net/gcoap: Use nanocoap pkt/options API

examples/gcoap/gcoap_cli.c

@@ -72,8 +72,9 @@ static void _resp_handler(unsigned req_state, coap_pkt_t* pdu,
                                                 coap_get_code_class(pdu),
                                                 coap_get_code_detail(pdu));
     if (pdu->payload_len) {
-        if (pdu->content_type == COAP_FORMAT_TEXT
-                || pdu->content_type == COAP_FORMAT_LINK
+        unsigned content_type = coap_get_content_type(pdu);
+        if (content_type == COAP_FORMAT_TEXT
+                || content_type == COAP_FORMAT_LINK
                 || coap_get_code_class(pdu) == COAP_CLASS_CLIENT_FAILURE
                 || coap_get_code_class(pdu) == COAP_CLASS_SERVER_FAILURE) {
             /* Expecting diagnostic payload in failure cases */

sys/include/net/gcoap.h

@@ -252,28 +252,6 @@ extern "C" {
 #define GCOAP_PDU_BUF_SIZE      (128)
 #endif
 
-/**
- * @brief   Size of the buffer used to write options, other than Uri-Path, in a
- *          request
- *
- * Accommodates Content-Format and Uri-Queries
- */
-#define GCOAP_REQ_OPTIONS_BUF   (40)
-
-/**
- * @brief   Size of the buffer used to write options in a response
- *
- * Accommodates Content-Format.
- */
-#define GCOAP_RESP_OPTIONS_BUF  (8)
-
-/**
- * @brief   Size of the buffer used to write options in an Observe notification
- *
- * Accommodates Content-Format and Observe.
- */
-#define GCOAP_OBS_OPTIONS_BUF   (8)
-
 /**
  * @brief   Maximum number of requests awaiting a response
  */
@@ -506,6 +484,11 @@ void gcoap_register_listener(gcoap_listener_t *listener);
 
 /**
  * @brief   Initializes a CoAP request PDU on a buffer.
+
+ * @warning After you use this function, you may not add Options with option
+ * number less than COAP_OPT_URI_PATH. Otherwise, use the struct-based API
+ * described with @link net_nanocoap nanocoap @endlink to initialize the
+ * message. See the implementation of gcoap_req_init() itself as an example.
  *
  * @param[out] pdu      Request metadata
  * @param[out] buf      Buffer containing the PDU
@@ -525,8 +508,14 @@ int gcoap_req_init(coap_pkt_t *pdu, uint8_t *buf, size_t len,
 /**
  * @brief   Finishes formatting a CoAP PDU after the payload has been written
  *
- * Assumes the PDU has been initialized with gcoap_req_init() or
- * gcoap_resp_init().
+ * Assumes the PDU has been initialized with a gcoap_xxx_init() function, like
+ * gcoap_req_init().
+ *
+ * @warning To use this function, you only may have added an Option with
+ * option number less than COAP_OPT_CONTENT_FORMAT. Otherwise, use the
+ * struct-based API described with @link net_nanocoap nanocoap. @endlink With
+ * this API, you specify the format with coap_opt_add_uint(), prepare for the
+ * payload with coap_opt_finish(), and then write the payload.
  *
  * @param[in,out] pdu       Request metadata
  * @param[in] payload_len   Length of the payload, or 0 if none

sys/include/net/nanocoap.h

@@ -175,7 +175,7 @@ extern "C" {
 /**
  * @brief   Nanocoap-specific value to indicate no format specified
  */
-#define COAP_FORMAT_NONE        (65535)
+#define COAP_FORMAT_NONE        (UINT16_MAX)
 
 /**
  * @name    Nanocoap specific maximum values
@@ -232,9 +232,6 @@ typedef struct {
     uint16_t options_len;                       /**< length of options array */
     coap_optpos_t options[NANOCOAP_NOPTS_MAX];  /**< option offset array     */
 #ifdef MODULE_GCOAP
-    uint8_t url[NANOCOAP_URI_MAX];              /**< parsed request URL      */
-    uint8_t qs[NANOCOAP_QS_MAX];                /**< parsed query string     */
-    uint16_t content_type;                      /**< content type            */
     uint32_t observe_value;                     /**< observe value           */
 #endif
 } coap_pkt_t;

sys/net/application_layer/cord/ep/cord_ep.c

@@ -273,18 +273,19 @@ int cord_ep_register(const sock_udp_ep_t *remote, const char *regif)
     }
     /* set some packet options and write query string */
     coap_hdr_set_type(pkt.hdr, COAP_TYPE_CON);
+    coap_opt_add_uint(&pkt, COAP_OPT_CONTENT_FORMAT, COAP_FORMAT_LINK);
     cord_common_add_qstring(&pkt);
 
+    pkt_len = coap_opt_finish(&pkt, COAP_OPT_FINISH_PAYLOAD);
+
     /* add the resource description as payload */
     res = gcoap_get_resource_list(pkt.payload, pkt.payload_len,
                                   COAP_FORMAT_LINK);
     if (res < 0) {
         retval = CORD_EP_ERR;
         goto end;
     }
-
-    /* finish up the packet */
-    pkt_len = gcoap_finish(&pkt, res, COAP_FORMAT_LINK);
+    pkt_len += res;
 
     /* send out the request */
     res = gcoap_req_send2(buf, pkt_len, remote, _on_register);