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net/packet, wgengine/{filter,tstun}: add TSMP ping

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Fixes #1467

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2021-03-23 15:16:15 -07:00
committed by Brad Fitzpatrick
parent 4b77eca2de
commit 2384c112c9
13 changed files with 247 additions and 18 deletions
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102
wgengine/userspace.go
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@@ -8,6 +8,7 @@ import (
"bufio"
"bytes"
"context"
crand "crypto/rand"
"errors"
"fmt"
"io"
@@ -128,6 +129,7 @@ type userspaceEngine struct {
pendOpen map[flowtrack.Tuple]*pendingOpenFlow // see pendopen.go
networkMapCallbacks map[*someHandle]NetworkMapCallback
tsIPByIPPort map[netaddr.IPPort]netaddr.IP // allows registration of IP:ports as belonging to a certain Tailscale IP for whois lookups
pongCallback map[[8]byte]func() // for TSMP pong responses
// Lock ordering: magicsock.Conn.mu, wgLock, then mu.
}
@@ -351,6 +353,16 @@ func newUserspaceEngine(logf logger.Logf, rawTUNDev tun.Device, conf Config) (_
SkipBindUpdate: true,
}
e.tundev.OnTSMPPongReceived = func(data [8]byte) {
e.mu.Lock()
defer e.mu.Unlock()
cb := e.pongCallback[data]
e.logf("wgengine: got TSMP pong %02x; cb=%v", data, cb != nil)
if cb != nil {
go cb()
}
}
// wgdev takes ownership of tundev, will close it when closed.
e.logf("Creating wireguard device...")
e.wgdev = device.NewDevice(e.tundev, opts)
@@ -1342,7 +1354,7 @@ func (e *userspaceEngine) UpdateStatus(sb *ipnstate.StatusBuilder) {
e.magicConn.UpdateStatus(sb)
}
func (e *userspaceEngine) Ping(ip netaddr.IP, cb func(*ipnstate.PingResult)) {
func (e *userspaceEngine) Ping(ip netaddr.IP, useTSMP bool, cb func(*ipnstate.PingResult)) {
res := &ipnstate.PingResult{IP: ip.String()}
peer, err := e.peerForIP(ip)
if err != nil {
@@ -1357,8 +1369,92 @@ func (e *userspaceEngine) Ping(ip netaddr.IP, cb func(*ipnstate.PingResult)) {
cb(res)
return
}
e.logf("ping(%v): sending ping to %v %v ...", ip, peer.Key.ShortString(), peer.ComputedName)
e.magicConn.Ping(peer, res, cb)
pingType := "disco"
if useTSMP {
pingType = "TSMP"
}
e.logf("ping(%v): sending %v ping to %v %v ...", ip, pingType, peer.Key.ShortString(), peer.ComputedName)
if useTSMP {
e.sendTSMPPing(ip, peer, res, cb)
} else {
e.magicConn.Ping(peer, res, cb)
}
}
func (e *userspaceEngine) mySelfIPMatchingFamily(dst netaddr.IP) (src netaddr.IP, err error) {
e.mu.Lock()
defer e.mu.Unlock()
if e.netMap == nil {
return netaddr.IP{}, errors.New("no netmap")
}
for _, a := range e.netMap.Addresses {
if a.IsSingleIP() && a.IP.BitLen() == dst.BitLen() {
return a.IP, nil
}
}
if len(e.netMap.Addresses) == 0 {
return netaddr.IP{}, errors.New("no self address in netmap")
}
return netaddr.IP{}, errors.New("no self address in netmap matching address family")
}
func (e *userspaceEngine) sendTSMPPing(ip netaddr.IP, peer *tailcfg.Node, res *ipnstate.PingResult, cb func(*ipnstate.PingResult)) {
srcIP, err := e.mySelfIPMatchingFamily(ip)
if err != nil {
res.Err = err.Error()
cb(res)
return
}
var iph packet.Header
if srcIP.Is4() {
iph = packet.IP4Header{
IPProto: ipproto.TSMP,
Src: srcIP,
Dst: ip,
}
} else {
iph = packet.IP6Header{
IPProto: ipproto.TSMP,
Src: srcIP,
Dst: ip,
}
}
var data [8]byte
crand.Read(data[:])
expireTimer := time.AfterFunc(10*time.Second, func() {
e.setTSMPPongCallback(data, nil)
})
t0 := time.Now()
e.setTSMPPongCallback(data, func() {
expireTimer.Stop()
d := time.Since(t0)
res.LatencySeconds = d.Seconds()
res.NodeIP = ip.String()
res.NodeName = peer.ComputedName
cb(res)
})
var tsmpPayload [9]byte
tsmpPayload[0] = byte(packet.TSMPTypePing)
copy(tsmpPayload[1:], data[:])
tsmpPing := packet.Generate(iph, tsmpPayload[:])
e.tundev.InjectOutbound(tsmpPing)
}
func (e *userspaceEngine) setTSMPPongCallback(data [8]byte, cb func()) {
e.mu.Lock()
defer e.mu.Unlock()
if e.pongCallback == nil {
e.pongCallback = map[[8]byte]func(){}
}
if cb == nil {
delete(e.pongCallback, data)
} else {
e.pongCallback[data] = cb
}
}
func (e *userspaceEngine) RegisterIPPortIdentity(ipport netaddr.IPPort, tsIP netaddr.IP) {