GitHub user benweint opened a pull request:
https://github.com/apache/thrift/pull/1352
THRIFT-4326 Allow safer reuse of BufferedTransport instances in Ruby
Addresses [THRIFT-4326](https://issues.apache.org/jira/browse/THRIFT-4326).
## The problem
In the case where a single `Thrift::BufferedTransport` instance is re-used
across multiple service calls, certain kinds of malformed responses from one
service call can 'leak' into subsequent calls and cause them to fail with a
`Thrift::ProtocolException`.
The most easily reproducible example is when a service returns a
well-formed Thrift response for the first service call, but with N extra bytes
of garbage tacked onto the end.
In such a case, the initial service call will be handled just fine (at
least when using the compact protocol), however, the next N service calls that
go through the same `Thrift::BufferedTransport` instance will fail with a
`Thrift::ProtocolException`. This happens because the `BufferedTransport`
doesn't re-set the `@rbuf` instance variable until the read buffer is fully
exhausted, so each of the N subsequent service calls will attempt to read one
byte identifying the protocol from the remaining buffer, and will get some
bogus value from the garbage bytes at the end of the response from the initial
service call.
This can also happen if reading from `@rbuf` is interrupted part-way
through, while `@index` is still pointing to the middle of the read buffer
(e.g. due to a Ruby timeout exception).
## Proposed solution
Re-setting the `@rbuf` instance variable to an empty byte buffer upon every
call to `#flush` addresses this problem, and is conceptually similar to what
happens in `HttpClientTransport#flush` (where `@inbuf` and `@outbuf` are both
always reset).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/benweint/thrift THRIFT-4326
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/thrift/pull/1352.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1352
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commit 79936408af223c5df3fe8a52ec65873ccc32a255
Author: Ben Weintraub <[email protected]>
Date: 2017-09-10T04:17:42Z
THRIFT-4326 Ensure rbuf in BufferedTransport reset upon flush to allow reuse
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