rlp: new package for streaming RLP decoder

1 files changed, 469 insertions, 0 deletions

diff --git a/rlp/decode_test.go b/rlp/decode_test.go
new file mode 100644
index 000000000..5cb42b870
--- /dev/null
+++ b/rlp/decode_test.go
@@ -0,0 +1,469 @@
+package rlp
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"math/big"
+	"reflect"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/ethutil"
+)
+
+func TestStreamKind(t *testing.T) {
+	tests := []struct {
+		input    string
+		wantKind Kind
+		wantLen  uint64
+	}{
+		{"00", Byte, 0},
+		{"01", Byte, 0},
+		{"7F", Byte, 0},
+		{"80", String, 0},
+		{"B7", String, 55},
+		{"B800", String, 0},
+		{"B90400", String, 1024},
+		{"BA000400", String, 1024},
+		{"BB00000400", String, 1024},
+		{"BFFFFFFFFFFFFFFFFF", String, ^uint64(0)},
+		{"C0", List, 0},
+		{"C8", List, 8},
+		{"F7", List, 55},
+		{"F800", List, 0},
+		{"F804", List, 4},
+		{"F90400", List, 1024},
+		{"FFFFFFFFFFFFFFFFFF", List, ^uint64(0)},
+	}
+
+	for i, test := range tests {
+		s := NewStream(bytes.NewReader(unhex(test.input)))
+		kind, len, err := s.Kind()
+		if err != nil {
+			t.Errorf("test %d: Type returned error: %v", i, err)
+			continue
+		}
+		if kind != test.wantKind {
+			t.Errorf("test %d: kind mismatch: got %d, want %d", i, kind, test.wantKind)
+		}
+		if len != test.wantLen {
+			t.Errorf("test %d: len mismatch: got %d, want %d", i, len, test.wantLen)
+		}
+	}
+}
+
+func TestStreamErrors(t *testing.T) {
+	type calls []string
+	tests := []struct {
+		string
+		calls
+		error
+	}{
+		{"", calls{"Kind"}, io.EOF},
+		{"", calls{"List"}, io.EOF},
+		{"", calls{"Uint"}, io.EOF},
+		{"C0", calls{"Bytes"}, ErrExpectedString},
+		{"C0", calls{"Uint"}, ErrExpectedString},
+		{"81", calls{"Bytes"}, io.ErrUnexpectedEOF},
+		{"81", calls{"Uint"}, io.ErrUnexpectedEOF},
+		{"BFFFFFFFFFFFFFFF", calls{"Bytes"}, io.ErrUnexpectedEOF},
+		{"89000000000000000001", calls{"Uint"}, errors.New("rlp: string is larger than 64 bits")},
+		{"00", calls{"List"}, ErrExpectedList},
+		{"80", calls{"List"}, ErrExpectedList},
+		{"C0", calls{"List", "Uint"}, EOL},
+		{"C801", calls{"List", "Uint", "Uint"}, io.ErrUnexpectedEOF},
+		{"C8C9", calls{"List", "Kind"}, ErrElemTooLarge},
+		{"C3C2010201", calls{"List", "List", "Uint", "Uint", "ListEnd", "Uint"}, EOL},
+		{"00", calls{"ListEnd"}, errNotInList},
+		{"C40102", calls{"List", "Uint", "ListEnd"}, errNotAtEOL},
+	}
+
+testfor:
+	for i, test := range tests {
+		s := NewStream(bytes.NewReader(unhex(test.string)))
+		rs := reflect.ValueOf(s)
+		for j, call := range test.calls {
+			fval := rs.MethodByName(call)
+			ret := fval.Call(nil)
+			err := "<nil>"
+			if lastret := ret[len(ret)-1].Interface(); lastret != nil {
+				err = lastret.(error).Error()
+			}
+			if j == len(test.calls)-1 {
+				if err != test.error.Error() {
+					t.Errorf("test %d: last call (%s) error mismatch\ngot:  %s\nwant: %v",
+						i, call, err, test.error)
+				}
+			} else if err != "<nil>" {
+				t.Errorf("test %d: call %d (%s) unexpected error: %q", i, j, call, err)
+				continue testfor
+			}
+		}
+	}
+}
+
+func TestStreamList(t *testing.T) {
+	s := NewStream(bytes.NewReader(unhex("C80102030405060708")))
+
+	len, err := s.List()
+	if err != nil {
+		t.Fatalf("List error: %v", err)
+	}
+	if len != 8 {
+		t.Fatalf("List returned invalid length, got %d, want 8", len)
+	}
+
+	for i := uint64(1); i <= 8; i++ {
+		v, err := s.Uint()
+		if err != nil {
+			t.Fatalf("Uint error: %v", err)
+		}
+		if i != v {
+			t.Errorf("Uint returned wrong value, got %d, want %d", v, i)
+		}
+	}
+
