[client] Keep NetBird traffic out of third-party fwmark rules (#7314)

client/net/fwmark_test.go

@@ -0,0 +1,111 @@
+package net
+
+import (
+	"testing"
+)
+
+func TestParseFwmarkBase(t *testing.T) {
+	tests := []struct {
+		name    string
+		val     string
+		want    uint32
+		wantErr bool
+	}{
+		{name: "hex", val: "0x5A000", want: 0x5A000},
+		{name: "hex upper case", val: "0X5A000", want: 0x5A000},
+		{name: "decimal", val: "65536", want: 65536},
+		{name: "octal", val: "0o400", want: 0o400},
+		{name: "surrounding space", val: "  0x5A000 ", want: 0x5A000},
+		{name: "highest usable base", val: "0xFFFFFF00", want: 0xFFFFFF00},
+		{name: "low byte in use", val: "0x1BD01", wantErr: true},
+		{name: "zero", val: "0", wantErr: true},
+		{name: "not a number", val: "wireguard", wantErr: true},
+		{name: "wider than 32 bit", val: "0x1FFFFFFFF", wantErr: true},
+		{name: "negative", val: "-0x100", wantErr: true},
+		{name: "empty", val: "", wantErr: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := parseFwmarkBase(tc.val)
+			if tc.wantErr {
+				if err == nil {
+					t.Fatalf("parseFwmarkBase(%q) = %#x, want an error", tc.val, got)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("parseFwmarkBase(%q): %v", tc.val, err)
+			}
+			if got != tc.want {
+				t.Errorf("parseFwmarkBase(%q) = %#x, want %#x", tc.val, got, tc.want)
+			}
+		})
+	}
+}
+
+// The marks have to stay inside the range the base defines, otherwise a host
+// that moved the range to dodge a collision would still emit the old values.
+func TestMarksStayWithinTheRange(t *testing.T) {
+	lower, upper := fwmarkBase, fwmarkBase|fwmarkOffsetMask
+
+	marks := map[string]uint32{
+		"ControlPlaneMark":                 ControlPlaneMark,
+		"DataPlaneMarkLower":               DataPlaneMarkLower,
+		"DataPlaneMarkUpper":               DataPlaneMarkUpper,
+		"DataPlaneMarkIn":                  DataPlaneMarkIn,
+		"DataPlaneMarkOut":                 DataPlaneMarkOut,
+		"PreroutingFwmarkRedirected":       PreroutingFwmarkRedirected,
+		"PreroutingFwmarkMasquerade":       PreroutingFwmarkMasquerade,
+		"PreroutingFwmarkMasqueradeReturn": PreroutingFwmarkMasqueradeReturn,
+	}
+
+	for name, mark := range marks {
+		if mark < lower || mark > upper {
+			t.Errorf("%s = %#x, outside the range %#x-%#x", name, mark, lower, upper)
+		}
+	}
+
+	// the control plane mark must stay out of the data plane range, the netflow
+	// conntrack path tells them apart by it
+	if IsDataPlaneMark(ControlPlaneMark) {
+		t.Errorf("ControlPlaneMark %#x is inside the data plane range", ControlPlaneMark)
+	}
+	for name, mark := range map[string]uint32{
+		"DataPlaneMarkIn":                  DataPlaneMarkIn,
+		"DataPlaneMarkOut":                 DataPlaneMarkOut,
+		"PreroutingFwmarkRedirected":       PreroutingFwmarkRedirected,
+		"PreroutingFwmarkMasquerade":       PreroutingFwmarkMasquerade,
+		"PreroutingFwmarkMasqueradeReturn": PreroutingFwmarkMasqueradeReturn,
+	} {
+		if !IsDataPlaneMark(mark) {
+			t.Errorf("%s = %#x is outside the data plane range %#x-%#x", name, mark, DataPlaneMarkLower, DataPlaneMarkUpper)
+		}
+	}
+}
+
+func TestDefaultMarksAreUnchanged(t *testing.T) {
+	tests := map[string]struct {
+		got  uint32
+		want uint32
+	}{
+		"ControlPlaneMark":                 {ControlPlaneMark, 0x1BD00},
+		"DataPlaneMarkLower":               {DataPlaneMarkLower, 0x1BD10},
+		"DataPlaneMarkUpper":               {DataPlaneMarkUpper, 0x1BDFF},
+		"DataPlaneMarkIn":                  {DataPlaneMarkIn, 0x1BD10},
+		"DataPlaneMarkOut":                 {DataPlaneMarkOut, 0x1BD11},
+		"PreroutingFwmarkRedirected":       {PreroutingFwmarkRedirected, 0x1BD20},
+		"PreroutingFwmarkMasquerade":       {PreroutingFwmarkMasquerade, 0x1BD21},
+		"PreroutingFwmarkMasqueradeReturn": {PreroutingFwmarkMasqueradeReturn, 0x1BD22},
+	}
+
+	if fwmarkBase != defaultFwmarkBase {
+		t.Skipf("%s is set, the defaults do not apply", envFwmarkBase)
+	}
+
+	for name, tc := range tests {
+		if tc.got != tc.want {
+			t.Errorf("%s = %#x, want %#x", name, tc.got, tc.want)
+		}
+	}
+}