Date:   Mon, 15 Nov 2021 17:27:43 +0800
Message-Id: <20211115172714.Bluez.v3.1.I9fc087b25433a9347b2d8c8ff7a25fadf448ef49@changeid>
Mime-Version: 1.0
Subject: [Bluez PATCH v3 1/3] Listen and process remote name resolving failure
From:   Archie Pusaka <apusaka@google.com>
To:     linux-bluetooth <linux-bluetooth@vger.kernel.org>,
        Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        Marcel Holtmann <marcel@holtmann.org>
Cc:     CrosBT Upstreaming <chromeos-bluetooth-upstreaming@chromium.org>,
        Archie Pusaka <apusaka@chromium.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

From: Archie Pusaka <apusaka@chromium.org>

When Remote Name Resolve ends with failure, record this occurrence and
prevent remote name resolving for the same device for some time.
Increase the time duration for subsequent failures.
---
Hi maintainers,

This is the patch series for remote name request as was discussed here.
https://patchwork.kernel.org/project/bluetooth/patch/20211028191805.1.I35b7f3a496f834de6b43a32f94b6160cb1467c94@changeid/
Please also review the corresponding kernel space change.

Changes in v3:
* Rename MGMT const to align with the doc

Changes in v2:
* Stay silent instead of sending MGMT_OP_CONFIRM_NAME with DONT_CARE flag.

 lib/mgmt.h    |  1 +
 src/adapter.c | 15 +++++++++++++--
 src/device.c  | 23 +++++++++++++++++++++++
 src/device.h  |  2 ++
 4 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/lib/mgmt.h b/lib/mgmt.h
index 0d1678f01d..d860b27401 100644
--- a/lib/mgmt.h
+++ b/lib/mgmt.h
@@ -856,6 +856,7 @@ struct mgmt_ev_auth_failed {
 #define MGMT_DEV_FOUND_CONFIRM_NAME	0x01
 #define MGMT_DEV_FOUND_LEGACY_PAIRING	0x02
 #define MGMT_DEV_FOUND_NOT_CONNECTABLE	0x04
+#define MGMT_DEV_FOUND_NAME_REQUEST_FAILED 0x10
 
 #define MGMT_EV_DEVICE_FOUND		0x0012
 struct mgmt_ev_device_found {
diff --git a/src/adapter.c b/src/adapter.c
index d0d38621b8..6100448b5f 100644
--- a/src/adapter.c
+++ b/src/adapter.c
@@ -6989,6 +6989,7 @@ static void update_found_devices(struct btd_adapter *adapter,
 					uint8_t bdaddr_type, int8_t rssi,
 					bool confirm, bool legacy,
 					bool not_connectable,
+					bool name_resolve_failed,
 					const uint8_t *data, uint8_t data_len)
 {
 	struct btd_device *dev;
@@ -7081,6 +7082,9 @@ static void update_found_devices(struct btd_adapter *adapter,
 
 	device_set_legacy(dev, legacy);
 
+	if (name_resolve_failed)
+		device_name_resolve_fail(dev);
+
 	if (adapter->filtered_discovery)
 		device_set_rssi_with_delta(dev, rssi, 0);
 	else
@@ -7151,7 +7155,10 @@ static void update_found_devices(struct btd_adapter *adapter,
 	if (g_slist_find(adapter->discovery_found, dev))
 		return;
 
-	if (confirm)
+	/* If name is unknown but it's not allowed to resolve, don't send
+	 * MGMT_OP_CONFIRM_NAME.
+	 */
+	if (confirm && (name_known || device_name_resolve_allowed(dev)))
 		confirm_name(adapter, bdaddr, bdaddr_type, name_known);
 
 	adapter->discovery_found = g_slist_prepend(adapter->discovery_found,
@@ -7201,6 +7208,8 @@ static void device_found_callback(uint16_t index, uint16_t length,
 	uint32_t flags;
 	bool confirm_name;
 	bool legacy;
+	bool not_connectable;
+	bool name_resolve_failed;
 	char addr[18];
 
 	if (length < sizeof(*ev)) {
@@ -7230,10 +7239,12 @@ static void device_found_callback(uint16_t index, uint16_t length,
 
 	confirm_name = (flags & MGMT_DEV_FOUND_CONFIRM_NAME);
 	legacy = (flags & MGMT_DEV_FOUND_LEGACY_PAIRING);
+	not_connectable = (flags & MGMT_DEV_FOUND_NOT_CONNECTABLE);
+	name_resolve_failed = (flags & MGMT_DEV_FOUND_NAME_REQUEST_FAILED);
 
 	update_found_devices(adapter, &ev->addr.bdaddr, ev->addr.type,
 					ev->rssi, confirm_name, legacy,
-					flags & MGMT_DEV_FOUND_NOT_CONNECTABLE,
+					not_connectable, name_resolve_failed,
 					eir, eir_len);
 }
 
diff --git a/src/device.c b/src/device.c
index fdc2d50a47..699faeba3b 100644
--- a/src/device.c
+++ b/src/device.c
@@ -79,6 +79,8 @@
 #define GATT_INCLUDE_UUID_STR "2802"
 #define GATT_CHARAC_UUID_STR "2803"
 
+#define NAME_RESOLVE_RETRY_DELAY	120 /* seconds */
+
 static DBusConnection *dbus_conn = NULL;
 static unsigned service_state_cb_id;
 
@@ -272,6 +274,9 @@ struct btd_device {
 
 	GIOChannel	*att_io;
 	guint		store_id;
+
+	time_t		name_resolve_earliest_allow_time;
+	uint8_t		name_resolve_fail_count;
 };
 
 static const uint16_t uuid_list[] = {
@@ -4361,6 +4366,24 @@ bool device_name_known(struct btd_device *device)
 	return device->name[0] != '\0';
 }
 
+bool device_name_resolve_allowed(struct btd_device *device)
+{
+	return time(NULL) >= device->name_resolve_earliest_allow_time;
+}
+
+void device_name_resolve_fail(struct btd_device *device)
+{
+	if (!device)
+		return;
+
+	/* Punish this device by not allowing name resolve for some time.
+	 * increase punishment time for subsequent failures.
+	 */
+	device->name_resolve_fail_count++;
+	device->name_resolve_earliest_allow_time = time(NULL) +
+		NAME_RESOLVE_RETRY_DELAY * device->name_resolve_fail_count;
+}
+
 void device_set_class(struct btd_device *device, uint32_t class)
 {
 	if (device->class == class)
diff --git a/src/device.h b/src/device.h
index 5f615cb4b6..76d79855f8 100644
--- a/src/device.h
+++ b/src/device.h
@@ -25,6 +25,8 @@ void btd_device_device_set_name(struct btd_device *device, const char *name);
 void device_store_cached_name(struct btd_device *dev, const char *name);
 void device_get_name(struct btd_device *device, char *name, size_t len);
 bool device_name_known(struct btd_device *device);
+bool device_name_resolve_allowed(struct btd_device *device);
+void device_name_resolve_fail(struct btd_device *device);
 void device_set_class(struct btd_device *device, uint32_t class);
 void device_update_addr(struct btd_device *device, const bdaddr_t *bdaddr,
 							uint8_t bdaddr_type);
-- 
2.34.0.rc1.387.gb447b232ab-goog