wgengine{,/wgint}: add wgint.Peer wrapper type, add to wgengine.Engine

This adds a method to wgengine.Engine and plumbed down into magicsock
to add a way to get a type-safe Tailscale-safe wrapper around a
wireguard-go device.Peer that only exposes methods that are safe for
Tailscale to use internally.

It also removes HandshakeAttempts from PeerStatusLite that was just
added as it wasn't needed yet and is now accessible ala cart as needed
from the Peer type accessor.

None of this is used yet.

Updates #7617

Change-Id: I07be0c4e6679883e6eeddf8dbed7394c9e79c5f4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscaled/depaware.txt

@@ -405,7 +405,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/wgengine/router                                from tailscale.com/cmd/tailscaled+
         tailscale.com/wgengine/wgcfg                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/wgengine/wgcfg/nmcfg                           from tailscale.com/ipn/ipnlocal
-     💣 tailscale.com/wgengine/wgint                                 from tailscale.com/wgengine
+     💣 tailscale.com/wgengine/wgint                                 from tailscale.com/wgengine+
         tailscale.com/wgengine/wglog                                 from tailscale.com/wgengine
    W 💣 tailscale.com/wgengine/winnet                                from tailscale.com/wgengine/router
         golang.org/x/crypto/argon2                                   from tailscale.com/tka

ipn/ipnstate/ipnstate.go

@@ -203,11 +203,6 @@ type PeerStatusLite struct {
 	// since this peer was last known to WireGuard. (Tailscale removes peers
 	// from the wireguard peer that are idle.)
 	LastHandshake time.Time
-
-	// HandshakeAttempts is how many failed attempts there have been at
-	// completing the current WireGuard handshake. This resets to zero on every
-	// successful handshake.
-	HandshakeAttempts uint32
 }
 
 // PeerStatus describes a peer node and its current state.

wgengine/magicsock/magicsock.go

@@ -60,6 +60,7 @@ import (
 	"tailscale.com/util/testenv"
 	"tailscale.com/util/uniq"
 	"tailscale.com/wgengine/capture"
+	"tailscale.com/wgengine/wgint"
 )
 
 const (
@@ -298,6 +299,10 @@ type Conn struct {
 	// onPortUpdate is called with the new port when magicsock rebinds to
 	// a new port.
 	onPortUpdate func(port uint16, network string)
+
+	// getPeerByKey optionally specifies a function to look up a peer's
+	// wireguard state by its public key. If nil, it's not used.
+	getPeerByKey func(key.NodePublic) (_ wgint.Peer, ok bool)
 }
 
 // SetDebugLoggingEnabled controls whether spammy debug logging is enabled.
@@ -367,6 +372,11 @@ type Options struct {
 	// OnPortUpdate is called with the new port when magicsock rebinds to
 	// a new port.
 	OnPortUpdate func(port uint16, network string)
+
+	// PeerByKeyFunc optionally specifies a function to look up a peer's
+	// WireGuard state by its public key. If nil, it's not used.
+	// In regular use, this will be wgengine.(*userspaceEngine).PeerByKey.
+	PeerByKeyFunc func(key.NodePublic) (_ wgint.Peer, ok bool)
 }
 
 func (o *Options) logf() logger.Logf {
@@ -440,6 +450,7 @@ func NewConn(opts Options) (*Conn, error) {
 	}
 	c.netMon = opts.NetMon
 	c.onPortUpdate = opts.OnPortUpdate
+	c.getPeerByKey = opts.PeerByKeyFunc
 
 	if err := c.rebind(keepCurrentPort); err != nil {
 		return nil, err

wgengine/userspace.go

@@ -1011,25 +1011,30 @@ func (e *userspaceEngine) getStatusCallback() StatusCallback {
 
 var ErrEngineClosing = errors.New("engine closing; no status")
 
