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cmcnicholas's avatar
cmcnicholas
Icon for Cirrus rankCirrus
Apr 04, 2024

Empty JSON payload blocked

I received a Support ID in which I can see the following error:

"Malformed document. Document is too short : less than 2 bytes"

I can see that there is no JSON in the payload which makes sense. However, for users it is optional to send a body to this end point so it should work anyway even if it is empty.

 

Weirdly it does seem to work ok on most requests (PATCH calls)

It's just this inconsistency that is concerning. Why does it randomly fail with the error above on occasion?

Is there anything that can be done config wise to eliminate the error above being thrown?

Thanks,

application delivery
security

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  • Lucas_Thompson's avatar
    Lucas_Thompson
    Icon for Employee rankEmployee
    Apr 05, 2024

    It seems like this error can occur during parsing of http chunk mode transfer-encoding where it thinks the payload should be JSON or XML with JSON inside it, but the chunk is malformed. Like maybe it doesn't have the correct CR/LF sequence or is missing a chunk-size header. 

    BIG-IP also had a long standing problem/bug with HTTP content that was both compressed and chunked, and this may be some side effect of that issue. It generally caused the chunk-size headers to be duplicated, but only when using certain kinds of profiles. This would cause random numbers to appear in the processed HTTP messages, and could definitely throw off the parser. You may want to try to reconfigure the HTTP profile you're using to Rechunk the request or response instead of Sustain.

    If that doesn't have any effect, it may indicate that some clients aren't sending valid HTTP messages. You could spot this in a (decrypted) packet capture by carefully comparing what you see to the specification.