87 lines
2.7 KiB
Rust
87 lines
2.7 KiB
Rust
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use crate::{ByteConversionError, SizeMissmatch};
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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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pub struct Tlv<'a> {
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tlv_type: TlvType,
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data: &'a [u8],
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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 TlvError {
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DataTooLarge(usize),
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ByteConversionError(ByteConversionError),
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UnknownTlvType(u8),
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}
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impl From<ByteConversionError> for TlvError {
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fn from(value: ByteConversionError) -> Self {
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Self::ByteConversionError(value)
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}
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}
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impl<'a> Tlv<'a> {
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pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvError> {
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if data.len() > u8::MAX as usize {
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return Err(TlvError::DataTooLarge(data.len()));
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}
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Ok(Tlv { tlv_type, data })
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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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if buf.len() < self.data.len() + MIN_TLV_LEN {
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return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
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found: buf.len(),
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expected: self.data.len() + MIN_TLV_LEN,
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}));
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}
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buf[0] = self.tlv_type as u8;
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// Length check in constructor ensures the length always has a valid value.
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buf[1] = self.data.len() as u8;
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buf[MIN_TLV_LEN..self.data.len() + MIN_TLV_LEN].copy_from_slice(self.data);
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Ok(MIN_TLV_LEN + self.data.len())
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}
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pub fn from_be_bytes(buf: &'a [u8]) -> Result<Tlv<'a>, TlvError> {
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if buf.len() < MIN_TLV_LEN {
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return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
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found: buf.len(),
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expected: MIN_TLV_LEN,
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})
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.into());
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}
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let tlv_type_res = TlvType::try_from(buf[0]);
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if tlv_type_res.is_err() {
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return Err(TlvError::UnknownTlvType(buf[1]));
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}
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let value_len = buf[1] as usize;
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if buf.len() < value_len {
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return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
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found: buf.len(),
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expected: MIN_TLV_LEN + value_len,
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})
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.into());
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}
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Ok(Self {
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tlv_type: tlv_type_res.unwrap(),
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data: &buf[MIN_TLV_LEN..MIN_TLV_LEN + value_len],
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})
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}
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}
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