+	if _, err := s.Uint(); err != EOL {
+		t.Errorf("Uint error mismatch, got %v, want %v", err, EOL)
+	}
+	if err = s.ListEnd(); err != nil {
+		t.Fatalf("ListEnd error: %v", err)
+	}
+}
+
+func TestDecodeErrors(t *testing.T) {
+	r := bytes.NewReader(nil)
+
+	if err := Decode(r, nil); err != errDecodeIntoNil {
+		t.Errorf("Decode(r, nil) error mismatch, got %q, want %q", err, errDecodeIntoNil)
+	}
+
+	var nilptr *struct{}
+	if err := Decode(r, nilptr); err != errDecodeIntoNil {
+		t.Errorf("Decode(r, nilptr) error mismatch, got %q, want %q", err, errDecodeIntoNil)
+	}
+
+	if err := Decode(r, struct{}{}); err != errNoPointer {
+		t.Errorf("Decode(r, struct{}{}) error mismatch, got %q, want %q", err, errNoPointer)
+	}
+
+	expectErr := "rlp: type chan bool is not RLP-serializable"
+	if err := Decode(r, new(chan bool)); err == nil || err.Error() != expectErr {
+		t.Errorf("Decode(r, new(chan bool)) error mismatch, got %q, want %q", err, expectErr)
+	}
+
+	if err := Decode(r, new(int)); err != io.EOF {
+		t.Errorf("Decode(r, new(int)) error mismatch, got %q, want %q", err, io.EOF)
+	}
+}
+
+type decodeTest struct {
+	input string
+	ptr   interface{}
+	value interface{}
+	error error
+}
+
+type simplestruct struct {
+	A int
+	B string
+}
+
+type recstruct struct {
+	I     int
+	Child *recstruct
+}
+
+var sharedByteArray [5]byte
+
+var (
+	veryBigInt = big.NewInt(0).Add(
+		big.NewInt(0).Lsh(big.NewInt(0xFFFFFFFFFFFFFF), 16),
+		big.NewInt(0xFFFF),
+	)
+)
+
+var decodeTests = []decodeTest{
+	// integers
+	{input: "05", ptr: new(uint32), value: uint32(5)},
+	{input: "80", ptr: new(uint32), value: uint32(0)},
+	{input: "8105", ptr: new(uint32), value: uint32(5)},
+	{input: "820505", ptr: new(uint32), value: uint32(0x0505)},
+	{input: "83050505", ptr: new(uint32), value: uint32(0x050505)},
+	{input: "8405050505", ptr: new(uint32), value: uint32(0x05050505)},
+	{input: "850505050505", ptr: new(uint32), error: errors.New("rlp: string is larger than 32 bits")},
+	{input: "C0", ptr: new(uint32), error: ErrExpectedString},
+
+	// slices
+	{input: "C0", ptr: new([]int), value: []int{}},
+	{input: "C80102030405060708", ptr: new([]int), value: []int{1, 2, 3, 4, 5, 6, 7, 8}},
+
+	// arrays
+	{input: "C0", ptr: new([5]int), value: [5]int{}},
+	{input: "C50102030405", ptr: new([5]int), value: [5]int{1, 2, 3, 4, 5}},
+	{input: "C6010203040506", ptr: new([5]int), error: errors.New("rlp: input List has more than 5 elements")},
+
+	// byte slices
+	{input: "01", ptr: new([]byte), value: []byte{1}},
+	{input: "80", ptr: new([]byte), value: []byte{}},
+	{input: "8D6162636465666768696A6B6C6D", ptr: new([]byte), value: []byte("abcdefghijklm")},
+	{input: "C0", ptr: new([]byte), value: []byte{}},
+	{input: "C3010203", ptr: new([]byte), value: []byte{1, 2, 3}},
+	{input: "C3820102", ptr: new([]byte), error: errors.New("rlp: string is larger than 8 bits")},
+
+	// byte arrays
+	{input: "01", ptr: new([5]byte), value: [5]byte{1}},
+	{input: "80", ptr: new([5]byte), value: [5]byte{}},
+	{input: "850102030405", ptr: new([5]byte), value: [5]byte{1, 2, 3, 4, 5}},
+	{input: "C0", ptr: new([5]byte), value: [5]byte{}},
+	{input: "C3010203", ptr: new([5]byte), value: [5]byte{1, 2, 3, 0, 0}},
+	{input: "C3820102", ptr: new([5]byte), error: errors.New("rlp: string is larger than 8 bits")},
+	{input: "86010203040506", ptr: new([5]byte), error: errStringDoesntFitArray},
+	{input: "850101", ptr: new([5]byte), error: io.ErrUnexpectedEOF},
+
+	// byte array reuse (should be zeroed)
+	{input: "850102030405", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 4, 5}},
