conn, device: use UDP GSO and GRO on Linux

StdNetBind probes for UDP GSO and GRO support at runtime. UDP GSO is
dependent on checksum offload support on the egress netdev. UDP GSO
will be disabled in the event sendmmsg() returns EIO, which is a strong
signal that the egress netdev does not support checksum offload.

The iperf3 results below demonstrate the effect of this commit between
two Linux computers with i5-12400 CPUs. There is roughly ~13us of round
trip latency between them.

The first result is from commit 052af4a without UDP GSO or GRO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-10.00  sec  9.85 GBytes  8.46 Gbits/sec  1139   3.01 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  9.85 GBytes  8.46 Gbits/sec  1139  sender
[  5]   0.00-10.04  sec  9.85 GBytes  8.42 Gbits/sec        receiver

The second result is with UDP GSO and GRO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-10.00  sec  12.3 GBytes  10.6 Gbits/sec  232   3.15 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  12.3 GBytes  10.6 Gbits/sec  232   sender
[  5]   0.00-10.04  sec  12.3 GBytes  10.6 Gbits/sec        receiver

Reviewed-by: Adrian Dewhurst <adrian@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 0 insertions, 266 deletions

diff --git a/conn/sticky_linux_test.go b/conn/sticky_linux_test.go
deleted file mode 100644
index 679213a..0000000
--- a/conn/sticky_linux_test.go
+++ /dev/null
@@ -1,266 +0,0 @@
-//go:build linux && !android
-
-/* SPDX-License-Identifier: MIT
- *
- * Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
- */
-
-package conn
-
-import (
-	"context"
-	"net"
-	"net/netip"
-	"runtime"
-	"testing"
-	"unsafe"
-
-	"golang.org/x/sys/unix"
-)
-
-func setSrc(ep *StdNetEndpoint, addr netip.Addr, ifidx int32) {
-	var buf []byte
-	if addr.Is4() {
-		buf = make([]byte, unix.CmsgSpace(unix.SizeofInet4Pktinfo))
-		hdr := unix.Cmsghdr{
-			Level: unix.IPPROTO_IP,
-			Type:  unix.IP_PKTINFO,
-		}
-		hdr.SetLen(unix.CmsgLen(unix.SizeofInet4Pktinfo))
-		copy(buf, unsafe.Slice((*byte)(unsafe.Pointer(&hdr)), int(unsafe.Sizeof(hdr))))
-
-		info := unix.Inet4Pktinfo{
-			Ifindex:  ifidx,
-			Spec_dst: addr.As4(),
-		}
-		copy(buf[unix.CmsgLen(0):], unsafe.Slice((*byte)(unsafe.Pointer(&info)), unix.SizeofInet4Pktinfo))
-	} else {
-		buf = make([]byte, unix.CmsgSpace(unix.SizeofInet6Pktinfo))
-		hdr := unix.Cmsghdr{
-			Level: unix.IPPROTO_IPV6,
-			Type:  unix.IPV6_PKTINFO,
-		}
-		hdr.SetLen(unix.CmsgLen(unix.SizeofInet6Pktinfo))
-		copy(buf, unsafe.Slice((*byte)(unsafe.Pointer(&hdr)), int(unsafe.Sizeof(hdr))))
-
-		info := unix.Inet6Pktinfo{
-			Ifindex: uint32(ifidx),
-			Addr:    addr.As16(),
-		}
-		copy(buf[unix.CmsgLen(0):], unsafe.Slice((*byte)(unsafe.Pointer(&info)), unix.SizeofInet6Pktinfo))
-	}
-
-	ep.src = buf
-}
-
-func Test_setSrcControl(t *testing.T) {
-	t.Run("IPv4", func(t *testing.T) {
-		ep := &StdNetEndpoint{
-			AddrPort: netip.MustParseAddrPort("127.0.0.1:1234"),
-		}
-		setSrc(ep, netip.MustParseAddr("127.0.0.1"), 5)
-
-		control := make([]byte, srcControlSize)
