GSoC 2018 – DAWN a decentralized WiFi controller (2st update)

I still try to get my patches upstream.
For the libiwinfo patch I had to add the lua bindings. I never used lua so first I had to get comfortable with this. Additionally I wanted to add the channel utilization in the luci statistics app. But suddenly Luci is giving me a null pointer exception in the dev branch.

Additionally I tried to get comfortable with Luci for developing my own app.
Meanwhile another developer created nearly the same patch for iwinfo that add the survey data for the nl802.11 driver… This patch is still not accepted. The only difference is that it returns all survey data for all channels (like iw dev wlan0 survey dump)…
Furthermore, my pull request for the hostapd ubus bindings that add information about the ht and vht capabilities had to be rewritten. ( Again I have to wait for some feedback. While rewriting this patch, I had a new idea: If you subscribe to the hostapd via ubus and want to notify on the messages you have to activate it. It would be possible to add flags in the hostapd_ubus_bss to select what information should be published via the ubus bus. Before doing so, I want some feedback if this is a good idea.If somebody is interested why I am interested in the capabilities: I want to create a hearing map for every client. I’m building this hearing map using probe request messages. This probe request messages contain information like (rssi, capabilities, ht capabilities, vht capabilities, …). VHT give clients the opportunity to transfer up to 1,750 Gigabits (theoretical…) If you want to select some AP you should consider capabilities… In the normal hostapd configuration you can even set a flag that forbids 802.11b rates. If you are interested what happens if a 802.11b joins your network search for: WiFi performance anomaly. 🙂

Summarizing, I spent a lot of time waiting for feedback, debugging, modifying my patches or replying on the email lists. It is a bit frustrating.
The cool stuff was that I had my first pull request. 🙂 (it was just a typo ^^) But somebody took the time to fork my project and create a pull request. 😉
Furthermore, it is exam time and I have a lot of stuff to do for the university.

Actually I wanted to go on with more interesting stuff like connecting to the netifd demo to get more information.

Or to look at PLC. There is an interesting paper EMPoWER Hybrid Networks: Exploiting Multiple Paths over Wireless and ElectRical Mediums.


Routing and WiFi experimentation

The beginning of my work period was pretty busy, not always with Summer of Code things. My mentor math and I had already talked about a lot of the things that needed to happen in order to move away from an OLSR based routing protocol and make it extendable as well.

As previously hinted, we are using Rust for the protocol implementation, allowing for easy integrating into the existing C code as well as giving us the option to bit-by-bit rewrite the entire software in Rust, a much more modern and forgiving language. The first thing I tackled was to design a common API for the library (libqaul) to use to talk to any networking backend. The routing code holds the state of the network and allows the sending of direct and flooded messages into a network (regardless of implementation under the hood). But to do that we also had to define some common characteristics for nodes and messages.

In the end, a lot of the work was sitting down, going through old notes and determining what our protocol was supposed to do. We looked at existing protocols a lot, thinking about extendability and backwards compatibility. The protocol itself will be binary encoded, although not yet sure which format. There is msgpack, cpnproto/ protobuf as well as some Rust specifics (Rust Object Notation to mention one) to look at. But that shouldn’t actually matter for now. All the versioning and extend-ability are being done in the struct level of the protocol, meaning that we could even switch binary encoding half way through. Keeping the encoding and decoding written in Rust, this is actually incredibly easy with the `From` traits. But I digress…

The protocl we ended up designing can handle any type that already exists in, as well as allows for custom user extentions – messages that have a type field and a random binary message payload which allows plugins on both sides to interact with it.


So…so far the routing core isn’t doing much routing. But that’s okay, that comes later 🙂 With the networking API in place, we actually have something what we’ve wanted for the last 2 years: a hardware abstraction over any networking backend. The API is implemented in Rust as a trait (think like a Java interface), which makes implementations and even implementation specific code very easy.

The next thing on our todo list is working out how WiFi direct behaves. This is kinda disconnected from the rest of the project, but it’s something that has to happen. For this purpose I’ve written a small demo app (still WIP at the time of this writing), which will let us explore the way that WiFi direct works, how to build mesh groups, etc. These experiments are still ongoing, and we hope to have something to show until the end of the week. I will probably publish a small article on my blog about it – check it out (if you’re reading this in the future 😉 )

All in all, the amount of code written in the first section of GSoC2018 is medium. We have however answered a lot of open questions, have a good plan on how to continue and hope to have more to show off by the time of the next evaluation.

If you’re curious about the progress being made, check out the github repository.


Until next time,