-func (e *userspaceEngine) getPeerStatusLite(pk key.NodePublic) (status ipnstate.PeerStatusLite, ok bool) {
+func (e *userspaceEngine) PeerByKey(pubKey key.NodePublic) (_ wgint.Peer, ok bool) {
 	e.wgLock.Lock()
 	dev := e.wgdev
 	e.wgLock.Unlock()
 
 	if dev == nil {
-		return status, false
+		return wgint.Peer{}, false
 	}
-	peer := dev.LookupPeer(pk.Raw32())
+	peer := dev.LookupPeer(pubKey.Raw32())
 	if peer == nil {
+		return wgint.Peer{}, false
+	}
+	return wgint.PeerOf(peer), true
+}
+
+func (e *userspaceEngine) getPeerStatusLite(pk key.NodePublic) (status ipnstate.PeerStatusLite, ok bool) {
+	peer, ok := e.PeerByKey(pk)
+	if !ok {
 		return status, false
 	}
 	status.NodeKey = pk
-	status.RxBytes = int64(wgint.PeerRxBytes(peer))
-	status.TxBytes = int64(wgint.PeerTxBytes(peer))
-	status.HandshakeAttempts = wgint.PeerHandshakeAttempts(peer)
-	if nano := wgint.PeerLastHandshakeNano(peer); nano != 0 {
-		status.LastHandshake = time.Unix(0, nano)
-	}
+	status.RxBytes = int64(peer.RxBytes())
+	status.TxBytes = int64(peer.TxBytes())
+	status.LastHandshake = peer.LastHandshake()
 	return status, true
 }
 

wgengine/watchdog.go

@@ -18,11 +18,13 @@ import (
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/dns"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 	"tailscale.com/types/netmap"
 	"tailscale.com/wgengine/capture"
 	"tailscale.com/wgengine/filter"
 	"tailscale.com/wgengine/router"
 	"tailscale.com/wgengine/wgcfg"
+	"tailscale.com/wgengine/wgint"
 )
 
 // NewWatchdog wraps an Engine and makes sure that all methods complete
@@ -157,3 +159,7 @@ func (e *watchdogEngine) Done() <-chan struct{} {
 func (e *watchdogEngine) InstallCaptureHook(cb capture.Callback) {
 	e.wrap.InstallCaptureHook(cb)
 }
+
+func (e *watchdogEngine) PeerByKey(pubKey key.NodePublic) (_ wgint.Peer, ok bool) {
+	return e.wrap.PeerByKey(pubKey)
+}

wgengine/wgengine.go

@@ -11,11 +11,13 @@ import (
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/dns"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 	"tailscale.com/types/netmap"
 	"tailscale.com/wgengine/capture"
 	"tailscale.com/wgengine/filter"
 	"tailscale.com/wgengine/router"
 	"tailscale.com/wgengine/wgcfg"
+	"tailscale.com/wgengine/wgint"
 )
 
 // Status is the Engine status.
@@ -84,6 +86,10 @@ type Engine interface {
 	// away, sent to the callback registered via SetStatusCallback.
 	RequestStatus()
 
+	// PeerByKey returns the WireGuard status of the provided peer.
+	// If the peer is not found, ok is false.
+	PeerByKey(key.NodePublic) (_ wgint.Peer, ok bool)
+
 	// Close shuts down this wireguard instance, remove any routes
 	// it added, etc. To bring it up again later, you'll need a
 	// new Engine.

wgengine/wgint/wgint.go

@@ -8,6 +8,7 @@ package wgint
 import (
 	"reflect"
 	"sync/atomic"
+	"time"
 	"unsafe"
 
 	"github.com/tailscale/wireguard-go/device"
@@ -49,24 +50,59 @@ func getPeerHandshakeAttemptsOffset() uintptr {
 	return field.Offset + field2.Offset
 }
 
