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"
"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()
}