Bluetooth: att: Add option to disable GATT writable name

This allow to set name at runtime while leaving GAP name characteristic
read only.

Signed-off-by: Szymon Janc <szymon.janc@codecoup.pl>

samples/bluetooth/peripheral/prj.conf

@@ -10,6 +10,7 @@ CONFIG_BT_ATT_PREPARE_COUNT=2
 CONFIG_BT_PRIVACY=y
 CONFIG_BT_DEVICE_NAME="Zephyr Peripheral Sample Long Name"
 CONFIG_BT_DEVICE_APPEARANCE=833
+CONFIG_BT_DEVICE_NAME_DYNAMIC=y
 CONFIG_BT_DEVICE_NAME_MAX=65
 
 CONFIG_BT_SETTINGS=y

subsys/bluetooth/host/Kconfig

@@ -341,16 +341,28 @@ config BT_SCAN_WITH_IDENTITY
 	  disclosing local identity information. However, if the use case
 	  requires disclosing it then enable this option.
 
+config BT_DEVICE_NAME_DYNAMIC
+	bool "Allow to set Bluetooth device name on runtime"
+	help
+	  Enabling this option allows for runtime configuration of Bluetooth
+	  device name.
+
 config BT_DEVICE_NAME_MAX
 	int "Maximum size in bytes for device name"
+	depends on BT_DEVICE_NAME_DYNAMIC
 	default 28
-	default 0 if !BT_SETTINGS
-	range 0 248
+	range 2 248
 	help
 	  Bluetooth device name storage size. Storage can be up to 248 bytes
-	  long (excluding NULL termination). 0 means that no storage space is
-	  allocated for device name in which case the device name cannot be
-	  changed at runtime.
+	  long (excluding NULL termination).
+
+config BT_DEVICE_NAME_GATT_WRITABLE
+	bool "Allow to write name by remote GATT clients"
+	depends on BT_CONN && BT_DEVICE_NAME_DYNAMIC
+	default y
+	help
+	  Enabling this option allows remote GATT clients to write to device
+	  name GAP characteristic.
 
 config BT_DEVICE_NAME
 	string "Bluetooth device name"

subsys/bluetooth/host/gatt.c

@@ -53,13 +53,13 @@ static sys_slist_t db;
 static ssize_t read_name(struct bt_conn *conn, const struct bt_gatt_attr *attr,
 			 void *buf, u16_t len, u16_t offset)
 {
-	const char *name = attr->user_data;
+	const char *name = bt_get_name();
 
 	return bt_gatt_attr_read(conn, attr, buf, len, offset, name,
 				 strlen(name));
 }
 
-#if CONFIG_BT_DEVICE_NAME_MAX > 0
+#if defined(CONFIG_BT_DEVICE_NAME_GATT_WRITABLE)
 
 static ssize_t write_name(struct bt_conn *conn, const struct bt_gatt_attr *attr,
 			 const void *buf, u16_t len, u16_t offset,
@@ -86,7 +86,7 @@ static ssize_t write_name(struct bt_conn *conn, const struct bt_gatt_attr *attr,
 	return len;
 }
 
-#endif /* CONFIG_BT_DEVICE_NAME */
+#endif /* CONFIG_BT_DEVICE_NAME_GATT_WRITABLE */
 
 static ssize_t read_appearance(struct bt_conn *conn,
 			       const struct bt_gatt_attr *attr, void *buf,
@@ -100,7 +100,7 @@ static ssize_t read_appearance(struct bt_conn *conn,
 
