path: root/core/vm/log.go

// 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