区块链教程Fabric1.0源代码分析policy（背书策略），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 policy（背书策略）

1、policy概述

policy代码分布在core/policy、core/policyprovider、common/policies目录下。目录结构如下：

• core/policy/policy.go，PolicyChecker接口定义及实现、PolicyCheckerFactory接口定义。
• core/policyprovider/provider.go，PolicyChecker工厂默认实现。
• common/policies目录
      * policy.go，ChannelPolicyManagerGetter接口及实现。

    * implicitmeta_util.go，通道策略工具函数。

2、PolicyChecker工厂

2.1、PolicyCheckerFactory接口定义

type PolicyCheckerFactory interface {     NewPolicyChecker() PolicyChecker //构造PolicyChecker实例 } var pcFactory PolicyCheckerFactory //全局变量定义及赋值函数 func RegisterPolicyCheckerFactory(f PolicyCheckerFactory) {     pcFactory = f } //代码在core/policy/policy.go

2.2、PolicyCheckerFactory接口默认实现

type defaultFactory struct{} //构造policy.PolicyChecker func (f *defaultFactory) NewPolicyChecker() policy.PolicyChecker {     return policy.NewPolicyChecker(         peer.NewChannelPolicyManagerGetter(), //&channelPolicyManagerGetter{}         mgmt.GetLocalMSP(),         mgmt.NewLocalMSPPrincipalGetter(),     ) } //获取policy.PolicyChecker，即调用policy.GetPolicyChecker() func GetPolicyChecker() policy.PolicyChecker func init() { //初始化全局变量pcFactory     policy.RegisterPolicyCheckerFactory(&defaultFactory{}) }

3、PolicyChecker接口定义及实现

3.1、PolicyChecker接口定义

type PolicyChecker interface {     CheckPolicy(channelID, policyName string, signedProp *pb.SignedProposal) error     CheckPolicyBySignedData(channelID, policyName string, sd []*common.SignedData) error     CheckPolicyNoChannel(policyName string, signedProp *pb.SignedProposal) error } //代码在core/policy/policy.go

3.2、PolicyChecker接口实现

PolicyChecker接口实现，即policyChecker结构体及方法。

type policyChecker struct {     channelPolicyManagerGetter policies.ChannelPolicyManagerGetter //通道策略管理器     localMSP msp.IdentityDeserializer //身份     principalGetter mgmt.MSPPrincipalGetter //委托人 } //构造policyChecker func NewPolicyChecker(channelPolicyManagerGetter policies.ChannelPolicyManagerGetter, localMSP msp.IdentityDeserializer, principalGetter mgmt.MSPPrincipalGetter) PolicyChecker //检查签名提案是否符合通道策略 func (p *policyChecker) CheckPolicy(channelID, policyName string, signedProp *pb.SignedProposal) error func (p *policyChecker) CheckPolicyNoChannel(policyName string, signedProp *pb.SignedProposal) error //检查签名数据是否符合通道策略，获取策略并调取policy.Evaluate(sd) func (p *policyChecker) CheckPolicyBySignedData(channelID, policyName string, sd []*common.SignedData) error func GetPolicyChecker() PolicyChecker //pcFactory.NewPolicyChecker() //代码在core/policy/policy.go

func (p policyChecker) CheckPolicy(channelID, policyName string, signedProp pb.SignedProposal) error代码如下：

func (p *policyChecker) CheckPolicy(channelID, policyName string, signedProp *pb.SignedProposal) error {     if channelID == "" { //channelID为空，调取CheckPolicyNoChannel()         return p.CheckPolicyNoChannel(policyName, signedProp)     }          policyManager, _ := p.channelPolicyManagerGetter.Manager(channelID)     proposal, err := utils.GetProposal(signedProp.ProposalBytes) //获取proposal     header, err := utils.GetHeader(proposal.Header)     shdr, err := utils.GetSignatureHeader(header.SignatureHeader) //SignatureHeader     sd := []*common.SignedData{&common.SignedData{         Data: signedProp.ProposalBytes,         Identity: shdr.Creator,         Signature: signedProp.Signature,     }}     return p.CheckPolicyBySignedData(channelID, policyName, sd) } //代码在core/policy/policy.go

