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Message-ID: <CAMuHMdX7w0RF0Azn2-p88=maXOcy1pfXy_KHznV4Vozd9=5mfg@mail.gmail.com>
Date: Mon, 15 Dec 2014 12:40:39 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Marcel Holtmann <marcel@...tmann.org>,
Johan Hedberg <johan.hedberg@...el.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: Bluetooth: Add framework for device found filtering based on UUID
On Thu, Dec 11, 2014 at 11:48 PM, Linux Kernel Mailing List
<linux-kernel@...r.kernel.org> wrote:
> Gitweb: http://git.kernel.org/linus/;a=commit;h=b487b9ce9340a6e98d7f8277399304b23b7be456
> Commit: b487b9ce9340a6e98d7f8277399304b23b7be456
> Parent: bda157a40077447b25a1172a17b8ef81a2905cb7
> Refname: refs/heads/master
> Author: Marcel Holtmann <marcel@...tmann.org>
> AuthorDate: Fri Dec 5 10:55:57 2014 +0100
> Committer: Johan Hedberg <johan.hedberg@...el.com>
> CommitDate: Fri Dec 5 12:37:35 2014 +0200
>
> Bluetooth: Add framework for device found filtering based on UUID
>
> Using Start Service Discovery provides the option to specifiy a list
> of UUID that are used to filter out device found events. This patch
> provides the framework for hooking up the UUID filter.
>
> Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
> Signed-off-by: Johan Hedberg <johan.hedberg@...el.com>
> ---
> net/bluetooth/mgmt.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 52 insertions(+), 2 deletions(-)
>
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 1715c91..e39190a 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -6802,6 +6802,11 @@ void mgmt_read_local_oob_data_complete(struct hci_dev *hdev, u8 *hash192,
> mgmt_pending_remove(cmd);
> }
>
> +static bool eir_has_uuids(u8 *eir, u16 eir_len, u16 uuid_count, u8 (*uuids)[16])
> +{
> + return false;
> +}
> +
> void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> u8 addr_type, u8 *dev_class, s8 rssi, u32 flags,
> u8 *eir, u16 eir_len, u8 *scan_rsp, u8 scan_rsp_len)
> @@ -6809,6 +6814,7 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> char buf[512];
> struct mgmt_ev_device_found *ev = (void *) buf;
> size_t ev_size;
> + bool match;
net/bluetooth/mgmt.c: In function ‘mgmt_device_found’:
net/bluetooth/mgmt.c:6993: warning: ‘match’ may be used uninitialized
in this function
All tests for "match" are protected by "if (hdev->discovery.uuid_count > 0)",
so we only have to care about that case.
> /* Don't send events for a non-kernel initiated discovery. With
> * LE one exception is if we have pend_le_reports > 0 in which
> @@ -6843,15 +6849,59 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> ev->rssi = rssi;
> ev->flags = cpu_to_le32(flags);
>
> - if (eir_len > 0)
> + if (eir_len > 0) {
> + /* When using service discovery and a list of UUID is
> + * provided, results with no matching UUID should be
> + * dropped. In case there is a match the result is
> + * kept and checking possible scan response data
> + * will be skipped.
> + */
> + if (hdev->discovery.uuid_count > 0) {
> + match = eir_has_uuids(eir, eir_len,
> + hdev->discovery.uuid_count,
> + hdev->discovery.uuids);
> + if (!match)
> + return;
> + }
If we get here and if (hdev->discovery.uuid_count > 0), "match" must be true.
> +
> + /* Copy EIR or advertising data into event */
> memcpy(ev->eir, eir, eir_len);
> + } else {
> + /* When using service discovery and a list of UUID is
> + * provided, results with empty EIR or advertising data
> + * should be dropped since they do not match any UUID.
> + */
> + if (hdev->discovery.uuid_count > 0)
> + return;
We will never get here if (hdev->discovery.uuid_count > 0).
> + }
Hence if we get here and if (hdev->discovery.uuid_count > 0),
"match" is always true.
> if (dev_class && !eir_has_data_type(ev->eir, eir_len, EIR_CLASS_OF_DEV))
> eir_len = eir_append_data(ev->eir, eir_len, EIR_CLASS_OF_DEV,
> dev_class, 3);
>
> - if (scan_rsp_len > 0)
> + if (scan_rsp_len > 0) {
> + /* When using service discovery and a list of UUID is
> + * provided, results with no matching UUID should be
> + * dropped if there is no previous match from the
> + * advertising data.
> + */
> + if (hdev->discovery.uuid_count > 0) {
> + if (!match && !eir_has_uuids(scan_rsp, scan_rsp_len,
"match" is true, so this whole block is useless.
> + hdev->discovery.uuid_count,
> + hdev->discovery.uuids))
> + return;
> + }
> +
> + /* Append scan response data to event */
> memcpy(ev->eir + eir_len, scan_rsp, scan_rsp_len);
> + } else {
> + /* When using service discovery and a list of UUID is
> + * provided, results with empty scan response and no
> + * previous matched advertising data should be dropped.
> + */
> + if (hdev->discovery.uuid_count > 0 && !match)
"match" is true, so this whole block is useless.
> + return;
> + }
>
> ev->eir_len = cpu_to_le16(eir_len + scan_rsp_len);
> ev_size = sizeof(*ev) + eir_len + scan_rsp_len;
Is my analysis correct?
Am I missing something?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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