Documentation
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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, err error)
- func New(logf logger.Logf, tunName string) (tun.Device, string, error)
- func NewFake() tun.Device
- type FilterFunc
- type Wrapper
- func (t *Wrapper) Close() error
- func (t *Wrapper) Events() chan tun.Event
- func (t *Wrapper) EventsUpDown() chan tun.Event
- func (t *Wrapper) ExtractStatistics() map[netlogtype.Connection]netlogtype.Counts
- 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) InjectInboundPacketBuffer(pkt *stack.PacketBuffer) error
- func (t *Wrapper) InjectOutbound(packet []byte) error
- func (t *Wrapper) InjectOutboundPacketBuffer(packet *stack.PacketBuffer) 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[netip.Addr]func())
- func (t *Wrapper) SetDiscoKey(k key.DiscoPublic)
- func (t *Wrapper) SetFilter(filt *filter.Filter)
- func (t *Wrapper) SetStatisticsEnabled(enable bool)
- func (t *Wrapper) Unwrap() tun.Device
- func (t *Wrapper) Write(buf []byte, offset int) (int, error)
Constants ¶
const DefaultMTU = 1280
DefaultMTU is the Tailscale default MTU for now.
wireguard-go defaults to 1420 bytes, which only works if the "outer" MTU is 1500 bytes. This breaks on DSL connections (typically 1492 MTU) and on GCE (1460 MTU?!).
1280 is the smallest MTU allowed for IPv6, which is a sensible "probably works everywhere" setting until we develop proper PMTU discovery.
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 ¶
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.
The tunName is the name of the tun device that was requested but failed. The err error is how the tun creation failed.
Types ¶
type FilterFunc ¶
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
// PreFilterFromTunToNetstack is a filter function that runs before the main filter
// for packets from the local system. This filter is populated by netstack to hook
// packets that should be handled by netstack. If set, this filter runs before
// PreFilterFromTunToEngine.
PreFilterFromTunToNetstack FilterFunc
// PreFilterFromTunToEngine is a filter function that runs before the main filter
// for packets from the local system. This filter is populated by wgengine to hook
// packets which it handles internally. If both this and PreFilterFromTunToNetstack
// filter functions are non-nil, this filter runs second.
PreFilterFromTunToEngine 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)
// OnICMPEchoResponseReceived, if non-nil, is called whenever a ICMP echo response
// arrives. If the packet is to be handled internally this returns true,
// false otherwise.
OnICMPEchoResponseReceived func(*packet.Parsed) bool
// PeerAPIPort, if non-nil, returns the peerapi port that's
// running for the given IP address.
PeerAPIPort func(netip.Addr) (port uint16, ok bool)
// contains filtered or unexported fields
}
Wrapper augments a tun.Device with packet filtering and injection.
func (*Wrapper) Events ¶
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 ¶
EventsUpDown returns a TUN event channel that contains all Up and Down events.
func (*Wrapper) ExtractStatistics ¶
func (t *Wrapper) ExtractStatistics() map[netlogtype.Connection]netlogtype.Counts
ExtractStatistics extracts and resets the counters for all active connections. It must be called periodically otherwise the memory used is unbounded.
func (*Wrapper) IdleDuration ¶
IdleDuration reports how long it's been since the last read or write to this device.
Its value should only be presumed accurate to roughly 10ms granularity. If there's never been activity, the duration is since the wrapper was created.
func (*Wrapper) InjectInboundCopy ¶
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 ¶
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) InjectInboundPacketBuffer ¶
func (t *Wrapper) InjectInboundPacketBuffer(pkt *stack.PacketBuffer) error
InjectInboundPacketBuffer makes the Wrapper device behave as if a packet with the given contents was received from the network. It takes ownership of one reference count on the packet. The injected packet will not pass through inbound filters.
This path is typically used to deliver synthesized packets to the host networking stack.
func (*Wrapper) InjectOutbound ¶
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) InjectOutboundPacketBuffer ¶
func (t *Wrapper) InjectOutboundPacketBuffer(packet *stack.PacketBuffer) error
InjectOutboundPacketBuffer logically behaves as InjectOutbound. It takes ownership of one reference count on the packet, and the packet may be mutated. The packet refcount will be decremented after the injected buffer has been read.
func (*Wrapper) SetDestIPActivityFuncs ¶
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) SetDiscoKey ¶
func (t *Wrapper) SetDiscoKey(k key.DiscoPublic)
SetDiscoKey sets the current discovery key.
It is only used for filtering out bogus traffic when network stack(s) get confused; see Issue 1526.
func (*Wrapper) SetStatisticsEnabled ¶
SetStatisticsEnabled enables per-connections packet counters. Disabling statistics gathering does not reset the counters. ExtractStatistics must be called to reset the counters and be periodically called while enabled to avoid unbounded memory use.
Source Files