package udp import ( "crypto/rand" "errors" "io" "net" "runtime" "testing" "time" "github.com/stretchr/testify/assert" "github.com/stretchr/testify/require" ) func TestConsecutiveWrites(t *testing.T) { addr, err := net.ResolveUDPAddr("udp", ":0") require.NoError(t, err) ln, err := Listen("udp", addr, 3*time.Second) require.NoError(t, err) defer func() { err := ln.Close() require.NoError(t, err) }() go func() { for { conn, err := ln.Accept() if errors.Is(err, errClosedListener) { return } require.NoError(t, err) go func() { b := make([]byte, 2048) b2 := make([]byte, 2048) var n int var n2 int n, err = conn.Read(b) require.NoError(t, err) // Wait to make sure that the second packet is received time.Sleep(10 * time.Millisecond) n2, err = conn.Read(b2) require.NoError(t, err) _, err = conn.Write(b[:n]) require.NoError(t, err) _, err = conn.Write(b2[:n2]) require.NoError(t, err) }() } }() udpConn, err := net.Dial("udp", ln.Addr().String()) require.NoError(t, err) // Send multiple packets of different content and length consecutively // Read back packets afterwards and make sure that content matches // This checks if any buffers are overwritten while the receiver is enqueuing multiple packets b := make([]byte, 2048) var n int _, err = udpConn.Write([]byte("TESTLONG0")) require.NoError(t, err) _, err = udpConn.Write([]byte("1TEST")) require.NoError(t, err) n, err = udpConn.Read(b) require.NoError(t, err) require.Equal(t, "TESTLONG0", string(b[:n])) n, err = udpConn.Read(b) require.NoError(t, err) require.Equal(t, "1TEST", string(b[:n])) } func TestListenNotBlocking(t *testing.T) { addr, err := net.ResolveUDPAddr("udp", ":0") require.NoError(t, err) ln, err := Listen("udp", addr, 3*time.Second) require.NoError(t, err) defer func() { err := ln.Close() require.NoError(t, err) }() go func() { for { conn, err := ln.Accept() if errors.Is(err, errClosedListener) { return } require.NoError(t, err) go func() { b := make([]byte, 2048) n, err := conn.Read(b) require.NoError(t, err) _, err = conn.Write(b[:n]) require.NoError(t, err) n, err = conn.Read(b) require.NoError(t, err) _, err = conn.Write(b[:n]) require.NoError(t, err) // This should not block second call time.Sleep(10 * time.Second) }() } }() udpConn, err := net.Dial("udp", ln.Addr().String()) require.NoError(t, err) _, err = udpConn.Write([]byte("TEST")) require.NoError(t, err) b := make([]byte, 2048) n, err := udpConn.Read(b) require.NoError(t, err) require.Equal(t, "TEST", string(b[:n])) _, err = udpConn.Write([]byte("TEST2")) require.NoError(t, err) n, err = udpConn.Read(b) require.NoError(t, err) require.Equal(t, "TEST2", string(b[:n])) _, err = udpConn.Write([]byte("TEST")) require.NoError(t, err) done := make(chan struct{}) go func() { udpConn2, err := net.Dial("udp", ln.Addr().String()) require.NoError(t, err) _, err = udpConn2.Write([]byte("TEST")) require.NoError(t, err) n, err = udpConn2.Read(b) require.NoError(t, err) assert.Equal(t, "TEST", string(b[:n])) _, err = udpConn2.Write([]byte("TEST2")) require.NoError(t, err) n, err = udpConn2.Read(b) require.NoError(t, err) assert.Equal(t, "TEST2", string(b[:n])) close(done) }() select { case <-time.Tick(time.Second): t.Error("Timeout") case <-done: } } func TestListenWithZeroTimeout(t *testing.T) { addr, err := net.ResolveUDPAddr("udp", ":0") require.NoError(t, err) _, err = Listen("udp", addr, 0) assert.Error(t, err) } func TestTimeoutWithRead(t *testing.T) { testTimeout(t, true) } func TestTimeoutWithoutRead(t *testing.T) { testTimeout(t, false) } func testTimeout(t *testing.T, withRead bool) { t.Helper() addr, err := net.ResolveUDPAddr("udp", ":0") require.NoError(t, err) ln, err := Listen("udp", addr, 3*time.Second) require.NoError(t, err) defer func() { err := ln.Close() require.NoError(t, err) }() go func() { for { conn, err := ln.Accept() if errors.Is(err, errClosedListener) { return } require.NoError(t, err) if withRead { buf := make([]byte, 1024) _, err = conn.Read(buf) require.NoError(t, err) } } }() for range 10 { udpConn2, err := net.Dial("udp", ln.Addr().String()) require.NoError(t, err) _, err = udpConn2.Write([]byte("TEST")) require.NoError(t, err) } time.Sleep(10 * time.Millisecond) assert.Len(t, ln.conns, 10) time.Sleep(ln.timeout + time.Second) assert.Empty(t, ln.conns) } func TestShutdown(t *testing.T) { addr, err := net.ResolveUDPAddr("udp", ":0") require.NoError(t, err) l, err := Listen("udp", addr, 3*time.Second) require.NoError(t, err) go func() { for { conn, err := l.Accept() if err != nil { return } go func() { conn := 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", l.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() { err := l.Shutdown(5 * time.Second) require.NoError(t, err) 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", l.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) assert.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(5 * time.Second): // In case we introduce a regression that would make the test wait forever. t.Fatal("Timeout during shutdown") } } func TestReadLoopMaxDataSize(t *testing.T) { if runtime.GOOS == "darwin" { // sudo sysctl -w net.inet.udp.maxdgram=65507 t.Skip("Skip test on darwin as the maximum dgram size is set to 9216 bytes by default") } // Theoretical maximum size of data in a UDP datagram. // 65535 − 8 (UDP header) − 20 (IP header). dataSize := 65507 doneCh := make(chan struct{}) addr, err := net.ResolveUDPAddr("udp", ":0") require.NoError(t, err) l, err := Listen("udp", addr, 3*time.Second) require.NoError(t, err) defer func() { err := l.Close() require.NoError(t, err) }() go func() { defer close(doneCh) conn, err := l.Accept() require.NoError(t, err) buffer := make([]byte, dataSize) n, err := conn.Read(buffer) require.NoError(t, err) assert.Equal(t, dataSize, n) }() c, err := net.Dial("udp", l.Addr().String()) require.NoError(t, err) data := make([]byte, dataSize) _, err = rand.Read(data) require.NoError(t, err) _, err = c.Write(data) require.NoError(t, err) select { case <-doneCh: case <-time.Tick(5 * time.Second): t.Fatal("Timeout waiting for datagram read") } } // 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) { t.Helper() _, 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) assert.Equal(t, data, string(b[:n])) close(doneChan) }() select { case <-doneChan: case <-time.Tick(timeout): t.Fatalf("Timeout during echo for: %s", data) } }