list command: several fixes + documentation

* duplicate strings when filling the bencode structure
  * limit the number of results to avoid going over the UDP packet
    size limit

README.md

@@ -701,6 +701,17 @@ of zero or more strings. The following flags are defined:
 The reply message may contain additional keys with statistics about the deleted call. Those additional keys
 are the same as used in the `query` reply.
 
+`list` Message
+----------------
+
+The `list` command retrieves the list of currently active call-ids. This list is limited to 32 elements by
+default.
+
+* `limit`
+
+	Optional integer value that specifies the maximum number of results (default: 32). Must be > 0. Be
+	careful when setting big values, as the response may not fit in a UDP packet, and therefore be invalid.
+
 `query` Message
 ---------------
 

daemon/bencode.h

@@ -154,7 +154,9 @@ bencode_item_t *bencode_list_add(bencode_item_t *list, bencode_item_t *item);
 
 /* Convenience function to add the respective (newly created) objects to a list */
 INLINE bencode_item_t *bencode_list_add_string(bencode_item_t *list, const char *s);
+INLINE bencode_item_t *bencode_list_add_string_dup(bencode_item_t *list, const char *s);
 INLINE bencode_item_t *bencode_list_add_str(bencode_item_t *list, const str *s);
+INLINE bencode_item_t *bencode_list_add_str_dup(bencode_item_t *list, const str *s);
 INLINE bencode_item_t *bencode_list_add_list(bencode_item_t *list);
 INLINE bencode_item_t *bencode_list_add_dictionary(bencode_item_t *list);
 
@@ -442,10 +444,22 @@ INLINE bencode_item_t *bencode_list_add_string(bencode_item_t *list, const char
 	return bencode_list_add(list, bencode_string(bencode_item_buffer(list), s));
 }
 
+INLINE bencode_item_t *bencode_list_add_string_dup(bencode_item_t *list, const char *s) {
+	if (!s)
+		return NULL;
+	return bencode_list_add(list, bencode_string_dup(bencode_item_buffer(list), s));
+}
+
 INLINE bencode_item_t *bencode_list_add_str(bencode_item_t *list, const str *s) {
 	return bencode_list_add(list, bencode_str(bencode_item_buffer(list), s));
 }
 
+INLINE bencode_item_t *bencode_list_add_str_dup(bencode_item_t *list, const str *s) {
+	if (!s)
+		return NULL;
+	return bencode_list_add(list, bencode_str_dup(bencode_item_buffer(list), s));
+}
+
 INLINE bencode_item_t *bencode_list_add_list(bencode_item_t *list) {
 	return bencode_list_add(list, bencode_list(bencode_item_buffer(list)));
 }

daemon/call_interfaces.c

@@ -845,17 +845,18 @@ stats:
 	ng_stats(bencode_dictionary_add_dictionary(dict, "RTCP"), &totals->totals[1], NULL);
 }
 
-void ng_list_add_call(gpointer key, gpointer value, gpointer user_data) {
+void ng_list_calls( struct callmaster *m, bencode_item_t *output, long long int limit) {
+	GHashTableIter iter;
+	gpointer key, value;
 
-    bencode_item_t *output = (bencode_item_t *) user_data;
+	rwlock_lock_r(&m->hashlock);
 
-    bencode_list_add_str(output, key);
-}
+	g_hash_table_iter_init (&iter, m->callhash);
+	while (limit-- && g_hash_table_iter_next (&iter, &key, &value)) {
+		bencode_list_add_str_dup(output, key);
+	}
 
-void ng_list_calls( struct callmaster *m, bencode_item_t *output) {
-    rwlock_lock_r(&m->hashlock);
-    g_hash_table_foreach (m->callhash, ng_list_add_call, output);
-    rwlock_unlock_r(&m->hashlock);
+	rwlock_unlock_r(&m->hashlock);
 }
 
 
@@ -882,11 +883,18 @@ const char *call_query_ng(bencode_item_t *input, struct callmaster *m, bencode_i
 
 
 const char *call_list_ng(bencode_item_t *input, struct callmaster *m, bencode_item_t *output) {
-    bencode_item_t *calls = NULL;
+	bencode_item_t *calls = NULL;
+	long long int limit;
 
-    bencode_dictionary_add_string(output, "result", "ok");
-    calls = bencode_dictionary_add_list(output, "calls");
-    ng_list_calls(m, calls);
+	limit = bencode_dictionary_get_integer(input, "limit", 32);
 
-    return NULL;
+	if (limit < 0) {
+		return "invalid limit, must be >= 0";
+	}
+	bencode_dictionary_add_string(output, "result", "ok");
+	calls = bencode_dictionary_add_list(output, "calls");
+
+	ng_list_calls(m, calls, limit);
+
+	return NULL;
 }