Cotton

A collection of Rust crates for low-level networking functionality.

So far:

• cotton-netif : enumerating available network interfaces and their IP addresses, including ongoing (asynchronous) comings and goings of network interfaces (e.g. on USB hotplug/unplug); so far, for Linux only.

• cotton-ssdp : implementing SSDP, the Simple Service Discovery Protocol, a mechanism for discovering available resources (service) on a local network. Uses cotton-netif, in order to do the Right Thing on multi-homed hosts (but meaning that it is unlikely to work on Windows platforms).

• cotton-unique: creating deterministic but per-device unique identifiers such as MAC addresses. Not yet on crates.io as it depends on a small unmerged PR to the rp2040-flash crate, but released here in case anyone needs example code.

• cotton-w5500: smoltcp driver for the Wiznet W5500 Ethernet controller in MACRAW mode, including interrupt-driven mode. Not yet on crates.io as it depends on a git prerelease of the w5500 crate, but released here in case anyone needs example code.

These crates are no_std-compatible, meaning that they can be used on embedded systems. In fact, all pushes to my local (not Github) continuous-integration server are automatically tested on both STM32 and RP2040 platforms. You can read about how that is set up on my blog: Part one, Part two, Part three.

These system-tests also serve as example code combining the Cotton crates with the wider ecosystem, including examples where the combining of the wider ecosystem components needed a little research in its own right even before involving Cotton, so perhaps that in itself will be useful to others:

• stm32f746-nucleo-hello: basic test that an attached STM32F746-Nucleo development board is working correctly;

• stm32f746-nucleo-dhcp-rtic: combining RTIC (1.x) + stm32-eth + smoltcp + cotton-unique (a.k.a. how not to have a hardcoded, made-up MAC address!);

• stm32f746-nucleo-ssdp-rtic: combining RTIC + stm32-eth + smoltcp + cotton-unique + cotton-ssdp;

• rp2040-w5500-hello: basic test that an attached W5500-Pico-EVB development board (or anything that equivalently wires together an RP2040 and a W5500) is working correctly;

• rp2040-w5500-dhcp-rtic: combining rp2040-hal + RTIC + w5500-hl + w5500-dhcp + cotton-unique;

• rp2040-w5500macraw-dhcp-rtic: combining rp2040-hal + RTIC + w5500 (MACRAW mode with interrupts) + smoltcp + cotton-unique (note that's a different W5500 crate);

• rp2040-w5500macraw-ssdp-rtic: combining rp2040-hal + RTIC + w5500 (MACRAW mode with interrupts) + smoltcp + cotton-unique + cotton-ssdp;

My long-term goals for this project as a whole:

• provide useful, solid, well-tested components to folks needing Rust crates for networking, including UPnP and embedded devices

• develop skills in Rust coding, including the packaging, distributing, and publicising of it, after a career spent with C++

Everything is licensed under Creative Commons CC0, qv.