Merge pull request RIOT-OS#12074 from kb2ma/coap/options_iterate

net/nanocoap: iterate options

sys/include/net/nanocoap.h

@@ -328,7 +328,7 @@ static inline unsigned coap_get_id(coap_pkt_t *pkt)
  *
  * @returns     length of token in the given message (0-8 byte)
  */
-static inline unsigned coap_get_token_len(coap_pkt_t *pkt)
+static inline unsigned coap_get_token_len(const coap_pkt_t *pkt)
 {
     return (pkt->hdr->ver_t_tkl & 0xf);
 }
@@ -340,7 +340,7 @@ static inline unsigned coap_get_token_len(coap_pkt_t *pkt)
  *
  * @returns     total header length
  */
-static inline unsigned coap_get_total_hdr_len(coap_pkt_t *pkt)
+static inline unsigned coap_get_total_hdr_len(const coap_pkt_t *pkt)
 {
     return sizeof(coap_hdr_t) + coap_get_token_len(pkt);
 }
@@ -533,6 +533,38 @@ static inline ssize_t coap_get_uri_query(const coap_pkt_t *pkt, uint8_t *target)
     return coap_opt_get_string(pkt, COAP_OPT_URI_QUERY, target,
                                NANOCOAP_URI_MAX, '&');
 }
+
+/**
+ * @brief   Iterate over a packet's options
+ *
+ * To start iteration from the first option, set @p init_opt to true. To start
+ * iteration from a specific option, set @p init_opt to false, set
+ * @p opt->offset to the offset of the desired option from pkt->hdr, and
+ * @p opt->opt_num as required. See below for how @p opt->opt_num is modified.
+ *
+ * With each invocation, this function returns the length of the option value
+ * and sets @p value to point to the start of the value. The value for
+ * @p opt->opt_num is increased by the delta in the option number value over
+ * the preceding option in the packet. So, @p opt->opt_num is accurate if
+ * iteration started with the first option. Otherwise, it is useful for
+ * identification of repeated options. Finally, @p opt->offset is set to the
+ * offset for any following option, to prepare for the next iteration.
+ *
+ * The end of the options is indicated by a -ENOENT return value. In this case
+ * @p value and @p opt are unchanged from their input values.
+ *
+ * @param[in]     pkt         packet to read from
+ * @param[in,out] opt         option attributes; read on input if @p init_opt
+ *                            is false
+ * @param[out]    value       start of the option value
+ * @param[in]     init_opt    true to retrieve first option; false to retrieve
+ *                            option at opt->offset
+ *
+ * @return        length of option value
+ * @return        -ENOENT if option not found
+ */
+ssize_t coap_opt_get_next(const coap_pkt_t *pkt, coap_optpos_t *opt,
+                          uint8_t **value, bool init_opt);
 /**@}*/
 
 

sys/net/application_layer/nanocoap/nanocoap.c

@@ -185,14 +185,15 @@ uint8_t *coap_find_option(const coap_pkt_t *pkt, unsigned opt_num)
  * opt_len[out]   length of option value
  *
  * return         next byte after option header, usually the option value
- * return         NULL if initial pkt_pos is past options
+ * return         NULL if initial pkt_pos is payload marker or past options
  */
 static uint8_t *_parse_option(const coap_pkt_t *pkt,
                               uint8_t *pkt_pos, uint16_t *delta, int *opt_len)
 {
     uint8_t *hdr_end = pkt->payload;
 
-    if (pkt_pos == hdr_end) {
+    if ((pkt_pos >= hdr_end)
+            || (((pkt_pos + 1) == hdr_end) && (*pkt_pos == 0xFF))) {
         return NULL;
     }
 
@@ -268,6 +269,30 @@ unsigned coap_get_content_type(coap_pkt_t *pkt)
     return content_type;
 }
 
+ssize_t coap_opt_get_next(const coap_pkt_t *pkt, coap_optpos_t *opt,
+                          uint8_t **value, bool init_opt)
+{
+    if (init_opt) {
+        opt->opt_num = 0;
+        opt->offset = coap_get_total_hdr_len(pkt);
+    }
+    uint8_t *start = (uint8_t*)pkt->hdr + opt->offset;
+
+    /* Find start of option value and value length. */
+    uint16_t delta;
+    int len;
+
+    start = _parse_option(pkt, start, &delta, &len);
+    if (!start) {
+        return -ENOENT;
+    }
+
+    *value = start;
+    opt->opt_num += delta;
+    opt->offset = start + len - (uint8_t*)pkt->hdr;
+    return len;
+}
+
 ssize_t coap_opt_get_string(const coap_pkt_t *pkt, uint16_t optnum,
                             uint8_t *target, size_t max_len, char separator)
 {

