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.

3 files changed, 89 insertions, 1 deletions

diff --git a/NK_C_API.cc b/NK_C_API.cc
index 1d3fa3a..d993671 100644
--- a/NK_C_API.cc
+++ b/NK_C_API.cc
@@ -217,6 +217,12 @@ extern "C" {
 		});
 	}
 
+	NK_C_API int NK_write_config_struct(struct NK_config config,
+		const char *admin_temporary_password) {
+                return NK_write_config(config.numlock, config.capslock, config.scrolllock, config.enable_user_password,
+                    config.disable_user_password, admin_temporary_password);
+        }
+
 
 	NK_C_API uint8_t* NK_read_config() {
 		auto m = NitrokeyManager::instance();
@@ -226,6 +232,21 @@ extern "C" {
 		});
 	}
 
+	NK_C_API int NK_read_config_struct(struct NK_config* out) {
+		if (out == nullptr) {
+			return -1;
+		}
+		auto m = NitrokeyManager::instance();
+		return get_without_result([&]() {
+			auto v = m->read_config();
+                        out->numlock = v[0];
+                        out->capslock = v[1];
+                        out->scrolllock = v[2];
+                        out->enable_user_password = v[3];
+                        out->disable_user_password = v[4];
+		});
+	}
+
 
 	NK_C_API enum NK_device_model NK_get_device_model() {
 		auto m = NitrokeyManager::instance();
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
 
 	/**
diff --git a/unittest/test_pro.py b/unittest/test_pro.py
index 99d7b1f..e61d8bf 100644
--- a/unittest/test_pro.py
+++ b/unittest/test_pro.py
@@ -647,6 +647,30 @@ def test_read_write_config(C):
     config = cast_pointer_to_tuple(config_raw_data, 'uint8_t', 5)
     assert config == (0, 1, 2, True, False)
 
+    # use structs: read I
+    config_st = ffi.new('struct NK_config *')
+    if not config_st:
+        raise Exception("Could not allocate config")
+    assert C.NK_read_config_struct(config_st) == DeviceErrorCode.STATUS_OK
+    assert config_st.numlock == 0
+    assert config_st.capslock == 1
+    assert config_st.scrolllock == 2
+    assert config_st.enable_user_password
+    assert not config_st.disable_user_password
+
+    # use structs: write
+    config_st.numlock = 3
+    assert C.NK_write_config_struct(config_st[0], DefaultPasswords.ADMIN_TEMP) == DeviceErrorCode.STATUS_OK
+
+    # use structs: read II
+    err = C.NK_read_config_struct(config_st)
+    assert err == 0
+    assert config_st.numlock == 3
+    assert config_st.capslock == 1
+    assert config_st.scrolllock == 2
+    assert config_st.enable_user_password
+    assert not config_st.disable_user_password
+
     # restore defaults and check
     assert C.NK_first_authenticate(DefaultPasswords.ADMIN, DefaultPasswords.ADMIN_TEMP) == DeviceErrorCode.STATUS_OK
     assert C.NK_write_config(255, 255, 255, False, True, DefaultPasswords.ADMIN_TEMP) == DeviceErrorCode.STATUS_OK
@@ -1038,4 +1062,4 @@ def test_OTP_all_rw(C):
             this_loop_codes.append(('H', i, code))
         all_codes.append(this_loop_codes)
     from pprint import pprint
-    pprint(all_codes)
\ No newline at end of file
+    pprint(all_codes)