Cursed User-Agents

Nov 11 2022

I'm currently fiddling around with User-Agents of Smart TVs, or more specifically HbbTV. Interpreting them is an absolute nightmare, so let me rant about interesting edge-cases I discovered along the way.

To set the mood: User-Agents in this field have a standardized format, yet many vendors seem to do their own thing, making it impossible to build one parser to rule them all. For reference, here's what the HbbTV section in a user agent SHOULD look like:

HbbTV/<version> (<capabilities>; <vendorName>; <modelName>; <softwareVersion>; [<hardwareVersion>]; <familyName>; <reserved>)

The "we'll update that later"

HbbTV/1.1.1 (; Loewe; MB180; 1.0; 1.0;) NetFront/4.1

1.0 for both software and hardware versions suspiciously looks like a working title. At least we get some information about the vendor and the model.

The Overcommitted

Mozilla/5.0 (Linux armv7l) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36 OPR/40.0.2207.0 OMI/4.9.0.237.DOM3-OPT.245 Model/Vestel-MB211 VSTVB MB200 HbbTV/1.2.1 (; JVC; MB211; 3.19.4.2; _TV_NT72563_2017 SmartTvA/3.0.0

It's nice that we get a lot of information about the device, yet no one seemed to check if the string actually fits into storage.

The Lazy Boy

HbbTV/1.1.1 (;;;;;) Maple;2011

To be fair, this is one of the earliest HbbTV devices ever. No one knew that this technology would stand the test of time. Apparently not even Samsung.

Conclusion

I learned that building a generic parser for user agents isn't easy, especially if the devices you work with could be over a decade old.

One thing that all devices do seem to get right though is the presence of the HbbTV section in the User-Agent. I did not encounter a single device without it.

This is post 042 of #100DaysToOffload.


Reply via E-Mail

#note#100DaysToOffload#web