How could I find some development codes such as config. h, epan/packet.h, plugins/epan/gryphon)

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I try to find some development codes such as config.h, but I could not find them in my Wireshark folder.

The binary packages we supply for Windows and macOS do not include the source, and operating systems that include Wireshark as a package (Linux distributions, the *BSDs, etc.) generally don't provide the source in a binary package. (Build-from-source distributions such as Gentoo may be an exception.)

To get the source, either:

1. get it from our GitLab repository, as suggested by @grahamb;
2. download the source code for the release from the "Source Code" link on our download page, if your Wireshark was downloaded from our Web site;
3. install the source package if your Wireshark came from a binary package provided by your operating system (those operating systems should provide a source package of some sort).

config.h is created during the cmake step of the build process.

Wireshark source code is maintained in the Wireshark GitLab repository.

If developing code you should read the Wireshark Developers Guide thoroughly, there is a lot of very useful information in there.

There is also some ancillary info in the repository under the doc directory in the form of README.xxx files.