GSO/GRO offloads, with TCP+ECN and UDP support

overlay/batch/multi_coalesce_test.go

@@ -0,0 +1,94 @@
+package batch
+
+import (
+	"testing"
+)
+
+// TestMultiCoalescerRoutesByProto confirms TCP/UDP/other land in the right
+// lane: TCP and UDP get coalesced when their lanes are enabled, anything
+// else (ICMP here) falls through to plain Write.
+func TestMultiCoalescerRoutesByProto(t *testing.T) {
+	w := &fakeTunWriter{gsoEnabled: true}
+	m := NewMultiCoalescer(w, true, true)
+
+	tcpPay := make([]byte, 1200)
+	udpPay := make([]byte, 1200)
+	icmp := make([]byte, 28)
+	icmp[0] = 0x45
+	icmp[2] = 0
+	icmp[3] = 28
+	icmp[9] = 1
+
+	if err := m.Commit(buildTCPv4(1000, tcpAck, tcpPay)); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Commit(buildTCPv4(2200, tcpAck, tcpPay)); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Commit(buildUDPv4(2000, 53, udpPay)); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Commit(buildUDPv4(2000, 53, udpPay)); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Commit(icmp); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Flush(); err != nil {
+		t.Fatal(err)
+	}
+	// 1 TCP super (2 segments) + 1 UDP super (2 segments) = 2 gso writes.
+	if len(w.gsoWrites) != 2 {
+		t.Fatalf("want 2 gso writes (one TCP + one UDP), got %d", len(w.gsoWrites))
+	}
+	if len(w.writes) != 1 {
+		t.Fatalf("want 1 plain write (ICMP), got %d", len(w.writes))
+	}
+}
+
+// TestMultiCoalescerDisabledUDPFallsThrough verifies that when the UDP lane
+// is disabled (e.g. kernel doesn't support USO), UDP packets still reach
+// the kernel via the passthrough lane rather than being lost.
+func TestMultiCoalescerDisabledUDPFallsThrough(t *testing.T) {
+	w := &fakeTunWriter{gsoEnabled: true}
+	m := NewMultiCoalescer(w, true, false) // TSO on, USO off
+
+	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800))); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800))); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Flush(); err != nil {
+		t.Fatal(err)
+	}
+	if len(w.gsoWrites) != 0 {
+		t.Errorf("UDP must NOT be coalesced when USO disabled, got %d gso writes", len(w.gsoWrites))
+	}
+	if len(w.writes) != 2 {
+		t.Errorf("UDP must pass through as 2 plain writes, got %d", len(w.writes))
+	}
+}
+
+// TestMultiCoalescerDisabledTCPFallsThrough mirrors the TSO=off case.
+func TestMultiCoalescerDisabledTCPFallsThrough(t *testing.T) {
+	w := &fakeTunWriter{gsoEnabled: true}
+	m := NewMultiCoalescer(w, false, true) // TSO off, USO on
+
+	pay := make([]byte, 1200)
+	if err := m.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Commit(buildTCPv4(2200, tcpAck, pay)); err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Flush(); err != nil {
+		t.Fatal(err)
+	}
+	if len(w.gsoWrites) != 0 {
+		t.Errorf("TCP must NOT be coalesced when TSO disabled, got %d gso writes", len(w.gsoWrites))
+	}
+	if len(w.writes) != 2 {
+		t.Errorf("TCP must pass through as 2 plain writes, got %d", len(w.writes))
+	}
+}