net: lwm2m: Use link_format writer for Register/Update

The payload of the Register/Register Update message is also formatted as
application/link-format. Therefore it's reasonable to reuse the new
content writer instead of filling the payload manually.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

subsys/net/lib/lwm2m/lwm2m_engine.c

@@ -60,26 +60,6 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 #define ENGINE_UPDATE_INTERVAL_MS 500
 #define OBSERVE_COUNTER_START 0U
 
-/*
- * TODO: to implement a way for clients to specify alternate path
- * via Kconfig (LwM2M specification 8.2.2 Alternate Path)
- *
- * For now, in order to inform server we support JSON format, we have to
- * report 'ct=11543' to the server. '</>' is required in order to append
- * content attribute. And resource type attribute is appended because of
- * Eclipse wakaama will reject the registration when 'rt="oma.lwm2m"' is
- * missing.
- */
-
-#define RESOURCE_TYPE		";rt=\"oma.lwm2m\""
-
-#if defined(CONFIG_LWM2M_RW_JSON_SUPPORT)
-#define REG_PREFACE		"</>" RESOURCE_TYPE \
-				";ct=" STRINGIFY(LWM2M_FORMAT_OMA_JSON)
-#else
-#define REG_PREFACE		""
-#endif
-
 #if defined(CONFIG_COAP_EXTENDED_OPTIONS_LEN)
 #define	COAP_OPTION_BUF_LEN	(CONFIG_COAP_EXTENDED_OPTIONS_LEN_VALUE + 1)
 #else
@@ -1100,17 +1080,13 @@ void lwm2m_acknowledge(struct lwm2m_ctx *client_ctx)
 	request->acknowledged = true;
 }
 
-uint16_t lwm2m_get_rd_data(uint8_t *client_data, uint16_t size)
+int lwm2m_register_payload_handler(struct lwm2m_message *msg)
 {
 	struct lwm2m_engine_obj *obj;
 	struct lwm2m_engine_obj_inst *obj_inst;
-	uint8_t temp[32];
-	uint16_t pos = 0U;
-	int len;
+	int ret;
 
-	/* Add resource-type/content-type to the registration message */
-	memcpy(client_data, REG_PREFACE, sizeof(REG_PREFACE) - 1);
-	pos += sizeof(REG_PREFACE) - 1;
+	engine_put_begin(&msg->out, NULL);
 
 	SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_list, obj, node) {
 		/* Security obj MUST NOT be part of registration message */
@@ -1120,43 +1096,37 @@ uint16_t lwm2m_get_rd_data(uint8_t *client_data, uint16_t size)
 
 		/* Only report <OBJ_ID> when no instance available */
 		if (obj->instance_count == 0U) {
-			len = snprintk(temp, sizeof(temp), "%s</%u>",
-				       (pos > 0) ? "," : "", obj->obj_id);
-			if (pos + len >= size) {
-				/* full buffer -- exit loop */
-				break;
+			struct lwm2m_obj_path path = {
+				.obj_id = obj->obj_id,
+				.level = LWM2M_PATH_LEVEL_OBJECT,
+			};
+
+			ret = engine_put_corelink(&msg->out, &path);
+			if (ret < 0) {
+				return ret;
 			}
 
-			memcpy(&client_data[pos], temp, len);
-			pos += len;
 			continue;
 		}
 
 		SYS_SLIST_FOR_EACH_CONTAINER(&engine_obj_inst_list,
 					     obj_inst, node) {
 			if (obj_inst->obj->obj_id == obj->obj_id) {
-				len = snprintk(temp, sizeof(temp),
-					       "%s</%u/%u>",
-					       (pos > 0) ? "," : "",
-					       obj_inst->obj->obj_id,
-					       obj_inst->obj_inst_id);
-				/*
-				 * TODO: iterate through resources once block
-				 * transfer is handled correctly
-				 */
-				if (pos + len >= size) {
-					/* full buffer -- exit loop */
-					break;
-				}
+				struct lwm2m_obj_path path = {
+					.obj_id = obj_inst->obj->obj_id,
+					.obj_inst_id = obj_inst->obj_inst_id,
+					.level = LWM2M_PATH_LEVEL_OBJECT_INST,
+				};
 
-				memcpy(&client_data[pos], temp, len);
-				pos += len;
+				ret = engine_put_corelink(&msg->out, &path);
+				if (ret < 0) {
+					return ret;
+				}
 			}
 		}
 	}
 
