net/gcoap: Refactor lookup for outstanding request

Add support for a confirmable request and standardize token match.

sys/net/application_layer/gcoap/gcoap.c

@@ -35,8 +35,7 @@ static size_t _handle_req(coap_pkt_t *pdu, uint8_t *buf, size_t len,
                                                          sock_udp_ep_t *remote);
 static ssize_t _finish_pdu(coap_pkt_t *pdu, uint8_t *buf, size_t len);
 static void _expire_request(gcoap_request_memo_t *memo);
-static void _find_req_memo(gcoap_request_memo_t **memo_ptr, coap_pkt_t *pdu,
-                                                            uint8_t *buf, size_t len);
+static void _find_req_memo(gcoap_request_memo_t **memo_ptr, coap_pkt_t *pdu);
 static void _find_resource(coap_pkt_t *pdu, coap_resource_t **resource_ptr,
                                             gcoap_listener_t **listener_ptr);
 static int _find_observer(sock_udp_ep_t **observer, sock_udp_ep_t *remote);
@@ -156,7 +155,7 @@ static void _listen(sock_udp_t *sock)
 
     /* incoming response */
     else {
-        _find_req_memo(&memo, &pdu, buf, sizeof(buf));
+        _find_req_memo(&memo, &pdu);
         if (memo) {
             xtimer_remove(&memo->response_timer);
             memo->state = GCOAP_MEMO_RESP;
@@ -331,39 +330,41 @@ static ssize_t _finish_pdu(coap_pkt_t *pdu, uint8_t *buf, size_t len)
  * Finds the memo for an outstanding request within the _coap_state.open_reqs
  * array. Matches on token.
  *
- * src_pdu Source for the match token
+ * memo_ptr[out] -- Registered request memo, or NULL if not found
+ * src_pdu[in] -- PDU for token to match
  */
-static void _find_req_memo(gcoap_request_memo_t **memo_ptr, coap_pkt_t *src_pdu,
-                                                            uint8_t *buf, size_t len)
+static void _find_req_memo(gcoap_request_memo_t **memo_ptr, coap_pkt_t *src_pdu)
 {
-    gcoap_request_memo_t *memo;
-    coap_pkt_t memo_pdu = { .token = NULL };
-    (void) buf;
-    (void) len;
+    *memo_ptr = NULL;
+    /* no need to initialize struct; we only care about buffer contents below */
+    coap_pkt_t memo_pdu_data;
+    coap_pkt_t *memo_pdu = &memo_pdu_data;
+    unsigned cmplen      = coap_get_token_len(src_pdu);
 
     for (int i = 0; i < GCOAP_REQ_WAITING_MAX; i++) {
         if (_coap_state.open_reqs[i].state == GCOAP_MEMO_UNUSED)
             continue;
 
-        /* setup memo PDU from memo header */
-        memo                 = &_coap_state.open_reqs[i];
-        coap_hdr_t *memo_hdr = (coap_hdr_t *) &memo->msg.hdr_buf[0];
-        memo_pdu.hdr         = memo_hdr;
-        if (coap_get_token_len(&memo_pdu)) {
-            memo_pdu.token = &memo_hdr->data[0];
+        gcoap_request_memo_t *memo = &_coap_state.open_reqs[i];
+        if (memo->send_limit == GCOAP_SEND_LIMIT_NON) {
+            memo_pdu->hdr = (coap_hdr_t *) &memo->msg.hdr_buf[0];
         }
-        /* match on token */
-        if (coap_get_token_len(src_pdu) == coap_get_token_len(&memo_pdu)) {
-            uint8_t *src_byte  = src_pdu->token;
-            uint8_t *memo_byte = memo_pdu.token;
-            size_t j;
-            for (j = 0; j < coap_get_token_len(src_pdu); j++) {
-                if (*src_byte++ != *memo_byte++) {
-                    break;      /* token mismatch */
+        else {
+            memo_pdu->hdr = (coap_hdr_t *) memo->msg.data.pdu_buf;
+        }
+
+        if (coap_get_token_len(memo_pdu) == cmplen) {
+            if (cmplen) {
+                memo_pdu->token = &memo_pdu->hdr->data[0];
+                if (memcmp(src_pdu->token, memo_pdu->token, cmplen) == 0) {
+                    *memo_ptr = memo;
+                    break;
                 }
             }
-            if (j == coap_get_token_len(src_pdu)) {
+            /* if no token, just match the first memo */
+            else {
                 *memo_ptr = memo;
+                break;
             }
         }
     }