MMM-Hue CORS Policy Issue

[Fozi]

@karsten13 No worries! I just wanted to let you (and others) know that the config entry does not solve the issue.
I made a little research around CORS and -at least for me- it doesn’t seem to be trivial to configure electron in a way that specific origins are allowed without disabling the CORS policy completely.

Anyone around with more knowledge?

[karsten13]

@fozi

found this one https://pratikpc.medium.com/bypassing-cors-with-electron-ab7eaf331605 which could be tested in js/electron.js.

[mumblebaj]

Thanks @karsten13 , seems like it does not work as mentioned below by @Fozi . Seems like the modules uses jQuery and does a call to the bridge to get the data. Seems like I need to log an issue on Github for the module but it has not been touched in the last 3 to 4 years. I will fork it and see if I can make some changes to get it working. The last suggestion you made below seems like code changes module side so I will see what I can do to change it from jQuery to something that would work. Thanks for the replies.

[karsten13]

@mumblebaj

you can test the following, I couldn’t test this completely but the cors error was gone in my tests.

First yo need to create own certs, go into the config folder of mm (same folder where config.js is located) and run this command:

openssl req -newkey rsa:4096 \
            -x509 \
            -sha256 \
            -days 3650 \
            -nodes \
            -out example.crt \
            -keyout example.key \
            -subj "/C=DE/ST=Hessen/L=Frankfurt/O=MagicMirror/OU=MM/CN=www.example.com"

Then edit your config.js and add the following lines under the line with var config = {

	electronOptions: {
		webPreferences: {
			webSecurity: false
		}
	},
	useHttps: true,
	httpsPrivateKey: "config/example.key",
	httpsCertificate: "config/example.crt",

(Re)Start mm and test if MMM-Hue works now (there will still be a “mixed content” warning).

[mumblebaj]

@karsten13 Awesome. That worked. Much appreciated for the assist.

[Fozi]

@karsten13 You are a genius! That worked for me, too! Thanks so much!

[karsten13]

@fozi thanks but … no

would be better to have a solution without https, may someone else gets this figured out.

As an improvement for the above solution with https:

Holding the certs in the config directory makes them accessible from outside so better move them into a new directory beside config, e.g. certs which is not exposed. Don’t forget to update config.js afterwards.

[mumblebaj]

@karsten13 So I have been tinkering with the MMM-Hue module a bit and have replaced jQuery which seems to invoke XMLHttpRequest, with node-fetch, albeit the older version (2.6.1) of node-fetch, but it now returns data without requiring a certificate and the use of https.

[CarstenD]

The same problem appears to happen with MMM-Homematic. Getting same errors after update to 2.18.0

Access to XMLHttpRequest at 'http://192.168.178.xx/addons/xmlapi/state.cgi?datapoint_id=1824' from origin 'http://0.0.0.0:8080' has been blocked by CORS policy: The request client is not a secure context and the resource is in more-private address space private.

[karsten13]

@carstend

yes, was already reporty by @Fozi some posts above, MMM-Homematic uses jquery too.