spacepackets/src/cfdp/tlv.rs
2023-06-12 04:13:41 +02:00

367 lines
12 KiB
Rust

//! Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
use crate::cfdp::lv::{
generic_len_check_data_serialization, generic_len_check_deserialization, Lv, MIN_LV_LEN,
};
use crate::cfdp::TlvLvError;
use crate::util::{UnsignedByteField, UnsignedByteFieldError, UnsignedEnum};
use crate::{ByteConversionError, SizeMissmatch};
use num_enum::{IntoPrimitive, TryFromPrimitive};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
pub const MIN_TLV_LEN: usize = 2;
#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[repr(u8)]
pub enum TlvType {
FilestoreRequest = 0x00,
FilestoreResponse = 0x01,
MsgToUser = 0x02,
FaultHandler = 0x04,
FlowLabel = 0x05,
EntityId = 0x06,
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum TlvTypeField {
Standard(TlvType),
Custom(u8),
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[repr(u8)]
pub enum FsRequestActionCode {
CreateFile = 0b0000,
DeleteFile = 0b0001,
RenameFile = 0b0010,
AppendFile = 0b0011,
ReplaceFile = 0b0100,
CreateDirectory = 0b0101,
RemoveDirectory = 0b0110,
DenyFile = 0b0111,
DenyDirectory = 0b1000,
}
impl From<u8> for TlvTypeField {
fn from(value: u8) -> Self {
match TlvType::try_from(value) {
Ok(tlv_type) => TlvTypeField::Standard(tlv_type),
Err(_) => TlvTypeField::Custom(value),
}
}
}
impl From<TlvTypeField> for u8 {
fn from(value: TlvTypeField) -> Self {
match value {
TlvTypeField::Standard(std) => std as u8,
TlvTypeField::Custom(custom) => custom,
}
}
}
/// Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
///
/// # Lifetimes
/// * `data`: If the TLV is generated from a raw bytestream, this will be the lifetime of
/// the raw bytestream. If the TLV is generated from a raw slice or a similar data reference,
/// this will be the lifetime of that data reference.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Tlv<'data> {
tlv_type_field: TlvTypeField,
#[cfg_attr(feature = "serde", serde(borrow))]
lv: Lv<'data>,
}
impl<'data> Tlv<'data> {
pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvError> {
Ok(Tlv {
tlv_type_field: TlvTypeField::Standard(tlv_type),
lv: Lv::new(data)?,
})
}
/// Creates a TLV with an empty value field.
pub fn new_empty(tlv_type: TlvType) -> Tlv<'data> {
Tlv {
tlv_type_field: TlvTypeField::Standard(tlv_type),
lv: Lv::new_empty(),
}
}
pub fn tlv_type_field(&self) -> TlvTypeField {
self.tlv_type_field
}
pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
generic_len_check_data_serialization(buf, self.len_value(), MIN_TLV_LEN)?;
buf[0] = self.tlv_type_field.into();
self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
Ok(self.len_full())
}
pub fn value(&self) -> Option<&[u8]> {
self.lv.value()
}
/// Returns the length of the value part, not including the length byte.
pub fn len_value(&self) -> usize {
self.lv.len_value()
}
/// Returns the full raw length, including the length byte.
pub fn len_full(&self) -> usize {
self.lv.len_full() + 1
}
/// Checks whether the value field is empty.
pub fn is_empty(&self) -> bool {
self.lv.is_empty()
}
/// Creates a TLV give a raw bytestream. Please note that is is not necessary to pass the
/// bytestream with the exact size of the expected TLV. This function will take care
/// of parsing the length byte, and the length of the parsed TLV can be retrieved using
/// [Self::len_full].
pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
Ok(Self {
tlv_type_field: TlvTypeField::from(buf[0]),
lv: Lv::from_bytes(&buf[MIN_LV_LEN..])?,
})
}
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct EntityIdTlv {
entity_id: UnsignedByteField,
}
impl EntityIdTlv {
pub fn new(entity_id: UnsignedByteField) -> Self {
Self { entity_id }
}
fn len_check(buf: &[u8]) -> Result<(), ByteConversionError> {
if buf.len() < 2 {
return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
found: buf.len(),
expected: 2,
}));
}
Ok(())
}
pub fn len_value(&self) -> usize {
self.entity_id.len()
}
pub fn len_full(&self) -> usize {
2 + self.entity_id.len()
}
pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
Self::len_check(buf)?;
buf[0] = TlvType::EntityId as u8;
buf[1] = self.entity_id.len() as u8;
self.entity_id.write_to_be_bytes(&mut buf[2..])
}
pub fn from_bytes(buf: &[u8]) -> Result<Self, TlvLvError> {
Self::len_check(buf)?;
TlvType::try_from(buf[0]).map_err(|_| {
TlvLvError::InvalidTlvTypeField((buf[0], Some(TlvType::EntityId as u8)))
})?;
let len = buf[1];
if len != 1 && len != 2 && len != 4 && len != 8 {
return Err(TlvLvError::InvalidValueLength(len));
}
// Okay to unwrap here. The checks before make sure that the deserialization never fails
let entity_id = UnsignedByteField::new_from_be_bytes(len as usize, &buf[2..]).unwrap();
Ok(Self { entity_id })
}
pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv, ByteConversionError> {
Self::len_check(buf)?;
self.entity_id
.write_to_be_bytes(&mut buf[2..2 + self.entity_id.len()])?;
Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.len()]).map_err(|e| match e {
TlvLvError::ByteConversionError(e) => e,
// All other errors are impossible.
