Add hostname validation

Author: microdev1

locale/circuitpython.pot

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-10-12 14:16+0530\n"
+"POT-Creation-Date: 2020-10-15 16:06+0530\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <[email protected]>\n"
@@ -948,7 +948,7 @@ msgid "Hardware in use, try alternative pins"
 msgstr ""
 
 #: shared-bindings/wifi/Radio.c
-msgid "Hostname must be between 1 and 63 characters"
+msgid "Hostname must be between 1 and 253 characters"
 msgstr ""
 
 #: extmod/vfs_posix_file.c py/objstringio.c
@@ -2732,6 +2732,10 @@ msgstr ""
 msgid "invalid format specifier"
 msgstr ""
 
+#: shared-bindings/wifi/Radio.c
+msgid "invalid hostname"
+msgstr ""
+
 #: extmod/modussl_axtls.c
 msgid "invalid key"
 msgstr ""

shared-bindings/wifi/Radio.c

@@ -24,11 +24,13 @@
  * THE SOFTWARE.
  */
 
+#include "shared-bindings/wifi/__init__.h"
+
+#include <regex.h>
 #include <string.h>
 
-#include "py/objproperty.h"
 #include "py/runtime.h"
-#include "shared-bindings/wifi/__init__.h"
+#include "py/objproperty.h"
 
 //| class Radio:
 //|     """Native wifi radio.
@@ -115,9 +117,16 @@ STATIC mp_obj_t wifi_radio_set_hostname(mp_obj_t self_in, mp_obj_t hostname_in)
     mp_buffer_info_t hostname;
     mp_get_buffer_raise(hostname_in, &hostname, MP_BUFFER_READ);
 
-    if (hostname.len < 1 || hostname.len > 63) {
-        mp_raise_ValueError(translate("Hostname must be between 1 and 63 characters"));
+    if (hostname.len < 1 || hostname.len > 253) {
+        mp_raise_ValueError(translate("Hostname must be between 1 and 253 characters"));
+    }
+
+    regex_t regex; //validate hostname according to RFC 1123
+    regcomp(&regex,"^(([a-z0-9]|[a-z0-9][a-z0-9\\-]{0,61}[a-z0-9])\\.)*([a-z0-9]|[a-z0-9][a-z0-9\\-]{0,61}[a-z0-9])$", REG_EXTENDED | REG_ICASE | REG_NOSUB);
+    if (regexec(&regex, hostname.buf, 0, NULL, 0)) {
+        mp_raise_ValueError(translate("invalid hostname"));
     }
+    regfree(&regex);
 
     wifi_radio_obj_t *self = MP_OBJ_TO_PTR(self_in);
     common_hal_wifi_radio_set_hostname(self, hostname.buf);