Date:   Mon, 15 Nov 2021 17:06:23 +0800
In-Reply-To: <20211115170538.Bluez.v2.1.I9fc087b25433a9347b2d8c8ff7a25fadf448ef49@changeid>
Message-Id: <20211115170538.Bluez.v2.2.I08d192861aa6b2025fbc575a7e0caffaa6170ed5@changeid>
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References: <20211115170538.Bluez.v2.1.I9fc087b25433a9347b2d8c8ff7a25fadf448ef49@changeid>
Subject: [Bluez PATCH v2 2/3] device: Save remote name request attempts into
 cache file
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>,
        Sonny Sasaka <sonnysasaka@chromium.org>,
        Miao-chen Chou <mcchou@chromium.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

From: Archie Pusaka <apusaka@chromium.org>

Since a peer device is potentially removed if not discovered for more
than 30 seconds, we would lost the remote name request activity when
the device is rediscovered. This could end up with a remote name
request much sooner than we intend it to be.

Therefore, put the RNR record into a cache file, so we can recover it
when the peer device is rediscovered.

Reviewed-by: Sonny Sasaka <sonnysasaka@chromium.org>
Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
---

(no changes since v1)

 src/device.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 94 insertions(+), 2 deletions(-)

diff --git a/src/device.c b/src/device.c
index 699faeba3b..fa6e3abc37 100644
--- a/src/device.c
+++ b/src/device.c
@@ -568,6 +568,63 @@ void device_store_cached_name(struct btd_device *dev, const char *name)
 	g_key_file_free(key_file);
 }
 
+static void device_store_cached_name_resolve_attempts(struct btd_device *dev)
+{
+	char filename[PATH_MAX];
+	char d_addr[18];
+	GKeyFile *key_file;
+	GError *gerr = NULL;
+	char *data;
+	char *data_old;
+	gsize length = 0;
+	gsize length_old = 0;
+	uint64_t earliest_allowed;
+	unsigned int num_failures;
+
+	if (device_address_is_private(dev)) {
+		DBG("Can't store name resolve for private addressed device %s",
+								dev->path);
+		return;
+	}
+
+	ba2str(&dev->bdaddr, d_addr);
+	snprintf(filename, PATH_MAX, STORAGEDIR "/%s/cache/%s",
+			btd_adapter_get_storage_dir(dev->adapter), d_addr);
+	create_file(filename, 0600);
+
+	key_file = g_key_file_new();
+	if (!g_key_file_load_from_file(key_file, filename, 0, &gerr)) {
+		error("Unable to load key file from %s: (%s)", filename,
+								gerr->message);
+		g_error_free(gerr);
+	}
+
+	earliest_allowed = (uint64_t) dev->name_resolve_earliest_allow_time;
+	num_failures = dev->name_resolve_fail_count;
+
+	data_old = g_key_file_to_data(key_file, &length_old, NULL);
+
+	g_key_file_set_uint64(key_file, "NameResolve", "EarliestAllowed",
+							earliest_allowed);
+	g_key_file_set_integer(key_file, "NameResolve", "NumFailures",
+							num_failures);
+
+	data = g_key_file_to_data(key_file, &length, NULL);
+
+	if ((length != length_old) || (memcmp(data, data_old, length))) {
+		if (!g_file_set_contents(filename, data, length, &gerr)) {
+			error("Unable set contents for %s: (%s)", filename,
+								gerr->message);
+			g_error_free(gerr);
+		}
+	}
+
+	g_free(data);
+	g_free(data_old);
+
+	g_key_file_free(key_file);
+}
+
 static void browse_request_free(struct browse_req *req)
 {
 	struct btd_device *device = req->device;
@@ -3277,6 +3334,36 @@ failed:
 	return str;
 }
 
+static void load_cached_name_resolve_attempts(struct btd_device *device,
+					const char *local, const char *peer)
+{
+	char filename[PATH_MAX];
+	GKeyFile *key_file;
+	uint64_t earliest_allowed;
+	unsigned int num_failures;
+
+	if (device_address_is_private(device))
+		return;
+
+	snprintf(filename, PATH_MAX, STORAGEDIR "/%s/cache/%s", local, peer);
+
+	key_file = g_key_file_new();
+
+	if (!g_key_file_load_from_file(key_file, filename, 0, NULL))
+		goto failed;
+
+	earliest_allowed = g_key_file_get_uint64(key_file, "NameResolve",
+						"EarliestAllowed", NULL);
+	num_failures = g_key_file_get_uint64(key_file, "NameResolve",
+						"NumFailures", NULL);
+
+	device->name_resolve_earliest_allow_time = earliest_allowed;
+	device->name_resolve_fail_count = (uint8_t) num_failures;
+
+failed:
+	g_key_file_free(key_file);
+}
+
 static struct csrk_info *load_csrk(GKeyFile *key_file, const char *group)
 {
 	struct csrk_info *csrk;
@@ -4284,6 +4371,7 @@ struct btd_device *device_create(struct btd_adapter *adapter,
 	struct btd_device *device;
 	char dst[18];
 	char *str;
+	const char *storage_dir;
 
 	ba2str(bdaddr, dst);
 	DBG("dst %s", dst);
@@ -4299,13 +4387,15 @@ struct btd_device *device_create(struct btd_adapter *adapter,
 	else
 		device->le = true;
 
-	str = load_cached_name(device, btd_adapter_get_storage_dir(adapter),
-									dst);
+	storage_dir = btd_adapter_get_storage_dir(adapter);
+	str = load_cached_name(device, storage_dir, dst);
 	if (str) {
 		strcpy(device->name, str);
 		g_free(str);
 	}
 
+	load_cached_name_resolve_attempts(device, storage_dir, dst);
+
 	return device;
 }
 
@@ -4382,6 +4472,8 @@ void device_name_resolve_fail(struct btd_device *device)
 	device->name_resolve_fail_count++;
 	device->name_resolve_earliest_allow_time = time(NULL) +
 		NAME_RESOLVE_RETRY_DELAY * device->name_resolve_fail_count;
+
+	device_store_cached_name_resolve_attempts(device);
 }
 
 void device_set_class(struct btd_device *device, uint32_t class)
-- 
2.34.0.rc1.387.gb447b232ab-goog