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

@@ -547,6 +547,79 @@ static void test_nanocoap__server_option_count_overflow(void)
     TEST_ASSERT(res < 0);
 }
 
+/*
+ * Helper for options tests below.
+ * POST request to a CoRE RD server to update the entries for a node
+ * from RIOT cord_ep example. Generated by RIOT.
+ * Includes 4 options:
+ *   Uri-Path: resourcedirectory
+ *   Content-Format: 40 (0x28)
+ *   Uri-Query: ep-RIOT-0C49232323232323
+ *   Uri-Query: lt=60
+ * Payload: </node/info> (absent if omit_payload)
+ */
+static int _read_rd_post_req(coap_pkt_t *pkt, bool omit_payload)
+{
+     static uint8_t pkt_data[] = {
+        0x42, 0x02, 0x20, 0x92, 0xb9, 0x27, 0xbd, 0x04,
+        0x72, 0x65, 0x73, 0x6f, 0x75, 0x72, 0x63, 0x65,
+        0x64, 0x69, 0x72, 0x65, 0x63, 0x74, 0x6f, 0x72,
+        0x79, 0x11, 0x28, 0x3d, 0x0b, 0x65, 0x70, 0x3d,
+        0x52, 0x49, 0x4f, 0x54, 0x2d, 0x30, 0x43, 0x34,
+        0x39, 0x32, 0x33, 0x32, 0x33, 0x32, 0x33, 0x32,
+        0x33, 0x32, 0x33, 0x32, 0x33, 0x05, 0x6c, 0x74,
+        0x3d, 0x36, 0x30, 0xff, 0x3c, 0x2f, 0x6e, 0x6f,
+        0x64, 0x65, 0x2f, 0x69, 0x6e, 0x66, 0x6f, 0x3e
+     };
+
+    size_t len = omit_payload ? 59 : sizeof(pkt_data);
+    return coap_parse(pkt, pkt_data, len);
+}
+
+/*
+ * Tests use of coap_opt_get_next() to iterate over options.
+ */
+static void test_nanocoap__options_iterate(void)
+{
+    coap_pkt_t pkt;
+    int res = _read_rd_post_req(&pkt, true);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    /* read all options */
+    coap_optpos_t opt = {0, 0};
+    uint8_t *value;
+    ssize_t exp_len[] = {17, 1, 24, 5, -ENOENT};
+    ssize_t exp_optnum[] = {COAP_OPT_URI_PATH, COAP_OPT_CONTENT_FORMAT,
+                            COAP_OPT_URI_QUERY, COAP_OPT_URI_QUERY};
+
+    for (int i = 0; i < 5; i++) {
+        ssize_t optlen = coap_opt_get_next(&pkt, &opt, &value, !i);
+        TEST_ASSERT_EQUAL_INT(exp_len[i], optlen);
+        if (optlen >= 0) {
+            TEST_ASSERT_EQUAL_INT(exp_optnum[i], opt.opt_num);
+        }
+        else {
+            TEST_ASSERT_EQUAL_INT(4, i);
+        }
+    }
+
+    /* test with no payload to verify end of options handling */
+    memset(&pkt, 0, sizeof(pkt));
+    res = _read_rd_post_req(&pkt, false);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    for (int i = 0; i < 5; i++) {
+        ssize_t optlen = coap_opt_get_next(&pkt, &opt, &value, !i);
+        TEST_ASSERT_EQUAL_INT(exp_len[i], optlen);
+        if (optlen >= 0) {
+            TEST_ASSERT_EQUAL_INT(exp_optnum[i], opt.opt_num);
+        }
+        else {
+            TEST_ASSERT_EQUAL_INT(4, i);
+        }
+    }
+}
+
 Test *tests_nanocoap_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
@@ -561,6 +634,7 @@ 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_iterate),
         new_TestFixture(test_nanocoap__server_get_req),
         new_TestFixture(test_nanocoap__server_reply_simple),
         new_TestFixture(test_nanocoap__server_get_req_con),