udp_test.go

package udp_test

import (
	"crypto/rand"
	"log"
	"net"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
)

func TestUDPUnconnectedDualStack(t *testing.T) {
	conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
	require.NoError(t, err)
	defer conn.Close()

	done := make(chan struct{})
	go func() {
		defer close(done)
		b := make([]byte, 1000)
		n, addr, err := conn.ReadFrom(b)
		if err != nil {
			log.Fatal(err)
		}
		t.Logf("received %d bytes from %s", n, addr)
	}()

	c, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 0})
	require.NoError(t, err)
	defer c.Close()
	b := make([]byte, 1000)
	rand.Read(b)
	t.Logf("sending packet from %s to %s", c.LocalAddr(), conn.LocalAddr())
	_, err = c.WriteTo(b, &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: conn.LocalAddr().(*net.UDPAddr).Port})
	require.NoError(t, err)

	select {
	case <-done:
	case <-time.After(5 * time.Second):
		t.Fatal("timeout")
	}
}

func TestUDPUnconnectedDualStackWithRetransmission(t *testing.T) {
	conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
	require.NoError(t, err)
	defer conn.Close()

	done := make(chan struct{})
	go func() {
		defer close(done)
		b := make([]byte, 1000)
		n, addr, err := conn.ReadFrom(b)
		if err != nil {
			log.Fatal(err)
		}
		t.Logf("received %d bytes from %s", n, addr)
	}()

	c, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 0})
	require.NoError(t, err)
	defer c.Close()
	b := make([]byte, 1000)
	rand.Read(b)
	t.Logf("sending packet from %s to %s", c.LocalAddr(), conn.LocalAddr())
	_, err = c.WriteTo(b, &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: conn.LocalAddr().(*net.UDPAddr).Port})
	require.NoError(t, err)

	globalTimeout := time.After(5 * time.Second)
	ticker := time.NewTicker(100 * time.Millisecond)
	for {
		select {
		case <-done:
			return
		case <-ticker.C:
			// send a retransmission
			_, err = c.WriteTo(b, &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: conn.LocalAddr().(*net.UDPAddr).Port})
			require.NoError(t, err)
		case <-globalTimeout:
			t.Fatal("timeout")
		}
	}
}