Filecoin Lotus 链消息解析

Filecoin中的链消息的参数是通过CBOR方式编码的，在解码前是不知道里面存的具体是什么数据。CBOR将对象编码成二进制数据，在传输过程中以base64编码方式传输，所以在解码是现将base64格式字符串解码，然后在解析成对应类型。

这里以PreCommitSector提交扇区消息为例，说明如何解析链消息中的Params字段，其他字段按原来JSON格式解析。

链消息格式

type Message struct {
	Version uint64

	To   address.Address
	From address.Address

	Nonce uint64

	Value abi.TokenAmount

	GasLimit   int64
	GasFeeCap  abi.TokenAmount
	GasPremium abi.TokenAmount

	Method abi.MethodNum
	Params []byte
}

消息中的Params为消息参数，在传输过程中该字段会被编码成CBOR格式。

PreCommitSector消息对应的参数Params类型为: SectorPreCommitInfo，源码路径: github.com/filecoin-project/specs-actors/actors/builtin/miner/miner_state -> SectorPreCommitInfo。

SectorPreCommitInfo:

// Information provided by a miner when pre-committing a sector.
type SectorPreCommitInfo struct {
	SealProof       abi.RegisteredSealProof
	SectorNumber    abi.SectorNumber
	SealedCID       cid.Cid `checked:"true"` // CommR
	SealRandEpoch   abi.ChainEpoch
	DealIDs         []abi.DealID
	Expiration      abi.ChainEpoch
	ReplaceCapacity bool // Whether to replace a "committed capacity" no-deal sector (requires non-empty DealIDs)
	// The committed capacity sector to replace, and it's deadline/partition location
	ReplaceSectorDeadline  uint64
	ReplaceSectorPartition uint64
	ReplaceSectorNumber    abi.SectorNumber
}

查询一个PreCommitSector消息

// Get message by using lotus CLI
$> ~/hlm-miner/script/lotus/lotus-user# ./lotus.sh chain getmessage bafy2bzacec3x5rlwdveh46m55dbe47g7bmzlhncpczwwgcuoowvazumpf25se
{
	"Version": 0,
	"To": "f03176",
	"From": "f3ruolcbftfwhudz2qexbkylbj2y2awtxeopovv5jeoafikmstk4j7bwowynmnes66xv6fselgolug55uuxp4q",
	"Nonce": 687292,
	"Value": "150610342700684832",
	"GasLimit": 15145026,
	"GasFeeCap": "101967",
	"GasPremium": "100913",
	"Method": 6,
	"Params": "igMaAAVUk9gqWCkAAYLiA4HoAiCHKF0gQg0SAAfbmkUG8iNEAyelBUyRNNBOfCQJBZZXSxoAAslIgRoADudPGgAK4gz0AAAA",
	"CID": {
	"/": "bafy2bzacec3x5rlwdveh46m55dbe47g7bmzlhncpczwwgcuoowvazumpf25se"
	}
}

"Method:": 6 => 6表示此消息方法为PreCommitSector。

CID => 消息ID。

"Params": "igMaAAVUk9gqWCkAAYLiA4HoAiCHKF0gQg0SAAfbmkUG8iNEAyelBUyRNNBOfCQJBZZXSxoAAslIgRoADudPGgAK4gz0AAAA"

以上Params为传输中被编码为base64的SectorPreCommitInfo结构信息。

解码

解码base64:

// base64 encoded params
params := "igMaAAVUk9gqWCkAAYLiA4HoAiCHKF0gQg0SAAfbmkUG8iNEAyelBUyRNNBOfCQJBZZXSxoAAslIgRoADudPGgAK4gz0AAAA"

var precommitInfo miner.SectorPreCommitInfo
bin, err := base64.StdEncoding.DecodeString(params)
if err != nil {
	log.Error(err)
	return
}

解码CBOR格式数据：

解码CBOR格式数据的代码可以参考源码github.com/lotus/cmd/lotus-pcr/ -> main.go。

m := &types.Message{
	Params: bin,
}

if err := precommitInfo.UnmarshalCBOR(bytes.NewReader(m.Params)); err != nil {
	log.Error(err)
	return
}

解析后的precommitInfo数据:

