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use crate::cfdp::pdu::{
add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
PduError, PduHeader,
};
use crate::cfdp::{CrcFlag, LargeFileFlag, PduType, SegmentMetadataFlag};
use crate::ByteConversionError;
use num_enum::{IntoPrimitive, TryFromPrimitive};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use super::{CfdpPdu, FileDirectiveType, WritablePduPacket};
#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[repr(u8)]
pub enum RecordContinuationState {
NoStartNoEnd = 0b00,
StartWithoutEnd = 0b01,
EndWithoutStart = 0b10,
StartAndEnd = 0b11,
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub struct SegmentMetadata<'seg_meta> {
record_continuation_state: RecordContinuationState,
metadata: Option<&'seg_meta [u8]>,
impl<'seg_meta> SegmentMetadata<'seg_meta> {
pub fn new(
) -> Option<Self> {
if let Some(metadata) = metadata {
if metadata.len() > 2_usize.pow(6) - 1 {
return None;
Some(Self {
record_continuation_state,
metadata,
})
pub fn record_continuation_state(&self) -> RecordContinuationState {
self.record_continuation_state
pub fn metadata(&self) -> Option<&'seg_meta [u8]> {
self.metadata
pub fn written_len(&self) -> usize {
// Map empty metadata to 0 and slice to its length.
1 + self.metadata.map_or(0, |meta| meta.len())
pub(crate) fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
if buf.len() < self.written_len() {
return Err(ByteConversionError::ToSliceTooSmall {
found: buf.len(),
expected: self.written_len(),
});
buf[0] = ((self.record_continuation_state as u8) << 6)
| self.metadata.map_or(0, |meta| meta.len() as u8);
if let Some(metadata) = self.metadata {
buf[1..1 + metadata.len()].copy_from_slice(metadata)
Ok(self.written_len())
pub(crate) fn from_bytes(buf: &'seg_meta [u8]) -> Result<Self, ByteConversionError> {
if buf.is_empty() {
return Err(ByteConversionError::FromSliceTooSmall {
expected: 2,
let mut metadata = None;
let seg_metadata_len = (buf[0] & 0b111111) as usize;
if seg_metadata_len > 0 {
metadata = Some(&buf[1..1 + seg_metadata_len]);
Ok(Self {
// Can't fail, only 2 bits
record_continuation_state: RecordContinuationState::try_from((buf[0] >> 6) & 0b11)
.unwrap(),
struct FdPduBase<'seg_meta> {
pdu_header: PduHeader,
#[cfg_attr(feature = "serde", serde(borrow))]
segment_metadata: Option<SegmentMetadata<'seg_meta>>,
offset: u64,
impl CfdpPdu for FdPduBase<'_> {
fn pdu_header(&self) -> &PduHeader {
&self.pdu_header
fn file_directive_type(&self) -> Option<FileDirectiveType> {
None
impl FdPduBase<'_> {
fn calc_pdu_datafield_len(&self, file_data_len: u64) -> usize {
let mut len = core::mem::size_of::<u32>();
if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
len += 4;
if self.segment_metadata.is_some() {
len += self.segment_metadata.as_ref().unwrap().written_len()
len += file_data_len as usize;
if self.crc_flag() == CrcFlag::WithCrc {
len += 2;
len
fn write_common_fields_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
current_idx += self
.segment_metadata
.as_ref()
.unwrap()
.write_to_bytes(&mut buf[current_idx..])?;
current_idx += write_fss_field(
self.pdu_header.common_pdu_conf().file_flag,
self.offset,
&mut buf[current_idx..],
)?;
Ok(current_idx)
/// File Data PDU abstraction.
