/usr/share/gocode/src/github.com/weaveworks/mesh/connection.go is in golang-github-weaveworks-mesh-dev 0+git20161024.3dd75b1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"fmt"
"net"
"strconv"
"time"
)
// Connection describes a link between peers.
// It may be in any state, not necessarily established.
type Connection interface {
Remote() *Peer
getLocal() *Peer
remoteTCPAddress() string
isOutbound() bool
isEstablished() bool
}
type ourConnection interface {
Connection
breakTie(ourConnection) connectionTieBreak
shutdown(error)
logf(format string, args ...interface{})
}
// A local representation of the remote side of a connection.
// Limited capabilities compared to LocalConnection.
type remoteConnection struct {
local *Peer
remote *Peer
remoteTCPAddr string
outbound bool
established bool
}
func newRemoteConnection(from, to *Peer, tcpAddr string, outbound bool, established bool) *remoteConnection {
return &remoteConnection{
local: from,
remote: to,
remoteTCPAddr: tcpAddr,
outbound: outbound,
established: established,
}
}
func (conn *remoteConnection) Remote() *Peer { return conn.remote }
func (conn *remoteConnection) getLocal() *Peer { return conn.local }
func (conn *remoteConnection) remoteTCPAddress() string { return conn.remoteTCPAddr }
func (conn *remoteConnection) isOutbound() bool { return conn.outbound }
func (conn *remoteConnection) isEstablished() bool { return conn.established }
// LocalConnection is the local (our) side of a connection.
// It implements ProtocolSender, and manages per-channel GossipSenders.
type LocalConnection struct {
OverlayConn OverlayConnection
remoteConnection
tcpConn *net.TCPConn
trustRemote bool // is remote on a trusted subnet?
trustedByRemote bool // does remote trust us?
version byte
tcpSender tcpSender
sessionKey *[32]byte
heartbeatTCP *time.Ticker
router *Router
uid uint64
actionChan chan<- connectionAction
errorChan chan<- error
finished <-chan struct{} // closed to signal that actorLoop has finished
senders *gossipSenders
logger Logger
}
// If the connection is successful, it will end up in the local peer's
// connections map.
func startLocalConnection(connRemote *remoteConnection, tcpConn *net.TCPConn, router *Router, acceptNewPeer bool, logger Logger) {
if connRemote.local != router.Ourself.Peer {
panic("attempt to create local connection from a peer which is not ourself")
}
actionChan := make(chan connectionAction, ChannelSize)
errorChan := make(chan error, 1)
finished := make(chan struct{})
conn := &LocalConnection{
remoteConnection: *connRemote, // NB, we're taking a copy of connRemote here.
router: router,
tcpConn: tcpConn,
trustRemote: router.trusts(connRemote),
uid: randUint64(),
actionChan: actionChan,
errorChan: errorChan,
finished: finished,
logger: logger,
}
conn.senders = newGossipSenders(conn, finished)
go conn.run(actionChan, errorChan, finished, acceptNewPeer)
}
func (conn *LocalConnection) logf(format string, args ...interface{}) {
format = "->[" + conn.remoteTCPAddr + "|" + conn.remote.String() + "]: " + format
conn.logger.Printf(format, args...)
}
func (conn *LocalConnection) breakTie(dupConn ourConnection) connectionTieBreak {
dupConnLocal := dupConn.(*LocalConnection)
// conn.uid is used as the tie breaker here, in the knowledge that
// both sides will make the same decision.
if conn.uid < dupConnLocal.uid {
return tieBreakWon
} else if dupConnLocal.uid < conn.uid {
return tieBreakLost
}
return tieBreakTied
}
// Established returns true if the connection is established.
// TODO(pb): data race?
func (conn *LocalConnection) isEstablished() bool {
return conn.established
}
// SendProtocolMsg implements ProtocolSender.
func (conn *LocalConnection) SendProtocolMsg(m protocolMsg) error {
if err := conn.sendProtocolMsg(m); err != nil {
conn.shutdown(err)
return err
}
return nil
}
func (conn *LocalConnection) gossipSenders() *gossipSenders {
return conn.senders
}
// ACTOR methods
// NB: The conn.* fields are only written by the connection actor
// process, which is the caller of the ConnectionAction funs. Hence we
// do not need locks for reading, and only need write locks for fields
// read by other processes.
// Non-blocking.
func (conn *LocalConnection) shutdown(err error) {
// err should always be a real error, even if only io.EOF
if err == nil {
panic("nil error")
}
select {
case conn.errorChan <- err:
default:
}
}
// Send an actor request to the actorLoop, but don't block if actorLoop has
// exited. See http://blog.golang.org/pipelines for pattern.
