Sketch VM based bpf tests

bpf_vm_test.go

@@ -0,0 +1,53 @@
+package conntrack
+
+import (
+	"errors"
+	"testing"
+
+	"golang.org/x/net/bpf"
+)
+
+// Collection of reusable inputs to test bpf filters against.
+var (
+	// nlMsg1: UDP - src=192.168.1.105 dst=224.0.0.251
+	nlMsg1 = []byte{0x34, 0x00, 0x01, 0x80, 0x14, 0x00, 0x01, 0x80, 0x08, 0x00, 0x01, 0x00, 0xc0, 0xa8, 0x01, 0x69, 0x08, 0x00, 0x02, 0x00, 0xe0, 0x00, 0x00, 0xfb, 0x1c, 0x00, 0x02, 0x80, 0x05, 0x00, 0x01, 0x00, 0x11, 0x00, 0x00, 0x00, 0x06, 0x00, 0x02, 0x00, 0x14, 0xe9, 0x00, 0x00, 0x06, 0x00, 0x03, 0x00, 0x14, 0xe9, 0x00, 0x00, 0x08, 0x00, 0x0c, 0x00, 0x1a, 0xfb, 0x54, 0xa9, 0x08, 0x00, 0x03, 0x00, 0x00, 0x00, 0x01, 0x88, 0x08, 0x00, 0x07, 0x00, 0x00, 0x00, 0x00, 0x1e}
+)
+
+func TestConstructFilterVM(t *testing.T) {
+	t.Skipf("ExtNetlinkAttr and ExtNetlinkAttrNested are currently not implemented in x/net/bpf")
+
+	tests := map[string]struct {
+		filters      []ConnAttr
+		constructErr error
+		runErr       error
+		input        []byte
+	}{
+		"no filters": {input: nlMsg1},
+		"tcp-only":   {filters: []ConnAttr{{Type: AttrOrigL4Proto, Data: []byte{0x11}}}, input: nlMsg1},
+	}
+
+	for name, test := range tests {
+		name := name
+		test := test
+		t.Run(name, func(t *testing.T) {
+			rawInstrs, constructErr := constructFilter(Conntrack, test.filters)
+			if !errors.Is(constructErr, test.constructErr) {
+				t.Fatalf("Expected '%v' but got '%v'", test.constructErr, constructErr)
+			}
+			instrs, _ := bpf.Disassemble(rawInstrs)
+			t.Logf("%#v", instrs)
+			vm, vmErr := bpf.NewVM(instrs)
+			if vmErr != nil {
+				t.Fatal(vmErr)
+			}
+
+			accepted, runErr := vm.Run(test.input)
+			if !errors.Is(runErr, test.runErr) {
+				t.Fatalf("Expected '%v' but got '%v'", test.runErr, runErr)
+			}
+
+			// TODO: validate result
+			_ = accepted
+		})
+	}
+}