GATTS API improvements

 * Added ability to register custom descriptors in the service
   definition. Set is_desc to true for these.
 * Added ability to specify binary UUID when registering services.
   Set is_uuid_bin and initialize uuid_bin.
 * Added `mgos_bt_gatts_read_{1,2,4}()` - a handler for read-only
   attributes that responds with 1, 2 or 4 bytes from the handler arg value.
 * Added `mgos_bt_gatts_unregister_service()` to unregister a previously registered service.
 * Library now automatically handles long reads - if user sends more
   data than MTU allows, library buffers it and automatically responds
   to subsequent ling reads of the same characteristic.
 * Added mgos_bt_uuid_eq() to compare UUIDs.

include/esp32/esp32_bt.h

@@ -36,13 +36,11 @@ extern "C" {
 #define MGOS_BT_ADDR_LEN 6
 
 const char *esp32_bt_addr_to_str(const esp_bd_addr_t addr, char *out);
-bool esp32_bt_addr_from_str(const struct mg_str addr_str, esp_bd_addr_t addr);
 int esp32_bt_addr_cmp(const esp_bd_addr_t a, const esp_bd_addr_t b);
-bool esp32_bt_addr_is_null(const esp_bd_addr_t addr);
-
 const char *esp32_bt_uuid_to_str(const esp_bt_uuid_t *uuid, char *out);
-bool esp32_bt_uuid_from_str(const struct mg_str uuid_str, esp_bt_uuid_t *uuid);
-int esp32_bt_uuid_cmp(const esp_bt_uuid_t *a, const esp_bt_uuid_t *b);
+
+void mgos_bt_uuid_to_esp32(const struct mgos_bt_uuid *in, esp_bt_uuid_t *out);
+void esp32_bt_uuid_to_mgos(const esp_bt_uuid_t *in, struct mgos_bt_uuid *out);
 
 #ifdef __cplusplus
 }

include/mgos_bt.h

@@ -69,6 +69,8 @@ bool mgos_bt_addr_is_null(const struct mgos_bt_addr *addr);
 
 const char *mgos_bt_uuid_to_str(const struct mgos_bt_uuid *uuid, char *out);
 bool mgos_bt_uuid_from_str(const struct mg_str str, struct mgos_bt_uuid *uuid);
+bool mgos_bt_uuid_eq(const struct mgos_bt_uuid *a,
+                     const struct mgos_bt_uuid *b);
 int mgos_bt_uuid_cmp(const struct mgos_bt_uuid *a,
                      const struct mgos_bt_uuid *b);
 void mgos_bt_uuid128_from_bytes(const uint8_t *bytes, bool reverse,

include/mgos_bt_gatt.h

@@ -33,6 +33,7 @@ struct mgos_bt_gatt_conn {
 #define MGOS_BT_GATT_PROP_WRITE (1 << 1)
 #define MGOS_BT_GATT_PROP_NOTIFY (1 << 2)
 #define MGOS_BT_GATT_PROP_INDICATE (1 << 3)
+#define MGOS_BT_GATT_PROP_WRITE_NR (1 << 4)
 
 #define MGOS_BT_GATT_PROP_RWNI(r, w, n, i)                                    \
   (((r) ? MGOS_BT_GATT_PROP_READ : 0) | ((w) ? MGOS_BT_GATT_PROP_WRITE : 0) | \

include/mgos_bt_gatts.h

@@ -40,20 +40,22 @@ enum mgos_bt_gatts_ev {
 };
 
 struct mgos_bt_gatts_conn {
-  const struct mgos_bt_gatt_conn gc;
+  struct mgos_bt_uuid svc_uuid;
+  struct mgos_bt_gatt_conn gc;
   void *user_data; /* Opaque pointer for user. */
 };
 
 struct mgos_bt_gatts_read_arg {
-  struct mgos_bt_uuid uuid;
+  struct mgos_bt_uuid svc_uuid;
+  struct mgos_bt_uuid char_uuid;
   uint16_t handle;
   uint32_t trans_id;
   uint16_t offset;
-  uint16_t len;
 };
 
 struct mgos_bt_gatts_write_arg {
-  struct mgos_bt_uuid uuid;
+  struct mgos_bt_uuid svc_uuid;
+  struct mgos_bt_uuid char_uuid;
   uint16_t handle;
   uint32_t trans_id;
   uint16_t offset;
@@ -62,7 +64,8 @@ struct mgos_bt_gatts_write_arg {
 };
 
 struct mgos_bt_gatts_notify_mode_arg {
-  struct mgos_bt_uuid uuid;
+  struct mgos_bt_uuid svc_uuid;
+  struct mgos_bt_uuid char_uuid;
   uint16_t handle;
   enum mgos_bt_gatt_notify_mode mode;
 };
@@ -80,16 +83,21 @@ typedef enum mgos_bt_gatt_status (*mgos_bt_gatts_ev_handler_t)(
     void *handler_arg);
 
 struct mgos_bt_gatts_char_def {
-  const char *uuid;
-  uint8_t prop;
+  union {
+    const char *uuid;
+    struct mgos_bt_uuid uuid_bin;
+  };
+  uint32_t prop : 5;
+  uint32_t is_desc : 1;
+  uint32_t is_uuid_bin : 1;
   /* Separate event handler for the characteristic.
    * If not provided, connection handler will be used. */
   mgos_bt_gatts_ev_handler_t handler;
   void *handler_arg;
 };
 
