Fix for blockwise observation failure

This commit includes
 - Fix for https://github.com/ARMmbed/mbed-client/issues/481
 - Detailed Changelog available here https://github.com/ARMmbed/mbed-coap/compare/v4.0.3...v4.0.4

features/FEATURE_COMMON_PAL/mbed-coap/CHANGELOG.md

@@ -1,5 +1,12 @@
 # Change Log
 
+## [v4.0.4](https://github.com/ARMmbed/mbed-coap/releases/tag/v4.0.4) 
+
+-[Full Changelog](https://github.com/ARMmbed/mbed-coap/compare/v4.0.3...v4.0.4)
+
+ **Closed issues:**
+	- https://github.com/ARMmbed/mbed-client/issues/481 - Obs Con blockwise fails to transmit 2nd block
+
 ## [v4.0.3](https://github.com/ARMmbed/mbed-coap/releases/tag/v4.0.3)
 
 -[Full Changelog](https://github.com/ARMmbed/mbed-coap/compare/v4.0.2...v4.0.3)

features/FEATURE_COMMON_PAL/mbed-coap/source/sn_coap_protocol.c

@@ -474,7 +474,6 @@ int16_t sn_coap_protocol_build(struct coap_s *handle, sn_nsdl_addr_s *dst_addr_p
         memcpy(stored_blockwise_msg_ptr->coap_msg_ptr->payload_ptr, src_coap_msg_ptr->payload_ptr, stored_blockwise_msg_ptr->coap_msg_ptr->payload_len);
 
         stored_blockwise_msg_ptr->coap = handle;
-
         ns_list_add_to_end(&handle->linked_list_blockwise_sent_msgs, stored_blockwise_msg_ptr);
     }
 
@@ -499,7 +498,6 @@ int16_t sn_coap_protocol_build(struct coap_s *handle, sn_nsdl_addr_s *dst_addr_p
         }
 
         stored_blockwise_msg_ptr->coap = handle;
-
         ns_list_add_to_end(&handle->linked_list_blockwise_sent_msgs, stored_blockwise_msg_ptr);
     }
 
@@ -641,11 +639,21 @@ sn_coap_hdr_s *sn_coap_protocol_parse(struct coap_s *handle, sn_nsdl_addr_s *src
                 break;
             }
         }
-
+        /* Remove from the list if not an notification message.
+         * Initial notification message is needed for sending rest of the blocks (GET request).
+        */
+        bool remove_from_the_list = false;
         if (stored_blockwise_msg_temp_ptr) {
-            tr_debug("sn_coap_protocol_parse - remove block message %d", stored_blockwise_msg_temp_ptr->coap_msg_ptr->msg_id);
+            if (stored_blockwise_msg_temp_ptr->coap_msg_ptr &&
+                stored_blockwise_msg_temp_ptr->coap_msg_ptr->options_list_ptr &&
+                stored_blockwise_msg_temp_ptr->coap_msg_ptr->options_list_ptr->observe != COAP_OBSERVE_NONE) {
+                remove_from_the_list = false;
+            } else {
+                remove_from_the_list = true;
+            }
+        }
+        if (remove_from_the_list) {
             ns_list_remove(&handle->linked_list_blockwise_sent_msgs, stored_blockwise_msg_temp_ptr);
-
             if (stored_blockwise_msg_temp_ptr->coap_msg_ptr) {
                 if(stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_ptr){
                     handle->sn_coap_protocol_free(stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_ptr);
@@ -733,6 +741,10 @@ int8_t sn_coap_protocol_exec(struct coap_s *handle, uint32_t current_time)
                     uint16_t temp_msg_id = (stored_msg_ptr->send_msg_ptr->packet_ptr[2] << 8);
                     temp_msg_id += (uint16_t)stored_msg_ptr->send_msg_ptr->packet_ptr[3];
 
+                    /* Remove message from Linked list */
+                    ns_list_remove(&handle->linked_list_resent_msgs, stored_msg_ptr);
+                    --handle->count_resent_msgs;
+
                     /* If RX callback have been defined.. */
                     if (stored_msg_ptr->coap->sn_coap_rx_callback != 0) {
                         sn_coap_hdr_s *tmp_coap_hdr_ptr;
@@ -747,8 +759,9 @@ int8_t sn_coap_protocol_exec(struct coap_s *handle, uint32_t current_time)
                             sn_coap_parser_release_allocated_coap_msg_mem(stored_msg_ptr->coap, tmp_coap_hdr_ptr);
                         }
                     }
-                    /* Remove message from Linked list */
+
-                    sn_coap_protocol_linked_list_send_msg_remove(handle, stored_msg_ptr->send_msg_ptr->dst_addr_ptr, temp_msg_id);
+                    /* Free memory of stored message */
+                    sn_coap_protocol_release_allocated_send_msg_mem(handle, stored_msg_ptr);
                 } else {
                     /* Send message  */
                     stored_msg_ptr->coap->sn_coap_tx_callback(stored_msg_ptr->send_msg_ptr->packet_ptr,
@@ -1801,7 +1814,6 @@ static sn_coap_hdr_s *sn_coap_handle_blockwise_message(struct coap_s *handle, sn
 
                 stored_blockwise_msg_ptr->coap_msg_ptr = src_coap_blockwise_ack_msg_ptr;
                 stored_blockwise_msg_ptr->coap = handle;
-
                 ns_list_add_to_end(&handle->linked_list_blockwise_sent_msgs, stored_blockwise_msg_ptr);
 
                 /* * * Then release memory of CoAP Acknowledgement message * * */
@@ -1903,6 +1915,21 @@ static sn_coap_hdr_s *sn_coap_handle_blockwise_message(struct coap_s *handle, sn
                     src_coap_blockwise_ack_msg_ptr->payload_ptr = stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_ptr + (block_size * block_number);
                 }
 
+                /* Update token to match one which is in GET request.
+                 * This is needed only in case of notification message.
+                */
+                if (src_coap_blockwise_ack_msg_ptr->options_list_ptr &&
+                    src_coap_blockwise_ack_msg_ptr->options_list_ptr->observe != COAP_OBSERVE_NONE) {
+                    if (received_coap_msg_ptr->token_len && src_coap_blockwise_ack_msg_ptr->token_ptr) {
+                        handle->sn_coap_protocol_free(src_coap_blockwise_ack_msg_ptr->token_ptr);
+                        src_coap_blockwise_ack_msg_ptr->token_ptr = handle->sn_coap_protocol_malloc(received_coap_msg_ptr->token_len);
+                        if (src_coap_blockwise_ack_msg_ptr->token_ptr) {
+                            memcpy(src_coap_blockwise_ack_msg_ptr->token_ptr, received_coap_msg_ptr->token_ptr, received_coap_msg_ptr->token_len);
+                            src_coap_blockwise_ack_msg_ptr->token_len = received_coap_msg_ptr->token_len;
+                        }
+                    }
+                }
+
                 /* Build and send block message */
                 dst_packed_data_needed_mem = sn_coap_builder_calc_needed_packet_data_size_2(src_coap_blockwise_ack_msg_ptr, handle->sn_coap_block_data_size);