click

It's possible to create an IPSec + firewall based on the Click Modular Router[0] and run this on top of Unikraft[1]. [0]: https://github.com/kohler/click/wiki/IPsecEncap (and other IPSec* elements) [1]: https://github.com/unikraft/app-click It could make for an interesting tutorial with a full Click-based IPSec router though! :)

Many unikernel projects were ahead of their time. For example ClickOS [0] is ~7 years old but all its ideas still sound innovative. Someone could build an entire business on top of network function virtualization, using unikernels as an efficient sandboxing mechanism. I’m not sure why unikernels have not caught on widely. I suspect their time has yet to come for some applications, but at least for NFV and sandboxing, I would bet on solutions using eBPF or XDP with WASM for sandboxing. [0] https://github.com/kohler/click

In similar C-string trickery, consider this lovely bool-to-string function: /** @brief Construct a String equal to "true" or "false" depending on the value of @a x. */ inline String::String(bool x) { // bool_data equals "false\0true\0" assign_memo(bool_data + (-x & 6), 5 - x, 0); } Source: https://github.com/kohler/click/blob/6fa978f0188bd0b8a266f65... Context: This is the source code of the Click Modular Router, a system for implementing packet processing logic with a graph-like DSL. Both primitives, and certain complex logic, are implemented in C++; however, as this has to be able to run as a Linux kernel module or in userspace or as a BSD kernel module, it can't use the C++ standard library, and do has its own stdlib.

Click is a very good software router to read and learn: https://github.com/kohler/click It can be more than a router though.

https://github.com/kohler/click is a library that I've found has a lot of reusability built into it, and operates a lot like snapping Lego blocks together. When you're talking about not being able to reuse code, I think it depends on how you've designed your system. Design for reusability seems like it needs to be key goal in development in order to achieve software re-use.

Despite any staleness in regards to what constitutes news on the page, the Github shows the project still has momentum: https://github.com/kohler/click/