spacepackets/src/cfdp/tlv.rs

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//! Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
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use crate::cfdp::lv::{
generic_len_check_data_serialization, generic_len_check_deserialization, Lv, MIN_LV_LEN,
};
use crate::cfdp::TlvLvError;
use crate::ByteConversionError;
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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,
}
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum TlvTypeField {
Standard(TlvType),
Custom(u8),
}
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,
}
}
}
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/// Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
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///
/// # 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>,
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}
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impl<'data> Tlv<'data> {
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pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvError> {
Ok(Tlv {
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tlv_type_field: TlvTypeField::Standard(tlv_type),
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lv: Lv::new(data)?,
})
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}
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/// Creates a TLV with an empty value field.
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pub fn new_empty(tlv_type: TlvType) -> Tlv<'data> {
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Tlv {
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tlv_type_field: TlvTypeField::Standard(tlv_type),
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lv: Lv::new_empty(),
}
}
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pub fn tlv_type_field(&self) -> TlvTypeField {
self.tlv_type_field
}
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pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
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generic_len_check_data_serialization(buf, self.len_value(), MIN_TLV_LEN)?;
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buf[0] = self.tlv_type_field.into();
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self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
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Ok(self.len_full())
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}
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pub fn value(&self) -> Option<&[u8]> {
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self.lv.value()
}
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/// Returns the length of the value part, not including the length byte.
pub fn len_value(&self) -> usize {
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self.lv.len_value()
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}
/// Returns the full raw length, including the length byte.
pub fn len_full(&self) -> usize {
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self.lv.len_full() + 1
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}
/// Checks whether the value field is empty.
pub fn is_empty(&self) -> bool {
self.lv.is_empty()
}
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/// 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
/// [len_full].
pub fn from_be_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
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generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
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Ok(Self {
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tlv_type_field: TlvTypeField::from(buf[0]),
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lv: Lv::from_be_bytes(&buf[MIN_LV_LEN..])?,
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})
}
}
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#[cfg(test)]
mod tests {
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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);
}
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#[test]
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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_be_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_be_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_be_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_be_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_be_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);
}
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}