examples/gcoap: update README and add new handlers

examples/gcoap/README.md

@@ -1,19 +1,29 @@
-# gcoap Example
+## About
 
-This application provides command line access to gcoap, a high-level API for CoAP messaging. See the [CoAP spec][1] for background, and the Modules>Networking>CoAP topic in the source documentation for detailed usage instructions and implementation notes.
+This application provides command line access to gcoap, a high-level API for
+CoAP messaging. See the [CoAP spec][1] for background, and the
+Modules>Networking>CoAP topic in the source documentation for detailed usage
+instructions and implementation notes.
 
 We support two setup options for this example:
 
 ### Native networking
-Build with the standard `Makefile`. Follow the setup [instructions][2] for the gnrc_networking example.
+
+Build with the standard `Makefile`. Follow the setup [instructions][2] for
+the gnrc_networking example.
 
 ### SLIP-based border router
 
-Build with `Makefile.slip`. Follow the setup instructions in README-slip.md, which are based on the [SLIP instructions][3] for the gnrc_border_router example. We also plan to provide or reference the ethos/UHCP instructions, but we don't have it working yet.
+Build with `Makefile.slip`. Follow the setup instructions in README-slip.md,
+which are based on the [SLIP instructions][3] for the gnrc_border_router
+example. We also plan to provide or reference the ethos/UHCP instructions,
+but we don't have it working yet.
 
 
 ## Example Use
-This example uses gcoap as a server on RIOT native. Then we send a request from a libcoap example client on the Linux host.
+
+This example uses gcoap as a server on RIOT native. Then we send a request
+from a libcoap example client on the Linux host.
 
 ### Verify setup from RIOT terminal
 
@@ -26,7 +36,10 @@ Expected response:
     CoAP open requests: 0
 
 ### Query from libcoap example client
-gcoap does not provide any output to the CoAP terminal when it handles a request. We recommend use of Wireshark to see the request and response. You also can add some debug output in the endpoint function callback.
+
+gcoap does not provide any output to the CoAP terminal when it handles a
+request. We recommend use of Wireshark to see the request and response. You
+also can add some debug output in the endpoint function callback.
 
     ./coap-client -N -m get -p 5683 coap://[fe80::1843:8eff:fe40:4eaa%tap0]/.well-known/core
 
@@ -38,6 +51,7 @@ Example response:
 The response shows the endpoint registered by the gcoap CLI example.
 
 ### Send query to libcoap example server
+
 Start the libcoap example server with the command below.
 
     ./coap-server
@@ -53,6 +67,19 @@ CLI output:
     </>;title="General Info";ct=0,</time>;if="clock";rt="Ticks";title="Internal Clock";ct=0;obs,</async>;ct=0
 
 
+## Other available CoAP implementations and applications
+
+RIOT also provides package imports and test applications for other CoAP
+implementations:
+
+* [Nanocoap](../nanocoap_server): a very lightweight CoAP server based on the
+  [nanocoap library](https://github.com/kaspar030/sock/tree/master/nanocoap)
+  implementation
+
+* [Microcoap](../../tests/pkg_microcoap): another lightweight CoAP server based
+  on the [microcoap library](https://github.com/1248/microcoap) implementation
+
+
 [1]: https://tools.ietf.org/html/rfc7252    "CoAP spec"
 [2]: https://github.com/RIOT-OS/RIOT/tree/master/examples/gnrc_networking    "instructions"
 [3]: https://github.com/RIOT-OS/RIOT/tree/master/examples/gnrc_border_router    "SLIP instructions"

examples/gcoap/gcoap_cli.c

@@ -32,11 +32,14 @@
 static void _resp_handler(unsigned req_state, coap_pkt_t* pdu,
                           sock_udp_ep_t *remote);
 static ssize_t _stats_handler(coap_pkt_t* pdu, uint8_t *buf, size_t len);
+static ssize_t _riot_board_handler(coap_pkt_t* pdu, uint8_t *buf, size_t len);
 
 /* CoAP resources */
 static const coap_resource_t _resources[] = {
-    { "/cli/stats", COAP_GET, _stats_handler },
+    { "/cli/stats", COAP_GET | COAP_PUT, _stats_handler },
+    { "/riot/board", COAP_GET, _riot_board_handler },
 };
+
 static gcoap_listener_t _listener = {
     (coap_resource_t *)&_resources[0],
     sizeof(_resources) / sizeof(_resources[0]),
@@ -88,16 +91,50 @@ static void _resp_handler(unsigned req_state, coap_pkt_t* pdu,
 }
 
 /*
- * Server callback for /cli/stats. Returns the count of packets sent by the
+ * Server callback for /cli/stats. Accepts either a GET or a PUT.
- * CLI.
+ *
+ * GET: Returns the count of packets sent by the CLI.
+ * PUT: Updates the count of packets. Rejects an obviously bad request, but
+ *      allows any two byte value for example purposes. Semantically, the only
+ *      valid action is to set the value to 0.
  */
 static ssize_t _stats_handler(coap_pkt_t* pdu, uint8_t *buf, size_t len)
 {
+    /* read coap method type in packet */
+    unsigned method_flag = coap_method2flag(coap_get_code_detail(pdu));
+
+    switch(method_flag) {
+        case COAP_GET:
             gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTENT);
 
+            /* write the response buffer with the request count value */
             size_t payload_len = fmt_u16_dec((char *)pdu->payload, req_count);
 
             return gcoap_finish(pdu, payload_len, COAP_FORMAT_TEXT);
+
+        case COAP_PUT:
+            /* convert the payload to an integer and update the internal
+               value */
+            if (pdu->payload_len <= 5) {
+                char payload[6] = { 0 };
+                memcpy(payload, (char *)pdu->payload, pdu->payload_len);
+                req_count = (uint16_t)strtoul(payload, NULL, 10);
+                return gcoap_response(pdu, buf, len, COAP_CODE_CHANGED);
+            }
+            else {
+                return gcoap_response(pdu, buf, len, COAP_CODE_BAD_REQUEST);
+            }
+    }
+
+    return 0;
+}
+
+static ssize_t _riot_board_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len)
+{
+    gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTENT);
+    /* write the RIOT board name in the response buffer */
+    memcpy(pdu->payload, RIOT_BOARD, strlen(RIOT_BOARD));
+    return gcoap_finish(pdu, strlen(RIOT_BOARD), COAP_FORMAT_TEXT);
 }
 
 static size_t _send(uint8_t *buf, size_t len, char *addr_str, char *port_str)