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Re: What is the data-in packet format as passed by the debug callback?

From: Daniel Stenberg via curl-library <>
Date: Tue, 4 Feb 2020 22:49:49 +0100 (CET)

On Tue, 4 Feb 2020, Lazareanu, Sorin (S.) via curl-library wrote:

> In tcpdump I need to identify the packets received(sent) via curl-library. I
> use the debug callback to get the data (data_in) from a HTTP transfer. Is
> there a data_in format that I can use to parse the data and get the sequence
> number or any another identifier?

The data you see there is the protocol data that libcurl sends and receives,
which is in the application protocol layer. That is, if you send HTTP you see
the HTTP transaction.

There are no "sequence numbers" or similar in HTTP, mostly just headers and

If you want to capture "the whole shebang", consider using the SSLKEYLOGFILE
approach instead:

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Received on 2020-02-04