兄弟连区块链教程Fabric1.0源代码分析scc（系统链码）cscc（通道相关），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 scc（系统链码） #cscc（通道相关）
## 1、cscc概述
cscc代码在core/scc/cscc/configure.go。
## 2、PeerConfiger结构体
```go
type PeerConfiger struct {
policyChecker policy.PolicyChecker
}
//代码在core/scc/cscc/configure.go
```
## 3、Init方法
```go
func (e *PeerConfiger) Init(stub shim.ChaincodeStubInterface) pb.Response {
//初始化策略检查器，用于访问控制
e.policyChecker = policy.NewPolicyChecker(
peer.NewChannelPolicyManagerGetter(),
mgmt.GetLocalMSP(),
mgmt.NewLocalMSPPrincipalGetter(),
)
return shim.Success(nil)
}
//代码在core/scc/cscc/configure.go
```
## 4、Invoke方法
```go
func (e *PeerConfiger) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
//args[0]为JoinChain或GetChannels
args := stub.GetArgs()
fname := string(args[0]) //Invoke function
sp, err := stub.GetSignedProposal() //获取SignedProposal
switch fname {
case JoinChain: //加入通道
//此处args[1]为创世区块
block, err := utils.GetBlockFromBlockBytes(args[1])
cid, err := utils.GetChainIDFromBlock(block)
err := validateConfigBlock(block)
err = e.policyChecker.CheckPolicyNoChannel(mgmt.Admins, sp)
return joinChain(cid, block)
case GetConfigBlock:
err = e.policyChecker.CheckPolicy(string(args[1]), policies.ChannelApplicationReaders, sp)
return getConfigBlock(args[1])
case GetChannels:
err = e.policyChecker.CheckPolicyNoChannel(mgmt.Members, sp)
return getChannels()
}
}
//代码在core/scc/cscc/configure.go
```
## 5、其他方法
```go
//校验创世区块
func validateConfigBlock(block *common.Block) error
func joinChain(chainID string, block *common.Block) pb.Response
func getConfigBlock(chainID []byte) pb.Response
func getChannels() pb.Response
//代码在core/scc/cscc/configure.go
```
### 5.1、joinChain
```go
func joinChain(chainID string, block *common.Block) pb.Response {
err := peer.CreateChainFromBlock(block) //创建chain
peer.InitChain(chainID)
err := producer.SendProducerBlockEvent(block)
return shim.Success(nil)
}
//代码在core/scc/cscc/configure.go
```
#### 5.1.1、创建Chain（或channel）
peer.CreateChainFromBlock(block)代码如下：
```go
func CreateChainFromBlock(cb *common.Block) error {
cid, err := utils.GetChainIDFromBlock(cb) //获取ChainID
var l ledger.PeerLedger
l, err = ledgermgmt.CreateLedger(cb) //创建Ledger
return createChain(cid, l, cb)
}
//代码在core/peer/peer.go
```
createChain(cid, l, cb)代码如下：
```go
func createChain(cid string, ledger ledger.PeerLedger, cb *common.Block) error {
envelopeConfig, err := utils.ExtractEnvelope(cb, 0) //获取配置Envelope
configtxInitializer := configtx.NewInitializer() //type initializer struct
gossipEventer := service.GetGossipService().NewConfigEventer() //获取gossipServiceInstance
gossipCallbackWrapper := func(cm configtxapi.Manager) {
ac, ok := configtxInitializer.ApplicationConfig()
if !ok {
// TODO, handle a missing ApplicationConfig more gracefully
ac = nil
}
gossipEventer.ProcessConfigUpdate(&chainSupport{
Manager: cm,
Application: ac,
})
service.GetGossipService().SuspectPeers(func(identity api.PeerIdentityType) bool {
// TODO: this is a place-holder that would somehow make the MSP layer suspect
// that a given certificate is revoked, or its intermediate CA is revoked.
// In the meantime, before we have such an ability, we return true in order
// to suspect ALL identities in order to validate all of them.
return true
})
}
trustedRootsCallbackWrapper := func(cm configtxapi.Manager) {
updateTrustedRoots(cm)
}
configtxManager, err := configtx.NewManagerImpl(
envelopeConfig,
configtxInitializer,
[]func(cm configtxapi.Manager){gossipCallbackWrapper, trustedRootsCallbackWrapper},
)
if err != nil {
return err
}
// TODO remove once all references to mspmgmt are gone from peer code
mspmgmt.XXXSetMSPManager(cid, configtxManager.MSPManager())
ac, ok := configtxInitializer.ApplicationConfig()
if !ok {
ac = nil
}
cs := &chainSupport{
Manager: configtxManager,
Application: ac, // TODO, refactor as this is accessible through Manager
ledger: ledger,
}
c := committer.NewLedgerCommitterReactive(ledger, txvalidator.NewTxValidator(cs), func(block *common.Block) error {
chainID, err := utils.GetChainIDFromBlock(block)
if err != nil {
return err
}
return SetCurrConfigBlock(block, chainID)
})
ordererAddresses := configtxManager.ChannelConfig().OrdererAddresses()
if len(ordererAddresses) == 0 {
return errors.New("No ordering service endpoint provided in configuration block")
}
service.GetGossipService().InitializeChannel(cs.ChainID(), c, ordererAddresses)
chains.Lock()
defer chains.Unlock()
chains.list[cid] = &chain{
cs: cs,
cb: cb,
committer: c,
}
return nil
}
//代码在core/peer/peer.go
```
补充initializer：
```go
type initializer struct {
*resources
ppr *policyProposerRoot
}
//代码在common/configtx/initializer.go
```
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