func (conn *LocalConnection) sendAction(action connectionAction) {
select {
case conn.actionChan <- action:
case <-conn.finished:
}
}
// ACTOR server
func (conn *LocalConnection) run(actionChan <-chan connectionAction, errorChan <-chan error, finished chan<- struct{}, acceptNewPeer bool) {
var err error // important to use this var and not create another one with 'err :='
defer func() { conn.teardown(err) }()
defer close(finished)
if err = conn.tcpConn.SetLinger(0); err != nil {
return
}
intro, err := protocolIntroParams{
MinVersion: conn.router.ProtocolMinVersion,
MaxVersion: ProtocolMaxVersion,
Features: conn.makeFeatures(),
Conn: conn.tcpConn,
Password: conn.router.Password,
Outbound: conn.outbound,
}.doIntro()
if err != nil {
return
}
conn.sessionKey = intro.SessionKey
conn.tcpSender = intro.Sender
conn.version = intro.Version
remote, err := conn.parseFeatures(intro.Features)
if err != nil {
return
}
if err = conn.registerRemote(remote, acceptNewPeer); err != nil {
return
}
isRestartedPeer := conn.Remote().UID != remote.UID
conn.logf("connection ready; using protocol version %v", conn.version)
// only use negotiated session key for untrusted connections
var sessionKey *[32]byte
if conn.untrusted() {
sessionKey = conn.sessionKey
}
params := OverlayConnectionParams{
RemotePeer: conn.remote,
LocalAddr: conn.tcpConn.LocalAddr().(*net.TCPAddr),
RemoteAddr: conn.tcpConn.RemoteAddr().(*net.TCPAddr),
Outbound: conn.outbound,
ConnUID: conn.uid,
SessionKey: sessionKey,
SendControlMessage: conn.sendOverlayControlMessage,
Features: intro.Features,
}
if conn.OverlayConn, err = conn.router.Overlay.PrepareConnection(params); err != nil {
return
}
// As soon as we do AddConnection, the new connection becomes
// visible to the packet routing logic. So AddConnection must
// come after PrepareConnection
if err = conn.router.Ourself.doAddConnection(conn, isRestartedPeer); err != nil {
return
}
conn.router.ConnectionMaker.connectionCreated(conn)
// OverlayConnection confirmation comes after AddConnection,
// because only after that completes do we know the connection is
// valid: in particular that it is not a duplicate connection to
// the same peer. Overlay communication on a duplicate connection
// can cause problems such as tripping up overlay crypto at the
// other end due to data being decoded by the other connection. It
// is also generally wasteful to engage in any interaction with
// the remote on a connection that turns out to be invalid.
conn.OverlayConn.Confirm()
// receiveTCP must follow also AddConnection. In the absence
// of any indirect connectivity to the remote peer, the first
// we hear about it (and any peers reachable from it) is
// through topology gossip it sends us on the connection. We
// must ensure that the connection has been added to Ourself
// prior to processing any such gossip, otherwise we risk
// immediately gc'ing part of that newly received portion of
// the topology (though not the remote peer itself, since that
// will have a positive ref count), leaving behind dangling
// references to peers. Hence we must invoke AddConnection,
// which is *synchronous*, first.
conn.heartbeatTCP = time.NewTicker(tcpHeartbeat)
go conn.receiveTCP(intro.Receiver)
// AddConnection must precede actorLoop. More precisely, it
// must precede shutdown, since that invokes DeleteConnection
// and is invoked on termination of this entire
// function. Essentially this boils down to a prohibition on
// running AddConnection in a separate goroutine, at least not
// without some synchronisation. Which in turn requires the
// launching of the receiveTCP goroutine to precede actorLoop.
err = conn.actorLoop(actionChan, errorChan)
}
func (conn *LocalConnection) makeFeatures() map[string]string {
features := map[string]string{
"PeerNameFlavour": PeerNameFlavour,
"Name": conn.local.Name.String(),
"NickName": conn.local.NickName,
"ShortID": fmt.Sprint(conn.local.ShortID),
"UID": fmt.Sprint(conn.local.UID),
"ConnID": fmt.Sprint(conn.uid),
"Trusted": fmt.Sprint(conn.trustRemote),
}
conn.router.Overlay.AddFeaturesTo(features)
return features
}
func (conn *LocalConnection) parseFeatures(features map[string]string) (*Peer, error) {
if err := mustHave(features, []string{"PeerNameFlavour", "Name", "NickName", "UID", "ConnID"}); err != nil {
return nil, err
}
remotePeerNameFlavour := features["PeerNameFlavour"]
if remotePeerNameFlavour != PeerNameFlavour {
return nil, fmt.Errorf("Peer name flavour mismatch (ours: '%s', theirs: '%s')", PeerNameFlavour, remotePeerNameFlavour)
}
name, err := PeerNameFromString(features["Name"])
if err != nil {
return nil, err
}
nickName := features["NickName"]
var shortID uint64
var hasShortID bool
if shortIDStr, ok := features["ShortID"]; ok {
hasShortID = true
