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rlp: fix nil pointer decoding

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The generic pointer decoder did not advance the input position
for empty values. This can lead to strange issues and even
infinite loops.
This commit is contained in:
Felix Lange 2015-03-20 22:33:40 +01:00
parent 28ddc16a9b
commit b41185a68f
2 changed files with 27 additions and 2 deletions
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7
rlp/decode.go
View File

@ -367,7 +367,12 @@ func makePtrDecoder(typ reflect.Type) (decoder, error) {
dec := func(s *Stream, val reflect.Value) (err error) {
_, size, err := s.Kind()
if err != nil || size == 0 && s.byteval == 0 {
val.Set(reflect.Zero(typ)) // set to nil
// rearm s.Kind. This is important because the input
// position must advance to the next value even though
// we don't read anything.
s.kind = -1
// set the pointer to nil.
val.Set(reflect.Zero(typ))
return err
}
newval := val

22
rlp/decode_test.go
View File

@ -39,7 +39,7 @@ func TestStreamKind(t *testing.T) {
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)
t.Errorf("test %d: Kind returned error: %v", i, err)
continue
}
if kind != test.wantKind {
@ -93,6 +93,23 @@ func TestStreamErrors(t *testing.T) {
{"C3C2010201", calls{"List", "List", "Uint", "Uint", "ListEnd", "Uint"}, EOL},
{"00", calls{"ListEnd"}, errNotInList},
{"C40102", calls{"List", "Uint", "ListEnd"}, errNotAtEOL},
// This test verifies that the input position is advanced
// correctly when calling Bytes for empty strings. Kind can be called
// any number of times in between and doesn't advance.
{"C3808080", calls{
"List", // enter the list
"Bytes", // past first element
"Kind", "Kind", "Kind", // this shouldn't advance
"Bytes", // past second element
"Kind", "Kind", // can't hurt to try
"Bytes", // past final element
"Bytes", // this one should fail
}, EOL},
}
testfor:
@ -314,6 +331,9 @@ var decodeTests = []decodeTest{
{input: "C109", ptr: new(*[]uint), value: &[]uint{9}},
{input: "C58403030303", ptr: new(*[][]byte), value: &[][]byte{{3, 3, 3, 3}}},
// check that input position is advanced also empty values.
{input: "C3808005", ptr: new([]*uint), value: []*uint{nil, nil, uintp(5)}},
// pointer should be reset to nil
{input: "05", ptr: sharedPtr, value: uintp(5)},
{input: "80", ptr: sharedPtr, value: (*uint)(nil)},