-
-		setSrcControl(&control, ep)
-
-		hdr := (*unix.Cmsghdr)(unsafe.Pointer(&control[0]))
-		if hdr.Level != unix.IPPROTO_IP {
-			t.Errorf("unexpected level: %d", hdr.Level)
-		}
-		if hdr.Type != unix.IP_PKTINFO {
-			t.Errorf("unexpected type: %d", hdr.Type)
-		}
-		if uint(hdr.Len) != uint(unix.CmsgLen(int(unsafe.Sizeof(unix.Inet4Pktinfo{})))) {
-			t.Errorf("unexpected length: %d", hdr.Len)
-		}
-		info := (*unix.Inet4Pktinfo)(unsafe.Pointer(&control[unix.CmsgLen(0)]))
-		if info.Spec_dst[0] != 127 || info.Spec_dst[1] != 0 || info.Spec_dst[2] != 0 || info.Spec_dst[3] != 1 {
-			t.Errorf("unexpected address: %v", info.Spec_dst)
-		}
-		if info.Ifindex != 5 {
-			t.Errorf("unexpected ifindex: %d", info.Ifindex)
-		}
-	})
-
-	t.Run("IPv6", func(t *testing.T) {
-		ep := &StdNetEndpoint{
-			AddrPort: netip.MustParseAddrPort("[::1]:1234"),
-		}
-		setSrc(ep, netip.MustParseAddr("::1"), 5)
-
-		control := make([]byte, srcControlSize)
-
-		setSrcControl(&control, ep)
-
-		hdr := (*unix.Cmsghdr)(unsafe.Pointer(&control[0]))
-		if hdr.Level != unix.IPPROTO_IPV6 {
-			t.Errorf("unexpected level: %d", hdr.Level)
-		}
-		if hdr.Type != unix.IPV6_PKTINFO {
-			t.Errorf("unexpected type: %d", hdr.Type)
-		}
-		if uint(hdr.Len) != uint(unix.CmsgLen(int(unsafe.Sizeof(unix.Inet6Pktinfo{})))) {
-			t.Errorf("unexpected length: %d", hdr.Len)
-		}
-		info := (*unix.Inet6Pktinfo)(unsafe.Pointer(&control[unix.CmsgLen(0)]))
-		if info.Addr != ep.SrcIP().As16() {
-			t.Errorf("unexpected address: %v", info.Addr)
-		}
-		if info.Ifindex != 5 {
-			t.Errorf("unexpected ifindex: %d", info.Ifindex)
-		}
-	})
-
-	t.Run("ClearOnNoSrc", func(t *testing.T) {
-		control := make([]byte, unix.CmsgLen(0))
-		hdr := (*unix.Cmsghdr)(unsafe.Pointer(&control[0]))
-		hdr.Level = 1
-		hdr.Type = 2
-		hdr.Len = 3
-
-		setSrcControl(&control, &StdNetEndpoint{})
-
-		if len(control) != 0 {
-			t.Errorf("unexpected control: %v", control)
-		}
-	})
-}
-
-func Test_getSrcFromControl(t *testing.T) {
-	t.Run("IPv4", func(t *testing.T) {
-		control := make([]byte, unix.CmsgSpace(unix.SizeofInet4Pktinfo))
-		hdr := (*unix.Cmsghdr)(unsafe.Pointer(&control[0]))
-		hdr.Level = unix.IPPROTO_IP
-		hdr.Type = unix.IP_PKTINFO
-		hdr.SetLen(unix.CmsgLen(int(unsafe.Sizeof(unix.Inet4Pktinfo{}))))
-		info := (*unix.Inet4Pktinfo)(unsafe.Pointer(&control[unix.CmsgLen(0)]))
-		info.Spec_dst = [4]byte{127, 0, 0, 1}
-		info.Ifindex = 5
-
-		ep := &StdNetEndpoint{}
-		getSrcFromControl(control, ep)
-
-		if ep.SrcIP() != netip.MustParseAddr("127.0.0.1") {
-			t.Errorf("unexpected address: %v", ep.SrcIP())
-		}
-		if ep.SrcIfidx() != 5 {
-			t.Errorf("unexpected ifindex: %d", ep.SrcIfidx())
-		}
-	})
-	t.Run("IPv6", func(t *testing.T) {
-		control := make([]byte, unix.CmsgSpace(unix.SizeofInet6Pktinfo))
-		hdr := (*unix.Cmsghdr)(unsafe.Pointer(&control[0]))
-		hdr.Level = unix.IPPROTO_IPV6
-		hdr.Type = unix.IPV6_PKTINFO
-		hdr.SetLen(unix.CmsgLen(int(unsafe.Sizeof(unix.Inet6Pktinfo{}))))
-		info := (*unix.Inet6Pktinfo)(unsafe.Pointer(&control[unix.CmsgLen(0)]))
