nanocoap_sock: implement FETCH methods

sys/include/net/nanocoap_sock.h

@@ -432,6 +432,61 @@ ssize_t nanocoap_sock_post_url(const char *url,
                                const void *request, size_t len,
                                void *response, size_t len_max);
 
+/**
+ * @brief   Simple synchronous CoAP (confirmable) FETCH
+ *          ([RFC 8132](https://datatracker.ietf.org/doc/html/rfc8132))
+ *
+ * @param[in]   sock    socket to use for the request
+ * @param[in]   path    remote path
+ * @param[in]   request buffer containing the payload
+ * @param[in]   len     length of the payload to send
+ * @param[out]  response buffer for the response, may be NULL
+ * @param[in]   len_max length of @p response
+ *
+ * @returns     length of response payload on success
+ * @returns     <0 on error
+ */
+ssize_t nanocoap_sock_fetch(nanocoap_sock_t *sock, const char *path,
+                            const void *request, size_t len,
+                            void *response, size_t len_max);
+
+/**
+ * @brief   Simple non-confirmable FETCH
+ *          ([RFC 8132](https://datatracker.ietf.org/doc/html/rfc8132))
+ *
+ * @param[in]   sock    socket to use for the request
+ * @param[in]   path    remote path
+ * @param[in]   request buffer containing the payload
+ * @param[in]   len     length of the payload to send
+ * @param[out]  response buffer for the response, may be NULL
+ * @param[in]   len_max length of @p response
+ *
+ * @returns     length of response payload on success
+ * @returns     0 if the request was sent and no response buffer was provided,
+ *              independently of success (because no response is requested in that case)
+ * @returns     <0 on error
+ */
+ssize_t nanocoap_sock_fetch_non(nanocoap_sock_t *sock, const char *path,
+                                const void *request, size_t len,
+                                void *response, size_t len_max);
+
+/**
+ * @brief   Simple synchronous CoAP (confirmable) FETCH to URL
+ *          ([RFC 8132](https://datatracker.ietf.org/doc/html/rfc8132))
+ *
+ * @param[in]   url     Absolute URL pointer to source path
+ * @param[in]   request buffer containing the payload
+ * @param[in]   len     length of the payload to send
+ * @param[out]  response buffer for the response, may be NULL
+ * @param[in]   len_max length of @p response
+ *
+ * @returns     length of response payload on success
+ * @returns     <0 on error
+ */
+ssize_t nanocoap_sock_fetch_url(const char *url,
+                                const void *request, size_t len,
+                                void *response, size_t len_max);
+
 /**
  * @brief   Simple synchronous CoAP (confirmable) DELETE
  *
@@ -571,7 +626,7 @@ ssize_t nanocoap_request(coap_pkt_t *pkt, const sock_udp_ep_t *local,
  * @param[out]  ctx     The block request context to initialize
  * @param[out]  sock    Socket to initialize and use for the request
  * @param[in]   url     The request URL
- * @param[in]   method  Request method (`COAP_METHOD_{GET|PUT|POST}`)
+ * @param[in]   method  Request method (`COAP_METHOD_{GET|PUT|POST|FETCH}`)
  * @param[in]   blksize Request blocksize exponent
  *
  * @retval      0       Success

sys/net/application_layer/nanocoap/sock.c

@@ -190,7 +190,7 @@
 
     /* random timeout, deadline for receive retries */
     uint32_t timeout = random_uint32_range(CONFIG_COAP_ACK_TIMEOUT_MS * US_PER_MS,
                                            CONFIG_COAP_ACK_TIMEOUT_MS * CONFIG_COAP_RANDOM_FACTOR_1000);
     uint32_t deadline = _deadline_from_interval(timeout);
 
     /* check if we expect a reply */
@@ -451,6 +451,14 @@
                           response, len_max);
 }
 
+ssize_t nanocoap_sock_fetch(nanocoap_sock_t *sock, const char *path,
+                            const void *request, size_t len,
+                            void *response, size_t len_max)
+{
+    return _sock_put_post(sock, path, COAP_METHOD_FETCH, COAP_TYPE_CON, request, len,
+                          response, len_max);
+}
+
 ssize_t nanocoap_sock_put_non(nanocoap_sock_t *sock, const char *path,
                               const void *request, size_t len,
                               void *response, size_t len_max)
@@ -467,6 +475,14 @@
                           response, len_max);
 }
 
+ssize_t nanocoap_sock_fetch_non(nanocoap_sock_t *sock, const char *path,
+                               const void *request, size_t len,
+                               void *response, size_t len_max)
+{
+    return _sock_put_post(sock, path, COAP_METHOD_FETCH, COAP_TYPE_NON, request, len,
+                          response, len_max);
+}
+
 static ssize_t _sock_put_post_url(const char *url, unsigned code,
                                   const void *request, size_t len,
                                   void *response, size_t len_max)
@@ -498,6 +514,13 @@
     return _sock_put_post_url(url, COAP_METHOD_POST, request, len, response, len_max);
 }
 
+ssize_t nanocoap_sock_fetch_url(const char *url,
+                                const void *request, size_t len,
+                                void *response, size_t len_max)
+{
+    return _sock_put_post_url(url, COAP_METHOD_FETCH, request, len, response, len_max);
+}
+
 ssize_t nanocoap_sock_delete(nanocoap_sock_t *sock, const char *path)
 {
     /* buffer for CoAP header */