Add set_time_soft to replace get_time

The SetTime command supports two modes: set the time without checking
the currently set time, or verify that the currently set time is not
zero and not larger than the new time (see cmd_set_time(uint8_t*,
uint8_t*) in src/keyboard/report_protocol.c, lines 678--710, in the
Nitrokey Pro firmware).

NitrokeyManager called these two modes set_time(uint64_t) and
get_time(uint64_t), which is highly misleading -- the command does never
get the time.  Furthermore, the get_time method per default calls the
command with the time zero, which will always result in an error.

The C API has the methods NK_totp_set_time(uint64_t) and
NK_totp_get_time().  NK_totp_get_time() calls get_time(uint64_t) with
the time zero, leading to an error, and is therefore useless.

This patch proposes a new wording.  While it would make sense to call
the first mode “reset” and the second mode “set”, this would break
compatibility.  Therefore, new methods set_time_soft(uint64_t) and
NK_totp_set_time_soft(uint64_t) are introduced to represent the
difference between a hard and a soft setting of the time.

The old methods, get_time(uint64_t) and NK_totp_get_time(), are not
removed but marked as deprecated.  They should be removed in an upcoming
major release.

1 files changed, 13 insertions, 0 deletions

diff --git a/NK_C_API.h b/NK_C_API.h
index 5bcc484..28e83b9 100644
--- a/NK_C_API.h
+++ b/NK_C_API.h
@@ -386,6 +386,19 @@ extern "C" {
 	 */
 	NK_C_API int NK_totp_set_time(uint64_t time);
 
+	/**
+	 * Set the device time used for TOTP to the given time.  Contrary to
+	 * {@code set_time(uint64_t)}, this command fails if {@code old_time}
+	 * > {@code time} or if {@code old_time} is zero (where {@code
+	 * old_time} is the current time on the device).
+	 *
+	 * @param time new device time as Unix timestamp (seconds since
+	 *        1970-01-01)
+	 * @return command processing error code
+	 */
+	NK_C_API int NK_totp_set_time_soft(uint64_t time);
+
+	/* NK_totp_get_time() is deprecated -- use NK_totp_set_time_soft */
 	NK_C_API int NK_totp_get_time();
 
 	//passwords