-	client_data[pos] = '\0';
-	return pos;
+	return 0;
 }
 
 /* input / output selection */

subsys/net/lib/lwm2m/lwm2m_engine.h

@@ -87,7 +87,7 @@ int lwm2m_init_message(struct lwm2m_message *msg);
 int lwm2m_send_message(struct lwm2m_message *msg);
 int lwm2m_send_empty_ack(struct lwm2m_ctx *client_ctx, uint16_t mid);
 
-uint16_t lwm2m_get_rd_data(uint8_t *client_data, uint16_t size);
+int lwm2m_register_payload_handler(struct lwm2m_message *msg);
 
 int lwm2m_perform_read_op(struct lwm2m_message *msg, uint16_t content_format);
 

subsys/net/lib/lwm2m/lwm2m_rd_client.c

@@ -58,6 +58,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 
 #include "lwm2m_object.h"
 #include "lwm2m_engine.h"
+#include "lwm2m_rw_link_format.h"
 
 #define LWM2M_RD_CLIENT_URI "rd"
 
@@ -122,7 +123,6 @@ struct lwm2m_rd_client_info {
  * documented in the LwM2M specification.
  */
 static char query_buffer[MAX(32, sizeof("ep=") + CLIENT_EP_LEN)];
-static uint8_t client_data[256]; /* allocate some data for the RD */
 
 void engine_update_tx_time(void)
 {
@@ -663,7 +663,6 @@ static int sm_send_registration(bool send_obj_support_data,
 				lwm2m_message_timeout_cb_t timeout_cb)
 {
 	struct lwm2m_message *msg;
-	uint16_t client_data_len;
 	int ret;
 	char binding[CLIENT_BINDING_LEN];
 
@@ -766,11 +765,10 @@ static int sm_send_registration(bool send_obj_support_data,
 			goto cleanup;
 		}
 
-		/* generate the rd data */
-		client_data_len = lwm2m_get_rd_data(client_data,
-						    sizeof(client_data));
-		ret = buf_append(CPKT_BUF_WRITE(&msg->cpkt), client_data,
-				 client_data_len);
+		msg->out.out_cpkt = &msg->cpkt;
+		msg->out.writer = &link_format_writer;
+
+		ret = do_register_op_link_format(msg);
 		if (ret < 0) {
 			goto cleanup;
 		}

subsys/net/lib/lwm2m/lwm2m_rw_link_format.c

@@ -14,38 +14,82 @@ LOG_MODULE_REGISTER(net_lwm2m_link_format, CONFIG_LWM2M_LOG_LEVEL);
 
 #define CORELINK_BUF_SIZE 24
 
+#define ENABLER_VERSION "lwm2m=\"" LWM2M_PROTOCOL_VERSION "\""
+
+/*
+ * TODO: to implement a way for clients to specify alternate path
+ * via Kconfig (LwM2M specification 8.2.2 Alternate Path)
+ *
+ * For now, in order to inform server we support JSON format, we have to
+ * report 'ct=11543' to the server. '</>' is required in order to append
+ * content attribute. And resource type attribute is appended because of
+ * Eclipse wakaama will reject the registration when 'rt="oma.lwm2m"' is
+ * missing.
+ */
+
+#if defined(CONFIG_LWM2M_RW_JSON_SUPPORT)
+#define RESOURCE_TYPE		";rt=\"oma.lwm2m\""
+
+#define REG_PREFACE		"</>" RESOURCE_TYPE \
+				";ct=" STRINGIFY(LWM2M_FORMAT_OMA_JSON)
+#else
+#define REG_PREFACE		""
+#endif
+
+enum link_format_mode {
+	LINK_FORMAT_MODE_DISCOVERY,
+	LINK_FORMAT_MODE_BOOTSTRAP_DISCOVERY,
+	LINK_FORMAT_MODE_REGISTER,
+};
+
 struct link_format_out_formatter_data {
 	uint8_t request_level;
-	bool is_bootstrap : 1;
+	uint8_t mode;
 	bool is_first : 1;
 };
 
 static size_t put_begin(struct lwm2m_output_context *out,
 			struct lwm2m_obj_path *path)
 {
-	char enabler_ver[] = "lwm2m=\"" LWM2M_PROTOCOL_VERSION "\"";
+	char init_string[MAX(sizeof(ENABLER_VERSION), sizeof(REG_PREFACE))];
 	struct link_format_out_formatter_data *fd;
 	int ret;
 
+	ARG_UNUSED(path);
+
 	fd = engine_get_out_user_data(out);
 	if (fd == NULL) {
 		return 0;
 	}
 
