net: coap: Add function to check for block option in message

The added function allows to check if a descriptive block
option was already added to a message.

Signed-off-by: Lukas Woodtli <[email protected]>

Author: LukasWoodtli

include/zephyr/net/coap.h

@@ -606,6 +606,19 @@ int coap_block_transfer_init(struct coap_block_context *ctx,
  */
 int coap_append_descriptive_block_option(struct coap_packet *cpkt, struct coap_block_context *ctx);
 
+/**
+ * @brief Check if a descriptive block option is set in the packet.
+ *
+ * If the CoAP packet is a request then an available BLOCK1 option
+ * would be checked otherwise a BLOCK2 option would be checked.
+ *
+ * @param cpkt Packet to be checked.
+ *
+ * @return true if the corresponding block option is set,
+ *        false otherwise.
+ */
+bool coap_has_descriptive_block_option(struct coap_packet *cpkt);
+
 /**
  * @brief Remove BLOCK1 or BLOCK2 option from the packet.
  *

subsys/net/lib/coap/coap.c

@@ -1096,6 +1096,15 @@ int coap_append_descriptive_block_option(struct coap_packet *cpkt, struct coap_b
 	}
 }
 
+bool coap_has_descriptive_block_option(struct coap_packet *cpkt)
+{
+	if (is_request(cpkt)) {
+		return coap_get_option_int(cpkt, COAP_OPTION_BLOCK1) >= 0;
+	} else {
+		return coap_get_option_int(cpkt, COAP_OPTION_BLOCK2) >= 0;
+	}
+}
+
 int coap_remove_descriptive_block_option(struct coap_packet *cpkt)
 {
 	if (is_request(cpkt)) {