-		info.Addr = [16]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
-		info.Ifindex = 5
-
-		ep := &StdNetEndpoint{}
-		getSrcFromControl(control, ep)
-
-		if ep.SrcIP() != netip.MustParseAddr("::1") {
-			t.Errorf("unexpected address: %v", ep.SrcIP())
-		}
-		if ep.SrcIfidx() != 5 {
-			t.Errorf("unexpected ifindex: %d", ep.SrcIfidx())
-		}
-	})
-	t.Run("ClearOnEmpty", func(t *testing.T) {
-		var control []byte
-		ep := &StdNetEndpoint{}
-		setSrc(ep, netip.MustParseAddr("::1"), 5)
-
-		getSrcFromControl(control, ep)
-		if ep.SrcIP().IsValid() {
-			t.Errorf("unexpected address: %v", ep.SrcIP())
-		}
-		if ep.SrcIfidx() != 0 {
-			t.Errorf("unexpected ifindex: %d", ep.SrcIfidx())
-		}
-	})
-	t.Run("Multiple", func(t *testing.T) {
-		zeroControl := make([]byte, unix.CmsgSpace(0))
-		zeroHdr := (*unix.Cmsghdr)(unsafe.Pointer(&zeroControl[0]))
-		zeroHdr.SetLen(unix.CmsgLen(0))
-
-		control := make([]byte, unix.CmsgSpace(unix.SizeofInet4Pktinfo))
-		hdr := (*unix.Cmsghdr)(unsafe.Pointer(&control[0]))
-		hdr.Level = unix.IPPROTO_IP
-		hdr.Type = unix.IP_PKTINFO
-		hdr.SetLen(unix.CmsgLen(int(unsafe.Sizeof(unix.Inet4Pktinfo{}))))
-		info := (*unix.Inet4Pktinfo)(unsafe.Pointer(&control[unix.CmsgLen(0)]))
-		info.Spec_dst = [4]byte{127, 0, 0, 1}
-		info.Ifindex = 5
-
-		combined := make([]byte, 0)
-		combined = append(combined, zeroControl...)
-		combined = append(combined, control...)
-
-		ep := &StdNetEndpoint{}
-		getSrcFromControl(combined, ep)
-
-		if ep.SrcIP() != netip.MustParseAddr("127.0.0.1") {
-			t.Errorf("unexpected address: %v", ep.SrcIP())
-		}
-		if ep.SrcIfidx() != 5 {
-			t.Errorf("unexpected ifindex: %d", ep.SrcIfidx())
-		}
-	})
-}
-
-func Test_listenConfig(t *testing.T) {
-	t.Run("IPv4", func(t *testing.T) {
-		conn, err := listenConfig().ListenPacket(context.Background(), "udp4", ":0")
-		if err != nil {
-			t.Fatal(err)
-		}
-		defer conn.Close()
-		sc, err := conn.(*net.UDPConn).SyscallConn()
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		if runtime.GOOS == "linux" {
-			var i int
-			sc.Control(func(fd uintptr) {
-				i, err = unix.GetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_PKTINFO)
-			})
-			if err != nil {
-				t.Fatal(err)
-			}
-			if i != 1 {
-				t.Error("IP_PKTINFO not set!")
-			}
-		} else {
-			t.Logf("listenConfig() does not set IPV6_RECVPKTINFO on %s", runtime.GOOS)
-		}
-	})
-	t.Run("IPv6", func(t *testing.T) {
-		conn, err := listenConfig().ListenPacket(context.Background(), "udp6", ":0")
-		if err != nil {
-			t.Fatal(err)
-		}
-		sc, err := conn.(*net.UDPConn).SyscallConn()
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		if runtime.GOOS == "linux" {
-			var i int
-			sc.Control(func(fd uintptr) {
-				i, err = unix.GetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_RECVPKTINFO)
-			})
-			if err != nil {
-				t.Fatal(err)
-			}
-			if i != 1 {
-				t.Error("IPV6_PKTINFO not set!")
-			}
-		} else {
-			t.Logf("listenConfig() does not set IPV6_RECVPKTINFO on %s", runtime.GOOS)
-		}
-	})
-}