兄弟连区块链教程Fabric1.0源代码分析Peer（Endorser服务端），2018年下半年，区块链行业正逐渐褪去发展之初的浮躁、回归理性，表面上看相关人才需求与身价似乎正在回落。但事实上，正是初期泡沫的渐退，让人们更多的关注点放在了区块链真正的技术之上。

# Fabric 1.0源代码笔记 之 Peer #EndorserServer（Endorser服务端）

## 1、EndorserServer概述

EndorserServer相关代码在protos/peer、core/endorser目录下。

* protos/peer/peer.pb.go，EndorserServer接口定义。

* core/endorser/endorser.go，EndorserServer接口实现，即Endorser结构体及方法，以及Endorser服务端ProcessProposal处理流程。

## 2、EndorserServer接口定义

### 2.1、EndorserServer接口定义

```go

type EndorserServer interface {

    ProcessProposal(context.Context, *SignedProposal) (*ProposalResponse, error)

}

//代码在protos/peer/peer.pb.go

```

### 2.2、gRPC相关实现

```go

var _Endorser_serviceDesc = grpc.ServiceDesc{

    ServiceName: "protos.Endorser",

    HandlerType: (*EndorserServer)(nil),

    Methods: []grpc.MethodDesc{

        {

            MethodName: "ProcessProposal",

            Handler:    _Endorser_ProcessProposal_Handler,

        },

    },

    Streams:  []grpc.StreamDesc{},

    Metadata: "peer/peer.proto",

}

func RegisterEndorserServer(s *grpc.Server, srv EndorserServer) {

    s.RegisterService(&_Endorser_serviceDesc, srv)

}

func _Endorser_ProcessProposal_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {

    in := new(SignedProposal)

    if err := dec(in); err != nil {

        return nil, err

    }

    if interceptor == nil {

        return srv.(EndorserServer).ProcessProposal(ctx, in)

    }

    info := &grpc.UnaryServerInfo{

        Server:     srv,

        FullMethod: "/protos.Endorser/ProcessProposal",

    }

    handler := func(ctx context.Context, req interface{}) (interface{}, error) {

        return srv.(EndorserServer).ProcessProposal(ctx, req.(*SignedProposal))

    }

    return interceptor(ctx, in, info, handler)

}

//代码在protos/peer/peer.pb.go

```

## 3、EndorserServer接口实现

### 3.1、Endorser结构体及方法

```go

type Endorser struct {

    policyChecker policy.PolicyChecker //策略检查器

}

//代码在core/endorser/endorser.go

```

涉及方法如下：

```go

//构造Endorser

func NewEndorserServer() pb.EndorserServer

//执行提案

func (e *Endorser) ProcessProposal(ctx context.Context, signedProp *pb.SignedProposal) (*pb.ProposalResponse, error)

//检查SignedProposal是否符合通道策略，调用e.policyChecker.CheckPolicy()

func (e *Endorser) checkACL(signedProp *pb.SignedProposal, chdr *common.ChannelHeader, shdr *common.SignatureHeader, hdrext *pb.ChaincodeHeaderExtension) error

//检查Escc和Vscc，暂未实现

func (*Endorser) checkEsccAndVscc(prop *pb.Proposal) error

//获取账本的交-易模拟器，调用peer.GetLedger(ledgername).NewTxSimulator()

func (*Endorser) getTxSimulator(ledgername string) (ledger.TxSimulator, error)

//获取账本历史交-易查询器，调用peer.GetLedger(ledgername).NewHistoryQueryExecutor()

func (*Endorser) getHistoryQueryExecutor(ledgername string) (ledger.HistoryQueryExecutor, error)

//执行链码

func (e *Endorser) callChaincode(ctxt context.Context, chainID string, version string, txid string, signedProp *pb.SignedProposal, prop *pb.Proposal, cis *pb.ChaincodeInvocationSpec, cid *pb.ChaincodeID, txsim ledger.TxSimulator) (*pb.Response, *pb.ChaincodeEvent, error)

func (e *Endorser) disableJavaCCInst(cid *pb.ChaincodeID, cis *pb.ChaincodeInvocationSpec) error

//通过调用chaincode来模拟提案

func (e *Endorser) simulateProposal(ctx context.Context, chainID string, txid string, signedProp *pb.SignedProposal, prop *pb.Proposal, cid *pb.ChaincodeID, txsim ledger.TxSimulator) (*ccprovider.ChaincodeData, *pb.Response, []byte, *pb.ChaincodeEvent, error)

//从LSCC获取链码数据

func (e *Endorser) getCDSFromLSCC(ctx context.Context, chainID string, txid string, signedProp *pb.SignedProposal, prop *pb.Proposal, chaincodeID string, txsim ledger.TxSimulator) (*ccprovider.ChaincodeData, error)

//提案背书

func (e *Endorser) endorseProposal(ctx context.Context, chainID string, txid string, signedProp *pb.SignedProposal, proposal *pb.Proposal, response *pb.Response, simRes []byte, event *pb.ChaincodeEvent, visibility []byte, ccid *pb.ChaincodeID, txsim ledger.TxSimulator, cd *ccprovider.ChaincodeData) (*pb.ProposalResponse, error)

//提交模拟交-易，仅测试使用

func (e *Endorser) commitTxSimulation(proposal *pb.Proposal, chainID string, signer msp.SigningIdentity, pResp *pb.ProposalResponse, blockNumber uint64) error

//代码在core/endorser/endorser.go

