• Felix Lange's avatar
    core/types, core/vm: improve docs, add JSON marshaling methods · 704fde01
    Felix Lange authored
    In this commit, core/types's types learn how to encode and decode
    themselves as JSON. The encoding is very similar to what the RPC API
    uses. The RPC API is missing some output fields (e.g. transaction
    signature values) which will be added to the API in a later commit. Some
    fields that the API generates are ignored by the decoder methods here.
    704fde01
log.go 4.49 KB
// Copyright 2014 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 vm

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/rlp"
)

var errMissingLogFields = errors.New("missing required JSON log fields")

// Log represents a contract log event. These events are generated by the LOG
// opcode and stored/indexed by the node.
type Log struct {
	// Consensus fields.
	Address common.Address // address of the contract that generated the event
	Topics  []common.Hash  // list of topics provided by the contract.
	Data    []byte         // supplied by the contract, usually ABI-encoded

	// Derived fields (don't reorder!).
	BlockNumber uint64      // block in which the transaction was included
	TxHash      common.Hash // hash of the transaction
	TxIndex     uint        // index of the transaction in the block
	BlockHash   common.Hash // hash of the block in which the transaction was included
	Index       uint        // index of the log in the receipt
}

type jsonLog struct {
	Address     *common.Address `json:"address"`
	Topics      *[]common.Hash  `json:"topics"`
	Data        string          `json:"data"`
	BlockNumber string          `json:"blockNumber"`
	TxIndex     string          `json:"transactionIndex"`
	TxHash      *common.Hash    `json:"transactionHash"`
	BlockHash   *common.Hash    `json:"blockHash"`
	Index       string          `json:"logIndex"`
}

func NewLog(address common.Address, topics []common.Hash, data []byte, number uint64) *Log {
	return &Log{Address: address, Topics: topics, Data: data, BlockNumber: number}
}

func (l *Log) EncodeRLP(w io.Writer) error {
	return rlp.Encode(w, []interface{}{l.Address, l.Topics, l.Data})
}

func (l *Log) DecodeRLP(s *rlp.Stream) error {
	var log struct {
		Address common.Address
		Topics  []common.Hash
		Data    []byte
	}
	if err := s.Decode(&log); err != nil {
		return err
	}
	l.Address, l.Topics, l.Data = log.Address, log.Topics, log.Data
	return nil
}

func (l *Log) String() string {
	return fmt.Sprintf(`log: %x %x %x %x %d %x %d`, l.Address, l.Topics, l.Data, l.TxHash, l.TxIndex, l.BlockHash, l.Index)
}

// MarshalJSON implements json.Marshaler.
func (r *Log) MarshalJSON() ([]byte, error) {
	return json.Marshal(&jsonLog{
		Address:     &r.Address,
		Topics:      &r.Topics,
		Data:        fmt.Sprintf("0x%x", r.Data),
		BlockNumber: fmt.Sprintf("0x%x", r.BlockNumber),
		TxIndex:     fmt.Sprintf("0x%x", r.TxIndex),
		TxHash:      &r.TxHash,
		BlockHash:   &r.BlockHash,
		Index:       fmt.Sprintf("0x%x", r.Index),
	})
}

// UnmarshalJSON implements json.Umarshaler.
func (r *Log) UnmarshalJSON(input []byte) error {
	var dec jsonLog
	if err := json.Unmarshal(input, &dec); err != nil {
		return err
	}
	if dec.Address == nil || dec.Topics == nil || dec.Data == "" || dec.BlockNumber == "" ||
		dec.TxIndex == "" || dec.TxHash == nil || dec.BlockHash == nil || dec.Index == "" {
		return errMissingLogFields
	}
	declog := Log{
		Address:   *dec.Address,
		Topics:    *dec.Topics,
		TxHash:    *dec.TxHash,
		BlockHash: *dec.BlockHash,
	}
	if _, err := fmt.Sscanf(dec.Data, "0x%x", &declog.Data); err != nil {
		return fmt.Errorf("invalid hex log data")
	}
	if _, err := fmt.Sscanf(dec.BlockNumber, "0x%x", &declog.BlockNumber); err != nil {
		return fmt.Errorf("invalid hex log block number")
	}
	if _, err := fmt.Sscanf(dec.TxIndex, "0x%x", &declog.TxIndex); err != nil {
		return fmt.Errorf("invalid hex log tx index")
	}
	if _, err := fmt.Sscanf(dec.Index, "0x%x", &declog.Index); err != nil {
		return fmt.Errorf("invalid hex log index")
	}
	*r = declog
	return nil
}

type Logs []*Log

// LogForStorage is a wrapper around a Log that flattens and parses the entire
// content of a log, as opposed to only the consensus fields originally (by hiding
// the rlp interface methods).
type LogForStorage Log