Add OS-dependent reuse-port helpers

reuseport/control_default.go

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build !unix && !windows
+
+package reuseport
+
+import (
+	"syscall"
+)
+
+func Control(network, address string, c syscall.RawConn) error {
+	return nil
+}

reuseport/control_unix.go

@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build unix
+
+package reuseport
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func Control(network, address string, conn syscall.RawConn) error {
+	return conn.Control(func(fd uintptr) {
+		err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEADDR, 1)
+		if err != nil {
+			return
+		}
+		_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
+	})
+}

reuseport/control_windows.go

@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build windows
+
+package reuseport
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/windows"
+)
+
+func Control(network, address string, c syscall.RawConn) (err error) {
+	return c.Control(func(fd uintptr) {
+		_ = windows.SetsockoptInt(windows.Handle(fd), windows.SOL_SOCKET, windows.SO_REUSEADDR, 1)
+	})
+}

reuseport/reuse_test.go

@@ -0,0 +1,88 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build unix || windows
+
+package reuseport
+
+import (
+	"context"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func testDialFromListeningTCPPort(t *testing.T, network, host string) {
+	t.Helper()
+
+	lc := net.ListenConfig{
+		Control: Control,
+	}
+	ctx := context.Background()
+
+	// Allocate a listener that supplies the source address.
+	ll, err := lc.Listen(ctx, network, host+":0")
+	assert.NoError(t, err)
+
+	// Allocate another listener that supplies the destination address.
+	rl, err := lc.Listen(ctx, network, host+":0")
+	assert.NoError(t, err)
+
+	// Create a dialer do bind to local address.
+	d := net.Dialer{
+		LocalAddr: ll.Addr(),
+		Control:   Control,
+	}
+
+	// Dial.
+	c, err := d.Dial(network, rl.Addr().String())
+	assert.NoError(t, err)
+
+	assert.NoError(t, c.Close())
+}
+
+func testDialFromListeningUDPPort(t *testing.T, network, host string) {
+	t.Helper()
+
+	lc := net.ListenConfig{
+		Control: Control,
+	}
+	ctx := context.Background()
+
+	// Allocate a listener that supplies the source address.
+	ll, err := lc.ListenPacket(ctx, network, host+":0")
+	assert.NoError(t, err)
+
+	// Allocate another listener that supplies the destination address.
+	rl, err := lc.ListenPacket(ctx, network, host+":0")
+	assert.NoError(t, err)
+
+	// Create a dialer do bind to local address.
+	d := net.Dialer{
+		LocalAddr: ll.LocalAddr(),
+		Control:   Control,
+	}
+
+	// Dial.
+	c, err := d.Dial(network, rl.LocalAddr().String())
+	assert.NoError(t, err)
+
+	assert.NoError(t, c.Close())
+}
+
+func TestDialFromListeningPortTCP4(t *testing.T) {
+	testDialFromListeningTCPPort(t, "tcp", "localhost")
+}
+
+func TestDialFromListeningPortTCP6(t *testing.T) {
+	testDialFromListeningTCPPort(t, "tcp6", "[::1]")
+}
+
+func TestDialFromListeningPortUdp4(t *testing.T) {
+	testDialFromListeningUDPPort(t, "udp", "localhost")
+}
+
+func TestDialFromListeningPortUdp6(t *testing.T) {
+	testDialFromListeningUDPPort(t, "udp6", "[::1]")
+}

reuseport/reuseport.go

@@ -0,0 +1,5 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+// Package reuseport implements an OS-dependent reuse-port helper.
+package reuseport