Branch: refs/heads/master
Home: https://github.com/btcsuite/btcd
Commit: 79aac01b020d56abfdac5a7525ca0b8ae17d9f3d
https://github.com/btcsuite/btcd/commit/79aac01b020d56abfdac5a7525ca0b8ae17d9f3d
Author: Dave Collins <[email protected]>
Date: 2015-09-26 (Sat, 26 Sep 2015)
Changed paths:
M wire/common.go
M wire/common_test.go
M wire/msgversion.go
Log Message:
-----------
wire: Reject non-canonically encoded varints.
The Bitcoin wire protocol includes several fields with their lengths
encoded according to a variable length integer encoding scheme that does
not enforce a unique encoding for all numbers.
This can lead to a situation where deserializing and re-serializing the
same data can result in different bytes. There are no currently known
issues due to this, but it is safer to reject such subtle differences as
they could potentially lead to exploits.
Consequently, this commit modifies the varint decoding function to error
when the value is not canonically encoded which effectively means that
all messages with varints that are not canonically encoded will now be
rejected. This will not cause issues with old client versions in
regards to blocks and transactions since the data is deserialized into
memory and then reserialized before being relayed thereby effectively
erasing any non-canonical encodings.
Also, new tests have been added to ensure non-canonical encodings are
properly rejected and exercise the new code, and the default user agent
version for wire has been bumped to version 0.2.1 to differentiate the
new behavior.
The equivalent logic was implemented in Bitcoin Core by PR 2884.