+	{input: "8101", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: String
+	{input: "850102030405", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 4, 5}},
+	{input: "01", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: Byte
+	{input: "C3010203", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 0, 0}},
+	{input: "C101", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: List
+
+	// zero sized byte arrays
+	{input: "80", ptr: new([0]byte), value: [0]byte{}},
+	{input: "C0", ptr: new([0]byte), value: [0]byte{}},
+	{input: "01", ptr: new([0]byte), error: errStringDoesntFitArray},
+	{input: "8101", ptr: new([0]byte), error: errStringDoesntFitArray},
+
+	// strings
+	{input: "00", ptr: new(string), value: "\000"},
+	{input: "8D6162636465666768696A6B6C6D", ptr: new(string), value: "abcdefghijklm"},
+	{input: "C0", ptr: new(string), error: ErrExpectedString},
+
+	// big ints
+	{input: "01", ptr: new(*big.Int), value: big.NewInt(1)},
+	{input: "89FFFFFFFFFFFFFFFFFF", ptr: new(*big.Int), value: veryBigInt},
+	{input: "10", ptr: new(big.Int), value: *big.NewInt(16)}, // non-pointer also works
+	{input: "C0", ptr: new(*big.Int), error: ErrExpectedString},
+
+	// structs
+	{input: "C0", ptr: new(simplestruct), value: simplestruct{0, ""}},
+	{input: "C105", ptr: new(simplestruct), value: simplestruct{5, ""}},
+	{input: "C50583343434", ptr: new(simplestruct), value: simplestruct{5, "444"}},
+	{input: "C3010101", ptr: new(simplestruct), error: errors.New("rlp: input List has too many elements")},
+	{
+		input: "C501C302C103",
+		ptr:   new(recstruct),
+		value: recstruct{1, &recstruct{2, &recstruct{3, nil}}},
+	},
+
+	// pointers
+	{input: "00", ptr: new(*int), value: (*int)(nil)},
+	{input: "80", ptr: new(*int), value: (*int)(nil)},
+	{input: "C0", ptr: new(*int), value: (*int)(nil)},
+	{input: "07", ptr: new(*int), value: intp(7)},
+	{input: "8108", ptr: new(*int), value: intp(8)},
+	{input: "C109", ptr: new(*[]int), value: &[]int{9}},
+	{input: "C58403030303", ptr: new(*[][]byte), value: &[][]byte{{3, 3, 3, 3}}},
+
+	// interface{}
+	{input: "00", ptr: new(interface{}), value: []byte{0}},
+	{input: "01", ptr: new(interface{}), value: []byte{1}},
+	{input: "80", ptr: new(interface{}), value: []byte{}},
+	{input: "850505050505", ptr: new(interface{}), value: []byte{5, 5, 5, 5, 5}},
+	{input: "C0", ptr: new(interface{}), value: []interface{}{}},
+	{input: "C50183040404", ptr: new(interface{}), value: []interface{}{[]byte{1}, []byte{4, 4, 4}}},
+}
+
+func intp(i int) *int { return &i }
+
+func TestDecode(t *testing.T) {
+	for i, test := range decodeTests {
+		input, err := hex.DecodeString(test.input)
+		if err != nil {
+			t.Errorf("test %d: invalid hex input %q", i, test.input)
+			continue
+		}
+		err = Decode(bytes.NewReader(input), test.ptr)
+		if err != nil && test.error == nil {
+			t.Errorf("test %d: unexpected Decode error: %v\ndecoding into %T\ninput %q",
+				i, err, test.ptr, test.input)
+			continue
+		}
+		if test.error != nil && fmt.Sprint(err) != fmt.Sprint(test.error) {
+			t.Errorf("test %d: Decode error mismatch\ngot  %v\nwant %v\ndecoding into %T\ninput %q",
+				i, err, test.error, test.ptr, test.input)
+			continue
+		}
+		deref := reflect.ValueOf(test.ptr).Elem().Interface()
+		if err == nil && !reflect.DeepEqual(deref, test.value) {
+			t.Errorf("test %d: value mismatch\ngot  %#v\nwant %#v\ndecoding into %T\ninput %q",
+				i, deref, test.value, test.ptr, test.input)
+		}
+	}
+}
+
+type testDecoder struct{ called bool }
+
+func (t *testDecoder) DecodeRLP(s *Stream) error {
+	if _, err := s.Uint(); err != nil {