///
/// For more information, refer to CFDP chapter 5.3.
pub struct FileDataPdu<'seg_meta, 'file_data> {
common: FdPduBase<'seg_meta>,
file_data: &'file_data [u8],
impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
pub fn new_with_seg_metadata(
segment_metadata: SegmentMetadata<'seg_meta>,
) -> Self {
Self::new_generic(pdu_header, Some(segment_metadata), offset, file_data)
pub fn new_no_seg_metadata(
Self::new_generic(pdu_header, None, offset, file_data)
pub fn new_generic(
mut pdu_header: PduHeader,
pdu_header.pdu_type = PduType::FileData;
if segment_metadata.is_some() {
pdu_header.seg_metadata_flag = SegmentMetadataFlag::Present;
let mut pdu = Self {
common: FdPduBase {
pdu_header,
segment_metadata,
offset,
},
file_data,
pdu.common.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
pdu
fn calc_pdu_datafield_len(&self) -> usize {
self.common
.calc_pdu_datafield_len(self.file_data.len() as u64)
pub fn segment_metadata(&self) -> Option<&SegmentMetadata> {
self.common.segment_metadata.as_ref()
pub fn offset(&self) -> u64 {
self.common.offset
pub fn file_data(&self) -> &'file_data [u8] {
self.file_data
pub fn from_bytes<'buf: 'seg_meta + 'file_data>(buf: &'buf [u8]) -> Result<Self, PduError> {
let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
let min_expected_len = current_idx + core::mem::size_of::<u32>();
generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
let mut segment_metadata = None;
if pdu_header.seg_metadata_flag == SegmentMetadataFlag::Present {
segment_metadata = Some(SegmentMetadata::from_bytes(&buf[current_idx..])?);
current_idx += segment_metadata.as_ref().unwrap().written_len();
let (fss, offset) = read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
current_idx += fss;
if current_idx > full_len_without_crc {
found: current_idx,
expected: full_len_without_crc,
.into());
file_data: &buf[current_idx..full_len_without_crc],
impl CfdpPdu for FileDataPdu<'_, '_> {
&self.common.pdu_header
impl WritablePduPacket for FileDataPdu<'_, '_> {
fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
if buf.len() < self.len_written() {
expected: self.len_written(),
let mut current_idx = self.common.write_common_fields_to_bytes(buf)?;
buf[current_idx..current_idx + self.file_data.len()].copy_from_slice(self.file_data);
current_idx += self.file_data.len();
current_idx = add_pdu_crc(buf, current_idx);
fn len_written(&self) -> usize {
self.common.pdu_header.header_len() + self.calc_pdu_datafield_len()
/// File Data PDU creator abstraction.
/// This special creator object allows to read into the file data buffer directly. This avoids
/// the need of an additional buffer to create a file data PDU. This structure therefore
/// does not implement the regular [WritablePduPacket] trait.
pub struct FileDataPduCreatorWithReservedDatafield<'seg_meta> {
file_data_len: u64,
impl<'seg_meta> FileDataPduCreatorWithReservedDatafield<'seg_meta> {
Self::new_generic(pdu_header, Some(segment_metadata), offset, file_data_len)
pub fn new_no_seg_metadata(pdu_header: PduHeader, offset: u64, file_data_len: u64) -> Self {
Self::new_generic(pdu_header, None, offset, file_data_len)
file_data_len,
self.common.calc_pdu_datafield_len(self.file_data_len)
pub fn len_written(&self) -> usize {
/// This function performs a partial write by writing all data except the file data
/// and the CRC.
/// It returns a [FileDataPduCreatorWithUnwrittenData] which provides a mutable slice to
/// the reserved file data field. The user can read file data into this field directly and
/// then finish the PDU creation using the [FileDataPduCreatorWithUnwrittenData::finish] call.
pub fn write_to_bytes_partially<'buf>(
&self,
buf: &'buf mut [u8],
) -> Result<FileDataPduCreatorWithUnwrittenData<'buf>, PduError> {
let file_data_offset = current_idx as u64;
current_idx += self.file_data_len as usize;
current_idx += 2;
Ok(FileDataPduCreatorWithUnwrittenData {
write_buf: &mut buf[0..current_idx],
file_data_offset,
file_data_len: self.file_data_len,
needs_crc: self.crc_flag() == CrcFlag::WithCrc,
impl CfdpPdu for FileDataPduCreatorWithReservedDatafield<'_> {
/// This structure is created with [FileDataPduCreatorReservedDatafield::write_to_bytes_partially]
/// and provides an API to read file data from the virtual filesystem into the file data PDU buffer
/// directly.
