Re: [Bluez-users] broadcast packets

[Aleksandar Kanchev <kanchev@in.tum.de>]

Hi Marcel,

I was away for a while :) But here's what I'm trying to do:
I'm using 2 laptops with 2 Belkin class 2 USB bluetooth dongles. Both 
laptops are running linux with bluez.
I want to broadcast packets from the one side to the other. To do that 
I'm connection both laptops with the hcitool and then from the master 
side I'm using the following code:
  int dd, i, ret = -1, hci_dev;
  u_short handle, flags;

  char buf[HCI_ACL_HDR_SIZE + L2CAP_SIZE];
  hci_acl_hdr *acl_hdr = (hci_acl_hdr *) buf;
  l2cap_hdr *l2hdr = (l2cap_hdr *) (buf + HCI_ACL_HDR_SIZE);
  uint16_t *psm = (uint16_t *) (((char *) l2hdr) + L2CAP_HDR_SIZE);
  char *l2cap_data = ((char *) psm) + sizeof(uint16_t);

  struct iovec iv[2];
  uint8_t type = HCI_ACLDATA_PKT;

  hci_dev = hci_get_route(NULL);
  dd = hci_open_dev(hci_dev);

  handle = 1;
  flags |= ACL_START;
  flags |= ACL_ACTIVE_BCAST;
  acl_hdr->handle = htobs(acl_handle_pack(handle, flags));
  acl_hdr->dlen = htobs(L2CAP_SIZE);

  l2hdr->len = htobs(sizeof(uint16_t) + L2CAP_DATA_SIZE);
  l2hdr->cid = htobs(0x0002);
  *psm = htobs(4097);

  for (i = 0; i < L2CAP_DATA_SIZE; i++)
    l2cap_data[i] = 'A';

  iv[0].iov_base = &type;
  iv[0].iov_len = 1;
  iv[1].iov_base = buf;
  iv[1].iov_len = sizeof(buf);
  writev(dd, iv, 2);

I can see the packet being transmitted on the local master side (with 
hcidump) but the other end doesn't seem to see it. At least hcidump is 
not dumping the packet.

Thanks

Marcel Holtmann wrote:

>Hi Aleksandar,
>
>  
>
>>Marcel, could you please answer me that ? :)
>>    
>>
>
>I already told you everything I know and I have no idea why you still
>stick to the broadcast thing. Once you have established the piconet
>between two devices, you can use it to transfer data. Doing everything
>on HCI level is not a good idea. Use at least the L2CAP level for it,
>but you might need to add some kernel code to make it work properly. The
>broadcast stuff is not really used in any Bluetooth application so far.
>
>Regards
>
>Marcel
>
>
>
>
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