Please note that this patch depends on a previously submitted kernel
patch [1] to ensure that connection parameters are not lost when
rebonding.
[1] [PATCH] Bluetooth: Defer connection-parameter removal when
unpairing without disconnecting
On Sat, Oct 11, 2014 at 1:53 AM, Alfonso Acosta <fons@xxxxxxxxxxx> wrote:
> This patch adds btd_adapter_recreate_bonding() which rebonds a device,
> i.e. it performs an unbonding operation inmediately followed by a
> bonding operation.
>
> Although there is no internal use for btd_adapter_recreate_bonding()
> yet, it is useful for plugins dealing with devices which require
> renegotiaing their keys. For instance, when dealing with devices
> without persistent storage which lose their keys on reset.
>
> Certain caveats have been taken into account when rebonding with a LE
> device:
>
> * If the device to rebond is already connected, the rebonding is done
> without disconnecting to avoid the extra latency of reestablishing
> the connection.
>
> * If no connection exists, we connect before unbonding anyways to
> avoid losing the device's autoconnection and connection parameters,
> which are removed by the kernel when unpairing if no connection
> exists.
>
> * Not closing the connection requires defering attribute discovery
> until the rebonding is done. Otherwise, the security level could be
> elavated with the old LTK, which may be invalid since we are
> rebonding. When rebonding, attribute discovery is suspended and the
> ATT socket is saved to allow resuming it once bonding is finished.
> ---
> src/adapter.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
> src/adapter.h | 7 ++++++-
> src/device.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++---
> src/device.h | 4 ++++
> 4 files changed, 119 insertions(+), 7 deletions(-)
>
> diff --git a/src/adapter.c b/src/adapter.c
> index 92ee1a0..81e8f22 100644
> --- a/src/adapter.c
> +++ b/src/adapter.c
> @@ -5195,14 +5195,15 @@ int btd_adapter_read_clock(struct btd_adapter *adapter, const bdaddr_t *bdaddr,
> }
>
> int btd_adapter_remove_bonding(struct btd_adapter *adapter,
> - const bdaddr_t *bdaddr, uint8_t bdaddr_type)
> + const bdaddr_t *bdaddr, uint8_t bdaddr_type,
> + uint8_t disconnect)
> {
> struct mgmt_cp_unpair_device cp;
>
> memset(&cp, 0, sizeof(cp));
> bacpy(&cp.addr.bdaddr, bdaddr);
> cp.addr.type = bdaddr_type;
> - cp.disconnect = 1;
> + cp.disconnect = disconnect;
>
> if (mgmt_send(adapter->mgmt, MGMT_OP_UNPAIR_DEVICE,
> adapter->dev_id, sizeof(cp), &cp,
> @@ -5212,6 +5213,53 @@ int btd_adapter_remove_bonding(struct btd_adapter *adapter,
> return -EIO;
> }
>
> +int btd_adapter_recreate_bonding(struct btd_adapter *adapter,
> + const bdaddr_t *bdaddr,
> + uint8_t bdaddr_type,
> + uint8_t io_cap)
> +{
> + struct btd_device *device;
> + int err;
> +
> + device = btd_adapter_get_device(adapter, bdaddr, bdaddr_type);
> +
> + if (!device || !device_is_bonded(device, bdaddr_type))
> + return -EINVAL;
> +
> + device_set_rebonding(device, bdaddr_type, true);
> +
> + /* Make sure the device is connected before unbonding to avoid
> + * losing the device's autoconnection and connection
> + * parameters, which are removed by the kernel when unpairing
> + * if no connection exists. We would had anyways implicitly
> + * connected when bonding later on, so we might as well just
> + * do it explicitly now.
> + */
> + if (bdaddr_type != BDADDR_BREDR && !btd_device_is_connected(device)) {
> + err = device_connect_le(device);
> + if (err < 0)
> + goto failed;
> + }
> +
> + /* Unbond without disconnecting to avoid the connection
> + * re-establishment latency
> + */
> + err = btd_adapter_remove_bonding(adapter, bdaddr, bdaddr_type, 0);
> + if (err < 0)
> + goto failed;
> +
> + err = adapter_create_bonding(adapter, bdaddr, bdaddr_type, io_cap);
> + if (err < 0)
> + goto failed;
> +
> + return 0;
> +
> +failed:
> + error("failed: %s", strerror(-err));
> + device_set_rebonding(device, bdaddr_type, false);
> + return err;
> +}
> +
> static void pincode_reply_complete(uint8_t status, uint16_t length,
> const void *param, void *user_data)
> {
> @@ -5594,8 +5642,11 @@ static void bonding_complete(struct btd_adapter *adapter,
> else
> device = btd_adapter_find_device(adapter, bdaddr, addr_type);
>
> - if (device != NULL)
> + if (device != NULL) {
> device_bonding_complete(device, addr_type, status);
> + if (device_is_rebonding(device, addr_type))
> + device_rebonding_complete(device, addr_type);
> + }
>
> resume_discovery(adapter);
>
> diff --git a/src/adapter.h b/src/adapter.h
> index 6801fee..bd00d3e 100644
> --- a/src/adapter.h
> +++ b/src/adapter.h
> @@ -158,7 +158,12 @@ int btd_adapter_disconnect_device(struct btd_adapter *adapter,
> uint8_t bdaddr_type);
>
> int btd_adapter_remove_bonding(struct btd_adapter *adapter,
