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authorFelix Lange <fjl@twurst.com>2015-03-21 05:33:40 +0800
committerFelix Lange <fjl@twurst.com>2015-03-21 05:33:40 +0800
commitb41185a68f2ec8c492a7dbec1a6bf65f29b0843a (patch)
tree309fe50a122cd1db099381e8961349d842fac765 /rlp
parent28ddc16a9b5779b6b31036e8248ed8457de7b443 (diff)
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rlp: fix nil pointer decoding
The generic pointer decoder did not advance the input position for empty values. This can lead to strange issues and even infinite loops.
Diffstat (limited to 'rlp')
-rw-r--r--rlp/decode.go7
-rw-r--r--rlp/decode_test.go22
2 files changed, 27 insertions, 2 deletions
diff --git a/rlp/decode.go b/rlp/decode.go
index 6d7e670c2..0e99d9caa 100644
--- a/rlp/decode.go
+++ b/rlp/decode.go
@@ -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
diff --git a/rlp/decode_test.go b/rlp/decode_test.go
index 9f66840b1..0f034d5d8 100644
--- a/rlp/decode_test.go
+++ b/rlp/decode_test.go
@@ -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)},