250 lines
8.0 KiB
Rust
250 lines
8.0 KiB
Rust
//! Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
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use crate::cfdp::lv::{
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generic_len_check_data_serialization, generic_len_check_deserialization, Lv, MIN_LV_LEN,
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};
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use crate::cfdp::TlvLvError;
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use crate::ByteConversionError;
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use num_enum::{IntoPrimitive, TryFromPrimitive};
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#[cfg(feature = "serde")]
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use serde::{Deserialize, Serialize};
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pub const MIN_TLV_LEN: usize = 2;
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#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
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#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
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#[repr(u8)]
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pub enum TlvType {
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FilestoreRequest = 0x00,
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FilestoreResponse = 0x01,
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MsgToUser = 0x02,
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FaultHandler = 0x04,
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FlowLabel = 0x05,
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EntityId = 0x06,
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}
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
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pub enum TlvTypeField {
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Standard(TlvType),
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Custom(u8),
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}
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impl From<u8> for TlvTypeField {
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fn from(value: u8) -> Self {
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match TlvType::try_from(value) {
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Ok(tlv_type) => TlvTypeField::Standard(tlv_type),
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Err(_) => TlvTypeField::Custom(value),
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}
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}
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}
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impl From<TlvTypeField> for u8 {
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fn from(value: TlvTypeField) -> Self {
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match value {
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TlvTypeField::Standard(std) => std as u8,
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TlvTypeField::Custom(custom) => custom,
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}
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}
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}
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/// Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
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///
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/// # Lifetimes
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/// * `data`: If the TLV is generated from a raw bytestream, this will be the lifetime of
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/// the raw bytestream. If the TLV is generated from a raw slice or a similar data reference,
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/// this will be the lifetime of that data reference.
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
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pub struct Tlv<'data> {
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tlv_type_field: TlvTypeField,
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#[cfg_attr(feature = "serde", serde(borrow))]
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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> {
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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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}
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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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}
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}
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pub fn tlv_type_field(&self) -> TlvTypeField {
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self.tlv_type_field
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}
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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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}
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/// Returns the length of the value part, not including the length byte.
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pub fn len_value(&self) -> usize {
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self.lv.len_value()
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}
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/// Returns the full raw length, including the length byte.
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pub fn len_full(&self) -> usize {
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self.lv.len_full() + 1
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}
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/// Checks whether the value field is empty.
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pub fn is_empty(&self) -> bool {
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self.lv.is_empty()
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}
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/// Creates a TLV give a raw bytestream. Please note that is is not necessary to pass the
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/// bytestream with the exact size of the expected TLV. This function will take care
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/// of parsing the length byte, and the length of the parsed TLV can be retrieved using
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/// [len_full].
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pub fn from_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_bytes(&buf[MIN_LV_LEN..])?,
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})
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::cfdp::tlv::{Tlv, TlvType, TlvTypeField};
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use crate::cfdp::TlvLvError;
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use crate::util::{UbfU8, UnsignedEnum};
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#[test]
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fn test_basic() {
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let entity_id = UbfU8::new(5);
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let mut buf: [u8; 4] = [0; 4];
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assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
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let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
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assert!(tlv_res.is_ok());
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let tlv_res = tlv_res.unwrap();
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assert_eq!(
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tlv_res.tlv_type_field(),
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TlvTypeField::Standard(TlvType::EntityId)
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);
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assert_eq!(tlv_res.len_full(), 3);
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assert_eq!(tlv_res.len_value(), 1);
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assert!(!tlv_res.is_empty());
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assert!(tlv_res.value().is_some());
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assert_eq!(tlv_res.value().unwrap()[0], 5);
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}
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#[test]
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fn test_serialization() {
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let entity_id = UbfU8::new(5);
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let mut buf: [u8; 4] = [0; 4];
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assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
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let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
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assert!(tlv_res.is_ok());
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let tlv_res = tlv_res.unwrap();
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let mut ser_buf: [u8; 4] = [0; 4];
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assert!(tlv_res.write_to_be_bytes(&mut ser_buf).is_ok());
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assert_eq!(ser_buf[0], TlvType::EntityId as u8);
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assert_eq!(ser_buf[1], 1);
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assert_eq!(ser_buf[2], 5);
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}
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#[test]
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fn test_deserialization() {
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let entity_id = UbfU8::new(5);
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let mut buf: [u8; 4] = [0; 4];
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assert!(entity_id.write_to_be_bytes(&mut buf[2..]).is_ok());
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buf[0] = TlvType::EntityId as u8;
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buf[1] = 1;
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let tlv_from_raw = Tlv::from_bytes(&mut buf);
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assert!(tlv_from_raw.is_ok());
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let tlv_from_raw = tlv_from_raw.unwrap();
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assert_eq!(
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tlv_from_raw.tlv_type_field(),
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TlvTypeField::Standard(TlvType::EntityId)
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);
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assert_eq!(tlv_from_raw.len_value(), 1);
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assert_eq!(tlv_from_raw.len_full(), 3);
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assert!(tlv_from_raw.value().is_some());
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assert_eq!(tlv_from_raw.value().unwrap()[0], 5);
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}
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#[test]
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fn test_empty() {
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let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
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assert!(tlv_empty.value().is_none());
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assert!(tlv_empty.is_empty());
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assert_eq!(tlv_empty.len_full(), 2);
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assert_eq!(tlv_empty.len_value(), 0);
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assert_eq!(
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tlv_empty.tlv_type_field(),
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TlvTypeField::Standard(TlvType::MsgToUser)
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);
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}
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#[test]
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fn test_empty_serialization() {
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let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
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let mut buf: [u8; 4] = [0; 4];
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assert!(tlv_empty.write_to_be_bytes(&mut buf).is_ok());
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assert_eq!(buf[0], TlvType::MsgToUser as u8);
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assert_eq!(buf[1], 0);
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}
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#[test]
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fn test_empty_deserialization() {
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let mut buf: [u8; 4] = [0; 4];
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buf[0] = TlvType::MsgToUser as u8;
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buf[1] = 0;
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let tlv_empty = Tlv::from_bytes(&mut buf);
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assert!(tlv_empty.is_ok());
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let tlv_empty = tlv_empty.unwrap();
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assert!(tlv_empty.is_empty());
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assert!(tlv_empty.value().is_none());
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assert_eq!(
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tlv_empty.tlv_type_field(),
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TlvTypeField::Standard(TlvType::MsgToUser)
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);
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assert_eq!(tlv_empty.len_full(), 2);
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assert_eq!(tlv_empty.len_value(), 0);
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}
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#[test]
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fn test_buf_too_large() {
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let buf_too_large: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
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let tlv_res = Tlv::new(TlvType::MsgToUser, &buf_too_large);
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assert!(tlv_res.is_err());
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let error = tlv_res.unwrap_err();
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if let TlvLvError::DataTooLarge(size) = error {
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assert_eq!(size, u8::MAX as usize + 1);
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} else {
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panic!("unexpected error {:?}", error);
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}
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}
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#[test]
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fn test_deserialization_custom_tlv_type() {
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let mut buf: [u8; 4] = [0; 4];
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buf[0] = 3;
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buf[1] = 1;
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buf[2] = 5;
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let tlv = Tlv::from_bytes(&mut buf);
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assert!(tlv.is_ok());
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let tlv = tlv.unwrap();
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assert_eq!(tlv.tlv_type_field(), TlvTypeField::Custom(3));
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assert_eq!(tlv.len_value(), 1);
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assert_eq!(tlv.len_full(), 3);
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}
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}
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