[
https://issues.apache.org/jira/browse/KAFKA-3160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15234610#comment-15234610
]
Magnus Edenhill commented on KAFKA-3160:
----------------------------------------
[~ijuma] It needs to go through slow-path to "fix-down" (i.e., break the
checksum) for older clients connecting to a newer broker.
But yeah, the plan is to bundle this functionality with Message format 1, so
that Message format v0 attribute flag LZ4 has a broken checksum, while Message
format 1 with attribute flag LZ4 has a correct checksum.
> Kafka LZ4 framing code miscalculates header checksum
> ----------------------------------------------------
>
> Key: KAFKA-3160
> URL: https://issues.apache.org/jira/browse/KAFKA-3160
> Project: Kafka
> Issue Type: Bug
> Components: compression
> Affects Versions: 0.8.2.0, 0.8.2.1, 0.9.0.0, 0.8.2.2, 0.9.0.1
> Reporter: Dana Powers
> Assignee: Magnus Edenhill
> Labels: compatibility, compression, lz4
>
> KAFKA-1493 partially implements the LZ4 framing specification, but it
> incorrectly calculates the header checksum. This causes
> KafkaLZ4BlockInputStream to raise an error
> [IOException(DESCRIPTOR_HASH_MISMATCH)] if a client sends *correctly* framed
> LZ4 data. It also causes KafkaLZ4BlockOutputStream to generate incorrectly
> framed LZ4 data, which means clients decoding LZ4 messages from kafka will
> always receive incorrectly framed data.
> Specifically, the current implementation includes the 4-byte MagicNumber in
> the checksum, which is incorrect.
> http://cyan4973.github.io/lz4/lz4_Frame_format.html
> Third-party clients that attempt to use off-the-shelf lz4 framing find that
> brokers reject messages as having a corrupt checksum. So currently non-java
> clients must 'fixup' lz4 packets to deal with the broken checksum.
> Magnus first identified this issue in librdkafka; kafka-python has the same
> problem.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