4、ChannelPolicyManagerGetter接口及实现

4.1、ChannelPolicyManagerGetter接口定义

type ChannelPolicyManagerGetter interface {     Manager(channelID string) (Manager, bool) } //代码在common/policies/policy.go

4.2、ChannelPolicyManagerGetter接口实现

ChannelPolicyManagerGetter接口实现，即ManagerImpl结构体及方法。

type ManagerImpl struct {     parent *ManagerImpl     basePath string     fqPrefix string     providers map[int32]Provider //type Provider interface     config *policyConfig //type policyConfig struct     pendingConfig map[interface{}]*policyConfig //type policyConfig struct     pendingLock sync.RWMutex     SuppressSanityLogMessages bool } type Provider interface {     NewPolicy(data []byte) (Policy, proto.Message, error) } type policyConfig struct {     policies map[string]Policy //type Policy interface     managers map[string]*ManagerImpl     imps []*implicitMetaPolicy } type Policy interface {     //对给定的签名数据，按规则检验确认是否符合约定的条件     Evaluate(signatureSet []*cb.SignedData) error } //构造ManagerImpl func NewManagerImpl(basePath string, providers map[int32]Provider) *ManagerImpl //获取pm.basePath func (pm *ManagerImpl) BasePath() string //获取pm.config.policies，即map[string]Policy中Key列表 func (pm *ManagerImpl) PolicyNames() []string //获取指定路径的子管理器 func (pm *ManagerImpl) Manager(path []string) (Manager, bool) //获取pm.config.policies[relpath] //获取Policy func (pm *ManagerImpl) GetPolicy(id string) (Policy, bool) func (pm *ManagerImpl) BeginPolicyProposals(tx interface{}, groups []string) ([]Proposer, error) func (pm *ManagerImpl) RollbackProposals(tx interface{}) func (pm *ManagerImpl) PreCommit(tx interface{}) error func (pm *ManagerImpl) CommitProposals(tx interface{}) func (pm *ManagerImpl) ProposePolicy(tx interface{}, key string, configPolicy *cb.ConfigPolicy) (proto.Message, error) //代码在common/policies/policy.go

type implicitMetaPolicy struct {     conf *cb.ImplicitMetaPolicy     threshold int     subPolicies []Policy } //代码在common/policies/implicitmeta.go

5、通道策略工具函数

type ImplicitMetaPolicy_Rule int32 const (     ImplicitMetaPolicy_ANY ImplicitMetaPolicy_Rule = 0 //任意     ImplicitMetaPolicy_ALL ImplicitMetaPolicy_Rule = 1 //所有     ImplicitMetaPolicy_MAJORITY ImplicitMetaPolicy_Rule = 2 //大多数 ) //代码在protos/common/policies.pb.go

//构造cb.Policy func ImplicitMetaPolicyWithSubPolicy(subPolicyName string, rule cb.ImplicitMetaPolicy_Rule) *cb.ConfigPolicy func TemplateImplicitMetaPolicyWithSubPolicy(path []string, policyName string, subPolicyName string, rule cb.ImplicitMetaPolicy_Rule) *cb.ConfigGroup //调取TemplateImplicitMetaPolicyWithSubPolicy(path, policyName, policyName, rule) func TemplateImplicitMetaPolicy(path []string, policyName string, rule cb.ImplicitMetaPolicy_Rule) *cb.ConfigGroup //任意，TemplateImplicitMetaPolicy(path, policyName, cb.ImplicitMetaPolicy_ANY) func TemplateImplicitMetaAnyPolicy(path []string, policyName string) *cb.ConfigGroup //所有，TemplateImplicitMetaPolicy(path, policyName, cb.ImplicitMetaPolicy_ALL) func TemplateImplicitMetaAllPolicy(path []string, policyName string) *cb.ConfigGroup //大多数，TemplateImplicitMetaPolicy(path, policyName, cb.ImplicitMetaPolicy_MAJORITY) func TemplateImplicitMetaMajorityPolicy(path []string, policyName string) *cb.ConfigGroup //代码在common/policies/implicitmeta_util.go