3 files changed, 67 insertions, 1 deletions

diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index e31464c9b..d29f0f81b 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -594,6 +594,11 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 		e.rcvAutoParams.disabled = !bool(mrb)
 	}
 
+	var de DelayEnabled
+	if err := s.TransportProtocolOption(ProtocolNumber, &de); err == nil && de {
+		e.SetSockOptInt(tcpip.DelayOption, 1)
+	}
+
 	if p := s.GetTCPProbe(); p != nil {
 		e.probe = p
 	}
diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go
index c4f1a84bb..c8e4a0d7e 100644
--- a/pkg/tcpip/transport/tcp/protocol.go
+++ b/pkg/tcpip/transport/tcp/protocol.go
@@ -60,6 +60,9 @@ const (
 // protocol. See: https://tools.ietf.org/html/rfc2018.
 type SACKEnabled bool
 
+// DelayEnabled option can be used to enable Nagle's algorithm in the TCP protocol.
+type DelayEnabled bool
+
 // SendBufferSizeOption allows the default, min and max send buffer sizes for
 // TCP endpoints to be queried or configured.
 type SendBufferSizeOption struct {
@@ -84,6 +87,7 @@ const (
 type protocol struct {
 	mu                         sync.Mutex
 	sackEnabled                bool
+	delayEnabled               bool
 	sendBufferSize             SendBufferSizeOption
 	recvBufferSize             ReceiveBufferSizeOption
 	congestionControl          string
@@ -97,7 +101,7 @@ func (*protocol) Number() tcpip.TransportProtocolNumber {
 }
 
 // NewEndpoint creates a new tcp endpoint.
-func (*protocol) NewEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
+func (p *protocol) NewEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
 	return newEndpoint(stack, netProto, waiterQueue), nil
 }
 
@@ -165,6 +169,12 @@ func (p *protocol) SetOption(option interface{}) *tcpip.Error {
 		p.mu.Unlock()
 		return nil
 
+	case DelayEnabled:
+		p.mu.Lock()
+		p.delayEnabled = bool(v)
+		p.mu.Unlock()
+		return nil
+
 	case SendBufferSizeOption:
 		if v.Min <= 0 || v.Default < v.Min || v.Default > v.Max {
 			return tcpip.ErrInvalidOptionValue
@@ -216,6 +226,12 @@ func (p *protocol) Option(option interface{}) *tcpip.Error {
 		p.mu.Unlock()
 		return nil
 
+	case *DelayEnabled:
+		p.mu.Lock()
+		*v = DelayEnabled(p.delayEnabled)
+		p.mu.Unlock()
+		return nil
+
 	case *SendBufferSizeOption:
 		p.mu.Lock()
 		*v = p.sendBufferSize
diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go
index beaa40210..f4ea5f091 100644
--- a/pkg/tcpip/transport/tcp/tcp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_test.go
@@ -4848,3 +4848,48 @@ func TestReceiveBufferAutoTuning(t *testing.T) {
 		payloadSize *= 2
 	}
 }
+
+func TestDelayEnabled(t *testing.T) {
+	c := context.New(t, defaultMTU)
+	defer c.Cleanup()
+	checkDelayOption(t, c, false, 0) // Delay is disabled by default.
+
+	for _, v := range []struct {
+		delayEnabled    tcp.DelayEnabled
+		wantDelayOption int
+	}{
+		{delayEnabled: false, wantDelayOption: 0},
+		{delayEnabled: true, wantDelayOption: 1},
+	} {
+		c := context.New(t, defaultMTU)
+		defer c.Cleanup()
+		if err := c.Stack().SetTransportProtocolOption(tcp.ProtocolNumber, v.delayEnabled); err != nil {
+			t.Fatalf("SetTransportProtocolOption(tcp, %t) failed: %v", v.delayEnabled, err)
+		}
+		checkDelayOption(t, c, v.delayEnabled, v.wantDelayOption)
+	}
+}
+
+func checkDelayOption(t *testing.T, c *context.Context, wantDelayEnabled tcp.DelayEnabled, wantDelayOption int) {
+	t.Helper()
+
+	var gotDelayEnabled tcp.DelayEnabled
+	if err := c.Stack().TransportProtocolOption(tcp.ProtocolNumber, &gotDelayEnabled); err != nil {
+		t.Fatalf("TransportProtocolOption(tcp, &gotDelayEnabled) failed: %v", err)
+	}
+	if gotDelayEnabled != wantDelayEnabled {
+		t.Errorf("TransportProtocolOption(tcp, &gotDelayEnabled) got %t, want %t", gotDelayEnabled, wantDelayEnabled)
+	}
+
+	ep, err := c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, new(waiter.Queue))
+	if err != nil {
+		t.Fatalf("NewEndPoint(tcp, ipv4, new(waiter.Queue)) failed: %v", err)
+	}
+	gotDelayOption, err := ep.GetSockOptInt(tcpip.DelayOption)
+	if err != nil {
+		t.Fatalf("ep.GetSockOptInt(tcpip.DelayOption) failed: %v", err)
+	}
+	if gotDelayOption != wantDelayOption {
+		t.Errorf("ep.GetSockOptInt(tcpip.DelayOption) got: %d, want: %d", gotDelayOption, wantDelayOption)
+	}
+}