> - const bdaddr_t *bdaddr, uint8_t bdaddr_type);
> + const bdaddr_t *bdaddr, uint8_t bdaddr_type,
> + uint8_t disconnect);
> +int btd_adapter_recreate_bonding(struct btd_adapter *adapter,
> + const bdaddr_t *bdaddr,
> + uint8_t bdaddr_type,
> + uint8_t io_cap);
>
> int btd_adapter_pincode_reply(struct btd_adapter *adapter,
> const bdaddr_t *bdaddr,
> diff --git a/src/device.c b/src/device.c
> index 875a5c5..4aab349 100644
> --- a/src/device.c
> +++ b/src/device.c
> @@ -158,6 +158,7 @@ struct att_callbacks {
> struct bearer_state {
> bool paired;
> bool bonded;
> + bool rebonding;
> bool connected;
> bool svc_resolved;
> };
> @@ -221,6 +222,8 @@ struct btd_device {
> int8_t rssi;
>
> GIOChannel *att_io;
> + GIOChannel *att_rebond_io;
> +
> guint cleanup_id;
> guint store_id;
> };
> @@ -522,6 +525,9 @@ static void device_free(gpointer user_data)
>
> attio_cleanup(device);
>
> + if (device->att_rebond_io)
> + g_io_channel_unref(device->att_rebond_io);
> +
> if (device->tmp_records)
> sdp_list_free(device->tmp_records,
> (sdp_free_func_t) sdp_record_free);
> @@ -1739,6 +1745,23 @@ long device_bonding_last_duration(struct btd_device *device)
> return bonding->last_attempt_duration_ms;
> }
>
> +bool device_is_rebonding(struct btd_device *device, uint8_t bdaddr_type)
> +{
> + struct bearer_state *state = get_state(device, bdaddr_type);
> +
> + return state->rebonding;
> +}
> +
> +void device_set_rebonding(struct btd_device *device, uint8_t bdaddr_type,
> + bool rebonding)
> +{
> + struct bearer_state *state = get_state(device, bdaddr_type);
> +
> + state->rebonding = rebonding;
> +
> + DBG("rebonding = %d", rebonding);
> +}
> +
> static void create_bond_req_exit(DBusConnection *conn, void *user_data)
> {
> struct btd_device *device = user_data;
> @@ -2029,7 +2052,7 @@ void device_remove_connection(struct btd_device *device, uint8_t bdaddr_type)
>
> if (state->paired && !state->bonded)
> btd_adapter_remove_bonding(device->adapter, &device->bdaddr,
> - bdaddr_type);
> + bdaddr_type, 1);
>
> if (device->bredr_state.connected || device->le_state.connected)
> return;
> @@ -2639,13 +2662,13 @@ static void device_remove_stored(struct btd_device *device)
> if (device->bredr_state.bonded) {
> device->bredr_state.bonded = false;
> btd_adapter_remove_bonding(device->adapter, &device->bdaddr,
> - BDADDR_BREDR);
> + BDADDR_BREDR, 1);
> }
>
> if (device->le_state.bonded) {
> device->le_state.bonded = false;
> btd_adapter_remove_bonding(device->adapter, &device->bdaddr,
> - device->bdaddr_type);
> + device->bdaddr_type, 1);
> }
>
> device->bredr_state.paired = false;
> @@ -3628,6 +3651,18 @@ bool device_attach_attrib(struct btd_device *dev, GIOChannel *io)
> GAttrib *attrib;
> BtIOSecLevel sec_level;
>
> + DBG("");
> +
> + if (dev->le_state.rebonding) {
> + DBG("postponing due to rebonding");
> + /* Keep the att socket, and defer attaching the attributes
> + * until rebonding is done.
> + */
> + if (!dev->att_rebond_io)
> + dev->att_rebond_io = g_io_channel_ref(io);
> + return false;
> + }
> +
> bt_io_get(io, &gerr, BT_IO_OPT_SEC_LEVEL, &sec_level,
> BT_IO_OPT_INVALID);
> if (gerr) {
> @@ -4269,6 +4304,23 @@ void device_bonding_complete(struct btd_device *device, uint8_t bdaddr_type,
> }
> }
>
> +bool device_rebonding_complete(struct btd_device *device, uint8_t bdaddr_type)
> +{
> + bool ret = true;
> +
> + DBG("");
> +
> + device_set_rebonding(device, bdaddr_type, false);
> +
> + if (bdaddr_type != BDADDR_BREDR && device->att_rebond_io) {
> + ret = device_attach_attrib(device, device->att_rebond_io);
> + g_io_channel_unref(device->att_rebond_io);
> + device->att_rebond_io = NULL;
> + }
> +
> + return ret;
> +}
> +
> static gboolean svc_idle_cb(gpointer user_data)
> {
> struct svc_callback *cb = user_data;
> diff --git a/src/device.h b/src/device.h
> index 2e0473e..65b1018 100644
> --- a/src/device.h
> +++ b/src/device.h
> @@ -94,6 +94,10 @@ bool device_is_retrying(struct btd_device *device);
> void device_bonding_complete(struct btd_device *device, uint8_t bdaddr_type,
> uint8_t status);
> gboolean device_is_bonding(struct btd_device *device, const char *sender);
> +bool device_is_rebonding(struct btd_device *device, uint8_t bdaddr_type);
> +void device_set_rebonding(struct btd_device *device, uint8_t bdaddr_type,
> + bool rebonding);
> +bool device_complete_rebonding(struct btd_device *device, uint8_t bdaddr_type);
> void device_bonding_attempt_failed(struct btd_device *device, uint8_t status);
> void device_bonding_failed(struct btd_device *device, uint8_t status);
> struct btd_adapter_pin_cb_iter *device_bonding_iter(struct btd_device *device);
> --
> 1.9.1
>
--
Alfonso Acosta
Embedded Systems Engineer at Spotify
Birger Jarlsgatan 61, Stockholm, Sweden
http://www.spotify.com
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