Merge pull request #20273 from benpicco/coap_find_uri_query

nanocoap: implement coap_find_uri_query()

sys/include/net/nanocoap.h

@@ -861,6 +861,23 @@ static inline ssize_t coap_get_uri_query_string(coap_pkt_t *pkt, char *target,
                                (uint8_t *)target, max_len, '&');
 }
 
+/**
+ * @brief   Find a URI query option of the packet
+ *
+ * This function searches for a query option of the form "?key=value"
+ * and would, when present, return the pointer to "value" when searching
+ * for "key".
+ *
+ * @param[in]   pkt     pkt to work on
+ * @param[in]   key     key string to look for
+ * @param[out]  value   found value if present, may be NULL
+ * @param[out]  len     length of value if present, may be NULL if value is NULL
+ *
+ * @returns     true if the key was found, false if not
+ */
+bool coap_find_uri_query(coap_pkt_t *pkt, const char *key,
+                         const char **value, size_t *len);
+
 /**
  * @brief   Iterate over a packet's options
  *

sys/net/application_layer/nanocoap/nanocoap.c

@@ -439,6 +439,45 @@ int coap_get_blockopt(coap_pkt_t *pkt, uint16_t option, uint32_t *blknum, uint8_
     return (blkopt & 0x8) ? 1 : 0;
 }
 
+bool coap_find_uri_query(coap_pkt_t *pkt, const char *key, const char **value, size_t *len)
+{
+    uint8_t *opt_pos = NULL;
+
+    while (1) {
+        int len_query;
+        const void *key_data = coap_iterate_option(pkt, COAP_OPT_URI_QUERY,
+                                                   &opt_pos, &len_query);
+        if (key_data == NULL) {
+            return false;
+        }
+
+        const char *separator = memchr(key_data, '=', len_query);
+        size_t len_key = separator
+                       ? (separator - (char *)key_data)
+                       : len_query;
+
+        if (memcmp(key, key_data, len_key)) {
+            continue;
+        }
+
+        if (value == NULL) {
+            return true;
+        }
+
+        assert(len);
+        if (separator) {
+            *value = separator + 1;
+            *len = len_query - len_key - 1;
+        } else {
+            *value = NULL;
+            *len   = 0;
+        }
+        return true;
+    }
+
+    return false;
+}
+
 bool coap_has_unprocessed_critical_options(const coap_pkt_t *pkt)
 {
     for (unsigned i = 0; i < sizeof(pkt->opt_crit); ++i){

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

@@ -368,7 +368,19 @@ static void test_nanocoap__get_multi_query(void)
     coap_get_uri_query_string(&pkt, query, sizeof(query));
     /* skip initial '&' from coap_get_uri_query_string() */
     TEST_ASSERT_EQUAL_STRING((char *)qs, &query[1]);
+
+    const char *val;
+    size_t val_len;
+    TEST_ASSERT(coap_find_uri_query(&pkt, "ab", &val, &val_len));
+    TEST_ASSERT_EQUAL_INT(3, val_len);
+    TEST_ASSERT_EQUAL_INT(0, memcmp(val, "cde", val_len));
+    TEST_ASSERT(coap_find_uri_query(&pkt, "f", &val, &val_len));
+    TEST_ASSERT_EQUAL_INT(0, val_len);
+    TEST_ASSERT_EQUAL_INT((uintptr_t)NULL, (uintptr_t)val);
+    TEST_ASSERT(!coap_find_uri_query(&pkt, "cde", &val, &val_len));
+    TEST_ASSERT(coap_find_uri_query(&pkt, "ab", NULL, 0));
 }
+
 /*
  * Builds on get_multi_query test, to use coap_opt_add_uri_query2().
  */