-	if (!fd->is_bootstrap) {
+	switch (fd->mode) {
+	case LINK_FORMAT_MODE_DISCOVERY:
 		/* Nothing to add in device management mode. */
 		return 0;
-	}
 
-	fd->is_first = false;
+	case LINK_FORMAT_MODE_BOOTSTRAP_DISCOVERY:
+		strcpy(init_string, ENABLER_VERSION);
+		break;
+
+	case LINK_FORMAT_MODE_REGISTER:
+		/* Only indicate content type if json is enabled.  */
+		if (!IS_ENABLED(CONFIG_LWM2M_RW_JSON_SUPPORT)) {
+			return 0;
+		}
+
+		strcpy(init_string, REG_PREFACE);
+		break;
+	}
 
-	ret = buf_append(CPKT_BUF_WRITE(out->out_cpkt), enabler_ver,
-			 strlen(enabler_ver));
+	ret = buf_append(CPKT_BUF_WRITE(out->out_cpkt), init_string,
+			 strlen(init_string));
 	if (ret < 0) {
 		return 0;
 	}
 
-	return strlen(enabler_ver);
+	fd->is_first = false;
+
+	return strlen(init_string);
 }
 
 static int put_corelink_separator(struct lwm2m_output_context *out)
@@ -235,7 +279,7 @@ static int put_obj_corelink(struct lwm2m_output_context *out,
 		return ret;
 	}
 
-	if (!fd->is_bootstrap) {
+	if (fd->mode == LINK_FORMAT_MODE_DISCOVERY) {
 		/* Report object attributes only in device management mode
 		 * (5.4.2).
 		 */
@@ -278,10 +322,14 @@ static int put_obj_inst_corelink(struct lwm2m_output_context *out,
 		return ret;
 	}
 
+	if (fd->mode == LINK_FORMAT_MODE_REGISTER) {
+		return len;
+	}
+
 	/* Bootstrap object instance corelink shall only contain ssid
 	 * parameter for Security and Server objects (5.2.7.3).
 	 */
-	if (fd->is_bootstrap) {
+	if (fd->mode == LINK_FORMAT_MODE_BOOTSTRAP_DISCOVERY) {
 		if (path->obj_id == LWM2M_OBJECT_SECURITY_ID ||
 		    path->obj_id == LWM2M_OBJECT_SERVER_ID) {
 			ret = put_corelink_ssid(out, path, obj_buf,
@@ -327,8 +375,8 @@ static int put_res_corelink(struct lwm2m_output_context *out,
 	int len = 0;
 	int ret;
 
-	if (fd->is_bootstrap) {
-		/* No resource reporting in bootstrap mode. */
+	if (fd->mode != LINK_FORMAT_MODE_DISCOVERY) {
+		/* Report resources only in device management discovery. */
 		return 0;
 	}
 
@@ -445,7 +493,8 @@ int do_discover_op_link_format(struct lwm2m_message *msg, bool is_bootstrap)
 	int ret;
 
 	fd.is_first = true;
-	fd.is_bootstrap = is_bootstrap;
+	fd.mode = is_bootstrap ? LINK_FORMAT_MODE_BOOTSTRAP_DISCOVERY :
+				 LINK_FORMAT_MODE_DISCOVERY;
 	fd.request_level = msg->path.level;
 
 	engine_set_out_user_data(&msg->out, &fd);
@@ -454,3 +503,19 @@ int do_discover_op_link_format(struct lwm2m_message *msg, bool is_bootstrap)
 
 	return ret;
 }
+
+int do_register_op_link_format(struct lwm2m_message *msg)
+{
+	struct link_format_out_formatter_data fd;
+	int ret;
+
+	fd.is_first = true;
+	fd.mode = LINK_FORMAT_MODE_REGISTER;
+	fd.request_level = LWM2M_PATH_LEVEL_NONE;
+
+	engine_set_out_user_data(&msg->out, &fd);
+	ret = lwm2m_register_payload_handler(msg);
+	engine_clear_out_user_data(&msg->out);
+
+	return ret;
+}

subsys/net/lib/lwm2m/lwm2m_rw_link_format.h

@@ -12,5 +12,6 @@
 extern const struct lwm2m_writer link_format_writer;
 
 int do_discover_op_link_format(struct lwm2m_message *msg, bool is_bootstrap);
+int do_register_op_link_format(struct lwm2m_message *msg);
 
 #endif /* LWM2M_RW_LINK_FORMAT_H_ */