```

### 3.2、Endorser服务端ProcessProposal处理流程

Endorser服务端ProcessProposal处理流程，即func (e *Endorser) ProcessProposal(ctx context.Context, signedProp *pb.SignedProposal) (*pb.ProposalResponse, error)方法实现。

#### 3.2.1、校验SignedProposal合法性，并获取ChannelHeader和SignatureHeader

```go

//校验SignedProposal合法性

prop, hdr, hdrExt, err := validation.ValidateProposalMessage(signedProp)

//获取ChannelHeader

chdr, err := putils.UnmarshalChannelHeader(hdr.ChannelHeader)

//获取SignatureHeader

shdr, err := putils.GetSignatureHeader(hdr.SignatureHeader)

//代码在core/endorser/endorser.go

```

validation.ValidateProposalMessage(signedProp)代码如下：

```go

func ValidateProposalMessage(signedProp *pb.SignedProposal) (*pb.Proposal, *common.Header, *pb.ChaincodeHeaderExtension, error) {

    prop, err := utils.GetProposal(signedProp.ProposalBytes) //获取type Proposal struct

    hdr, err := utils.GetHeader(prop.Header) //获取Proposal.Header

    chdr, shdr, err := validateCommonHeader(hdr) //校验Proposal.Header

    //检查来自创建者的签名

    err = checkSignatureFromCreator(shdr.Creator, signedProp.Signature, signedProp.ProposalBytes, chdr.ChannelId)

    //校验交-易TxID，TxID由Nonce和Creator构成

    err = utils.CheckProposalTxID(

        chdr.TxId, //ChannelHeader.TxId

        shdr.Nonce, //SignatureHeader.Nonce

        shdr.Creator) //SignatureHeader.Creator

    switch common.HeaderType(chdr.Type) {

    case common.HeaderType_CONFIG:

        fallthrough

    case common.HeaderType_ENDORSER_TRANSACTION:

        //校验ChaincodeHeaderExtension

        chaincodeHdrExt, err := validateChaincodeProposalMessage(prop, hdr)

        return prop, hdr, chaincodeHdrExt, err

    default:

        return nil, nil, nil, fmt.Errorf("Unsupported proposal type %d", common.HeaderType(chdr.Type))

    }

}

//代码在core/common/validation/msgvalidation.go

```

#### 3.2.2、校验是否系统链码且提案不可调用，获取chainID和TxId，获取Ledger并校验txid是否已存在，非系统链码校验提案权限（是否符合通道策略）

```go

//校验是否系统链码且提案不可调用

if syscc.IsSysCCAndNotInvokableExternal(hdrExt.ChaincodeId.Name) {

    //如果是系统链码且提案不可调用

}

//获取chainID，即ChannelId

chainID := chdr.ChannelId

//获取交-易TxId

txid := chdr.TxId

if chainID != "" {

    //获取Ledger

    lgr := peer.GetLedger(chainID)

    //校验txid是否已存在

    _, err := lgr.GetTransactionByID(txid)

    //非系统链码校验提案权限（是否符合通道策略）

    if !syscc.IsSysCC(hdrExt.ChaincodeId.Name) {

        err = e.checkACL(signedProp, chdr, shdr, hdrExt)

    }

}

//代码在core/endorser/endorser.go

```

#### 3.2.3、获取账本的交-易模拟器和历史记录查询器，并模拟提案执行

```go

var txsim ledger.TxSimulator

var historyQueryExecutor ledger.HistoryQueryExecutor

if chainID != "" {

    //获取账本的交-易模拟器

    txsim, err = e.getTxSimulator(chainID)

    //获取历史记录查询器

    historyQueryExecutor, err = e.getHistoryQueryExecutor(chainID)

    //HistoryQueryExecutorKey key = "historyqueryexecutorkey"

    //context.WithValue，将Key与对象建立关系

    ctx = context.WithValue(ctx, chaincode.HistoryQueryExecutorKey, historyQueryExecutor)

}

//模拟提案执行

cd, res, simulationResult, ccevent, err := e.simulateProposal(ctx, chainID, txid, signedProp, prop, hdrExt.ChaincodeId, txsim)

//代码在core/endorser/endorser.go

```

e.simulateProposal(ctx, chainID, txid, signedProp, prop, hdrExt.ChaincodeId, txsim)代码如下：模拟提案执行。

```go

func (e *Endorser) simulateProposal(ctx context.Context, chainID string, txid string, signedProp *pb.SignedProposal, prop *pb.Proposal, cid *pb.ChaincodeID, txsim ledger.TxSimulator) (*ccprovider.ChaincodeData

, *pb.Response, []byte, *pb.ChaincodeEvent, error) {

    //获取ChaincodeInvocationSpec

    cis, err := putils.GetChaincodeInvocationSpec(prop)

    //禁用Java安装、实例化和立即升级

    err = e.disableJavaCCInst(cid, cis)

    //检查Escc和Vscc，暂未实现

    err = e.checkEsccAndVscc(prop)

    var cdLedger *ccprovider.ChaincodeData

    var version string

    if !syscc.IsSysCC(cid.Name) { //非系统链码

        //获取链码数据ChaincodeData

        cdLedger, err = e.getCDSFromLSCC(ctx, chainID, txid, signedProp, prop, cid.Name, txsim)

        //获取链码数据版本

        version = cdLedger.Version

        //检查链码实例化策略

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