 static struct bt_gatt_attr gap_attrs[] = {
 	BT_GATT_PRIMARY_SERVICE(BT_UUID_GAP),
-#if CONFIG_BT_DEVICE_NAME_MAX > 0
+#if defined(CONFIG_BT_DEVICE_NAME_GATT_WRITABLE)
 	/* Require pairing for writes to device name */
 	BT_GATT_CHARACTERISTIC(BT_UUID_GAP_DEVICE_NAME,
 			       BT_GATT_CHRC_READ | BT_GATT_CHRC_WRITE,
@@ -108,9 +108,8 @@ static struct bt_gatt_attr gap_attrs[] = {
 			       read_name, write_name, bt_dev.name),
 #else
 	BT_GATT_CHARACTERISTIC(BT_UUID_GAP_DEVICE_NAME, BT_GATT_CHRC_READ,
-			       BT_GATT_PERM_READ, read_name, NULL,
-			       CONFIG_BT_DEVICE_NAME),
-#endif
+			       BT_GATT_PERM_READ, read_name, NULL, NULL),
+#endif /* CONFIG_BT_DEVICE_NAME_GATT_WRITABLE */
 	BT_GATT_CHARACTERISTIC(BT_UUID_GAP_APPEARANCE, BT_GATT_CHRC_READ,
 			       BT_GATT_PERM_READ, read_appearance, NULL, NULL),
 };

subsys/bluetooth/host/hci_core.c

@@ -4749,7 +4749,7 @@ static int set_ad(u16_t hci_op, const struct bt_ad *ad, size_t ad_len)
 
 int bt_set_name(const char *name)
 {
-#if CONFIG_BT_DEVICE_NAME_MAX > 0
+#if defined(CONFIG_BT_DEVICE_NAME_DYNAMIC)
 	size_t len = strlen(name);
 	int err;
 
@@ -4800,7 +4800,7 @@ int bt_set_name(const char *name)
 
 const char *bt_get_name(void)
 {
-#if CONFIG_BT_DEVICE_NAME_MAX > 0
+#if defined(CONFIG_BT_DEVICE_NAME_DYNAMIC)
 	return bt_dev.name;
 #else
 	return CONFIG_BT_DEVICE_NAME;

subsys/bluetooth/host/hci_core.h

@@ -166,7 +166,9 @@ struct bt_dev {
 #endif
 
 	/* Local Name */
+#if defined(CONFIG_BT_DEVICE_NAME_DYNAMIC)
 	char			name[CONFIG_BT_DEVICE_NAME_MAX];
+#endif
 };
 
 extern struct bt_dev bt_dev;

subsys/bluetooth/host/settings.c

@@ -121,6 +121,7 @@ static int set(int argc, char **argv, char *val)
 		return 0;
 	}
 
+#if defined(CONFIG_BT_DEVICE_NAME_DYNAMIC)
 	if (!strcmp(argv[0], "name")) {
 		len = sizeof(bt_dev.name) - 1;
 		settings_bytes_from_str(val, &bt_dev.name, &len);
@@ -129,6 +130,7 @@ static int set(int argc, char **argv, char *val)
 		BT_DBG("Name set to %s", bt_dev.name);
 		return 0;
 	}
+#endif
 
 #if defined(CONFIG_BT_PRIVACY)
 	if (!strcmp(argv[0], "irk")) {
@@ -212,7 +214,7 @@ static int commit(void)
 		generate_static_addr();
 	}
 
-#if CONFIG_BT_DEVICE_NAME_MAX > 0
+#if defined(CONFIG_BT_DEVICE_NAME_DYNAMIC)
 	if (bt_dev.name[0] == '\0') {
 		bt_set_name(CONFIG_BT_DEVICE_NAME);
 	}

tests/bluetooth/shell/prj.conf

@@ -18,7 +18,7 @@ CONFIG_BT_TINYCRYPT_ECC=y
 CONFIG_CONSOLE_SHELL=y
 CONFIG_BT_SHELL=y
 CONFIG_BT_DEVICE_NAME="test shell"
-CONFIG_BT_DEVICE_NAME_MAX=28
+CONFIG_BT_DEVICE_NAME_DYNAMIC=y
 CONFIG_BT_L2CAP_TX_BUF_COUNT=6
 
 CONFIG_BT_SETTINGS=y