Merge pull request #12075 from kb2ma/coap/options_get_opaque

net/nanocoap: get option bytes

sys/include/net/nanocoap.h

@@ -573,6 +573,23 @@ static inline ssize_t coap_get_uri_query(const coap_pkt_t *pkt, uint8_t *target)
  */
 ssize_t coap_opt_get_next(const coap_pkt_t *pkt, coap_optpos_t *opt,
                           uint8_t **value, bool init_opt);
+
+/**
+ * @brief   Retrieve the value for an option as an opaque array of bytes
+ *
+ * Retrieves the location and length of the option value of any type. Useful for
+ * an opaque option, which essentially is an array of bytes. If more than one
+ * option for a given option number, retrieves the first option. To retrieve
+ * subsequent options, see coap_opt_get_next().
+ *
+ * @param[in]     pkt         packet to read from
+ * @param[in]     opt_num     option number to retrieve
+ * @param[out]    value       start of the option value
+ *
+ * @return        length of option; 0 if the option exists but is empty
+ * @return        -ENOENT if option not found
+ */
+ssize_t coap_opt_get_opaque(coap_pkt_t *pkt, unsigned opt_num, uint8_t **value);
 /**@}*/
 
 

sys/net/application_layer/nanocoap/nanocoap.c

@@ -205,6 +205,20 @@ static uint8_t *_parse_option(const coap_pkt_t *pkt,
     return pkt_pos;
 }
 
+ssize_t coap_opt_get_opaque(coap_pkt_t *pkt, unsigned opt_num, uint8_t **value)
+{
+    uint8_t *start = coap_find_option(pkt, opt_num);
+    if (!start) {
+        return -ENOENT;
+    }
+
+    uint16_t delta;
+    int len;
+
+    *value = _parse_option(pkt, start, &delta, &len);
+    return len;
+}
+
 int coap_get_option_uint(coap_pkt_t *pkt, unsigned opt_num, uint32_t *target)
 {
     assert(target);

tests/unittests/tests-nanocoap/tests-nanocoap.c

@@ -620,6 +620,31 @@ static void test_nanocoap__options_iterate(void)
     }
 }
 
+/*
+ * Tests use of coap_opt_get_opaque() to find an option as a byte array, and
+ * coap_opt_get_next() to find a second option with the same option number.
+ */
+static void test_nanocoap__options_get_opaque(void)
+{
+    coap_pkt_t pkt;
+    int res = _read_rd_post_req(&pkt, true);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    /* read Uri-Query options */
+    uint8_t *value;
+    ssize_t optlen = coap_opt_get_opaque(&pkt, COAP_OPT_URI_QUERY, &value);
+    TEST_ASSERT_EQUAL_INT(24, optlen);
+
+    coap_optpos_t opt = {0, value + optlen - (uint8_t *)pkt.hdr};
+
+    optlen = coap_opt_get_next(&pkt, &opt, &value, false);
+    TEST_ASSERT_EQUAL_INT(0, opt.opt_num);
+    TEST_ASSERT_EQUAL_INT(5, optlen);
+
+    optlen = coap_opt_get_next(&pkt, &opt, &value, false);
+    TEST_ASSERT_EQUAL_INT(-ENOENT, optlen);
+}
+
 Test *tests_nanocoap_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
@@ -634,6 +659,7 @@ Test *tests_nanocoap_tests(void)
         new_TestFixture(test_nanocoap__get_query),
         new_TestFixture(test_nanocoap__get_multi_query),
         new_TestFixture(test_nanocoap__option_add_buffer_max),
+        new_TestFixture(test_nanocoap__options_get_opaque),
         new_TestFixture(test_nanocoap__options_iterate),
         new_TestFixture(test_nanocoap__server_get_req),
         new_TestFixture(test_nanocoap__server_reply_simple),