shortID, err = strconv.ParseUint(shortIDStr, 10, peerShortIDBits)
if err != nil {
return nil, err
}
}
var trusted bool
if trustedStr, ok := features["Trusted"]; ok {
trusted, err = strconv.ParseBool(trustedStr)
if err != nil {
return nil, err
}
}
conn.trustedByRemote = trusted
uid, err := parsePeerUID(features["UID"])
if err != nil {
return nil, err
}
remoteConnID, err := strconv.ParseUint(features["ConnID"], 10, 64)
if err != nil {
return nil, err
}
conn.uid ^= remoteConnID
peer := newPeer(name, nickName, uid, 0, PeerShortID(shortID))
peer.HasShortID = hasShortID
return peer, nil
}
func (conn *LocalConnection) registerRemote(remote *Peer, acceptNewPeer bool) error {
if acceptNewPeer {
conn.remote = conn.router.Peers.fetchWithDefault(remote)
} else {
conn.remote = conn.router.Peers.fetchAndAddRef(remote.Name)
if conn.remote == nil {
return fmt.Errorf("Found unknown remote name: %s at %s", remote.Name, conn.remoteTCPAddr)
}
}
if remote.Name == conn.local.Name && remote.UID != conn.local.UID {
return &peerNameCollisionError{conn.local, remote}
}
if conn.remote == conn.local {
return errConnectToSelf
}
return nil
}
func (conn *LocalConnection) actorLoop(actionChan <-chan connectionAction, errorChan <-chan error) (err error) {
fwdErrorChan := conn.OverlayConn.ErrorChannel()
fwdEstablishedChan := conn.OverlayConn.EstablishedChannel()
for err == nil {
select {
case err = <-errorChan:
case err = <-fwdErrorChan:
default:
select {
case action := <-actionChan:
err = action()
case <-conn.heartbeatTCP.C:
err = conn.sendSimpleProtocolMsg(ProtocolHeartbeat)
case <-fwdEstablishedChan:
conn.established = true
fwdEstablishedChan = nil
conn.router.Ourself.doConnectionEstablished(conn)
case err = <-errorChan:
case err = <-fwdErrorChan:
}
}
}
return
}
func (conn *LocalConnection) teardown(err error) {
if conn.remote == nil {
conn.logger.Printf("->[%s] connection shutting down due to error during handshake: %v", conn.remoteTCPAddr, err)
} else {
conn.logf("connection shutting down due to error: %v", err)
}
if conn.tcpConn != nil {
if err := conn.tcpConn.Close(); err != nil {
conn.logger.Printf("warning: %v", err)
}
}
if conn.remote != nil {
conn.router.Peers.dereference(conn.remote)
conn.router.Ourself.doDeleteConnection(conn)
}
if conn.heartbeatTCP != nil {
conn.heartbeatTCP.Stop()
}
if conn.OverlayConn != nil {
conn.OverlayConn.Stop()
}
conn.router.ConnectionMaker.connectionTerminated(conn, err)
}
func (conn *LocalConnection) sendOverlayControlMessage(tag byte, msg []byte) error {
return conn.sendProtocolMsg(protocolMsg{protocolTag(tag), msg})
}
// Helpers
func (conn *LocalConnection) sendSimpleProtocolMsg(tag protocolTag) error {
return conn.sendProtocolMsg(protocolMsg{tag: tag})
}
func (conn *LocalConnection) sendProtocolMsg(m protocolMsg) error {
return conn.tcpSender.Send(append([]byte{byte(m.tag)}, m.msg...))
}
func (conn *LocalConnection) receiveTCP(receiver tcpReceiver) {
var err error
for {
if err = conn.extendReadDeadline(); err != nil {
break
}
var msg []byte
if msg, err = receiver.Receive(); err != nil {
break
}
if len(msg) < 1 {
conn.logf("ignoring blank msg")
continue
}
if err = conn.handleProtocolMsg(protocolTag(msg[0]), msg[1:]); err != nil {
break
}
}
conn.shutdown(err)
}
func (conn *LocalConnection) handleProtocolMsg(tag protocolTag, payload []byte) error {
switch tag {
case ProtocolHeartbeat:
case ProtocolReserved1, ProtocolReserved2, ProtocolReserved3, ProtocolOverlayControlMsg:
conn.OverlayConn.ControlMessage(byte(tag), payload)
case ProtocolGossipUnicast, ProtocolGossipBroadcast, ProtocolGossip:
return conn.router.handleGossip(tag, payload)
default:
conn.logf("ignoring unknown protocol tag: %v", tag)
}
return nil
}
func (conn *LocalConnection) extendReadDeadline() error {
return conn.tcpConn.SetReadDeadline(time.Now().Add(tcpHeartbeat * 2))
}
// Untrusted returns true if either we don't trust our remote, or are not
// trusted by our remote.
func (conn *LocalConnection) untrusted() bool {
return !conn.trustRemote || !conn.trustedByRemote
}
type connectionTieBreak int
const (
tieBreakWon connectionTieBreak = iota
tieBreakLost
tieBreakTied
)
var errConnectToSelf = fmt.Errorf("cannot connect to ourself")
type peerNameCollisionError struct {
local, remote *Peer
}
func (err *peerNameCollisionError) Error() string {
return fmt.Sprintf("local %q and remote %q peer names collision", err.local, err.remote)
}
// The actor closure used by LocalConnection. If an action returns an error,
// it will terminate the actor loop, which terminates the connection in turn.
type connectionAction func() error
func mustHave(features map[string]string, keys []string) error {
for _, key := range keys {
if _, ok := features[key]; !ok {
return fmt.Errorf("field %s is missing", key)
}
}
return nil
}
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