Bluetooth Core v5.3 Set Extended Advertising Data Command

Question

I'm trying to re-implement HCITool functions in my application. Currently trying to get the command "cmd" working so that I can set extended advertising data which will hold manufacturer data.

My first approach was to see how HCITool registers the command and so I came up with this:

hcitool -i hci0 cmd 0x08 0x0037 01 03 01 0C FFFF 12 34

I also tried it this way:

hcitool -i hci0 cmd 0x08 0x0037 01 03 01 0C FF FF 12 34

These gave me error code 1, which is saying the command doesn't exist so I'm guessing I didn't write it correctly. My first request is if anyone can explain how to correctly send this command in HCITool.

The following is how I am trying to implment it in my code. This code is just a lightly altered version of open source HCITool's approach.

static void cmd_manufacturer(int dev_id)
{
    unsigned char buf[HCI_MAX_EVENT_SIZE], *ptr = buf;
    struct hci_filter flt;
    hci_event_hdr *hdr;
    int i, opt, len, dd;
    uint16_t ocf;
    uint8_t ogf;
    char arr[][20] = {"0xFFFF", "0x12", "0x34"};

    if (dev_id < 0)
        dev_id = hci_get_route(NULL);

    errno = 0;
    ogf = strtol("0x08", NULL, 16);
    ocf = strtol("0x0037", NULL, 16);
    if (errno == ERANGE || (ogf > 0x3f) || (ocf > 0x3ff)) 
    {
        return;
    }

    for (i = 2, len = 0; i < 12 && len < (int) sizeof(buf); i++, len++)
    {
        *ptr++ = (uint8_t) strtol(arr[i], NULL, 16);
    }

    dd = hci_open_dev(dev_id);
    if (dd < 0) {
        perror("Device open failed");
        exit(EXIT_FAILURE);
    }

    /* Setup filter */
    hci_filter_clear(&flt);
    hci_filter_set_ptype(HCI_EVENT_PKT, &flt);
    hci_filter_all_events(&flt);
    if (setsockopt(dd, SOL_HCI, HCI_FILTER, &flt, sizeof(flt)) < 0) {
        perror("HCI filter setup failed");
        exit(EXIT_FAILURE);
    }

    printf("< HCI Command: ogf 0x%02x, ocf 0x%04x, plen %d\n", ogf, ocf, len);

    if (hci_send_cmd(dd, ogf, ocf, len, buf) < 0) {
        perror("Send failed");
        exit(EXIT_FAILURE);
    }

    len = read(dd, buf, sizeof(buf));
    if (len < 0) {
        perror("Read failed");
        exit(EXIT_FAILURE);
    }

    hdr = (void *)(buf + 1);
    ptr = buf + (1 + HCI_EVENT_HDR_SIZE);
    len -= (1 + HCI_EVENT_HDR_SIZE);

    printf("> HCI Event: 0x%02x plen %d\n", hdr->evt, hdr->plen);

    hci_close_dev(dd);
}

I run my application, turn advertising on and am using btmon to see the HCI events/commands. Btmon doesn't show my extended advertising data being set.

Anyone have any idea on what I can do to make this work? I think I'm not providing the data correctly to the function.

Thank you for the help.