Add NK_config struct and read/write functions

This patch adds the NK_config struct to the C API that stores the
general configuration of a Nitrokey device.  It also adds the
NK_read_config_struct and NK_write_config_struct functions to make the
API easier to use.  While NK_write_config_struct is only a convenience
method, NK_read_config_struct makes the API more safe as the user no
longer has to read the data from a pointer to an array.

This patch also extends the test_read_write_config test case with the
two new functions.

1 files changed, 43 insertions, 0 deletions

diff --git a/NK_C_API.h b/NK_C_API.h
index d5c54a3..6aab7ca 100644
--- a/NK_C_API.h
+++ b/NK_C_API.h
@@ -265,6 +265,32 @@ extern "C" {
 		uint8_t write_level_max;
 	};
 
+        /**
+         * The general configuration of a Nitrokey device.
+         */
+        struct NK_config {
+            /**
+             * value in range [0-1] to send HOTP code from slot 'numlock' after double pressing numlock
+             * or outside the range to disable this function
+             */
+            uint8_t numlock;
+            /**
+	     * similar to numlock but with capslock
+             */
+            uint8_t capslock;
+            /**
+	     * similar to numlock but with scrolllock
+             */
+            uint8_t scrolllock;
+            /**
+             * True to enable OTP PIN protection (require PIN each OTP code request)
+             */
+            bool enable_user_password;
+            /**
+             * Unused.
+             */
+            bool disable_user_password;
+        };
 
    struct NK_storage_ProductionTest{
     uint8_t FirmwareVersion_au8[2];
@@ -450,6 +476,14 @@ extern "C" {
 		bool enable_user_password, bool delete_user_password, const char *admin_temporary_password);
 
 	/**
+	 * Write general config to the device
+	 * @param config the configuration data
+	 * @param admin_temporary_password current admin temporary password
+	 * @return command processing error code
+	 */
+	NK_C_API int NK_write_config_struct(struct NK_config config, const char *admin_temporary_password);
+
+	/**
 	 * Get currently set config - status of function Numlock/Capslock/Scrollock OTP sending and is enabled PIN protected OTP
 	 * @see NK_write_config
 	 * @return  uint8_t general_config[5]:
@@ -462,6 +496,15 @@ extern "C" {
 	 */
 	NK_C_API uint8_t* NK_read_config();
 
+	/**
+	 * Get currently set config and write it to the given pointer.
+         * @see NK_read_config
+	 * @see NK_write_config_struct
+         * @param out a pointer to the struct that should be written to
+	 * @return command processing error code
+	 */
+	NK_C_API int NK_read_config_struct(struct NK_config* out);
+
 	//OTP
 
 	/**