use le extended commands set if supported

[vicamo]

On some devices, observed on RTL8822CE and Intel AX201, issue 5.0 LE commands while bluetoothd has preconfigured 5.1 LE extended commands may cause Command Disallowed error and fails following scan:

@ RAW Open: python3 (privileged) version 2.22 {0x0003} [hci0] 4.021364
< HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7 #1 [hci0] 4.021692
        Type: Passive (0x00)
        Interval: 10.000 msec (0x0010)
        Window: 10.000 msec (0x0010)
        Own address type: Public (0x00)
        Filter policy: Accept all advertisement (0x00)
> HCI Event: Command Complete (0x0e) plen 4 #2 [hci0] 4.139014
      LE Set Scan Parameters (0x08|0x000b) ncmd 1
        Status: Command Disallowed (0x0c)
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2 #3 [hci0] 4.139129
        Scanning: Enabled (0x01)
        Filter duplicates: Disabled (0x00)
> HCI Event: Command Complete (0x0e) plen 4 #4 [hci0] 4.139962
      LE Set Scan Enable (0x08|0x000c) ncmd 1
        Status: Command Disallowed (0x0c)
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2 #5 [hci0] 121.924256
        Scanning: Disabled (0x00)
        Filter duplicates: Disabled (0x00)
@ RAW Close: python3

This pull request adds HCI_Read_Local_Supported_Commands, HCI_LE_Set_Extended_Scan_Params and HCI_LE_Set_Extended_Scan_Enable to the support list and refactor a bit to ensure all further commands will only be issued after full initialized.

[vicamo]

LE Advertising should have the same issue, but I'll file another pull request for that separately.

[frawau]

Hi,

Thank you for the pull request and sorry for waiting so long to reply... Was busy with work.

I do have one issue with you PR. The signature of the 'process' method changes in a non backward compatible way. If it is unavoidable, could you add a note in the README file to highlight the changes and give a short explanation as to why it was necessary.

I do not have a way to test those extended commands, but what tests I did seem to work.

Cheers,
François

[vicamo]

You're right. It seems this project is also used in others, e.g. python-bluezero. Breaking any, inclusive of other send_foo_request calls, API would not be acceptable. However, I have a strong feeling that trying to initiate a LE scan using raw HCI packets is going to create more problems as more and more new devices get involved. I'm working a replacement leveraging BlueZ bluetoothd using DBus APIs instead. So I'm going to close this PR. Should you find any bit useful here, please don't hesitate.