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derp: add PeerPresentFlags bitmask to Watch messages

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Updates tailscale/corp#17816

Change-Id: Ib5baf6c981a6a4c279f8bbfef02048cfbfb3323b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
pull/12586/head
Brad Fitzpatrick 3 months ago committed by Brad Fitzpatrick
parent d7a4f9d31c
commit 5ffb2668ef
4 changed files with 85 additions and 17 deletions
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26
derp/derp.go
Unescape Escape View File

@ -83,9 +83,16 @@ const (
// a bug).
framePeerGone = frameType(0x08) // 32B pub key of peer that's gone + 1 byte reason
// framePeerPresent is like framePeerGone, but for other
// members of the DERP region when they're meshed up together.
framePeerPresent = frameType(0x09) // 32B pub key of peer that's connected + optional 18B ip:port (16 byte IP + 2 byte BE uint16 port)
// framePeerPresent is like framePeerGone, but for other members of the DERP
// region when they're meshed up together.
//
// The message is at least 32 bytes (the public key of the peer that's
// connected). If there are at least 18 bytes remaining after that, it's the
// 16 byte IP + 2 byte BE uint16 port of the client. If there's another byte
// remaining after that, it's a PeerPresentFlags byte.
// While current servers send 41 bytes, old servers will send fewer, and newer
// servers might send more.
framePeerPresent = frameType(0x09)
// frameWatchConns is how one DERP node in a regional mesh
// subscribes to the others in the region.
@ -128,6 +135,19 @@ const (
PeerGoneReasonNotHere = PeerGoneReasonType(0x01) // server doesn't know about this peer, unexpected
)
// PeerPresentFlags is an optional byte of bit flags sent after a framePeerPresent message.
//
// For a modern server, the value should always be non-zero. If the value is zero,
// that means the server doesn't support this field.
type PeerPresentFlags byte
// PeerPresentFlags bits.
const (
PeerPresentIsRegular = 1 << 0
PeerPresentIsMeshPeer = 1 << 1
PeerPresentIsProber = 1 << 2
)
var bin = binary.BigEndian
func writeUint32(bw *bufio.Writer, v uint32) error {

38
derp/derp_client.go
Unescape Escape View File

@ -368,6 +368,8 @@ type PeerPresentMessage struct {
Key key.NodePublic
// IPPort is the remote IP and port of the client.
IPPort netip.AddrPort
// Flags is a bitmask of info about the client.
Flags PeerPresentFlags
}
func (PeerPresentMessage) msg() {}
@ -547,18 +549,33 @@ func (c *Client) recvTimeout(timeout time.Duration) (m ReceivedMessage, err erro
return pg, nil
case framePeerPresent:
if n < keyLen {
remain := b
chunk, remain, ok := cutLeadingN(remain, keyLen)
if !ok {
c.logf("[unexpected] dropping short peerPresent frame from DERP server")
continue
}
var msg PeerPresentMessage
msg.Key = key.NodePublicFromRaw32(mem.B(b[:keyLen]))
if n >= keyLen+16+2 {
msg.IPPort = netip.AddrPortFrom(
netip.AddrFrom16([16]byte(b[keyLen:keyLen+16])).Unmap(),
binary.BigEndian.Uint16(b[keyLen+16:keyLen+16+2]),
)
msg.Key = key.NodePublicFromRaw32(mem.B(chunk))
const ipLen = 16
const portLen = 2
chunk, remain, ok = cutLeadingN(remain, ipLen+portLen)
if !ok {
// Older server which didn't send the IP.
return msg, nil
}
msg.IPPort = netip.AddrPortFrom(
netip.AddrFrom16([16]byte(chunk[:ipLen])).Unmap(),
binary.BigEndian.Uint16(chunk[ipLen:]),
)
chunk, _, ok = cutLeadingN(remain, 1)
if !ok {
// Older server which doesn't send PeerPresentFlags.
return msg, nil
}
msg.Flags = PeerPresentFlags(chunk[0])
return msg, nil
case frameRecvPacket:
@ -636,3 +653,10 @@ func (c *Client) LocalAddr() (netip.AddrPort, error) {
}
return netip.ParseAddrPort(a.String())
}
func cutLeadingN(b []byte, n int) (chunk, remain []byte, ok bool) {
if len(b) >= n {
return b[:n], b[n:], true
}
return nil, b, false
}

