linux-kernel - [PATCH v5 BlueZ 4/4] Bluetooth: Handle Slave Connection Interval Range AD

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Date:   Thu, 13 Apr 2017 13:22:03 +0100
From:   "Felipe F. Tonello" <eu@...ipetonello.com>
To:     linux-bluetooth@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>
Subject: [PATCH v5 BlueZ 4/4] Bluetooth: Handle Slave Connection Interval Range AD

The Slave Connection Interval Range data type contains the Peripheral's
preferred connection interval range, for all logical connections.

It is useful to parse it in the Kernel so there is no multiple calls to
MGMT interface to update the device connection parameters and subsequent
connection command call to this device will use proper connection
parameters. This saves context-switches and eliminates user-space to
update the connection parameters each time a device is found or
bluetoothd is restarted and so on. Also, there is no need for the
user-space to know care about it because if the slave device wishes to
persist with these parameters, it should use the L2CAP connection
parameters upade request upon a completed connection.

Signed-off-by: Felipe F. Tonello <eu@...ipetonello.com>
---
 net/bluetooth/mgmt.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 1fba2a03f8ae..ea5d6c85f173 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -7442,6 +7442,46 @@ static bool is_filter_match(struct hci_dev *hdev, s8 rssi, u8 *eir,
 	return true;
 }
 
+static bool has_eir_slave_conn_int(const u8 *eir_data, u8 eir_len,
+				   u16 *min_conn, u16 *max_conn)
+{
+	u16 len = 0;
+	const u8 EIR_SLAVE_CONN_INT = 0x12; /* Slave Connection Interval Range */
+
+	while (len < eir_len - 1) {
+		u8 field_len = eir_data[0];
+		const u8 *data;
+		u8 data_len;
+
+		/* Check for the end of EIR */
+		if (field_len == 0)
+			break;
+
+		len += field_len + 1;
+
+		/* Do not continue EIR Data parsing if got
+		 * incorrect length
+		 */
+		if (len > eir_len)
+			break;
+
+		data = &eir_data[2];
+		data_len = field_len - 1;
+
+		if (eir_data[1] == EIR_SLAVE_CONN_INT) {
+			if (data_len < 4)
+				break;
+			*min_conn = le16_to_cpu(&data[0]);
+			*max_conn = le16_to_cpu(&data[2]);
+			return true;
+		}
+
+		eir_data += field_len + 1;
+	}
+
+	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)
@@ -7449,6 +7489,7 @@ 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;
+	struct hci_conn *hcon;
 
 	/* Don't send events for a non-kernel initiated discovery. With
 	 * LE one exception is if we have pend_le_reports > 0 in which
@@ -7521,6 +7562,18 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
 	ev->eir_len = cpu_to_le16(eir_len + scan_rsp_len);
 	ev_size = sizeof(*ev) + eir_len + scan_rsp_len;
 
+	/* Search for Slave Connection Interval AD */
+	hcon = hci_conn_hash_lookup_le(hdev, bdaddr, addr_type);
+	if (hcon) {
+		u16 min_conn_int, max_conn_int;
+
+		if (has_eir_slave_conn_int(ev->eir, ev->eir_len,
+					   &min_conn_int, &max_conn_int)) {
+			hcon->le_conn_min_interval = min_conn_int;
+			hcon->le_conn_max_interval = max_conn_int;
+		}
+	}
+
 	mgmt_event(MGMT_EV_DEVICE_FOUND, hdev, ev, ev_size, NULL);
 }
 
-- 
2.12.2