Add a few token validation functions

src/kike.c

@@ -89,6 +89,93 @@ setup_signal_handlers (void)
 	}
 }
 
+// --- IRC token validation ----------------------------------------------------
+
+enum validation_result
+{
+	VALIDATION_OK,
+	VALIDATION_ERROR_EMPTY,
+	VALIDATION_ERROR_TOO_LONG,
+	VALIDATION_ERROR_INVALID
+};
+
+// Everything as per RFC 2812
+#define IRC_NICKNAME_MAX    9
+#define IRC_HOSTNAME_MAX   63
+
+// Anything to keep it as short as possible
+#define SN "[0-9A-Za-z][-0-9A-Za-z]*[0-9A-Za-z]*"
+#define N4 "[0-9]{1,3}"
+#define N6 "[0-9ABCDEFabcdef]{1,}"
+
+#define LE "A-Za-z"
+#define SP "\\[\\]\\\\`_^{|}"
+
+static const char *
+irc_validate_to_str (enum validation_result result)
+{
+	switch (result)
+	{
+	case VALIDATION_OK:              return "success";
+	case VALIDATION_ERROR_EMPTY:     return "the value is empty";
+	case VALIDATION_ERROR_INVALID:   return "invalid format";
+	case VALIDATION_ERROR_TOO_LONG:  return "the value is too long";
+	default:                         abort ();
+	}
+}
+
+// TODO: at least cache the resulting `regex_t' in a `struct str_map'
+
+static enum validation_result
+irc_validate_hostname (const char *hostname)
+{
+	if (!*hostname)
+		return VALIDATION_ERROR_EMPTY;
+	if (!regex_match ("^" SN "(\\." SN ")*$", hostname, NULL))
+		return VALIDATION_ERROR_INVALID;
+	if (strlen (hostname) > IRC_HOSTNAME_MAX)
+		return VALIDATION_ERROR_TOO_LONG;
+	return VALIDATION_OK;
+}
+
+static bool
+irc_is_valid_hostaddr (const char *hostaddr)
+{
+	if (regex_match ("^" N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr, NULL)
+	 || regex_match ("^" N6 ":" N6 ":" N6 ":" N6 ":"
+		N6 ":" N6 ":" N6 ":" N6 "$", hostaddr, NULL)
+	 || regex_match ("^0:0:0:0:0:(0|[Ff]{4}):"
+		N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr, NULL))
+		return true;
+	return false;
+}
+
+static bool
+irc_is_valid_host (const char *host)
+{
+	return irc_validate_hostname (host) == VALIDATION_OK
+		|| irc_is_valid_hostaddr (host);
+}
+
+static bool
+irc_validate_nickname (const char *nickname)
+{
+	if (!*nickname)
+		return VALIDATION_ERROR_EMPTY;
+	if (!regex_match ("^[" LE SP "][-0-9" LE SP "]*$", nickname, NULL))
+		return VALIDATION_ERROR_INVALID;
+	if (strlen (nickname) > IRC_NICKNAME_MAX)
+		return VALIDATION_ERROR_TOO_LONG;
+	return VALIDATION_OK;
+}
+
+#undef SN
+#undef N4
+#undef N6
+
+#undef LE
+#undef SP
+
 // --- Application data --------------------------------------------------------
 
 enum