Bluetooth: add hci_connect_le_scan

This change “Bluetooth: add hci_connect_le_scan” in Linux kernel is authored by Jakub Pawlowski <jpawlowski [at] google.com> on Fri Aug 7 20:22:53 2015 +0200.

Bluetooth: add hci_connect_le_scan

Currently, when trying to connect to already paired device that just
rotated its RPA MAC address, old address would be used and connection
would fail. In order to fix that, kernel must scan and receive
advertisement with fresh RPA before connecting.

This patch adds hci_connect_le_scan with dependencies, new method that
will be used to connect to remote LE devices. Instead of just sending
connect request, it adds a device to whitelist. Later patches will make
use of this whitelist to send conenct request when advertisement is
received, and properly handle timeouts.

Signed-off-by: Jakub Pawlowski <jpawlowski@google.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit f75113a.

There are 213 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 include/net/bluetooth/hci_core.h |   6 ++
 net/bluetooth/hci_conn.c         | 174 +++++++++++++++++++++++++++++++++++++++
 net/bluetooth/hci_core.c         |  33 ++++++++
 3 files changed, 213 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index f0a9fc1..9e1a59e 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -846,6 +846,9 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
 void hci_chan_list_flush(struct hci_conn *conn);
 struct hci_chan *hci_chan_lookup_handle(struct hci_dev *hdev, __u16 handle);
 
+struct hci_conn *hci_connect_le_scan(struct hci_dev *hdev, bdaddr_t *dst,
+				     u8 dst_type, u8 sec_level,
+				     u16 conn_timeout, u8 role);
 struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
 				u8 dst_type, u8 sec_level, u16 conn_timeout,
 				u8 role);
@@ -1011,6 +1014,9 @@ struct hci_conn_params *hci_conn_params_add(struct hci_dev *hdev,
 struct hci_conn_params *hci_pend_le_action_lookup(struct list_head *list,
 						  bdaddr_t *addr,
 						  u8 addr_type);
+struct hci_conn_params *hci_explicit_connect_lookup(struct hci_dev *hdev,
+						    bdaddr_t *addr,
+						    u8 addr_type);
 
 void hci_uuids_clear(struct hci_dev *hdev);
 
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 0b4d919..534feb7 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -64,6 +64,48 @@ static void hci_le_create_connection_cancel(struct hci_conn *conn)
 	hci_send_cmd(conn->hdev, HCI_OP_LE_CREATE_CONN_CANCEL, 0, NULL);
 }
 
+/* This function requires the caller holds hdev->lock */
+static void hci_connect_le_scan_cleanup(struct hci_conn *conn)
+{
+	struct hci_conn_params *params;
+	struct smp_irk *irk;
+	bdaddr_t *bdaddr;
+	u8 bdaddr_type;
+
+	bdaddr = &conn->dst;
+	bdaddr_type = conn->dst_type;
+
+	/* Check if we need to convert to identity address */
+	irk = hci_get_irk(conn->hdev, bdaddr, bdaddr_type);
+	if (irk) {
+		bdaddr = &irk->bdaddr;
+		bdaddr_type = irk->addr_type;
+	}
+
+	params = hci_explicit_connect_lookup(conn->hdev, bdaddr, bdaddr_type);
+	if (!params)
+		return;
+
+	/* The connection attempt was doing scan for new RPA, and is
+	 * in scan phase. If params are not associated with any other
+	 * autoconnect action, remove them completely. If they are, just unmark
+	 * them as waiting for connection, by clearing explicit_connect field.
+	 */
+	if (params->auto_connect == HCI_AUTO_CONN_EXPLICIT)
+		hci_conn_params_del(conn->hdev, bdaddr, bdaddr_type);
+	else
+		params->explicit_connect = false;
+}
+
+/* This function requires the caller holds hdev->lock */
+static void hci_connect_le_scan_remove(struct hci_conn *conn)
+{
+	hci_connect_le_scan_cleanup(conn);
+
+	hci_conn_hash_del(conn->hdev, conn);
+	hci_update_background_scan(conn->hdev);
+}
+
 static void hci_acl_create_connection(struct hci_conn *conn)
 {
 	struct hci_dev *hdev = conn->hdev;
@@ -858,6 +900,138 @@ struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
 	return conn;
 }
 
