CAIT Setup page looping

The setup page of CAIT remains in an infinite loop on message “Retreiving device information …”

The only AJAX Request in error is the /getwifi page.

There is the following message in syslog

Feb  9 20:28:16 raspberrypi bash[467]: ERROR:flask.app:Exception on /getwifi [GET]
Feb  9 20:28:16 raspberrypi bash[467]: Traceback (most recent call last):
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/local/lib/python3.7/dist-packages/wifi/scan.py", line 39, in all
Feb  9 20:28:16 raspberrypi bash[467]:     stderr=subprocess.STDOUT)
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3.7/subprocess.py", line 395, in check_output
Feb  9 20:28:16 raspberrypi bash[467]:     **kwargs).stdout
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3.7/subprocess.py", line 487, in run
Feb  9 20:28:16 raspberrypi bash[467]:     output=stdout, stderr=stderr)
Feb  9 20:28:16 raspberrypi bash[467]: subprocess.CalledProcessError: Command '['/sbin/iwlist', 'wlan0', 'scan']' returned non-zero exit status 255.
Feb  9 20:28:16 raspberrypi bash[467]: During handling of the above exception, another exception occurred:
Feb  9 20:28:16 raspberrypi bash[467]: Traceback (most recent call last):
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3/dist-packages/flask/app.py", line 2292, in wsgi_app
Feb  9 20:28:16 raspberrypi bash[467]:     response = self.full_dispatch_request()
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3/dist-packages/flask/app.py", line 1815, in full_dispatch_request
Feb  9 20:28:16 raspberrypi bash[467]:     rv = self.handle_user_exception(e)
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/local/lib/python3.7/dist-packages/flask_cors/extension.py", line 165, in wrapped_function
Feb  9 20:28:16 raspberrypi bash[467]:     return cors_after_request(app.make_response(f(*args, **kwargs)))
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3/dist-packages/flask/app.py", line 1718, in handle_user_exception
Feb  9 20:28:16 raspberrypi bash[467]:     reraise(exc_type, exc_value, tb)
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3/dist-packages/flask/_compat.py", line 35, in reraise
Feb  9 20:28:16 raspberrypi bash[467]:     raise value
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3/dist-packages/flask/app.py", line 1813, in full_dispatch_request
Feb  9 20:28:16 raspberrypi bash[467]:     rv = self.dispatch_request()
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/lib/python3/dist-packages/flask/app.py", line 1799, in dispatch_request
Feb  9 20:28:16 raspberrypi bash[467]:     return self.view_functions[rule.endpoint](**req.view_args)
Feb  9 20:28:16 raspberrypi bash[467]:   File "/home/pi/ia/cep/src/cait/cortic_webapp/main.py", line 180, in getwifi
Feb  9 20:28:16 raspberrypi bash[467]:     cells = list(Cell.all("wlan0"))
Feb  9 20:28:16 raspberrypi bash[467]:   File "/usr/local/lib/python3.7/dist-packages/wifi/scan.py", line 41, in all
Feb  9 20:28:16 raspberrypi bash[467]:     raise InterfaceError(e.output.strip())
Feb  9 20:28:16 raspberrypi bash[467]: wifi.exceptions.InterfaceError: b"wlan0     Interface doesn't support scanning : Device or resource busy"

When I run the command : iwlist wlan0 scan

There is no error :

wlan0     Scan completed :
          Cell 01 - Address: XX:XX:XX:XX:XX
                    Channel:6
                    Frequency:2.437 GHz (Channel 6)
                    Quality=70/70  Signal level=-31 dBm
                    Encryption key:on
                    ESSID:"XZ"
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                    ....

[michaelhwn]

Ah I see, I know the cause of this issue then. Since the setup page is hosted on the raspberry pi, so when you access this page on a web browser, the hostname (of the raspberry pi) is extracted from the URL. If an IP address is used to access the web app, the extracted hostname will be incorrect. And since the MQTT topic subscription is based on the incorrectly extracted hostname, this explains why the “CAIT UP” MQTT message is not received and you are seeing an incorrect hostname in the field. This is a bug in the setup web app.

I will fix this by making sure the hostname is obtained by the Pi itself and not by the web app using the web browser.

[michaelhwn]

This commit in the dev branch has fixed the hostname issue. This change will be merged to main branch after some testings.