Files
nebula/overlay/user.go
JackDoan 913a37cfee overlay: replace per-fd tun readers with a batched Queue interface
Device loses io.ReadWriteCloser + NewMultiQueueReader in favor of
Queues(n), which returns up to n tio.Queue objects; platforms without
multiqueue hand back their single queue and the interface sizes its
reader routines to what it actually got. Queue.Read returns a batch of
borrowed packets (single-element for every current backend) so a future
backend can deliver more than one packet per syscall without another
interface change.

The Linux poll/eventfd machinery moves out of tun_linux.go into the new
overlay/tio package: nonblocking fds, a shared shutdown eventfd owned by
the queue set, and pollfd arrays built on the stack so concurrent
writers parked in blockOnWrite no longer share Revents storage. Other
platforms wrap their existing one-datagram Read/Write in a singleQueue
adapter that owns a private scratch buffer, so multiqueue-by-sharing
devices (user, disabled) no longer race concurrent readers on one
buffer.

This is the tun-interface subset of better-tun-interface-ordering,
extracted at 18dc13b with none of the GSO/GRO offload mechanics and no
udp/sendmmsg changes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-16 12:19:09 -05:00

79 lines
2.0 KiB
Go

package overlay
import (
"io"
"log/slog"
"net/netip"
"github.com/slackhq/nebula/config"
"github.com/slackhq/nebula/overlay/tio"
"github.com/slackhq/nebula/routing"
)
func NewUserDeviceFromConfig(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, routines int) (Device, error) {
return NewUserDevice(vpnNetworks)
}
func NewUserDevice(vpnNetworks []netip.Prefix) (Device, error) {
// these pipes guarantee each write/read will match 1:1
or, ow := io.Pipe()
ir, iw := io.Pipe()
return &UserDevice{
vpnNetworks: vpnNetworks,
outboundReader: or,
outboundWriter: ow,
inboundReader: ir,
inboundWriter: iw,
}, nil
}
type UserDevice struct {
vpnNetworks []netip.Prefix
outboundReader *io.PipeReader
outboundWriter *io.PipeWriter
inboundReader *io.PipeReader
inboundWriter *io.PipeWriter
}
func (d *UserDevice) Activate() error {
return nil
}
func (d *UserDevice) Networks() []netip.Prefix { return d.vpnNetworks }
func (d *UserDevice) Name() string { return "faketun0" }
func (d *UserDevice) RoutesFor(ip netip.Addr) routing.Gateways {
return routing.Gateways{routing.NewGateway(ip, 1)}
}
func (d *UserDevice) Queues(n int) ([]tio.Queue, error) {
out := make([]tio.Queue, n)
for i := range out {
// All queues share the underlying pipes (the io.Pipe serializes
// concurrent callers) but each owns a private scratch buffer so
// concurrent Reads across queues never alias. NoClose: the pipes are
// owned by the UserDevice and torn down once by UserDevice.Close.
out[i] = tio.NewSingleQueueNoClose(d, defaultBatchBufSize)
}
return out, nil
}
func (d *UserDevice) Pipe() (*io.PipeReader, *io.PipeWriter) {
return d.inboundReader, d.outboundWriter
}
func (d *UserDevice) Read(p []byte) (n int, err error) {
return d.outboundReader.Read(p)
}
func (d *UserDevice) Write(p []byte) (n int, err error) {
return d.inboundWriter.Write(p)
}
func (d *UserDevice) Close() error {
d.inboundWriter.Close()
d.outboundWriter.Close()
return nil
}