30
derp/derp_server.go
Unescape Escape View File

@ -566,7 +566,7 @@ func (s *Server) registerClient(c *sclient) {
}
s.keyOfAddr[c.remoteIPPort] = c.key
s.curClients.Add(1)
s.broadcastPeerStateChangeLocked(c.key, c.remoteIPPort, true)
s.broadcastPeerStateChangeLocked(c.key, c.remoteIPPort, c.presentFlags(), true)
}
// broadcastPeerStateChangeLocked enqueues a message to all watchers
@ -574,12 +574,13 @@ func (s *Server) registerClient(c *sclient) {
// presence changed.
//
// s.mu must be held.
func (s *Server) broadcastPeerStateChangeLocked(peer key.NodePublic, ipPort netip.AddrPort, present bool) {
func (s *Server) broadcastPeerStateChangeLocked(peer key.NodePublic, ipPort netip.AddrPort, flags PeerPresentFlags, present bool) {
for w := range s.watchers {
w.peerStateChange = append(w.peerStateChange, peerConnState{
peer: peer,
present: present,
ipPort: ipPort,
flags: flags,
})
go w.requestMeshUpdate()
}
@ -601,7 +602,7 @@ func (s *Server) unregisterClient(c *sclient) {
delete(s.clientsMesh, c.key)
s.notePeerGoneFromRegionLocked(c.key)
}
s.broadcastPeerStateChangeLocked(c.key, netip.AddrPort{}, false)
s.broadcastPeerStateChangeLocked(c.key, netip.AddrPort{}, 0, false)
case *dupClientSet:
c.debugLogf("removed duplicate client")
if set.removeClient(c) {
@ -700,6 +701,7 @@ func (s *Server) addWatcher(c *sclient) {
peer: peer,
present: true,
ipPort: ac.remoteIPPort,
flags: ac.presentFlags(),
})
}
@ -1435,11 +1437,26 @@ type sclient struct {
peerGoneLim *rate.Limiter
}
func (c *sclient) presentFlags() PeerPresentFlags {
var f PeerPresentFlags
if c.info.IsProber {
f |= PeerPresentIsProber
}
if c.canMesh {
f |= PeerPresentIsMeshPeer
}
if f == 0 {
return PeerPresentIsRegular
}
return f
}
// peerConnState represents whether a peer is connected to the server
// or not.
type peerConnState struct {
ipPort netip.AddrPort // if present, the peer's IP:port
peer key.NodePublic
flags PeerPresentFlags
present bool
}
@ -1634,9 +1651,9 @@ func (c *sclient) sendPeerGone(peer key.NodePublic, reason PeerGoneReasonType) e
}
// sendPeerPresent sends a peerPresent frame, without flushing.
func (c *sclient) sendPeerPresent(peer key.NodePublic, ipPort netip.AddrPort) error {
func (c *sclient) sendPeerPresent(peer key.NodePublic, ipPort netip.AddrPort, flags PeerPresentFlags) error {
c.setWriteDeadline()
const frameLen = keyLen + 16 + 2
const frameLen = keyLen + 16 + 2 + 1 // 16 byte IP + 2 byte port + 1 byte flags
if err := writeFrameHeader(c.bw.bw(), framePeerPresent, frameLen); err != nil {
return err
}
@ -1645,6 +1662,7 @@ func (c *sclient) sendPeerPresent(peer key.NodePublic, ipPort netip.AddrPort) er
a16 := ipPort.Addr().As16()
copy(payload[keyLen:], a16[:])
binary.BigEndian.PutUint16(payload[keyLen+16:], ipPort.Port())
payload[keyLen+18] = byte(flags)
_, err := c.bw.Write(payload)
return err
}
@ -1675,7 +1693,7 @@ drainUpdates:
}
var err error
if pcs.present {
err = c.sendPeerPresent(pcs.peer, pcs.ipPort)
err = c.sendPeerPresent(pcs.peer, pcs.ipPort, pcs.flags)
} else {
err = c.sendPeerGone(pcs.peer, PeerGoneReasonDisconnected)
}

8
derp/derp_test.go
Unescape Escape View File

@ -623,7 +623,13 @@ func (tc *testClient) wantPresent(t *testing.T, peers ...key.NodePublic) {
}
}))
}
t.Logf("got present with IP %v", m.IPPort)
t.Logf("got present with IP %v, flags=%v", m.IPPort, m.Flags)
switch m.Flags {
case PeerPresentIsMeshPeer, PeerPresentIsRegular:
// Okay
default:
t.Errorf("unexpected PeerPresentIsMeshPeer flags %v", m.Flags)
}
delete(want, got)
if len(want) == 0 {
return

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