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From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: Tue, 1 Aug 2017 13:21:40 +0300
Message-ID: <CABBYNZLhS+-ugFxXKZ6mmk2BvCHmLG8sxWhfdnW1U05OMqqNHA@mail.gmail.com>
Subject: Re: how to add local name in scan response when setting
 MGMT_ADV_FLAG_LOCAL_NAME in Bluez
To: Yunhan Wang <yunhanw@google.com>
Cc: "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Yunhan,

On Tue, Aug 1, 2017 at 10:37 AM, Yunhan Wang <yunhanw@google.com> wrote:
> Hi
>
> I am trying to do some small experiments that add local name in the
> scan response,  should I use data[0] to store both adv_data and
> scan_rsp?
>
> I tried to add local name(=E2=80=99TEST=E2=80=99) in data[0] under
> mgmt_cp_add_advertising on
> https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/src/advertising.c=
#n484,
> it seems it does not work, any idea?

Seems to be a limitation in the kernel, also setting the adapter name
doesn't change anything either so it seems it simply does not include
any scan response. I guess we would have to add support for that.

> Thanks
> Best wishes
> Yunhan
>
> static DBusMessage *refresh_advertisement(struct btd_adv_client *client)
> {
> struct mgmt_cp_add_advertising *cp;
> uint8_t param_len;
> uint8_t *adv_data;
> size_t adv_data_len;
> uint32_t flags =3D 0;
>
> uint8_t scan_rsp[] =3D {
> =E2=80=99T=E2=80=99,
> =E2=80=99E=E2=80=99,
> =E2=80=99S=E2=80=99,
> =E2=80=99T=E2=80=99
> };
> size_t scan_rsp_len =3D sizeof(scan_rsp);
>
> DBG("Refreshing advertisement: %s", client->path);
>
> if (client->type =3D=3D AD_TYPE_PERIPHERAL)
> flags =3D MGMT_ADV_FLAG_CONNECTABLE | MGMT_ADV_FLAG_DISCOV |
> MGMT_ADV_FLAG_LOCAL_NAME;
>
> if (client->include_tx_power)
> flags |=3D MGMT_ADV_FLAG_TX_POWER;
>
> adv_data =3D bt_ad_generate(client->data, &adv_data_len);
>
> if (!adv_data || (adv_data_len > calc_max_adv_len(client, flags))) {
> error("Advertising data too long or couldn't be generated.");
>
> return g_dbus_create_error(client->reg, ERROR_INTERFACE
> ".InvalidLength",
> "Advertising data too long.");
> }
>
> param_len =3D sizeof(struct mgmt_cp_add_advertising) + adv_data_len +
> scan_rsp_len;
>
> cp =3D malloc0(param_len);
>
> if (!cp) {
> error("Couldn't allocate for MGMT!");
>
> free(adv_data);
>
> return btd_error_failed(client->reg, "Failed");
> }
>
> cp->flags =3D htobl(flags);
> cp->instance =3D client->instance;
> cp->adv_data_len =3D adv_data_len;
> cp->scan_rsp_len =3D scan_rsp_len;
> memcpy(cp->data, adv_data, adv_data_len);
> memcpy(cp->data + adv_data_len, scan_rsp_data, scan_rsp_len);
> free(adv_data);
>
> if (!mgmt_send(client->manager->mgmt, MGMT_OP_ADD_ADVERTISING,
> client->manager->mgmt_index, param_len, cp,
> add_adv_callback, client, NULL)) {
> DBG("Failed to add Advertising Data");
>
> free(cp);
>
> return btd_error_failed(client->reg, "Failed");
> }
>
> free(cp);
>
> return NULL;
> }
>
> Reference:
> In lib/mgmt.h,
>
> #define MGMT_OP_ADD_ADVERTISING 0x003E
> struct mgmt_cp_add_advertising {
> uint8_t  instance;
> uint32_t flags;
> uint16_t duration;
> uint16_t timeout;
> uint8_t  adv_data_len;
> uint8_t  scan_rsp_len;
> uint8_t  data[0];
> } __packed;
> From mgmt-api.txt, I am
>
> Add Advertising Command
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
> Command Code: 0x003e
> Controller Index: <controller id>
> Command Parameters: Instance (1 Octet)
> Flags (4 Octets)
> Duration (2 Octets)
> Timeout (2 Octets)
> Adv_Data_Len (1 Octet)
> Scan_Rsp_len (1 Octet)
> Adv_Data (0-255 Octets)
> Scan_Rsp (0-255 Octets)
> =E2=80=A6...
> With the Flags value the type of advertising is controlled and
> the following flags are defined:
>
> 0 Switch into Connectable mode
> 1 Advertise as Discoverable
> 2 Advertise as Limited Discoverable
> 3 Add Flags field to Adv_Data
> 4 Add TX Power field to Adv_Data
> 5 Add Appearance field to Scan_Rsp
> 6 Add Local Name in Scan_Rsp
> --
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--=20
Luiz Augusto von Dentz