{
	SealProof:3 
	SectorNumber:349331 
	SealedCID:bagboea4b5abcbbziluqeedisaad5xgsfa3zcgrade6sqktergtie47bebeczmv2l 
	SealRandEpoch:182600 
	DealIDs:[976719] 
	Expiration:713228 
	ReplaceCapacity:false 
	ReplaceSectorDeadline:0 
	ReplaceSectorPartition:0 
	ReplaceSectorNumber:0
} 

完整的解析例子代码

package filmessage

import (
	"bytes"
	"encoding/base64"
	"testing"

	"github.com/filecoin-project/lotus/chain/types"
	"github.com/filecoin-project/specs-actors/actors/builtin/miner"
	log "github.com/sirupsen/logrus"
)

func TestChainMessageDecoding(t *testing.T) {
	// Message struct
	// lotus -> chain -> types -> Message
	// type Message struct {
	// 	Version uint64

	// 	To   address.Address
	// 	From address.Address

	// 	Nonce uint64

	// 	Value abi.TokenAmount

	// 	GasLimit   int64
	// 	GasFeeCap  abi.TokenAmount
	// 	GasPremium abi.TokenAmount

	// 	Method abi.MethodNum
	// 	Params []byte
	// }

	// Get message by using lotus CLI
	// $> ~/hlm-miner/script/lotus/lotus-user# ./lotus.sh chain getmessage bafy2bzacec3x5rlwdveh46m55dbe47g7bmzlhncpczwwgcuoowvazumpf25se
	// {
	//   "Version": 0,
	//   "To": "f03176",
	//   "From": "f3ruolcbftfwhudz2qexbkylbj2y2awtxeopovv5jeoafikmstk4j7bwowynmnes66xv6fselgolug55uuxp4q",
	//   "Nonce": 687292,
	//   "Value": "150610342700684832",
	//   "GasLimit": 15145026,
	//   "GasFeeCap": "101967",
	//   "GasPremium": "100913",
	//   "Method": 6,
	//   "Params": "igMaAAVUk9gqWCkAAYLiA4HoAiCHKF0gQg0SAAfbmkUG8iNEAyelBUyRNNBOfCQJBZZXSxoAAslIgRoADudPGgAK4gz0AAAA",
	//   "CID": {
	//     "/": "bafy2bzacec3x5rlwdveh46m55dbe47g7bmzlhncpczwwgcuoowvazumpf25se"
	//   }
	// }

	// base64 encoded params
	params := "igMaAAVUk9gqWCkAAYLiA4HoAiCHKF0gQg0SAAfbmkUG8iNEAyelBUyRNNBOfCQJBZZXSxoAAslIgRoADudPGgAK4gz0AAAA"

	var precommitInfo miner.SectorPreCommitInfo
	bin, err := base64.StdEncoding.DecodeString(params)
	if err != nil {
		log.Error(err)
		return
	}

	m := &types.Message{
		Params: bin,
	}

	log.Println("bin => ", bin)

	if err := precommitInfo.UnmarshalCBOR(bytes.NewReader(m.Params)); err != nil {
		// log.Warnw("failed to decode precommit params", "err", err, "method", messageMethod, "cid", msg.Cid, "miner", m.To)
		// return false, messageMethod, types.NewInt(0), nil
		log.Error(err)
		return
	}

	log.Printf("precommit info => %+v", precommitInfo)

	//Output:
	// INFO[0000] bin =>  [138 3 26 0 5 84 147 216 42 88 41 0 1 130 226 3 129 232 2 32 135 40 93 32 66 13 18 0 7 219 154 69 6 242 35 68 3 39 165 5 76 145 52 208 78 124 36 9 5 150 87 75 26 0 2 201 72 129 26 0 14 231 79 26 0 10 226 12 244 0 0 0]
	// INFO[0000] precommit info => {SealProof:3 SectorNumber:349331 SealedCID:bagboea4b5abcbbziluqeedisaad5xgsfa3zcgrade6sqktergtie47bebeczmv2l SealRandEpoch:182600 DealIDs:[976719] Expiration:713228 ReplaceCapacity:false ReplaceSectorDeadline:0 ReplaceSectorPartition:0 ReplaceSectorNumber:0}
	// PASS
	// ok  	grandhelmsman.com/test/chain	0.003s
}

参考

https://github.com/whyrusleeping/cbor/blob/master/go/cbor_test.go