sys/net/gcoap: reduce insanity of hack

sys/include/net/nanocoap.h

@@ -352,6 +352,10 @@
 #endif
 };
 
+/* forward declarations */
+static inline uint8_t *coap_hdr_data_ptr(const coap_hdr_t *hdr);
+static inline size_t coap_hdr_get_token_len(const coap_hdr_t *hdr);
+
 /**
  * @brief   Get resource path associated with a CoAP request
  *
@@ -548,28 +552,9 @@
  */
 static inline unsigned coap_get_token_len(const coap_pkt_t *pkt)
 {
-    uint8_t tkl = pkt->hdr->ver_t_tkl & 0xf;
-
-    if (!IS_USED(MODULE_NANOCOAP_TOKEN_EXT)) {
-        return tkl;
-    }
-
-    void *ext = pkt->hdr + 1;
-    switch (tkl) {
-    case 13:
-        return tkl + *(uint8_t *)ext;
-    case 14:
-        return tkl + 255 + byteorder_bebuftohs(ext);
-    case 15:
-        assert(0);
-        /* fall-through */
-    default:
-        return tkl;
-    }
+    return coap_hdr_get_token_len(pkt->hdr);
 }
 
-static inline uint8_t *coap_hdr_data_ptr(const coap_hdr_t *hdr);
-
 /**
  * @brief   Get pointer to a message's token
  *
@@ -714,6 +699,65 @@
     hdr->ver_t_tkl &= ~0x30;
     hdr->ver_t_tkl |= type << 4;
 }
+
+/**
+ * @brief       Get the token length of a CoAP over UDP (DTLS) packet
+ * @param[in]   hdr     CoAP over UDP header
+ * @return      The size of the token in bytes
+ *
+ * @warning     This API is super goofy. It assumes that the packet is valid
+ *              and will read more than `sizeof(*hdr)` into the data `hdr`
+ *              points to while crossing fingers hard.
+ *
+ * @deprecated  This function was introduced to keep legacy code alive.
+ *              Introducing new callers should be avoided. In the RX path an
+ *              @ref coap_pkt_t will be available, so that you can call
+ *              @ref coap_get_token instead. In the TX path the token was
+ *              added by us, so we really should know.
+ */
+static inline size_t coap_hdr_get_token_len(const coap_hdr_t *hdr)
+{
+    const uint8_t *buf = (const void *)hdr;
+    /* Regarding use unnamed magic numbers 13 and 269:
+     * - If token length is < 13 it fits into TKL field (4 bit)
+     * - If token length is < 269 it fits into 8-bit extended TKL field
+     * - Otherwise token length goes into 16-bit extended TKL field.
+     *
+     * (Not using named constants here, as RFC 8974 also has no names for those
+     * magic numbers.)
+     *
+     * See: https://www.rfc-editor.org/rfc/rfc8974#name-extended-token-length-tkl-f
+     */
+    switch (coap_hdr_tkl_ext_len(hdr)) {
+    case 0:
+        return hdr->ver_t_tkl & 0xf;
+    case 1:
+        return buf[sizeof(coap_hdr_t)] + 13;
+    case 2:
+        return byteorder_bebuftohs(buf + sizeof(coap_hdr_t)) + 269;
+    }
+
+    return 0;
+}
+
+/**
+ * @brief       Get the header length of a CoAP packet.
+ *
+ * @warning     This API is super goofy. It assumes that the packet is valid
+ *              and will read more than `sizeof(*hdr)` into the data `hdr`
+ *              points to while crossing fingers hard.
+ *
+ * @deprecated  This function was introduced to keep legacy code alive.
+ *              Introducing new callers should be avoided. In the RX path an
+ *              @ref coap_pkt_t will be available, so that you can call
+ *              @ref coap_get_total_hdr_len instead. In the TX path the header
+ *              was created by us (e.g. using @ref coap_build_hdr which returns
+ *              the header size), so we really should know already.
+ */
+static inline size_t coap_hdr_len(const coap_hdr_t *hdr)
+{
+    return sizeof(*hdr) + coap_hdr_tkl_ext_len(hdr) + coap_hdr_get_token_len(hdr);
+}
 /**@}*/
 
 /**
@@ -1880,7 +1924,7 @@
  *
  * @returns     amount of bytes written to @p buf
  */
 size_t coap_put_option(uint8_t *buf, uint16_t lastonum, uint16_t onum, const void *odata, size_t olen);
 
 /**
  * @brief   Insert block1 option into buffer
@@ -2319,4 +2363,4 @@
 }
 #endif
 #endif /* NET_NANOCOAP_H */
 /** @} */

sys/net/application_layer/gcoap/gcoap.c

@@ -53,7 +53,7 @@
 #define NO_IMMEDIATE_REPLY (-1)
 
 /* End of the range to pick a random timeout */
 #define TIMEOUT_RANGE_END ((uint32_t)CONFIG_COAP_ACK_TIMEOUT_MS * CONFIG_COAP_RANDOM_FACTOR_1000 / 1000)
 
 /* Internal functions */
 static void *_event_loop(void *arg);
@@ -399,7 +399,7 @@
         /* but store the header to keep the token for Observe notifications */
         memcpy(memo->msg.hdr_buf, hdr, sizeof(hdr));
         /* no further retransmissions should be made and
            gcoap_request_memo_get_hdr() has to know how to get the header for Observe notifications */
         memo->send_limit = GCOAP_SEND_LIMIT_NON;
     }
 }
@@ -959,13 +959,13 @@
 
         /* verbose debug to catch bugs with request/response matching */
 #if SOCK_HAS_IPV4
         DEBUG("Seeking memo for remote=%s, tkn=0x%02x%02x%02x%02x%02x%02x%02x%02x, tkl=%"PRIuSIZE"\n",
               ipv4_addr_to_str(_ipv6_addr_str, (ipv4_addr_t *)&remote->addr.ipv4,
                                IPV6_ADDR_MAX_STR_LEN),
               token[0], token[1], token[2], token[3], token[4], token[5], token[6], token[7],
               tkl);
 #else
         DEBUG("Seeking memo for remote=%s, tkn=0x%02x%02x%02x%02x%02x%02x%02x%02x, tkl=%"PRIuSIZE"\n",
               ipv6_addr_to_str(_ipv6_addr_str, (ipv6_addr_t *)&remote->addr.ipv6,
                                IPV6_ADDR_MAX_STR_LEN),
               token[0], token[1], token[2], token[3], token[4], token[5], token[6], token[7],
@@ -1454,10 +1454,9 @@
 
 static void _copy_hdr_from_req_memo(coap_pkt_t *pdu, gcoap_request_memo_t *memo)
 {
-    coap_pkt_t req_pdu;
-
-    req_pdu.hdr = gcoap_request_memo_get_hdr(memo);
-    memcpy(pdu->hdr, req_pdu.hdr, coap_get_total_hdr_len(&req_pdu));
+    const coap_hdr_t *hdr = gcoap_request_memo_get_hdr(memo);
+    size_t hdr_len = coap_hdr_len(hdr);
+    memcpy(pdu->hdr, hdr, hdr_len);
 }
 
 static void _receive_from_cache_cb(void *ctx)
@@ -1680,7 +1679,7 @@
     const coap_resource_t *resource = last_resource;
 
     while (listener) {
         if ((resource = _match_resource_path_iterator(listener, resource, (const uint8_t *)uri_path))) {
             *last_listener = listener;
             return resource;
         }
@@ -2107,4 +2106,4 @@
     event_post(&_queue, arg);
 }
 
 /** @} */