Fix Wi-SUN network name comparison (ARMmbed#2294)

Wi-SUN network name comparison function accepts partially matching
network names. Adjust comparison so that network names must fully
match.

Author: Arto Kinnunen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -822,19 +822,26 @@ void ws_bootstrap_configuration_reset(protocol_interface_info_entry_t *cur)
 
 static bool ws_bootstrap_network_name_matches(const struct mcps_data_ie_list *ie_ext, const char *network_name_ptr)
 {
+    ws_wp_network_name_t network_name;
+
     if (!network_name_ptr || !ie_ext) {
         return false;
     }
 
-    ws_wp_network_name_t network_name;
     if (!ws_wp_nested_network_name_read(ie_ext->payloadIeList, ie_ext->payloadIeListLength, &network_name)) {
         tr_warn("No network name IE");
         return false;
     }
 
-    if (network_name_ptr == NULL || strncmp(network_name_ptr, (char *)network_name.network_name, network_name.network_name_length) != 0) {
+    if (network_name.network_name_length != strlen(network_name_ptr)) {
         return false;
     }
+
+    if (strncmp(network_name_ptr, (char *)network_name.network_name, network_name.network_name_length) != 0) {
+        return false;
+    }
+
+    // names have equal length and same characters
     return true;
 }