+static void hci_connect_le_scan_complete(struct hci_dev *hdev, u8 status,
+					 u16 opcode)
+{
+	struct hci_conn *conn;
+
+	if (!status)
+		return;
+
+	BT_ERR("Failed to add device to auto conn whitelist: status 0x%2.2x",
+	       status);
+
+	hci_dev_lock(hdev);
+
+	conn = hci_conn_hash_lookup_state(hdev, LE_LINK, BT_CONNECT);
+	if (conn)
+		hci_le_conn_failed(conn, status);
+
+	hci_dev_unlock(hdev);
+}
+
+static bool is_connected(struct hci_dev *hdev, bdaddr_t *addr, u8 type)
+{
+	struct hci_conn *conn;
+
+	conn = hci_conn_hash_lookup_ba(hdev, LE_LINK, addr);
+	if (!conn)
+		return false;
+
+	if (conn->dst_type != type)
+		return false;
+
+	if (conn->state != BT_CONNECTED)
+		return false;
+
+	return true;
+}
+
+/* This function requires the caller holds hdev->lock */
+static int hci_explicit_conn_params_set(struct hci_request *req,
+					bdaddr_t *addr, u8 addr_type)
+{
+	struct hci_dev *hdev = req->hdev;
+	struct hci_conn_params *params;
+
+	if (is_connected(hdev, addr, addr_type))
+		return -EISCONN;
+
+	params = hci_conn_params_add(hdev, addr, addr_type);
+	if (!params)
+		return -EIO;
+
+	/* If we created new params, or existing params were marked as disabled,
+	 * mark them to be used just once to connect.
+	 */
+	if (params->auto_connect == HCI_AUTO_CONN_DISABLED) {
+		params->auto_connect = HCI_AUTO_CONN_EXPLICIT;
+		list_del_init(¶ms->action);
+		list_add(¶ms->action, &hdev->pend_le_conns);
+	}
+
+	params->explicit_connect = true;
+	__hci_update_background_scan(req);
+
+	BT_DBG("addr %pMR (type %u) auto_connect %u", addr, addr_type,
+	       params->auto_connect);
+
+	return 0;
+}
+
+/* This function requires the caller holds hdev->lock */
+struct hci_conn *hci_connect_le_scan(struct hci_dev *hdev, bdaddr_t *dst,
+				     u8 dst_type, u8 sec_level,
+				     u16 conn_timeout, u8 role)
+{
+	struct hci_conn *conn;
+	struct hci_request req;
+	int err;
+
+	/* Let's make sure that le is enabled.*/
+	if (!hci_dev_test_flag(hdev, HCI_LE_ENABLED)) {
+		if (lmp_le_capable(hdev))
+			return ERR_PTR(-ECONNREFUSED);
+
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+
+	/* Some devices send ATT messages as soon as the physical link is
+	 * established. To be able to handle these ATT messages, the user-
+	 * space first establishes the connection and then starts the pairing
+	 * process.
+	 *
+	 * So if a hci_conn object already exists for the following connection
+	 * attempt, we simply update pending_sec_level and auth_type fields
+	 * and return the object found.
+	 */
+	conn = hci_conn_hash_lookup_ba(hdev, LE_LINK, dst);
+	if (conn) {
+		if (conn->pending_sec_level < sec_level)
+			conn->pending_sec_level = sec_level;
+		goto done;
+	}
+
+	BT_DBG("requesting refresh of dst_addr");
+
+	conn = hci_conn_add(hdev, LE_LINK, dst, role);
+	if (!conn)
+		return ERR_PTR(-ENOMEM);
+
+	hci_req_init(&req, hdev);
+
+	if (hci_explicit_conn_params_set(&req, dst, dst_type) < 0)
+		return ERR_PTR(-EBUSY);
+
+	conn->state = BT_CONNECT;
+	set_bit(HCI_CONN_SCANNING, &conn->flags);
+
+	err = hci_req_run(&req, hci_connect_le_scan_complete);
+	if (err && err != -ENODATA) {
+		hci_conn_del(conn);
+		return ERR_PTR(err);
+	}
+
+	conn->dst_type = dst_type;
+	conn->sec_level = BT_SECURITY_LOW;
+	conn->pending_sec_level = sec_level;
+	conn->conn_timeout = conn_timeout;
+
+done:
+	hci_conn_hold(conn);
+	return conn;
+}
+
 struct hci_conn *hci_connect_acl(struct hci_dev *hdev, bdaddr_t *dst,
 				 u8 sec_level, u8 auth_type)
 {
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index bc43b64..adcbc74 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2848,6 +2848,30 @@ struct hci_conn_params *hci_pend_le_action_lookup(struct list_head *list,
 }
 
 /* This function requires the caller holds hdev->lock */
+struct hci_conn_params *hci_explicit_connect_lookup(struct hci_dev *hdev,
+						    bdaddr_t *addr,
+						    u8 addr_type)
+{
+	struct hci_conn_params *param;
+
+	list_for_each_entry(param, &hdev->pend_le_conns, action) {
+		if (bacmp(¶m->addr, addr) == 0 &&
+		    param->addr_type == addr_type &&
+		    param->explicit_connect)
+			return param;
+	}
+
+	list_for_each_entry(param, &hdev->pend_le_reports, action) {
+		if (bacmp(¶m->addr, addr) == 0 &&
+		    param->addr_type == addr_type &&
+		    param->explicit_connect)
+			return param;
+	}
+
+	return NULL;
+}
+
+/* This function requires the caller holds hdev->lock */
 struct hci_conn_params *hci_conn_params_add(struct hci_dev *hdev,
 					    bdaddr_t *addr, u8 addr_type)
 {
@@ -2916,6 +2940,15 @@ void hci_conn_params_clear_disabled(struct hci_dev *hdev)
 	list_for_each_entry_safe(params, tmp, &hdev->le_conn_params, list) {
 		if (params->auto_connect != HCI_AUTO_CONN_DISABLED)
 			continue;
+
+		/* If trying to estabilish one time connection to disabled
+		 * device, leave the params, but mark them as just once.
+		 */
+		if (params->explicit_connect) {
+			params->auto_connect = HCI_AUTO_CONN_EXPLICIT;
+			continue;
+		}
+
 		list_del(¶ms->list);
 		kfree(params);
 	}

The commit for this change in Linux stable tree is f75113a (patch).

Leave a Reply

Your email address will not be published. Required fields are marked *