https://github.com/Bytom/bytom
本章介绍bytom代码P2P网络中addrbook地址簿
作者使用MacOS操作系统,其他平台也大同小异
Golang Version: 1.8
addrbook介绍
addrbook用于存储P2P网络中保留最近的对端节点地址
在MacOS下,默认的地址簿路径存储在~/Library/Bytom/addrbook.json
地址簿格式
- ** ~/Library/Bytom/addrbook.json **
- {
- "Key": "359be6d08bc0c6e21c84bbb2",
- "Addrs": [
- {
- "Addr": {
- "IP": "122.224.11.144",
- "Port": 46657
- },
- "Src": {
- "IP": "198.74.61.131",
- "Port": 46657
- },
- "Attempts": 0,
- "LastAttempt": "2018-05-04T12:58:23.894057702+08:00",
- "LastSuccess": "0001-01-01T00:00:00Z",
- "BucketType": 1,
- "Buckets": [
- 181,
- 10
- ]
- }
- ]
- }
地址类型
在addrbook中存储的地址有两种:
- ** p2p/addrbook.go **
- const (
- bucketTypeNew = 0x01 // 标识新地址,不可靠地址(未成功连接过)。只存储在一个bucket中
- bucketTypeOld = 0x02 // 标识旧地址,可靠地址(已成功连接过)。可以存储在多个bucket中,最多为maxNewBucketsPerAddress个
- )
注意: 一个地址的类型变更不在此文章中做介绍,后期的文章会讨论该问题
地址簿相关结构体
地址簿
- type AddrBook struct {
- cmn.BaseService
- mtx sync.Mutex
- filePath string // 地址簿路径
- routabilityStrict bool // 是否可路由,默认为true
- rand *rand.Rand
- key string // 地址簿标识,用于计算addrNew和addrOld的索引
- ourAddrs map[string]*NetAddress // 存储本地网络地址,用于添加p2p地址时做排除使用
- addrLookup map[string]*knownAddress // 存储新、旧地址集,用于查询
- addrNew []map[string]*knownAddress // 存储新地址
- addrOld []map[string]*knownAddress // 存储旧地址
- wg sync.WaitGroup
- nOld int // 旧地址数量
- nNew int // 新地址数量
- }
已知地址
- type knownAddress struct {
- Addr *NetAddress // 已知peer的addr
- Src *NetAddress // 已知peer的addr的来源addr
- Attempts int32 // 连接peer的重试次数
- LastAttempt time.Time // 最近一次尝试连接的时间
- LastSuccess time.Time // 最近一次尝试成功连接的时间
- BucketType byte // 地址的类型(表示可靠地址或不可靠地址)
- Buckets []int // 当前addr所属的buckets
- }
routabilityStrict参数表示地址簿是否存储的ip是否可路由。可路由是根据RFC划分,具体参考资料:RFC标准
初始化地址簿
- // NewAddrBook creates a new address book.
- // Use Start to begin processing asynchronous address updates.
- func NewAddrBook(filePath string, routabilityStrict bool) *AddrBook {
- am := &AddrBook{
- rand: rand.New(rand.NewSource(time.Now().UnixNano())),
- ourAddrs: make(map[string]*NetAddress),
- addrLookup: make(map[string]*knownAddress),
- filePath: filePath,
- routabilityStrict: routabilityStrict,
- }
- am.init()
- am.BaseService = *cmn.NewBaseService(nil, "AddrBook", am)
- return am
- }
- // When modifying this, don't forget to update loadFromFile()
- func (a *AddrBook) init() {
- // 地址簿唯一标识
- a.key = crypto.CRandHex(24) // 24/2 * 8 = 96 bits
- // New addr buckets, 默认为256个大小
- a.addrNew = make([]map[string]*knownAddress, newBucketCount)
- for i := range a.addrNew {
- a.addrNew<i> = make(map[string]*knownAddress)
- }
- // Old addr buckets,默认为64个大小
- a.addrOld = make([]map[string]*knownAddress, oldBucketCount)
- for i := range a.addrOld {
- a.addrOld<i> = make(map[string]*knownAddress)
- }
- }</i></i>
bytomd启动时加载本地地址簿
loadFromFile在bytomd启动时,首先会加载本地的地址簿
- // OnStart implements Service.
- func (a *AddrBook) OnStart() error {
- a.BaseService.OnStart()
- a.loadFromFile(a.filePath)
- a.wg.Add(1)
- go a.saveRoutine()
- return nil
- }
- // Returns false if file does not exist.
- // cmn.Panics if file is corrupt.
- func (a *AddrBook) loadFromFile(filePath string) bool {
- // If doesn't exist, do nothing.