 /*
- * Register a GATTS service.
+ * Registers and starts a GATTS service.
  * `uuid` specifies the service UUID (in string form, "1234" for 16 bit UUIDs,
  * "12345678-90ab-cdef-0123-456789abcdef" for 128-bit).
  * `sec_level` specifies the minimum required security level of the connection.
@@ -105,6 +113,11 @@ bool mgos_bt_gatts_register_service(const char *uuid,
                                     mgos_bt_gatts_ev_handler_t handler,
                                     void *handler_arg);
 
+/*
+ * Stops and unregisters a previously registered service.
+ */
+bool mgos_bt_gatts_unregister_service(const char *uuid);
+
 /* Note: sending mtu - 1 bytes will usually trigger "long reads" by the client:
  * the client will ask for more data (with offset). */
 void mgos_bt_gatts_send_resp_data(struct mgos_bt_gatts_conn *gsc,
@@ -115,8 +128,24 @@ void mgos_bt_gatts_notify(struct mgos_bt_gatts_conn *gsc,
                           enum mgos_bt_gatt_notify_mode mode, uint16_t handle,
                           struct mg_str data);
 
+void mgos_bt_gatts_notify_uuid(struct mgos_bt_gatts_conn *gsc,
+                               const struct mgos_bt_uuid *char_uuid,
+                               enum mgos_bt_gatt_notify_mode mode,
+                               struct mg_str data);
+
 bool mgos_bt_gatts_disconnect(struct mgos_bt_gatts_conn *gsc);
 
+/* Handlers that respond to reads with 1/2/4 bytes from the arg's value. */
+enum mgos_bt_gatt_status mgos_bt_gatts_read_1(struct mgos_bt_gatts_conn *c,
+                                              enum mgos_bt_gatts_ev ev,
+                                              void *ev_arg, void *handler_arg);
+enum mgos_bt_gatt_status mgos_bt_gatts_read_2(struct mgos_bt_gatts_conn *c,
+                                              enum mgos_bt_gatts_ev ev,
+                                              void *ev_arg, void *handler_arg);
+enum mgos_bt_gatt_status mgos_bt_gatts_read_4(struct mgos_bt_gatts_conn *c,
+                                              enum mgos_bt_gatts_ev ev,
+                                              void *ev_arg, void *handler_arg);
+
 #ifdef __cplusplus
 }
 #endif

src/esp32/esp32_bt.c

@@ -39,19 +39,11 @@ const char *esp32_bt_addr_to_str(const esp_bd_addr_t addr, char *out) {
   return mgos_bt_addr_to_str((const struct mgos_bt_addr *) &addr[0], 0, out);
 }
 
-bool esp32_bt_addr_from_str(const struct mg_str addr_str, esp_bd_addr_t addr) {
-  return mgos_bt_addr_from_str(addr_str, (struct mgos_bt_addr *) &addr[0]);
-}
-
 int esp32_bt_addr_cmp(const esp_bd_addr_t a, const esp_bd_addr_t b) {
   return mgos_bt_addr_cmp((const struct mgos_bt_addr *) &a[0],
                           (const struct mgos_bt_addr *) &b[0]);
 }
 
-bool esp32_bt_addr_is_null(const esp_bd_addr_t addr) {
-  return mgos_bt_addr_is_null((const struct mgos_bt_addr *) &addr[0]);
-}
-
 const char *bt_uuid128_to_str(const uint8_t *u, char *out) {
   sprintf(out,
           "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
@@ -65,12 +57,14 @@ const char *esp32_bt_uuid_to_str(const esp_bt_uuid_t *uuid, char *out) {
   return mgos_bt_uuid_to_str((struct mgos_bt_uuid *) uuid, out);
 }
 
-bool esp32_bt_uuid_from_str(const struct mg_str uuid_str, esp_bt_uuid_t *uuid) {
-  return mgos_bt_uuid_from_str(uuid_str, (struct mgos_bt_uuid *) uuid);
+void mgos_bt_uuid_to_esp32(const struct mgos_bt_uuid *in, esp_bt_uuid_t *out) {
+  out->len = in->len;
+  memcpy(out->uuid.uuid128, in->uuid.uuid128, 16);
 }
 
-int esp32_bt_uuid_cmp(const esp_bt_uuid_t *a, const esp_bt_uuid_t *b) {
-  return mgos_bt_uuid_cmp((struct mgos_bt_uuid *) a, (struct mgos_bt_uuid *) b);
+void esp32_bt_uuid_to_mgos(const esp_bt_uuid_t *in, struct mgos_bt_uuid *out) {
+  out->len = in->len;
+  memcpy(out->uuid.uuid128, in->uuid.uuid128, 16);
 }
 
 enum cs_log_level ll_from_status(esp_bt_status_t status) {