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topics.go
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topics.go
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// Copyright 2018 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 abi
import (
"encoding/binary"
"errors"
"fmt"
"math/big"
"reflect"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
)
// MakeTopics converts a filter query argument list into a filter topic set.
func MakeTopics(query ...[]interface{}) ([][]common.Hash, error) {
topics := make([][]common.Hash, len(query))
for i, filter := range query {
for _, rule := range filter {
var topic common.Hash
// Try to generate the topic based on simple types
switch rule := rule.(type) {
case common.Hash:
copy(topic[:], rule[:])
case common.Address:
copy(topic[common.HashLength-common.AddressLength:], rule[:])
case *big.Int:
blob := rule.Bytes()
copy(topic[common.HashLength-len(blob):], blob)
case bool:
if rule {
topic[common.HashLength-1] = 1
}
case int8:
copy(topic[:], genIntType(int64(rule), 1))
case int16:
copy(topic[:], genIntType(int64(rule), 2))
case int32:
copy(topic[:], genIntType(int64(rule), 4))
case int64:
copy(topic[:], genIntType(rule, 8))
case uint8:
blob := new(big.Int).SetUint64(uint64(rule)).Bytes()
copy(topic[common.HashLength-len(blob):], blob)
case uint16:
blob := new(big.Int).SetUint64(uint64(rule)).Bytes()
copy(topic[common.HashLength-len(blob):], blob)
case uint32:
blob := new(big.Int).SetUint64(uint64(rule)).Bytes()
copy(topic[common.HashLength-len(blob):], blob)
case uint64:
blob := new(big.Int).SetUint64(rule).Bytes()
copy(topic[common.HashLength-len(blob):], blob)
case string:
hash := crypto.Keccak256Hash([]byte(rule))
copy(topic[:], hash[:])
case []byte:
hash := crypto.Keccak256Hash(rule)
copy(topic[:], hash[:])
default:
// todo(rjl493456442) according solidity documentation, indexed event
// parameters that are not value types i.e. arrays and structs are not
// stored directly but instead a keccak256-hash of an encoding is stored.
//
// We only convert stringS and bytes to hash, still need to deal with
// array(both fixed-size and dynamic-size) and struct.
// Attempt to generate the topic from funky types
val := reflect.ValueOf(rule)
switch {
// static byte array
case val.Kind() == reflect.Array && reflect.TypeOf(rule).Elem().Kind() == reflect.Uint8:
reflect.Copy(reflect.ValueOf(topic[:val.Len()]), val)
default:
return nil, fmt.Errorf("unsupported indexed type: %T", rule)
}
}
topics[i] = append(topics[i], topic)
}
}
return topics, nil
}
func genIntType(rule int64, size uint) []byte {
var topic [common.HashLength]byte
if rule < 0 {
// if a rule is negative, we need to put it into two's complement.
// extended to common.HashLength bytes.
topic = [common.HashLength]byte{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255}
}
for i := uint(0); i < size; i++ {
topic[common.HashLength-i-1] = byte(rule >> (i * 8))
}
return topic[:]
}
// ParseTopics converts the indexed topic fields into actual log field values.
func ParseTopics(out interface{}, fields Arguments, topics []common.Hash) error {
return parseTopicWithSetter(fields, topics,
func(arg Argument, reconstr interface{}) {
field := reflect.ValueOf(out).Elem().FieldByName(ToCamelCase(arg.Name))
field.Set(reflect.ValueOf(reconstr))
})
}
// ParseTopicsIntoMap converts the indexed topic field-value pairs into map key-value pairs.
func ParseTopicsIntoMap(out map[string]interface{}, fields Arguments, topics []common.Hash) error {
return parseTopicWithSetter(fields, topics,
func(arg Argument, reconstr interface{}) {
out[arg.Name] = reconstr
})
}
// parseTopicWithSetter converts the indexed topic field-value pairs and stores them using the
// provided set function.
//
// Note, dynamic types cannot be reconstructed since they get mapped to Keccak256
// hashes as the topic value!
func parseTopicWithSetter(fields Arguments, topics []common.Hash, setter func(Argument, interface{})) error {
// Sanity check that the fields and topics match up
if len(fields) != len(topics) {
return errors.New("topic/field count mismatch")
}
// Iterate over all the fields and reconstruct them from topics
for i, arg := range fields {
if !arg.Indexed {
return errors.New("non-indexed field in topic reconstruction")
}
var reconstr interface{}
switch arg.Type.T {
case TupleTy:
return errors.New("tuple type in topic reconstruction")
case StringTy, BytesTy, SliceTy, ArrayTy:
// Array types (including strings and bytes) have their keccak256 hashes stored in the topic- not a hash
// whose bytes can be decoded to the actual value- so the best we can do is retrieve that hash
reconstr = topics[i]
case FunctionTy:
if garbage := binary.BigEndian.Uint64(topics[i][0:8]); garbage != 0 {
return fmt.Errorf("bind: got improperly encoded function type, got %v", topics[i].Bytes())
}
var tmp [24]byte
copy(tmp[:], topics[i][8:32])
reconstr = tmp
default:
var err error
reconstr, err = toGoType(0, arg.Type, topics[i].Bytes())
if err != nil {
return err
}
}
// Use the setter function to store the value
setter(arg, reconstr)
}
return nil
}