This repo provides communityid.c, a self-contained, reusable C implementation of the Community ID standard.

To use this implementation in your own codebase, do the following:

• Since applications are likely to implement Community ID support in a single complation unit, simply drop communityid.c into your surrounding C code.
• To abstract low-level implementation details, communityid.c assumes you have GLib and Libgcrypt available. Modifications to accommodate other low-level data types, hash implementations, etc will be straightforward.
• There's a single function, communityid_calc() that implements the computation. Please take a look at its comments for details regarding arguments and return values.

For a quick usage example, take a look at the included example.c, which implements a command-line tool for computing ID values. If your system supports pkg-config and has GLib and Libgcrypt with development components installed, the (very basic) included Makefile should work. An example:

$ ./example tcp 128.232.110.120 66.35.250.204 34855 80
1:LQU9qZlK+B5F3KDmev6m5PMibrg=

See ./example --help for more details.

Please feel free to report issues or submit PRs via GitHub: https://github.com/corelight/c-community-id/issues

Contact: Christian Kreibich christian@corelight.com