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local_peer.go
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local_peer.go
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package router
import (
"fmt"
"log"
"net"
)
type LocalPeer struct {
*Peer
Router *Router
queryChan chan<- *PeerInteraction
}
type PeerInteraction struct {
Interaction
payload interface{}
}
func StartLocalPeer(name PeerName, router *Router) *LocalPeer {
peer := &LocalPeer{Peer: NewPeer(name, 0, 0), Router: router}
queryChan := make(chan *PeerInteraction, ChannelSize)
peer.queryChan = queryChan
go peer.queryLoop(queryChan)
return peer
}
func (peer *LocalPeer) Forward(dstPeer *Peer, df bool, frame []byte, dec *EthernetDecoder) error {
return peer.Relay(peer.Peer, dstPeer, df, frame, dec)
}
func (peer *LocalPeer) Broadcast(df bool, frame []byte, dec *EthernetDecoder) error {
return peer.RelayBroadcast(peer.Peer, df, frame, dec)
}
func (peer *LocalPeer) Relay(srcPeer, dstPeer *Peer, df bool, frame []byte, dec *EthernetDecoder) error {
relayPeerName, found := peer.Router.Routes.Unicast(dstPeer.Name)
if !found {
// Not necessarily an error as there could be a race with the
// dst disappearing whilst the frame is in flight
log.Println("Received packet for unknown destination:", dstPeer.Name)
return nil
}
conn, found := peer.ConnectionTo(relayPeerName)
if !found {
// Again, could just be a race, not necessarily an error
log.Println("Unable to find connection to relay peer", relayPeerName)
return nil
}
return conn.(*LocalConnection).Forward(df, &ForwardedFrame{
srcPeer: srcPeer,
dstPeer: dstPeer,
frame: frame},
dec)
}
func (peer *LocalPeer) RelayBroadcast(srcPeer *Peer, df bool, frame []byte, dec *EthernetDecoder) error {
nextHops := peer.Router.Routes.Broadcast(srcPeer.Name)
if len(nextHops) == 0 {
return nil
}
// We must not hold a read lock on peer during the conn.Forward
// below, since that is a potentially blocking operation (e.g. if
// the channel is full).
nextConns := make([]*LocalConnection, 0, len(nextHops))
peer.RLock()
for _, hopName := range nextHops {
conn, found := peer.connections[hopName]
// Again, !found could just be due to a race.
if found {
nextConns = append(nextConns, conn.(*LocalConnection))
}
}
peer.RUnlock()
var err error
for _, conn := range nextConns {
err = conn.Forward(df, &ForwardedFrame{
srcPeer: srcPeer,
dstPeer: conn.Remote(),
frame: frame},
dec)
if err != nil {
return err
}
}
return nil
}
func (peer *LocalPeer) CreateConnection(peerAddr string, acceptNewPeer bool) error {
if err := peer.checkConnectionLimit(); err != nil {
return err
}
// We're dialing the remote so that means connections will come from random ports
addrStr := NormalisePeerAddr(peerAddr)
tcpAddr, tcpErr := net.ResolveTCPAddr("tcp4", addrStr)
udpAddr, udpErr := net.ResolveUDPAddr("udp4", addrStr)
if tcpErr != nil || udpErr != nil {
// they really should have the same value, but just in case...
if tcpErr == nil {
return udpErr
}
return tcpErr
}
tcpConn, err := net.DialTCP("tcp4", nil, tcpAddr)
if err != nil {
return err
}
connRemote := NewRemoteConnection(peer.Peer, nil, tcpConn.RemoteAddr().String())
NewLocalConnection(connRemote, acceptNewPeer, tcpConn, udpAddr, peer.Router)
return nil
}
// ACTOR client API
const (
PAddConnection = iota
PBroadcastTCP = iota
PDeleteConnection = iota
PConnectionEstablished = iota
)
// Async: rely on the peer to shut us down if we shouldn't be adding
// ourselves, so therefore this can be async
func (peer *LocalPeer) AddConnection(conn *LocalConnection) {
peer.queryChan <- &PeerInteraction{
Interaction: Interaction{code: PAddConnection},
payload: conn}
}
// Sync.
func (peer *LocalPeer) DeleteConnection(conn *LocalConnection) {
resultChan := make(chan interface{})
peer.queryChan <- &PeerInteraction{
Interaction: Interaction{code: PDeleteConnection, resultChan: resultChan},
payload: conn}
<-resultChan
}
// Async.
func (peer *LocalPeer) ConnectionEstablished(conn *LocalConnection) {
peer.queryChan <- &PeerInteraction{
Interaction: Interaction{code: PConnectionEstablished},
payload: conn}
}
// Async.
