path: root/core/types/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 types

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

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/hexutil"
    "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. These fields are filled in by the node
    // but not secured by consensus.
    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

    // The Removed field is true if this log was reverted due to a chain reorganisation.
    // You must pay attention to this field if you receive logs through a filter query.
    Removed bool
}

type rlpLog struct {
    Address common.Address
    Topics  []common.Hash
    Data    []byte
}

type rlpStorageLog struct {
    Address     common.Address
    Topics      []common.Hash
    Data        []byte
    BlockNumber uint64
    TxHash      common.Hash
    TxIndex     uint
    BlockHash   common.Hash
    Index       uint
}

type jsonLog struct {
    Address     *common.Address `json:"address"`
    Topics      *[]common.Hash  `json:"topics"`
    Data        *hexutil.Bytes  `json:"data"`
    BlockNumber *hexutil.Uint64 `json:"blockNumber"`
    TxIndex     *hexutil.Uint   `json:"transactionIndex"`
    TxHash      *common.Hash    `json:"transactionHash"`
    BlockHash   *common.Hash    `json:"blockHash"`
    Index       *hexutil.Uint   `json:"logIndex"`
    Removed     bool            `json:"removed"`
}

// EncodeRLP implements rlp.Encoder.
func (l *Log) EncodeRLP(w io.Writer) error {
    return rlp.Encode(w, rlpLog{Address: l.Address, Topics: l.Topics, Data: l.Data})
}

// DecodeRLP implements rlp.Decoder.
func (l *Log) DecodeRLP(s *rlp.Stream) error {
    var dec rlpLog
    err := s.Decode(&dec)
    if err == nil {
        l.Address, l.Topics, l.Data = dec.Address, dec.Topics, dec.Data
    }
    return err
}

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 (l *Log) MarshalJSON() ([]byte, error) {
    jslog := &jsonLog{
        Address: &l.Address,
        Topics:  &l.Topics,
        Data:    (*hexutil.Bytes)(&l.Data),
        TxIndex: (*hexutil.Uint)(&l.TxIndex),
        TxHash:  &l.TxHash,
        Index:   (*hexutil.Uint)(&l.Index),
        Removed: l.Removed,
    }
    // Set block information for mined logs.
    if (l.BlockHash != common.Hash{}) {
        jslog.BlockHash = &l.BlockHash
        jslog.BlockNumber = (*hexutil.Uint64)(&l.BlockNumber)
    }
    return json.Marshal(jslog)
}

// UnmarshalJSON implements json.Umarshaler.
func (l *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 == nil ||
        dec.TxIndex == nil || dec.TxHash == nil || dec.Index == nil {
        return errMissingLogFields
    }
    declog := Log{
        Address: *dec.Address,
        Topics:  *dec.Topics,
        Data:    *dec.Data,
        TxHash:  *dec.TxHash,
        TxIndex: uint(*dec.TxIndex),
        Index:   uint(*dec.Index),
        Removed: dec.Removed,
    }
    // Block information may be missing if the log is received through
    // the pending log filter, so it's handled specially here.
    if dec.BlockHash != nil && dec.BlockNumber != nil {
        declog.BlockHash = *dec.BlockHash
        declog.BlockNumber = uint64(*dec.BlockNumber)
    }
    *l = declog
    return nil
}

// LogForStorage is a wrapper around a Log that flattens and parses the entire content of
// a log including non-consensus fields.
type LogForStorage Log

// EncodeRLP implements rlp.Encoder.
func (l *LogForStorage) EncodeRLP(w io.Writer) error {
    return rlp.Encode(w, rlpStorageLog{
        Address:     l.Address,
        Topics:      l.Topics,
        Data:        l.Data,
        BlockNumber: l.BlockNumber,
        TxHash:      l.TxHash,
        TxIndex:     l.TxIndex,
        BlockHash:   l.BlockHash,
        Index:       l.Index,
    })
}

// DecodeRLP implements rlp.Decoder.
func (l *LogForStorage) DecodeRLP(s *rlp.Stream) error {
    var dec rlpStorageLog
    err := s.Decode(&dec)
    if err == nil {
        *l = LogForStorage{
            Address:     dec.Address,
            Topics:      dec.Topics,
            Data:        dec.Data,
            BlockNumber: dec.BlockNumber,
            TxHash:      dec.TxHash,
            TxIndex:     dec.TxIndex,
            BlockHash:   dec.BlockHash,
            Index:       dec.Index,
        }
    }
    return err
}