_ => panic!("unexpected TLV error"),
})
}
}
impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
type Error = TlvLvError;
fn try_from(value: Tlv) -> Result<Self, Self::Error> {
match value.tlv_type_field {
TlvTypeField::Standard(tlv_type) => {
if tlv_type != TlvType::EntityId {
return Err(TlvLvError::InvalidTlvTypeField((
tlv_type as u8,
Some(TlvType::EntityId as u8),
)));
}
}
TlvTypeField::Custom(val) => {
return Err(TlvLvError::InvalidTlvTypeField((
val,
Some(TlvType::EntityId as u8),
)));
}
}
if value.len_value() != 1
&& value.len_value() != 2
&& value.len_value() != 4
&& value.len_value() != 8
{
return Err(TlvLvError::InvalidValueLength(value.len_value() as u8));
}
Ok(Self::new(
UnsignedByteField::new_from_be_bytes(value.len_value(), value.value().unwrap())
.map_err(|e| match e {
UnsignedByteFieldError::ByteConversionError(e) => e,
// This can not happen, we checked for the length validity, and the data is always smaller than
// 255 bytes.
_ => panic!("unexpected error"),
})?,
))
}
}
#[cfg(test)]
mod tests {
use crate::cfdp::tlv::{Tlv, TlvType, TlvTypeField};
use crate::cfdp::TlvLvError;
use crate::util::{UbfU8, UnsignedEnum};
#[test]
fn test_basic() {
let entity_id = UbfU8::new(5);
let mut buf: [u8; 4] = [0; 4];
assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
assert!(tlv_res.is_ok());
let tlv_res = tlv_res.unwrap();
assert_eq!(
tlv_res.tlv_type_field(),
TlvTypeField::Standard(TlvType::EntityId)
);
assert_eq!(tlv_res.len_full(), 3);
assert_eq!(tlv_res.len_value(), 1);
assert!(!tlv_res.is_empty());
assert!(tlv_res.value().is_some());
assert_eq!(tlv_res.value().unwrap()[0], 5);
}
#[test]
fn test_serialization() {
let entity_id = UbfU8::new(5);
let mut buf: [u8; 4] = [0; 4];
assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
assert!(tlv_res.is_ok());
let tlv_res = tlv_res.unwrap();
let mut ser_buf: [u8; 4] = [0; 4];
assert!(tlv_res.write_to_bytes(&mut ser_buf).is_ok());
assert_eq!(ser_buf[0], TlvType::EntityId as u8);
assert_eq!(ser_buf[1], 1);
assert_eq!(ser_buf[2], 5);
}
#[test]
fn test_deserialization() {
let entity_id = UbfU8::new(5);
let mut buf: [u8; 4] = [0; 4];
assert!(entity_id.write_to_be_bytes(&mut buf[2..]).is_ok());
buf[0] = TlvType::EntityId as u8;
buf[1] = 1;
let tlv_from_raw = Tlv::from_bytes(&mut buf);
assert!(tlv_from_raw.is_ok());
let tlv_from_raw = tlv_from_raw.unwrap();
assert_eq!(
tlv_from_raw.tlv_type_field(),
TlvTypeField::Standard(TlvType::EntityId)
);
assert_eq!(tlv_from_raw.len_value(), 1);
assert_eq!(tlv_from_raw.len_full(), 3);
assert!(tlv_from_raw.value().is_some());
assert_eq!(tlv_from_raw.value().unwrap()[0], 5);
}
#[test]
fn test_empty() {
let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
assert!(tlv_empty.value().is_none());
assert!(tlv_empty.is_empty());
assert_eq!(tlv_empty.len_full(), 2);
assert_eq!(tlv_empty.len_value(), 0);
assert_eq!(
tlv_empty.tlv_type_field(),
TlvTypeField::Standard(TlvType::MsgToUser)
);
}
#[test]
fn test_empty_serialization() {
let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
let mut buf: [u8; 4] = [0; 4];
assert!(tlv_empty.write_to_bytes(&mut buf).is_ok());
assert_eq!(buf[0], TlvType::MsgToUser as u8);
assert_eq!(buf[1], 0);
}
#[test]
fn test_empty_deserialization() {
let mut buf: [u8; 4] = [0; 4];
buf[0] = TlvType::MsgToUser as u8;
buf[1] = 0;
let tlv_empty = Tlv::from_bytes(&mut buf);
assert!(tlv_empty.is_ok());
let tlv_empty = tlv_empty.unwrap();
assert!(tlv_empty.is_empty());
assert!(tlv_empty.value().is_none());
assert_eq!(
tlv_empty.tlv_type_field(),
TlvTypeField::Standard(TlvType::MsgToUser)
);
assert_eq!(tlv_empty.len_full(), 2);
assert_eq!(tlv_empty.len_value(), 0);
}
#[test]
fn test_buf_too_large() {
let buf_too_large: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
let tlv_res = Tlv::new(TlvType::MsgToUser, &buf_too_large);
assert!(tlv_res.is_err());
let error = tlv_res.unwrap_err();
if let TlvLvError::DataTooLarge(size) = error {
assert_eq!(size, u8::MAX as usize + 1);
} else {
panic!("unexpected error {:?}", error);
}
}
#[test]
fn test_deserialization_custom_tlv_type() {
let mut buf: [u8; 4] = [0; 4];
buf[0] = 3;
buf[1] = 1;
buf[2] = 5;
let tlv = Tlv::from_bytes(&mut buf);
assert!(tlv.is_ok());
let tlv = tlv.unwrap();
assert_eq!(tlv.tlv_type_field(), TlvTypeField::Custom(3));
assert_eq!(tlv.len_value(), 1);
assert_eq!(tlv.len_full(), 3);
}
}