/// This structure provides a mutable slice to the reserved file data field. The user can read
/// file data into this field directly and then finish the PDU creation using the
/// [FileDataPduCreatorWithUnwrittenData::finish] call.
pub struct FileDataPduCreatorWithUnwrittenData<'buf> {
write_buf: &'buf mut [u8],
file_data_offset: u64,
needs_crc: bool,
impl FileDataPduCreatorWithUnwrittenData<'_> {
pub fn file_data_field_mut(&mut self) -> &mut [u8] {
&mut self.write_buf[self.file_data_offset as usize
..self.file_data_offset as usize + self.file_data_len as usize]
/// This functio needs to be called to add a CRC to the file data PDU where applicable.
/// It returns the full written size of the PDU.
pub fn finish(self) -> usize {
if self.needs_crc {
add_pdu_crc(
self.write_buf,
self.file_data_offset as usize + self.file_data_len as usize,
);
self.write_buf.len()
/// This function can be used to calculate the maximum allowed file segment size for
/// a given maximum packet length and the segment metadata if there is any.
pub fn calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(
pdu_header: &PduHeader,
max_packet_len: usize,
segment_metadata: Option<&SegmentMetadata>,
) -> usize {
let mut subtract = pdu_header.header_len();
subtract += 1 + segment_metadata.as_ref().unwrap().metadata().unwrap().len();
if pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
subtract += 8;
} else {
subtract += 4;
if pdu_header.common_pdu_conf().crc_flag == CrcFlag::WithCrc {
subtract += 2;
max_packet_len.saturating_sub(subtract)
#[cfg(test)]
mod tests {
use super::*;
use crate::cfdp::pdu::tests::{TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID};
use crate::cfdp::pdu::{CommonPduConfig, PduHeader};
use crate::cfdp::{Direction, SegmentMetadataFlag, SegmentationControl, TransmissionMode};
use postcard::{from_bytes, to_allocvec};
#[test]
fn test_basic() {
let common_conf =
CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
let file_data: [u8; 4] = [1, 2, 3, 4];
let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
assert_eq!(fd_pdu.file_data(), file_data);
assert_eq!(fd_pdu.offset(), 10);
assert!(fd_pdu.segment_metadata().is_none());
assert_eq!(
fd_pdu.len_written(),
fd_pdu.pdu_header().header_len() + core::mem::size_of::<u32>() + 4
assert_eq!(fd_pdu.crc_flag(), CrcFlag::NoCrc);
assert_eq!(fd_pdu.file_flag(), LargeFileFlag::Normal);
assert_eq!(fd_pdu.pdu_type(), PduType::FileData);
assert_eq!(fd_pdu.file_directive_type(), None);
assert_eq!(fd_pdu.transmission_mode(), TransmissionMode::Acknowledged);
assert_eq!(fd_pdu.direction(), Direction::TowardsReceiver);
assert_eq!(fd_pdu.source_id(), TEST_SRC_ID.into());
assert_eq!(fd_pdu.dest_id(), TEST_DEST_ID.into());
assert_eq!(fd_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
fn test_serialization() {
let mut buf: [u8; 32] = [0; 32];
let res = fd_pdu.write_to_bytes(&mut buf);
assert!(res.is_ok());
let written = res.unwrap();
written,
let mut current_idx = fd_pdu.pdu_header().header_len();
let file_size = u32::from_be_bytes(
buf[fd_pdu.pdu_header().header_len()..fd_pdu.pdu_header().header_len() + 4]
.try_into()
current_idx += 4;
assert_eq!(file_size, 10);
assert_eq!(buf[current_idx], 1);
current_idx += 1;
assert_eq!(buf[current_idx], 2);
assert_eq!(buf[current_idx], 3);
assert_eq!(buf[current_idx], 4);
fn test_write_to_vec() {
let mut buf: [u8; 64] = [0; 64];
let written = fd_pdu.write_to_bytes(&mut buf).unwrap();
let pdu_vec = fd_pdu.to_vec().unwrap();
assert_eq!(buf[0..written], pdu_vec);
fn test_deserialization() {
fd_pdu.write_to_bytes(&mut buf).unwrap();
