tailscale/wgengine/wgint/wgint.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package wgint provides somewhat shady access to wireguard-go
// internals that don't (yet) have public APIs.
package wgint
import (
"reflect"
"sync/atomic"
"time"
"unsafe"
"github.com/tailscale/wireguard-go/device"
)
var (
offHandshake = getPeerStatsOffset("lastHandshakeNano")
offRxBytes = getPeerStatsOffset("rxBytes")
offTxBytes = getPeerStatsOffset("txBytes")
offHandshakeAttempts = getPeerHandshakeAttemptsOffset()
)
func getPeerStatsOffset(name string) uintptr {
peerType := reflect.TypeFor[device.Peer]()
field, ok := peerType.FieldByName(name)
if !ok {
panic("no " + name + " field in device.Peer")
}
if s := field.Type.String(); s != "atomic.Int64" && s != "atomic.Uint64" {
panic("unexpected type " + s + " of field " + name + " in device.Peer")
}
return field.Offset
}
func getPeerHandshakeAttemptsOffset() uintptr {
peerType := reflect.TypeFor[device.Peer]()
field, ok := peerType.FieldByName("timers")
if !ok {
panic("no timers field in device.Peer")
}
field2, ok := field.Type.FieldByName("handshakeAttempts")
if !ok {
panic("no handshakeAttempts field in device.Peer.timers")
}
if g, w := field2.Type.String(), "atomic.Uint32"; g != w {
panic("unexpected type " + g + " of field handshakeAttempts in device.Peer.timers; want " + w)
}
return field.Offset + field2.Offset
}
// peerLastHandshakeNano returns the last handshake time in nanoseconds since the
// unix epoch.
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 {
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 {
return (*atomic.Uint64)(unsafe.Add(unsafe.Pointer(peer), offTxBytes)).Load()
}
// 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 {
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)
}