func (peer *LocalPeer) BroadcastTCP(msg []byte) {
peer.queryChan <- &PeerInteraction{
Interaction: Interaction{code: PBroadcastTCP},
payload: msg}
}
// ACTOR server
func (peer *LocalPeer) queryLoop(queryChan <-chan *PeerInteraction) {
for {
query, ok := <-queryChan
if !ok {
return
}
switch query.code {
case PAddConnection:
peer.handleAddConnection(query.payload.(*LocalConnection))
case PDeleteConnection:
peer.handleDeleteConnection(query.payload.(*LocalConnection))
query.resultChan <- nil
case PConnectionEstablished:
peer.handleConnectionEstablished(query.payload.(*LocalConnection))
case PBroadcastTCP:
peer.handleBroadcastTCP(query.payload.([]byte))
}
}
}
func (peer *LocalPeer) handleAddConnection(conn *LocalConnection) {
if peer.Peer != conn.Local() {
log.Fatal("Attempt made to add connection to peer where peer is not the source of connection")
}
if conn.Remote() == nil {
log.Fatal("Attempt made to add connection to peer with unknown remote peer")
}
toName := conn.Remote().Name
dupErr := fmt.Errorf("Multiple connections to %s added to %s", toName, peer.Name)
// deliberately non symmetrical
if dupConn, found := peer.connections[toName]; found {
if dupConn == conn {
return
}
// conn.UID is used as the tie breaker here, in the
// knowledge that both sides will make the same decision.
dupConnLocal := dupConn.(*LocalConnection)
if conn.UID == dupConnLocal.UID {
// oh good grief. Sod it, just kill both of them.
conn.CheckFatal(dupErr)
dupConnLocal.CheckFatal(dupErr)
peer.handleDeleteConnection(dupConnLocal)
return
} else if conn.UID < dupConnLocal.UID {
dupConnLocal.CheckFatal(dupErr)
peer.handleDeleteConnection(dupConnLocal)
} else {
conn.CheckFatal(dupErr)
return
}
}
if err := peer.checkConnectionLimit(); err != nil {
conn.CheckFatal(err)
return
}
peer.Lock()
peer.connections[toName] = conn
peer.Unlock()
}
func (peer *LocalPeer) handleDeleteConnection(conn *LocalConnection) {
if peer.Peer != conn.Local() {
log.Fatal("Attempt made to delete connection from peer where peer is not the source of connection")
}
if conn.Remote() == nil {
log.Fatal("Attempt made to delete connection to peer with unknown remote peer")
}
toName := conn.Remote().Name
if connFound, found := peer.connections[toName]; !found || connFound != conn {
return
}
peer.Lock()
delete(peer.connections, toName)
peer.Unlock()
broadcast := false
if conn.Established() {
peer.Lock()
peer.version += 1
peer.Unlock()
broadcast = true
}
// Must do garbage collection first to ensure we don't send out an
// update with unreachable peers (can cause looping)
peer.Router.Peers.GarbageCollect()
if broadcast {
peer.broadcastPeerUpdate()
}
}
func (peer *LocalPeer) handleConnectionEstablished(conn *LocalConnection) {
if peer.Peer != conn.Local() {
log.Fatal("Peer informed of active connection where peer is not the source of connection")
}
if dupConn, found := peer.connections[conn.Remote().Name]; !found || conn != dupConn {
conn.CheckFatal(fmt.Errorf("Cannot set unknown connection active"))
return
}
peer.Lock()
peer.version += 1
peer.Unlock()
log.Println("Peer", peer.Name, "established active connection to remote peer", conn.Remote().Name, "at", conn.RemoteTCPAddr())
peer.broadcastPeerUpdate(conn.Remote())
}
func (peer *LocalPeer) handleBroadcastTCP(msg []byte) {
peer.ForEachConnection(func(_ PeerName, conn Connection) {
conn.(*LocalConnection).SendTCP(msg)
})
}
func (peer *LocalPeer) broadcastPeerUpdate(peers ...*Peer) {
peer.Router.Routes.Recalculate()
peer.handleBroadcastTCP(Concat(ProtocolUpdateByte, EncodePeers(append(peers, peer.Peer)...)))
}
func (peer *LocalPeer) checkConnectionLimit() error {
if 0 != peer.Router.ConnLimit && peer.ConnectionCount() >= peer.Router.ConnLimit {
return fmt.Errorf("Connection limit reached (%v)", peer.Router.ConnLimit)
}
return nil
}