Report a rare case where multipart may fail to parse

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We encountered an issue where an iOS client app uploads a large file using multipart requests. The file is split into 32MB chunks, and the client sends a series of multipart HTTP requests. Each request contains several form-data fields to transfer additional information to the server.

On the server side, we are using actix-web with the multipart extractor to handle these requests. However, during transmission, the multipart extractor occasionally fails to parse one of the form-data fields. This issue is rare and difficult to reproduce.

After capturing the traffic using a pcap file, we observed that in one instance, the multipart boundary sequence (--) was split across two TCP frames. It seems this caused the multipart extractor to fail during parsing.

If you want to review the content using Wireshark, rename boundary-problem.pcap.txt to boundary-problem.pcap.

boudnary-problem.pcap.txt