Running on an old wifi router

[petm5]

Would it be feasible to run Agate on an old wifi router on top of OpenWrt?

In this case, the agate binary would need to fit within ~1MB and use less than 32MB of RAM at runtime.The binary size may be possible to achieve by optimizing aggressively for size and/or using UPX to compress it. However, I would be more worried about the limited available memory since zram can only do so much.

The document root could be either stored in nvram, or fetched from a git repo on boot.

This would not by any means be a production-ready server. It would be more like an experiment to push the limits of the device.

[petm5]

I recently looked into building Agate for my wrt54g router. The rust build target would have to be mips-unknown-linux-uclibc due to the old OpenWrt release that it runs. Apart from the standard library needing to be compiled from source, the main issue seems to be with ring not having support for the mips architecture. While there is a pull request to add mips support to rustls, the changes would still not allow building on mips big-endian targets.

Building std from source may have been necessary even if there was a pre-built version for this platform. Doing so could help to significantly reduce the binary size as well as the memory footprint of the resulting Agate binary.

[petm5]

I successfully got twind by thexhr to compile with some minor patches related to openssl using the openwrt toolchain. Let's see if it will work!

I guess I'll just give up on running agate for now since the rust stdlib doesn't want to compile for uclibc.

[petm5]

twind did in fact work, but I ran into an issue with the TLS connection. While it would work flawlessly with a ridiculously small RSA keysize like 512 or 1024, there was a noticeable delay with a more reasonable RSA key size of 2048, and it took a few moments to load anything with a key size of 4096. I tried to use ECC instead of RSA for better performance, but the openssl library on the version of OpenWRT that I was running didn't support ECC keys.

Anyways, I got version 21.02.5 of OpenWRT to run on the router by building a custom image. The version I was previously running (which was the last officially supported release for my router) is more than 6 years old! This much newer release uses musl instead of uclibc as well as more recent versions of libraries, so it should now be much easier to compile rust binaries and modern C code for it. Also, I discovered that this platform actually uses the mipsel target (instead of mips), so it may be possible to get ring working with patches from a pending pull request.