Lwm2m block transfer

include/zephyr/net/coap.h

@@ -579,6 +579,20 @@ int coap_block_transfer_init(struct coap_block_context *ctx,
 			     enum coap_block_size block_size,
 			     size_t total_size);
 
+/**
+ * @brief Append BLOCK1 or BLOCK2 option to the packet.
+ *
+ * If the CoAP packet is a request then BLOCK1 is appended
+ * otherwise BLOCK2 is appended.
+ *
+ * @param cpkt Packet to be updated
+ * @param ctx Block context from which to retrieve the
+ * information for the block option
+ *
+ * @return 0 in case of success or negative in case of error.
+ */
+int coap_append_descriptive_block_option(struct coap_packet *cpkt, struct coap_block_context *ctx);
+
 /**
  * @brief Append BLOCK1 option to the packet.
  *
@@ -638,6 +652,19 @@ int coap_append_size2_option(struct coap_packet *cpkt,
  */
 int coap_get_option_int(const struct coap_packet *cpkt, uint16_t code);
 
+/**
+ * @brief Get the block size, more flag and block number from the
+ * CoAP block1 option.
+ *
+ * @param cpkt Packet to be inspected
+ * @param has_more Is set to the value of the more flag
+ * @param block_number Is set to the number of the block
+ *
+ * @return Integer value of the block size in case of success
+ * or negative in case of error.
+ */
+int coap_get_block1_option(const struct coap_packet *cpkt, bool *has_more, uint8_t *block_number);
+
 /**
  * @brief Retrieves BLOCK{1,2} and SIZE{1,2} from @a cpkt and updates
  * @a ctx accordingly.

subsys/net/lib/coap/coap.c

@@ -972,6 +972,15 @@ int coap_block_transfer_init(struct coap_block_context *ctx,
 #define SET_MORE(v, m) ((v) |= (m) ? 0x08 : 0x00)
 #define SET_NUM(v, n) ((v) |= ((n) << 4))
 
+int coap_append_descriptive_block_option(struct coap_packet *cpkt, struct coap_block_context *ctx)
+{
+	if (is_request(cpkt)) {
+		return coap_append_block1_option(cpkt, ctx);
+	} else {
+		return coap_append_block2_option(cpkt, ctx);
+	}
+}
+
 int coap_append_block1_option(struct coap_packet *cpkt,
 			      struct coap_block_context *ctx)
 {
@@ -1041,6 +1050,20 @@ int coap_get_option_int(const struct coap_packet *cpkt, uint16_t code)
 	return val;
 }
 
+int coap_get_block1_option(const struct coap_packet *cpkt, bool *has_more, uint8_t *block_number)
+{
+	int ret = coap_get_option_int(cpkt, COAP_OPTION_BLOCK1);
+
+	if (ret < 0) {
+		return ret;
+	}
+
+	*has_more = GET_MORE(ret);
+	*block_number = GET_NUM(ret);
+	ret = 1 << (GET_BLOCK_SIZE(ret) + 4);
+	return ret;
+}
+
 int insert_option(struct coap_packet *cpkt, uint16_t code, const uint8_t *value, uint16_t len)
 {
 	uint16_t offset = cpkt->hdr_len;

subsys/net/lib/lwm2m/Kconfig

@@ -113,6 +113,38 @@ config LWM2M_COAP_MAX_MSG_SIZE
 	  CoAP message size used by LWM2M. Minimum is the block size used
 	  in blockwise transfers.
 
+config LWM2M_COAP_BLOCK_TRANSFER
+	bool "CoAP block transfer support for big outgoing LwM2M messages [EXPERIMENTAL]"
+	select EXPERIMENTAL
+	help
+	  LwM2M messages with a big body that exceed the block size will be split
+	  into blocks for sending.
+
+if LWM2M_COAP_BLOCK_TRANSFER
+config LWM2M_COAP_ENCODE_BUFFER_SIZE
+	int "LwM2M CoAP buffer size for encoding the full message for block-wise transfer"
+	default 1024
+	help
+	  Size of buffers for serializing big LwM2M CoAP messages that need to be
+	  split into blocks for sending.
+
+config LWM2M_NUM_OUTPUT_BLOCK_CONTEXT
+	int "Maximum # of LWM2M block contexts used for outgoing messages"
+	default 3
+	help
+	  Maximum number of CoAP block contexts needed to split messages into blocks for
+	  sending. This limits the numer of messages that need block transfer that can be
+	  handled at the same time.
+
+config LWM2M_LOG_ENCODE_BUFFER_ALLOCATIONS
+	bool "Log allocations of encode buffers for block wise transfer"
+	select MEM_SLAB_TRACE_MAX_UTILIZATION
+	help
+	  The allocation of encode buffers can be tracked to analyse the usage and
+	  to optimize the configuration of number of block contexts and indirectly
+	  the number of available encode buffers.
+endif # LWM2M_COAP_BLOCK_TRANSFER
+
 config LWM2M_ENGINE_VALIDATION_BUFFER_SIZE
 	int "Size of the validation buffer for the incoming data"
 	default 64

subsys/net/lib/lwm2m/lwm2m_engine.c

@@ -107,11 +107,20 @@ static struct zsock_pollfd sock_fds[MAX_POLL_FD];
 static struct lwm2m_ctx *sock_ctx[MAX_POLL_FD];
 static int sock_nfds;
 
+/* Resource wrappers */
+#if defined(CONFIG_LWM2M_COAP_BLOCK_TRANSFER)
+static struct coap_block_context output_block_contexts[NUM_OUTPUT_BLOCK_CONTEXT];
+#endif
+
 /* Resource wrappers */
 struct lwm2m_ctx **lwm2m_sock_ctx(void) { return sock_ctx; }
 
 int lwm2m_sock_nfds(void) { return sock_nfds; }
 
+#if defined(CONFIG_LWM2M_COAP_BLOCK_TRANSFER)
+struct coap_block_context *lwm2m_output_block_context(void) { return output_block_contexts; }
+#endif
+
 static int lwm2m_socket_update(struct lwm2m_ctx *ctx);
 
 /* utility functions */
@@ -979,6 +988,9 @@ static int lwm2m_engine_init(void)
 	}
 
 	lwm2m_clear_block_contexts();
+#if defined(CONFIG_LWM2M_COAP_BLOCK_TRANSFER)
+	(void)memset(output_block_contexts, 0, sizeof(output_block_contexts));
+#endif
 
 	if (IS_ENABLED(CONFIG_LWM2M_RESOURCE_DATA_CACHE_SUPPORT)) {
 		/* Init data cache */