- // 如果本地地址簿不存在则直接返回
- _, err := os.Stat(filePath)
- if os.IsNotExist(err) {
- return false
- }
- // 加载地址簿json内容
- // Load addrBookJSON{}
- r, err := os.Open(filePath)
- if err != nil {
- cmn.PanicCrisis(cmn.Fmt("Error opening file %s: %v", filePath, err))
- }
- defer r.Close()
- aJSON := &addrBookJSON{}
- dec := json.NewDecoder(r)
- err = dec.Decode(aJSON)
- if err != nil {
- cmn.PanicCrisis(cmn.Fmt("Error reading file %s: %v", filePath, err))
- }
- // 填充addrNew、addrOld等
- // Restore all the fields...
- // Restore the key
- a.key = aJSON.Key
- // Restore .addrNew & .addrOld
- for _, ka := range aJSON.Addrs {
- for _, bucketIndex := range ka.Buckets {
- bucket := a.getBucket(ka.BucketType, bucketIndex)
- bucket[ka.Addr.String()] = ka
- }
- a.addrLookup[ka.Addr.String()] = ka
- if ka.BucketType == bucketTypeNew {
- a.nNew++
- } else {
- a.nOld++
- }
- }
- return true
- }
定时更新地址簿
bytomd会定时更新本地地址簿,默认2分钟一次
- func (a *AddrBook) saveRoutine() {
- dumpAddressTicker := time.NewTicker(dumpAddressInterval)
- out:
- for {
- select {
- case
添加新地址
当peer之间交换addr时,节点会收到对端节点已知的地址信息,这些信息会被当前节点添加到地址簿中
- func (a *AddrBook) AddAddress(addr *NetAddress, src *NetAddress) {
- a.mtx.Lock()
- defer a.mtx.Unlock()
- log.WithFields(log.Fields{
- "addr": addr,
- "src": src,
- }).Debug("Add address to book")
- a.addAddress(addr, src)
- }
- func (a *AddrBook) addAddress(addr, src *NetAddress) {
- // 验证地址是否为可路由地址
- if a.routabilityStrict && !addr.Routable() {
- log.Error(cmn.Fmt("Cannot add non-routable address %v", addr))
- return
- }
- // 验证地址是否为本地节点地址
- if _, ok := a.ourAddrs[addr.String()]; ok {
- // Ignore our own listener address.
- return
- }
- // 验证地址是否存在地址集中
- // 如果存在:则判断该地址是否为old可靠地址、是否超过了最大buckets中。否则根据该地址已经被ka.Buckets引用的个数来随机决定是否添加到地址集中
- // 如果不存在:则添加到地址集中。并标识为bucketTypeNew地址类型
- ka := a.addrLookup[addr.String()]
- if ka != nil {
- // Already old.
- if ka.isOld() {
- return
- }
- // Already in max new buckets.
- if len(ka.Buckets) == maxNewBucketsPerAddress {
- return
- }
- // The more entries we have, the less likely we are to add more.
- factor := int32(2 * len(ka.Buckets))
- if a.rand.Int31n(factor) != 0 {
- return
- }
- } else {
- ka = newKnownAddress(addr, src)
- }
- // 找到该地址在地址集的索引位置并添加
- bucket := a.calcNewBucket(addr, src)
- a.addToNewBucket(ka, bucket)
- log.Info("Added new address ", "address:", addr, " total:", a.size())
- }
选择最优节点
地址簿中存储众多地址,在p2p网络中需选择最优的地址去连接
PickAddress(newBias int)函数中newBias是由pex_reactor产生的地址评分。如何计算地址分数在其他章节中再讲
根据地址评分随机选择地址可增加区块链安全性
- // Pick an address to connect to with new/old bias.
- func (a *AddrBook) PickAddress(newBias int) *NetAddress {
- a.mtx.Lock()
- defer a.mtx.Unlock()
- if a.size() == 0 {
- return nil
- }
- // newBias地址分数限制在0-100分数之间
- if newBias > 100 {
- newBias = 100
- }
- if newBias
移除一个地址
当一个地址被标记为Bad时则从地址集中移除。目前bytomd的代码版本并未调用过
- func (a *AddrBook) MarkBad(addr *NetAddress) {
- a.RemoveAddress(addr)
- }
- // RemoveAddress removes the address from the book.
- func (a *AddrBook) RemoveAddress(addr *NetAddress) {
- a.mtx.Lock()
- defer a.mtx.Unlock()
- ka := a.addrLookup[addr.String()]
- if ka == nil {
- return
- }
- log.WithField("addr", addr).Info("Remove address from book")
- a.removeFromAllBuckets(ka)
- }
- func (a *AddrBook) removeFromAllBuckets(ka *knownAddress) {
- for _, bucketIdx := range ka.Buckets {
- bucket := a.getBucket(ka.BucketType, bucketIdx)
- delete(bucket, ka.Addr.String())
- }
- ka.Buckets = nil
- if ka.BucketType == bucketTypeNew {
- a.nNew--
- } else {
- a.nOld--
- }
- delete(a.addrLookup, ka.Addr.String())
- }