let fd_pdu_read_back = FileDataPdu::from_bytes(&buf);
assert!(fd_pdu_read_back.is_ok());
let fd_pdu_read_back = fd_pdu_read_back.unwrap();
assert_eq!(fd_pdu_read_back, fd_pdu);
fn test_with_crc() {
let mut common_conf =
common_conf.crc_flag = true.into();
assert_eq!(written, fd_pdu.len_written());
let finished_pdu_from_raw = FileDataPdu::from_bytes(&buf).unwrap();
assert_eq!(finished_pdu_from_raw, fd_pdu);
buf[written - 1] -= 1;
let crc: u16 = ((buf[written - 2] as u16) << 8) | buf[written - 1] as u16;
let error = FileDataPdu::from_bytes(&buf).unwrap_err();
if let PduError::ChecksumError(e) = error {
assert_eq!(e, crc);
panic!("expected crc error");
fn test_with_seg_metadata_serialization() {
let pdu_header = PduHeader::new_for_file_data(
common_conf,
0,
SegmentMetadataFlag::Present,
SegmentationControl::WithRecordBoundaryPreservation,
let seg_metadata: [u8; 4] = [4, 3, 2, 1];
let segment_meta =
SegmentMetadata::new(RecordContinuationState::StartAndEnd, Some(&seg_metadata))
.unwrap();
let fd_pdu = FileDataPdu::new_with_seg_metadata(pdu_header, segment_meta, 10, &file_data);
assert!(fd_pdu.segment_metadata().is_some());
assert_eq!(*fd_pdu.segment_metadata().unwrap(), segment_meta);
fd_pdu.pdu_header().header_len()
+ 1
+ seg_metadata.len()
+ core::mem::size_of::<u32>()
+ 4
fd_pdu
.write_to_bytes(&mut buf)
.expect("writing FD PDU failed");
RecordContinuationState::try_from((buf[current_idx] >> 6) & 0b11).unwrap(),
RecordContinuationState::StartAndEnd
assert_eq!((buf[current_idx] & 0b111111) as usize, seg_metadata.len());
// Still verify that the rest is written correctly.
u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
10
assert_eq!(current_idx, fd_pdu.len_written());
fn test_with_seg_metadata_deserialization() {
fn test_serde_serialization() {
let output = to_allocvec(&fd_pdu).unwrap();
let output_converted_back: FileDataPdu = from_bytes(&output).unwrap();
assert_eq!(output_converted_back, fd_pdu);
fn test_serde_serialization_with_seg_metadata() {
fn test_fd_pdu_creator_with_reserved_field_no_crc() {
let test_str = "hello world!";
let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
10,
test_str.len() as u64,
let mut write_buf: [u8; 64] = [0; 64];
let mut pdu_unwritten = fd_pdu
.write_to_bytes_partially(&mut write_buf)
.expect("partial write failed");
pdu_unwritten
.file_data_field_mut()
.copy_from_slice(test_str.as_bytes());
pdu_unwritten.finish();
let pdu_reader = FileDataPdu::from_bytes(&write_buf).expect("reading file data PDU failed");
core::str::from_utf8(pdu_reader.file_data()).expect("reading utf8 string failed"),
"hello world!"
fn test_fd_pdu_creator_with_reserved_field_with_crc() {
fn test_fd_pdu_creator_with_reserved_field_with_crc_without_finish_fails() {
let pdu_reader_error = FileDataPdu::from_bytes(&write_buf);
assert!(pdu_reader_error.is_err());
let error = pdu_reader_error.unwrap_err();
match error {
PduError::ChecksumError(_) => (),
_ => {
panic!("unexpected PDU error {}", error)
fn test_max_file_seg_calculator_0() {
let pdu_header = PduHeader::new_for_file_data_default(CommonPduConfig::default(), 0);
calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
53
fn test_max_file_seg_calculator_1() {
let common_conf = CommonPduConfig {
crc_flag: CrcFlag::WithCrc,
..Default::default()
51
fn test_max_file_seg_calculator_2() {
file_flag: LargeFileFlag::Large,
49
fn test_max_file_seg_calculator_saturating_sub() {
calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 15, None),
0
calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 14, None),