HTTP2Stream request handling appears to cut off exception messages

[jshslt]

Hi,
We noticed that when we get a MessageRequest::onExceptionReceived callback, the exception message tends to look cut off. since this is often (always?) JSON, it leads to improperly formatted content.

It looks like this is due to how HTTP2Stream::m_exceptionBeingProcessed is used; as soon as it's non-zero length, HTTP2Stream::notifyRequestObserver assumes the message is complete and sends it to the request callback.

[scotthea-amazon]

Hi Jshslt,
Thank you for bringing this to our attention!

We can see some obvious code paths that could lead to this and will be working on a fix for those. To make sure we fully address the issue you described, can you provide us with a test case that triggers the error for you?

Thank you!
-SWH

[jshslt]

@scotthea-amazon sorry, I don't have an explicit repro case for this. Just a guess but it might trigger if you try and send an AVS event immediately after (e.g.) pulling a network cable, but before the SDK is aware of the disconnect.

if it helps, here's an example of a truncated exception message we got -

{"header":{"namespace":"System","name":"Exception","messageId":"1af199cd-b665-4d45-95b8-341884959e11"},"payload":{"code":"INVALID_R

[dhpp]

Hi jshslt,

I wanted to jump into this discussion. Looking over the HTTP2Transport and HTTP2Stream code within ACL, you've brought up an interesting use case.

The place where this happens in our code is HTTP2Transport::cleanupFinishedStreams, where the code checks for CURLMSG_DONE, then invokes the notifyRequestObserver overload on the stream which will send out the exception message. What is interesting to me is that the use case you've brought up is essentially a broken network, where partial data will be correctly received, but then libcurl will internally time out and close the stream.

Could I suggest you edit the final else within cleanupFinishedStreams:

auto it = m_activeStreams.find(message->easy_handle);
if (it != m_activeStreams.end()) {

long responseCode = 0;
curl_easy_getinfo(it->first, CURLINFO_RESPONSE_CODE, &responseCode);
ACSDK_INFO(LX("stream response code").m(std::to_string(responseCode)));

it->second->notifyRequestObserver();
cleanupStream(it->second);
} else {
ACSDK_ERROR(LX("cleanupFinishedStreamError").d("reason", "streamNotFound"));
}

I would like to know what the reponseCode is for the cases where received exception messages are incomplete. If it's something that libcurl is correctly exposing to us, we can then update that code accordingly to call notifyRequestObserver(MessageRequest::Status::INTERNAL_ERROR) instead.

Thanks.

[kclchan]

The issue is fixed in v1.1.0. Thanks!