Move p2p_connect PIN format validation into a separate function

This functionality could be shared for other commands, too, so move
it to a common function. In addition, implement the validation in a
bit more strict way to avoid accepting values like '-123' as a valid
PIN.

Signed-hostap: Jouni Malinen <j@w1.fi>

src/wps/wps.h

@@ -816,6 +816,7 @@ int wps_build_credential_wrap(struct wpabuf *msg,
 unsigned int wps_pin_checksum(unsigned int pin);
 unsigned int wps_pin_valid(unsigned int pin);
 unsigned int wps_generate_pin(void);
+int wps_pin_str_valid(const char *pin);
 void wps_free_pending_msgs(struct upnp_pending_message *msgs);
 
 struct oob_device_data * wps_get_oob_device(char *device_type);

src/wps/wps_common.c

@@ -249,6 +249,22 @@ unsigned int wps_generate_pin(void)
 }
 
 
+int wps_pin_str_valid(const char *pin)
+{
+	const char *p;
+	size_t len;
+
+	p = pin;
+	while (*p >= '0' && *p <= '9')
+		p++;
+	if (*p != '\0')
+		return 0;
+
+	len = p - pin;
+	return len == 4 || len == 8;
+}
+
+
 void wps_fail_event(struct wps_context *wps, enum wps_msg_type msg,
 		    u16 config_error, u16 error_indication)
 {