCallData struct {
signature string
name string
inputs []decodedArgument
}
// String implements stringer interface, tries to use the underlying value-type
func (arg decodedArgument) String() string {
var value string
switch val := arg.value.(type) {
case fmt.Stringer:
value = val.String()
default:
value = fmt.Sprintf("%v", val)
}
return fmt.Sprintf("%v: %v", arg.soltype.Type.String(), value)
}
// String implements stringer interface for decodedCallData
func (cd decodedCallData) String() string {
args := make([]string, len(cd.inputs))
for i, arg := range cd.inputs {
args[i] = arg.String()
}
return fmt.Sprintf("%s(%s)", cd.name, strings.Join(args, ","))
}
// parseCallData matches the provided call data against the abi definition,
// and returns a struct containing the actual go-typed values
func parseCallData(calldata []byte, abidata string) (*decodedCallData, error) {
if len(calldata) < 4 {
return nil, fmt.Errorf("Invalid ABI-data, incomplete method signature of (%d bytes)", len(calldata))
}
sigdata, argdata := calldata[:4], calldata[4:]
if len(argdata)%32 != 0 {
return nil, fmt.Errorf("Not ABI-encoded data; length should be a multiple of 32 (was %d)", len(argdata))
}
abispec, err := abi.JSON(strings.NewReader(abidata))
if err != nil {
return nil, fmt.Errorf("Failed parsing JSON ABI: %v, abidata: %v", err, abidata)
}
method, err := abispec.MethodById(sigdata)
if err != nil {
return nil, err
}
v, err := method.Inputs.UnpackValues(argdata)
if err != nil {
return nil, err
}
decoded := decodedCallData{signature: method.Sig(), name: method.Name}
for n, argument := range method.Inputs {
if err != nil {
return nil, fmt.Errorf("Failed to decode argument %d (signature %v): %v", n, method.Sig(), err)
}
decodedArg := decodedArgument{
soltype: argument,
value: v[n],
}
decoded.inputs = append(decoded.inputs, decodedArg)
}
// We're finished decoding the data. At this point, we encode the decoded data to see if it matches with the
// original data. If we didn't do that, it would e.g. be possible to stuff extra data into the arguments, which
// is not detected by merely decoding the data.
var (
encoded []byte
)
encoded, err = method.Inputs.PackValues(v)
if err != nil {
return nil, err
}
if !bytes.Equal(encoded, argdata) {
was := common.Bytes2Hex(encoded)
exp := common.Bytes2Hex(argdata)
return nil, fmt.Errorf("WARNING: Supplied data is stuffed with extra data. \nWant %s\nHave %s\nfor method %v", exp, was, method.Sig())
}
return &decoded, nil
}
// MethodSelectorToAbi converts a method selector into an ABI struct. The returned data is a valid json string
// which can be consumed by the standard abi package.
func MethodSelectorToAbi(selector string) ([]byte, error) {
re := regexp.MustCompile(`^([^\)]+)\(([a-z0-9,\[\]]*)\)`)
type fakeArg struct {
Type string `json:"type"`
}
type fakeABI struct {
Name string `json:"name"`
Type string `json:"type"`
Inputs []fakeArg `json:"inputs"`
}
groups := re.FindStringSubmatch(selector)
if len(groups) != 3 {
return nil, fmt.Errorf("Did not match: %v (%v matches)", selector, len(groups))
}
name := groups[1]
args := groups[2]
arguments := make([]fakeArg, 0)
if len(args) > 0 {
for _, arg := range strings.Split(args, ",") {
arguments = append(arguments, fakeArg{arg})
}
}
abicheat := fakeABI{
name, "function", arguments,
}
return json.Marshal([]fakeABI{abicheat})
}
type AbiDb struct {
db map[string]string
customdb map[string]string
customdbPath string
}
// NewEmptyAbiDB exists for test purposes
func NewEmptyAbiDB() (*AbiDb, error) {
return &AbiDb{make(map[string]string), make(map[string]string), ""}, nil
}
// NewAbiDBFromFile loads signature database from file, and
// errors if the file is not valid json. Does no other validation of contents
func NewAbiDBFromFile(path string) (*AbiDb, error) {
raw, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
db, err := NewEmptyAbiDB()
if err != nil {
return nil, err
}
json.Unmarshal(raw, &db.db)
return db, nil
}
// NewAbiDBFromFiles loads both the standard signature database and a custom database. The latter will be used
// to write new values into if they are submitted via the API
func NewAbiDBFromFiles(standard, custom string) (*AbiDb, error) {
db := &AbiDb{make(map[string]string), make(map[string]string), custom}
db.customdbPath = custom
raw, err := ioutil.ReadFile(standard)
if err != nil {
return nil, err
}
json.Unmarshal(raw, &db.db)
// Custom file may not exist. Will be created during save, if needed
if _, err := os.Stat(custom); err == nil {
raw, err = ioutil.ReadFile(custom)
if err != nil {
return nil, err
}
json.Unmarshal(raw, &db.customdb)
}
return db, nil
}
// LookupMethodSelector checks the given 4byte-sequence against the known ABI methods.
// OBS: This method does not validate the match, it's assumed the caller will do so
func (db *AbiDb) LookupMethodSelector(id []byte) (string, error) {
if len(id) < 4 {
return "", fmt.Errorf("Expected 4-byte id, got %d", len(id))
}
sig := common.ToHex(id[:4])
if key, exists := db.db[sig]; exists {
return key, nil
}
if key, exists := db.customdb[sig]; exists {
return key, nil
}
return "", fmt.Errorf("Signature %v not found", sig)
}
func (db *AbiDb) Size() int {
return len(db.db)
}
// saveCustomAbi saves a signature ephemerally. If custom file is used, also saves to disk
func (db *AbiDb) saveCustomAbi(selector, signature string) error {
db.customdb[signature] = selector
if db.customdbPath == "" {
return nil //Not an error per se, just not used
}
d, err := json.Marshal(db.customdb)
if err != nil {
return err
}
err = ioutil.WriteFile(db.customdbPath, d, 0600)
return err
}
// AddSignature to the database, if custom database saving is enabled.
// OBS: This method does _not_ validate the correctness of the data,
// it is assumed that the caller has already done so
func (db *AbiDb) AddSignature(selector string, data []byte) error {
if len(data) < 4 {
return nil
}
_, err := db.LookupMethodSelector(data[:4])
if err == nil {
return nil
}
sig := common.ToHex(data[:4])
return db.saveCustomAbi(selector, sig)
}
