lxd/network/acl/ovn: Add a new 'parseLogTime' function

This is used to parse a timestamp that is either contained in a log file 'fields' (parsed log entry)
or just passed as a parameter when we're parsing the syslogs (in the case of a MicroOVN deployment)
, in which case this timestamp needs parsing and conversion.

Signed-off-by: Gabriel Mougard <[email protected]>

lxd/network/acl/acl_ovn.go

@@ -1041,6 +1041,28 @@ type ovnLogEntry struct {
 	Action   string `json:"action"`
 }
 
+// parseLogTime parses a timestamp that is a string format and returns a time.Time object.
+// If 'timestamp' is empty (which is the case if the timestamp is contained in the 'fields' slice when we're reading an OVN log file for example),
+// we try to extract the timestamp from the 'fields'.
+func parseLogTime(timestamp string, fields []string) (time.Time, error) {
+	// When reading from a log file, the timestamp is provided as a message parameter.
+	if timestamp == "" {
+		// Parse the timestamp.
+		return time.Parse(time.RFC3339, fields[0])
+	}
+
+	// Else, if from syslog, the timestamp is provided as a separate field
+	// which is passed separately.
+	tsInt, err := strconv.ParseInt(timestamp, 10, 64)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("Failed to parse timestamp: %w", err)
+	}
+
+	// The provided timestamp is in microseconds and need to be converted to nanoseconds.
+	tsNs := tsInt * 1000
+	return time.Unix(0, tsNs).UTC(), nil
+}
+
 // ovnParseLogEntry takes a log line and expected ACL prefix and returns a re-formated log entry if matching.
 func ovnParseLogEntry(input string, prefix string) string {
 	fields := strings.Split(input, "|")