finish implementing XEP-0198

Signed-off-by: Steffen Jaeckel <jaeckel-floss@eyet-services.de>

src/util.c

@@ -15,6 +15,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <stdlib.h>
 
 #ifdef _WIN32
 #include <winsock2.h>
@@ -161,6 +162,13 @@ void disconnect_mem_error(xmpp_conn_t *conn)
     xmpp_disconnect(conn);
 }
 
+int string_to_ul(const char *s, unsigned long *ul)
+{
+    char *endptr;
+    *ul = strtoul(s, &endptr, 10);
+    return *endptr != '\0';
+}
+
 void hex_encode(char *writebuf, void *readbuf, size_t len)
 {
     size_t i;