-// PeerLastHandshakeNano returns the last handshake time in nanoseconds since the
+// peerLastHandshakeNano returns the last handshake time in nanoseconds since the
 // unix epoch.
-func PeerLastHandshakeNano(peer *device.Peer) int64 {
+func peerLastHandshakeNano(peer *device.Peer) int64 {
 	return (*atomic.Int64)(unsafe.Add(unsafe.Pointer(peer), offHandshake)).Load()
 }
 
-// PeerRxBytes returns the number of bytes received from this peer.
-func PeerRxBytes(peer *device.Peer) uint64 {
+// peerRxBytes returns the number of bytes received from this peer.
+func peerRxBytes(peer *device.Peer) uint64 {
 	return (*atomic.Uint64)(unsafe.Add(unsafe.Pointer(peer), offRxBytes)).Load()
 }
 
-// PeerTxBytes returns the number of bytes sent to this peer.
-func PeerTxBytes(peer *device.Peer) uint64 {
+// peerTxBytes returns the number of bytes sent to this peer.
+func peerTxBytes(peer *device.Peer) uint64 {
 	return (*atomic.Uint64)(unsafe.Add(unsafe.Pointer(peer), offTxBytes)).Load()
 }
 
-// PeerHandshakeAttempts returns the number of WireGuard handshake attempts
+// peerHandshakeAttempts returns the number of WireGuard handshake attempts
 // made for the current handshake. It resets to zero before every new handshake.
-func PeerHandshakeAttempts(peer *device.Peer) uint32 {
+func peerHandshakeAttempts(peer *device.Peer) uint32 {
 	return (*atomic.Uint32)(unsafe.Add(unsafe.Pointer(peer), offHandshakeAttempts)).Load()
 }
+
+// Peer is a wrapper around a wireguard-go device.Peer pointer.
+type Peer struct {
+	p *device.Peer
+}
+
+// PeerOf returns a Peer wrapper around a wireguard-go device.Peer.
+func PeerOf(p *device.Peer) Peer {
+	return Peer{p}
+}
+
+// LastHandshake returns the last handshake time.
+//
+// If the handshake has never happened, it returns the zero value.
+func (p Peer) LastHandshake() time.Time {
+	if n := peerLastHandshakeNano(p.p); n != 0 {
+		return time.Unix(0, n)
+	}
+	return time.Time{}
+}
+
+func (p Peer) IsValid() bool { return p.p != nil }
+
+// TxBytes returns the number of bytes sent to this peer.
+func (p Peer) TxBytes() uint64 { return peerTxBytes(p.p) }
+
+// RxBytes returns the number of bytes received from this peer.
+func (p Peer) RxBytes() uint64 { return peerRxBytes(p.p) }
+
+// HandshakeAttempts returns the number of failed WireGuard handshake attempts
+// made for the current handshake. It resets to zero before every new handshake
+// and after a successful handshake.
+func (p Peer) HandshakeAttempts() uint32 {
+	return peerHandshakeAttempts(p.p)
+}

wgengine/wgint/wgint_test.go

@@ -11,16 +11,16 @@ import (
 
 func TestInternalOffsets(t *testing.T) {
 	peer := new(device.Peer)
-	if got := PeerLastHandshakeNano(peer); got != 0 {
+	if got := peerLastHandshakeNano(peer); got != 0 {
 		t.Errorf("PeerLastHandshakeNano = %v, want 0", got)
 	}
-	if got := PeerRxBytes(peer); got != 0 {
+	if got := peerRxBytes(peer); got != 0 {
 		t.Errorf("PeerRxBytes = %v, want 0", got)
 	}
-	if got := PeerTxBytes(peer); got != 0 {
+	if got := peerTxBytes(peer); got != 0 {
 		t.Errorf("PeerTxBytes = %v, want 0", got)
 	}
-	if got := PeerHandshakeAttempts(peer); got != 0 {
+	if got := peerHandshakeAttempts(peer); got != 0 {
 		t.Errorf("PeerHandshakeAttempts = %v, want 0", got)
 	}
 }