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

type EndorserServer interface {     ProcessProposal(context.Context, *SignedProposal) (*ProposalResponse, error) } //代码在protos/peer/peer.pb.go

2.2、gRPC相关实现

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

type Endorser struct {     policyChecker policy.PolicyChecker //策略检查器 } //代码在core/endorser/endorser.go

涉及方法如下：

//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

//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：

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）

//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

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。

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         err = ccprovider.CheckInsantiationPolicy(cid.Name, version, cdLedger)     } else {         version = util.GetSysCCVersion() //获取系统链码版本     }     var simResult []byte     var res *pb.Response     var ccevent *pb.ChaincodeEvent     //执行链码     res, ccevent, err = e.callChaincode(ctx, chainID, version, txid, signedProp, prop, cis, cid, txsim)     if txsim != nil {         //获取交易模拟结果         simResult, err = txsim.GetTxSimulationResults()     }     return cdLedger, res, simResult, ccevent, nil } //代码在core/endorser/endorser.go

e.endorseProposal(ctx, chainID, txid, signedProp, prop, res, simulationResult, ccevent, hdrExt.PayloadVisibility, hdrExt.ChaincodeId, txsim, cd)代码如下：为提案背书。

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) {     var err error     var res *pb.Response     var ccevent *pb.ChaincodeEvent     if txsim != nil {         //TXSimulatorKey key = "txsimulatorkey"，key与对象建立关系         ctxt = context.WithValue(ctxt, chaincode.TXSimulatorKey, txsim)     }     scc := syscc.IsSysCC(cid.Name) //是否系统链码     cccid := ccprovider.NewCCContext(chainID, cid.Name, version, txid, scc, signedProp, prop)     //执行链码     res, ccevent, err = chaincode.ExecuteChaincode(ctxt, cccid, cis.ChaincodeSpec.Input.Args)     //如果是生命周期管理系统链码，并且参数为实例化或升级     if cid.Name == "lscc" && len(cis.ChaincodeSpec.Input.Args) >= 3 && (string(cis.ChaincodeSpec.Input.Args[0]) == "deploy" || string(cis.ChaincodeSpec.Input.Args[0]) == "upgrade") {         var cds *pb.ChaincodeDeploymentSpec         //获取ChaincodeDeploymentSpec         cds, err = putils.GetChaincodeDeploymentSpec(cis.ChaincodeSpec.Input.Args[2])         //待实例化或升级的链码执行实例化或升级         cccid = ccprovider.NewCCContext(chainID, cds.ChaincodeSpec.ChaincodeId.Name, cds.ChaincodeSpec.ChaincodeId.Version, txid, false, signedProp, prop)         _, _, err = chaincode.Execute(ctxt, cccid, cds)     }     return res, ccevent, err } //代码在core/endorser/endorser.go

Chaincode更详细内容，参考：Fabric 1.0源代码笔记 之 Chaincode（链码）

3.2.4、为提案背书，构造ProposalResponse并返回给Endorser客户端

var pResp *pb.ProposalResponse //为提案背书，即调取escc系统链码 pResp, err = e.endorseProposal(ctx, chainID, txid, signedProp, prop, res, simulationResult, ccevent, hdrExt.PayloadVisibility, hdrExt.ChaincodeId, txsim, cd) pResp.Response.Payload = res.Payload return pResp, nil //代码在core/endorser/endorser.go

e.endorseProposal(ctx, chainID, txid, signedProp, prop, res, simulationResult, ccevent, hdrExt.PayloadVisibility, hdrExt.ChaincodeId, txsim, cd)代码如下：

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) {     isSysCC := cd == nil     var escc string     if isSysCC {         escc = "escc"     } else {         escc = cd.Escc     }     var err error     var eventBytes []byte     if event != nil {         eventBytes, err = putils.GetBytesChaincodeEvent(event)     }     resBytes, err := putils.GetBytesResponse(response)     if isSysCC {         ccid.Version = util.GetSysCCVersion()     } else {         ccid.Version = cd.Version     }     ccidBytes, err := putils.Marshal(ccid)     args := [][]byte{[]byte(""), proposal.Header, proposal.Payload, ccidBytes, resBytes, simRes, eventBytes, visibility}     version := util.GetSysCCVersion()     ecccis := &pb.ChaincodeInvocationSpec{ChaincodeSpec: &pb.ChaincodeSpec{Type: pb.ChaincodeSpec_GOLANG, ChaincodeId: &pb.ChaincodeID{Name: escc}, Input: &pb.ChaincodeInput{Args: args}}}     //执行escc系统链码     res, _, err := e.callChaincode(ctx, chainID, version, txid, signedProp, proposal, ecccis, &pb.ChaincodeID{Name: escc}, txsim)     prBytes := res.Payload     pResp, err := putils.GetProposalResponse(prBytes)     return pResp, nil } //代码在core/endorser/endorser.go