+		return err
+	}
+	t.called = true
+	return nil
+}
+
+func TestDecodeDecoder(t *testing.T) {
+	var s struct {
+		T1 testDecoder
+		T2 *testDecoder
+		T3 **testDecoder
+	}
+	if err := Decode(bytes.NewReader(unhex("C3010203")), &s); err != nil {
+		t.Fatalf("Decode error: %v", err)
+	}
+
+	if !s.T1.called {
+		t.Errorf("DecodeRLP was not called for (non-pointer) testDecoder")
+	}
+
+	if s.T2 == nil {
+		t.Errorf("*testDecoder has not been allocated")
+	} else if !s.T2.called {
+		t.Errorf("DecodeRLP was not called for *testDecoder")
+	}
+
+	if s.T3 == nil || *s.T3 == nil {
+		t.Errorf("**testDecoder has not been allocated")
+	} else if !(*s.T3).called {
+		t.Errorf("DecodeRLP was not called for **testDecoder")
+	}
+}
+
+type byteDecoder byte
+
+func (bd *byteDecoder) DecodeRLP(s *Stream) error {
+	_, err := s.Uint()
+	*bd = 255
+	return err
+}
+
+func (bd byteDecoder) called() bool {
+	return bd == 255
+}
+
+// This test verifies that the byte slice/byte array logic
+// does not kick in for element types implementing Decoder.
+func TestDecoderInByteSlice(t *testing.T) {
+	var slice []byteDecoder
+	if err := Decode(bytes.NewReader(unhex("C101")), &slice); err != nil {
+		t.Errorf("unexpected Decode error %v", err)
+	} else if !slice[0].called() {
+		t.Errorf("DecodeRLP not called for slice element")
+	}
+
+	var array [1]byteDecoder
+	if err := Decode(bytes.NewReader(unhex("C101")), &array); err != nil {
+		t.Errorf("unexpected Decode error %v", err)
+	} else if !array[0].called() {
+		t.Errorf("DecodeRLP not called for array element")
+	}
+}
+
+func ExampleDecode() {
+	input, _ := hex.DecodeString("C90A1486666F6F626172")
+
+	type example struct {
+		A, B    int
+		private int // private fields are ignored
+		String  string
+	}
+
+	var s example
+	err := Decode(bytes.NewReader(input), &s)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+	} else {
+		fmt.Printf("Decoded value: %#v\n", s)
+	}
+	// Output:
+	// Decoded value: rlp.example{A:10, B:20, private:0, String:"foobar"}
+}
+
+func ExampleStream() {
+	input, _ := hex.DecodeString("C90A1486666F6F626172")
+	s := NewStream(bytes.NewReader(input))
+
+	// Check what kind of value lies ahead
+	kind, size, _ := s.Kind()
+	fmt.Printf("Kind: %v size:%d\n", kind, size)
+
+	// Enter the list
+	if _, err := s.List(); err != nil {
+		fmt.Printf("List error: %v\n", err)
+		return
+	}
+
+	// Decode elements
+	fmt.Println(s.Uint())
+	fmt.Println(s.Uint())
+	fmt.Println(s.Bytes())
+
+	// Acknowledge end of list
+	if err := s.ListEnd(); err != nil {
+		fmt.Printf("ListEnd error: %v\n", err)
+	}
+	// Output:
+	// Kind: List size:9
+	// 10 <nil>
+	// 20 <nil>
+	// [102 111 111 98 97 114] <nil>
+}
+
+func BenchmarkDecode(b *testing.B) {
+	enc := encTest(90000)
+	b.SetBytes(int64(len(enc)))
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		var s []int
+		r := bytes.NewReader(enc)
+		if err := Decode(r, &s); err != nil {
+			b.Fatalf("Decode error: %v", err)
+		}
+	}
+}
+
+func BenchmarkDecodeIntSliceReuse(b *testing.B) {
+	enc := encTest(100000)
+	b.SetBytes(int64(len(enc)))
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	var s []int
+	for i := 0; i < b.N; i++ {
+		r := bytes.NewReader(enc)
+		if err := Decode(r, &s); err != nil {
+			b.Fatalf("Decode error: %v", err)
+		}
+	}
+}
+
+func encTest(n int) []byte {
+	s := make([]interface{}, n)
+	for i := 0; i < n; i++ {
+		s[i] = i
+	}
+	return ethutil.Encode(s)
+}
+
+func unhex(str string) []byte {
+	b, err := hex.DecodeString(str)
+	if err != nil {
+		panic(fmt.Sprintf("invalid hex string: %q", str))
+	}
+	return b
+}