btcd的p2p网络（3）-连接ConnMgr-连接成功之后

我们继续上一节，先简要回顾一下
我们主要通过一下几个步骤建立了一个连接

func (cm *ConnManager) Start() {
    for i := atomic.LoadUint64(&cm.connReqCount); i < uint64(cm.cfg.TargetOutbound); i++ {
        go cm.NewConnReq()
    }
}

func (cm *ConnManager) NewConnReq() {
    ......
    c := &ConnReq{}
    addr, err := cm.cfg.GetNewAddress()
    c.Addr = addr
    cm.Connect(c)
}

// Connect assigns an id and dials a connection to the address of the
// connection request.
func (cm *ConnManager) Connect(c *ConnReq) {
    ......
    conn, err := cm.cfg.Dial(c.Addr)
    select {
    case cm.requests <- handleConnected{c, conn}:
    case <-cm.quit:
    }
}

然后在工作协程中

func (cm *ConnManager) connHandler() {

    var (
        // pending holds all registered conn requests that have yet to
        // succeed.
        pending = make(map[uint64]*ConnReq)

        // conns represents the set of all actively connected peers.
        conns = make(map[uint64]*ConnReq, cm.cfg.TargetOutbound)
    )

out:
    for {
        select {
        case req := <-cm.requests:
            switch msg := req.(type) {

            case registerPending:
                connReq := msg.c
                connReq.updateState(ConnPending)
                pending[msg.c.id] = connReq
                close(msg.done)
            // 连城成功后的处理
            case handleConnected:
                connReq := msg.c

                if _, ok := pending[connReq.id]; !ok {
                    if msg.conn != nil {
                        msg.conn.Close()
                    }
                    log.Debugf("Ignoring connection for "+
                        "canceled connreq=%v", connReq)
                    continue
                }

                connReq.updateState(ConnEstablished)
                connReq.conn = msg.conn
                conns[connReq.id] = connReq
                log.Debugf("Connected to %v", connReq)
                connReq.retryCount = 0
                cm.failedAttempts = 0

                delete(pending, connReq.id)

                if cm.cfg.OnConnection != nil {
                    go cm.cfg.OnConnection(connReq, msg.conn)
                }
}

我们接下来主要看的是，连接成功后干什么？

我们就来找cm.cfg.OnConnection(),在编辑器中全局搜索之后发现，OnConnection()只有在server.go中配置了,server.go中newServer()方法中

    cmgr, err := connmgr.New(&connmgr.Config{
        Listeners:      listeners,
        OnAccept:       s.inboundPeerConnected,
        RetryDuration:  connectionRetryInterval,
        TargetOutbound: uint32(targetOutbound),
        Dial:           btcdDial,
        OnConnection:   s.outboundPeerConnected,
        GetNewAddress:  newAddressFunc,
    })

就是这句OnConnection: s.outboundPeerConnected,然后我们就去找outboundPeerConnected,发现outboundPeerConnected是一个函数，这和我们连接成功调用时是符合的：go cm.cfg.OnConnection(connReq, msg.conn)

// outboundPeerConnected is invoked by the connection manager when a new
// outbound connection is established.  It initializes a new outbound server
// peer instance, associates it with the relevant state such as the connection
// request instance and the connection itself, and finally notifies the address
// manager of the attempt.
func (s *server) outboundPeerConnected(c *connmgr.ConnReq, conn net.Conn) {
    sp := newServerPeer(s, c.Permanent)
    p, err := peer.NewOutboundPeer(newPeerConfig(sp), c.Addr.String())
    if err != nil {
        srvrLog.Debugf("Cannot create outbound peer %s: %v", c.Addr, err)
        s.connManager.Disconnect(c.ID())
    }
    sp.Peer = p
    sp.connReq = c
    sp.isWhitelisted = isWhitelisted(conn.RemoteAddr())
    sp.AssociateConnection(conn)
    go s.peerDoneHandler(sp)
    s.addrManager.Attempt(sp.NA())
}

我们看到连接成功后，需要用到peer包来处理。请看霞姐的peer