rlp: stricter validation of canonical integer format

All integers (including size information in type tags) need to be
encoded using the smallest possible encoding. This commit expands the
stricter validation introduced for *big.Int in commit 59597d23a5ee268
to all integer types and size tags.

1 files changed, 30 insertions, 8 deletions

diff --git a/rlp/decode_test.go b/rlp/decode_test.go
index e5c7f3761..aa410de92 100644
--- a/rlp/decode_test.go
+++ b/rlp/decode_test.go
@@ -21,16 +21,11 @@ func TestStreamKind(t *testing.T) {
 		{"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)},
 	}
@@ -85,7 +80,7 @@ func TestStreamErrors(t *testing.T) {
 		string
 		calls
 		newStream func([]byte) *Stream // uses bytes.Reader if nil
-		error
+		error     error
 	}{
 		{"C0", calls{"Bytes"}, nil, ErrExpectedString},
 		{"C0", calls{"Uint"}, nil, ErrExpectedString},
@@ -98,6 +93,21 @@ func TestStreamErrors(t *testing.T) {
 		{"00", calls{"ListEnd"}, nil, errNotInList},
 		{"C401020304", calls{"List", "Uint", "ListEnd"}, nil, errNotAtEOL},
 
+		// Leading zero bytes are rejected when reading integers.
+		{"00", calls{"Uint"}, nil, ErrCanonInt},
+		{"820002", calls{"Uint"}, nil, ErrCanonInt},
+
+		// Size tags must use the smallest possible encoding.
+		// Leading zero bytes in the size tag are also rejected.
+		{"B800", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
+		{"B90000", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
+		{"B90055", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
+		{"BA0002FFFF", calls{"Bytes"}, withoutInputLimit, ErrCanonSize},
+		{"F800", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
+		{"F90000", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
+		{"F90055", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
+		{"FA0002FFFF", calls{"List"}, withoutInputLimit, ErrCanonSize},
+
 		// Expected EOF
 		{"", calls{"Kind"}, nil, io.EOF},
 		{"", calls{"Uint"}, nil, io.EOF},
@@ -170,10 +180,12 @@ testfor:
 					want = test.error.Error()
 				}
 				if err != want {
+					t.Log(test)
 					t.Errorf("test %d: last call (%s) error mismatch\ngot:  %s\nwant: %s",
 						i, call, err, test.error)
 				}
 			} else if err != "<nil>" {
+				t.Log(test)
 				t.Errorf("test %d: call %d (%s) unexpected error: %q", i, j, call, err)
 				continue testfor
 			}
@@ -289,15 +301,20 @@ var decodeTests = []decodeTest{
 	{input: "8405050505", ptr: new(uint32), value: uint32(0x05050505)},
 	{input: "850505050505", ptr: new(uint32), error: "rlp: input string too long for uint32"},
 	{input: "C0", ptr: new(uint32), error: "rlp: expected input string or byte for uint32"},
+	{input: "00", ptr: new(uint32), error: "rlp: non-canonical integer (leading zero bytes) for uint32"},
+	{input: "820004", ptr: new(uint32), error: "rlp: non-canonical integer (leading zero bytes) for uint32"},
+	{input: "B8020004", ptr: new(uint32), error: "rlp: non-canonical size information for uint32"},
 
 	// slices
 	{input: "C0", ptr: new([]uint), value: []uint{}},
 	{input: "C80102030405060708", ptr: new([]uint), value: []uint{1, 2, 3, 4, 5, 6, 7, 8}},
+	{input: "F8020004", ptr: new([]uint), error: "rlp: non-canonical size information for []uint"},
 
 	// arrays
 	{input: "C0", ptr: new([5]uint), value: [5]uint{}},
 	{input: "C50102030405", ptr: new([5]uint), value: [5]uint{1, 2, 3, 4, 5}},
 	{input: "C6010203040506", ptr: new([5]uint), error: "rlp: input list has too many elements for [5]uint"},
+	{input: "F8020004", ptr: new([5]uint), error: "rlp: non-canonical size information for [5]uint"},
 
 	// byte slices
 	{input: "01", ptr: new([]byte), value: []byte{1}},
@@ -352,7 +369,7 @@ var decodeTests = []decodeTest{
 	// big ints
 	{input: "01", ptr: new(*big.Int), value: big.NewInt(1)},
 	{input: "89FFFFFFFFFFFFFFFFFF", ptr: new(*big.Int), value: veryBigInt},
-	{input: "820001", ptr: new(big.Int), error: "rlp: canon int error appends zero's for *big.Int"},
+	{input: "820001", ptr: new(big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"},
 	{input: "10", ptr: new(big.Int), value: *big.NewInt(16)}, // non-pointer also works
 	{input: "C0", ptr: new(*big.Int), error: "rlp: expected input string or byte for *big.Int"},
 
@@ -367,6 +384,11 @@ var decodeTests = []decodeTest{
 	},
 
 	{
+		input: "83222222",
+		ptr:   new(simplestruct),
+		error: "rlp: expected input list for rlp.simplestruct",
+	},
+	{
 		input: "C3010101",
 		ptr:   new(simplestruct),
 		error: "rlp: input list has too many elements for rlp.simplestruct",
@@ -378,7 +400,7 @@ var decodeTests = []decodeTest{
 	},
 
 	// pointers
-	{input: "00", ptr: new(*uint), value: uintp(0)},
+	{input: "00", ptr: new(*[]byte), value: &[]byte{0}},
 	{input: "80", ptr: new(*uint), value: (*uint)(nil)},
 	{input: "C0", ptr: new(*uint), value: (*uint)(nil)},
 	{input: "07", ptr: new(*uint), value: uintp(7)},