1 files changed, 59 insertions, 0 deletions
diff --git a/rust/src/x509/time.rs b/rust/src/x509/time.rs
new file mode 100644
index 0000000..507b39c
--- /dev/null
+++ b/rust/src/x509/time.rs
@@ -0,0 +1,59 @@
+/* Copyright (C) 2023 Open Information Security Foundation
+ *
+ * You can copy, redistribute or modify this Program under the terms of
+ * the GNU General Public License version 2 as published by the Free
+ * Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+use std::os::raw::c_char;
+use time::macros::format_description;
+
+/// Format a timestamp in an ISO format suitable for TLS logging.
+///
+/// Negative timestamp values are used for dates prior to 1970.
+pub fn format_timestamp(timestamp: i64) -> Result<String, time::error::Error> {
+    let format = format_description!("[year]-[month]-[day]T[hour]:[minute]:[second]");
+    let ts = time::OffsetDateTime::from_unix_timestamp(timestamp)?;
+    let formatted = ts.format(&format)?;
+    Ok(formatted)
+}
+
+/// Format a x509 ISO timestamp into the provided C buffer.
+///
+/// Returns false if an error occurs, otherwise true is returned if
+/// the timestamp is properly formatted into the provided buffer.
+///
+/// # Safety
+///
+/// Access buffers from C that are expected to be valid.
+#[no_mangle]
+pub unsafe extern "C" fn sc_x509_format_timestamp(
+    timestamp: i64, buf: *mut c_char, size: usize,
+) -> bool {
+    let timestamp = match format_timestamp(timestamp) {
+        Ok(ts) => ts,
+        Err(_) => return false,
+    };
+    crate::ffi::strings::copy_to_c_char(timestamp, buf, size)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_format_timestamp() {
+        assert_eq!("1969-12-31T00:00:00", format_timestamp(-86400).unwrap());
+        assert_eq!("2038-12-31T00:10:03", format_timestamp(2177367003).unwrap());
+    }
+}