tstun

Documentation

Overview

Package tun creates a tuntap device, working around OS-specific quirks if necessary.

Package tstun provides a TUN struct implementing the tun.Device interface with additional features as required by wgengine.

Index

• Constants
• Variables
• func Diagnose(logf logger.Logf, tunName string)
• func New(logf logger.Logf, tunName string) (tun.Device, string, error)
• func NewFake() tun.Device
• type FilterFunc
• type Wrapper
  • func Wrap(logf logger.Logf, tdev tun.Device) *Wrapper
  • func (t *Wrapper) Close() error
  • func (t *Wrapper) Events() chan tun.Event
  • func (t *Wrapper) EventsUpDown() chan tun.Event
  • func (t *Wrapper) File() *os.File
  • func (t *Wrapper) Flush() error
  • func (t *Wrapper) GetFilter() *filter.Filter
  • func (t *Wrapper) IdleDuration() time.Duration
  • func (t *Wrapper) InjectInboundCopy(packet []byte) error
  • func (t *Wrapper) InjectInboundDirect(buf []byte, offset int) error
  • func (t *Wrapper) InjectOutbound(packet []byte) error
  • func (t *Wrapper) MTU() (int, error)
  • func (t *Wrapper) Name() (string, error)
  • func (t *Wrapper) Read(buf []byte, offset int) (int, error)
  • func (t *Wrapper) SetDestIPActivityFuncs(m map[netaddr.IP]func())
  • func (t *Wrapper) SetFilter(filt *filter.Filter)
  • func (t *Wrapper) Unwrap() tun.Device
  • func (t *Wrapper) Write(buf []byte, offset int) (int, error)

Constants

const MaxPacketSize = device.MaxContentSize

MaxPacketSize is the maximum size (in bytes) of a packet that can be injected into a tstun.Wrapper.

const PacketStartOffset = device.MessageTransportHeaderSize

PacketStartOffset is the minimal amount of leading space that must exist before &packet[offset] in a packet passed to Read, Write, or InjectInboundDirect. This is necessary to avoid reallocation in wireguard-go internals.

Variables

var (
	// ErrClosed is returned when attempting an operation on a closed Wrapper.
	ErrClosed = errors.New("device closed")
	// ErrFiltered is returned when the acted-on packet is rejected by a filter.
	ErrFiltered = errors.New("packet dropped by filter")
)

Functions

func Diagnose

func Diagnose(logf logger.Logf, tunName string)

Diagnose tries to explain a tuntap device creation failure. It pokes around the system and logs some diagnostic info that might help debug why tun creation failed. Because device creation has already failed and the program's about to end, log a lot.

func New

func New(logf logger.Logf, tunName string) (tun.Device, string, error)

New returns a tun.Device for the requested device name, along with the OS-dependent name that was allocated to the device.

func NewFake

func NewFake() tun.Device

NewFake returns a tun.Device that does nothing.

Types

type FilterFunc

type FilterFunc func(*packet.Parsed, *Wrapper) filter.Response

FilterFunc is a packet-filtering function with access to the Wrapper device. It must not hold onto the packet struct, as its backing storage will be reused.

type Wrapper

type Wrapper struct {

	// PreFilterIn is the inbound filter function that runs before the main filter
	// and therefore sees the packets that may be later dropped by it.
	PreFilterIn FilterFunc
	// PostFilterIn is the inbound filter function that runs after the main filter.
	PostFilterIn FilterFunc
	// PreFilterOut is the outbound filter function that runs before the main filter
	// and therefore sees the packets that may be later dropped by it.
	PreFilterOut FilterFunc
	// PostFilterOut is the outbound filter function that runs after the main filter.
	PostFilterOut FilterFunc

	// OnTSMPPongReceived, if non-nil, is called whenever a TSMP pong arrives.
	OnTSMPPongReceived func(packet.TSMPPongReply)

	// PeerAPIPort, if non-nil, returns the peerapi port that's
	// running for the given IP address.
	PeerAPIPort func(netaddr.IP) (port uint16, ok bool)
	// contains filtered or unexported fields
}

Wrapper augments a tun.Device with packet filtering and injection.

func Wrap

func Wrap(logf logger.Logf, tdev tun.Device) *Wrapper

func (*Wrapper) Close

func (t *Wrapper) Close() error

func (*Wrapper) Events

func (t *Wrapper) Events() chan tun.Event

Events returns a TUN event channel that contains all non-Up, non-Down events. It is named Events because it is the set of events that we want to expose to wireguard-go, and Events is the name specified by the wireguard-go tun.Device interface.

func (*Wrapper) EventsUpDown

func (t *Wrapper) EventsUpDown() chan tun.Event

EventsUpDown returns a TUN event channel that contains all Up and Down events.

func (*Wrapper) File

func (t *Wrapper) File() *os.File

func (*Wrapper) Flush

func (t *Wrapper) Flush() error

func (*Wrapper) GetFilter

func (t *Wrapper) GetFilter() *filter.Filter

func (*Wrapper) IdleDuration

func (t *Wrapper) IdleDuration() time.Duration

IdleDuration reports how long it's been since the last read or write to this device.

Its value is only accurate to roughly second granularity. If there's never been activity, the duration is since 1970.

func (*Wrapper) InjectInboundCopy

func (t *Wrapper) InjectInboundCopy(packet []byte) error

InjectInboundCopy takes a packet without leading space, reallocates it to conform to the InjectInboundDirect interface and calls InjectInboundDirect on it. Injecting a nil packet is a no-op.

func (*Wrapper) InjectInboundDirect

func (t *Wrapper) InjectInboundDirect(buf []byte, offset int) error

InjectInboundDirect makes the Wrapper device behave as if a packet with the given contents was received from the network. It blocks and does not take ownership of the packet. The injected packet will not pass through inbound filters.

The packet contents are to start at &buf[offset]. offset must be greater or equal to PacketStartOffset. The space before &buf[offset] will be used by Wireguard.

func (*Wrapper) InjectOutbound

func (t *Wrapper) InjectOutbound(packet []byte) error

InjectOutbound makes the Wrapper device behave as if a packet with the given contents was sent to the network. It does not block, but takes ownership of the packet. The injected packet will not pass through outbound filters. Injecting an empty packet is a no-op.

func (*Wrapper) MTU

func (t *Wrapper) MTU() (int, error)

func (*Wrapper) Name

func (t *Wrapper) Name() (string, error)

func (*Wrapper) Read

func (t *Wrapper) Read(buf []byte, offset int) (int, error)

func (*Wrapper) SetDestIPActivityFuncs

func (t *Wrapper) SetDestIPActivityFuncs(m map[netaddr.IP]func())

SetDestIPActivityFuncs sets a map of funcs to run per packet destination (the map keys).

The map ownership passes to the Wrapper. It must be non-nil.

func (*Wrapper) SetFilter

func (t *Wrapper) SetFilter(filt *filter.Filter)

func (*Wrapper) Unwrap

func (t *Wrapper) Unwrap() tun.Device

Unwrap returns the underlying tun.Device.

func (*Wrapper) Write

func (t *Wrapper) Write(buf []byte, offset int) (int, error)

Write accepts an incoming packet. The packet begins at buf[offset:], like wireguard-go/tun.Device.Write.