UDP support

Co-authored-by: Julien Salleyron <julien.salleyron@gmail.com>

pkg/server/server_entrypoint_udp_test.go

@@ -0,0 +1,123 @@
+package server
+
+import (
+	"context"
+	"io"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/containous/traefik/v2/pkg/config/static"
+	"github.com/containous/traefik/v2/pkg/types"
+	"github.com/containous/traefik/v2/pkg/udp"
+	"github.com/stretchr/testify/require"
+)
+
+func TestShutdownUDPConn(t *testing.T) {
+	entryPoint, err := NewUDPEntryPoint(&static.EntryPoint{
+		Address: ":0",
+		Transport: &static.EntryPointsTransport{
+			LifeCycle: &static.LifeCycle{
+				GraceTimeOut: types.Duration(5 * time.Second),
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	go entryPoint.Start(context.Background())
+	entryPoint.Switch(udp.HandlerFunc(func(conn *udp.Conn) {
+		for {
+			b := make([]byte, 1024*1024)
+			n, err := conn.Read(b)
+			require.NoError(t, err)
+			// We control the termination, otherwise we would block on the Read above, until
+			// conn is closed by a timeout. Which means we would get an error, and even though
+			// we are in a goroutine and the current test might be over, go test would still
+			// yell at us if this happens while other tests are still running.
+			if string(b[:n]) == "CLOSE" {
+				return
+			}
+			_, err = conn.Write(b[:n])
+			require.NoError(t, err)
+		}
+	}))
+
+	conn, err := net.Dial("udp", entryPoint.listener.Addr().String())
+	require.NoError(t, err)
+
+	// Start sending packets, to create a "session" with the server.
+	requireEcho(t, "TEST", conn, time.Second)
+
+	doneChan := make(chan struct{})
+	go func() {
+		entryPoint.Shutdown(context.Background())
+		close(doneChan)
+	}()
+
+	// Make sure that our session is still live even after the shutdown.
+	requireEcho(t, "TEST2", conn, time.Second)
+
+	// And make sure that on the other hand, opening new sessions is not possible anymore.
+	conn2, err := net.Dial("udp", entryPoint.listener.Addr().String())
+	require.NoError(t, err)
+
+	_, err = conn2.Write([]byte("TEST"))
+	// Packet is accepted, but dropped
+	require.NoError(t, err)
+
+	// Make sure that our session is yet again still live. This is specifically to
+	// make sure we don't create a regression in listener's readLoop, i.e. that we only
+	// terminate the listener's readLoop goroutine by closing its pConn.
+	requireEcho(t, "TEST3", conn, time.Second)
+
+	done := make(chan bool)
+	go func() {
+		defer close(done)
+		b := make([]byte, 1024*1024)
+		n, err := conn2.Read(b)
+		require.Error(t, err)
+		require.Equal(t, 0, n)
+	}()
+
+	conn2.Close()
+
+	select {
+	case <-done:
+	case <-time.Tick(time.Second):
+		t.Fatal("Timeout")
+	}
+
+	_, err = conn.Write([]byte("CLOSE"))
+	require.NoError(t, err)
+
+	select {
+	case <-doneChan:
+	case <-time.Tick(time.Second * 5):
+		// In case we introduce a regression that would make the test wait forever.
+		t.Fatal("Timeout during shutdown")
+	}
+}
+
+// requireEcho tests that the conn session is live and functional, by writing
+// data through it, and expecting the same data as a response when reading on it.
+// It fatals if the read blocks longer than timeout, which is useful to detect
+// regressions that would make a test wait forever.
+func requireEcho(t *testing.T, data string, conn io.ReadWriter, timeout time.Duration) {
+	_, err := conn.Write([]byte(data))
+	require.NoError(t, err)
+
+	doneChan := make(chan struct{})
+	go func() {
+		b := make([]byte, 1024*1024)
+		n, err := conn.Read(b)
+		require.NoError(t, err)
+		require.Equal(t, data, string(b[:n]))
+		close(doneChan)
+	}()
+
+	select {
+	case <-doneChan:
+	case <-time.Tick(timeout):
+		t.Fatalf("Timeout during echo for: %s", data)
+	}
+}