added basic TLV impl

src/cfdp/mod.rs

@@ -3,6 +3,7 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 use serde::{Deserialize, Serialize};
 
 pub mod pdu;
+pub mod tlv;
 
 pub const CFDP_VERSION_2_NAME: &str = "CCSDS 727.0-B-5";
 pub const CFDP_VERSION_2: u8 = 0b001;

src/cfdp/pdu/metadata.rs

@@ -0,0 +1,15 @@
+use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+use crate::cfdp::ChecksumType;
+
+pub struct MetadataParams {
+    closure_requested: bool,
+    checksum_type: ChecksumType,
+    file_size: u64,
+    //src_file_name:
+}
+
+pub struct MetadataPdu {
+    pdu_header: PduHeader,
+    file_directive: FileDirectiveType,
+    metadata_params: MetadataParams,
+}

src/cfdp/pdu/mod.rs

@@ -5,6 +5,21 @@ use core::fmt::{Display, Formatter};
 #[cfg(feature = "std")]
 use std::error::Error;
 
+pub mod metadata;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FileDirectiveType {
+    EofPdu = 0x04,
+    FinishedPdu = 0x05,
+    AckPdu = 0x06,
+    MetadataPdu = 0x07,
+    NakPdu = 0x08,
+    PromptPdu = 0x09,
+    KeepAlivePdu = 0x0c,
+}
+
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PduError {
@@ -148,7 +163,7 @@ impl CommonPduConfig {
     }
 }
 
-const FIXED_HEADER_LEN: usize = 4;
+pub const FIXED_HEADER_LEN: usize = 4;
 
 /// Abstraction for the PDU header common to all CFDP PDUs
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]

src/cfdp/tlv.rs

@@ -0,0 +1,86 @@
+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,
+}
+
+pub struct Tlv<'a> {
+    tlv_type: TlvType,
+    data: &'a [u8],
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum TlvError {
+    DataTooLarge(usize),
+    ByteConversionError(ByteConversionError),
+    UnknownTlvType(u8),
+}
+
+impl From<ByteConversionError> for TlvError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl<'a> Tlv<'a> {
+    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvError> {
+        if data.len() > u8::MAX as usize {
+            return Err(TlvError::DataTooLarge(data.len()));
+        }
+        Ok(Tlv { tlv_type, data })
+    }
+
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.data.len() + MIN_TLV_LEN {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: self.data.len() + MIN_TLV_LEN,
+            }));
+        }
+        buf[0] = self.tlv_type as u8;
+        // Length check in constructor ensures the length always has a valid value.
+        buf[1] = self.data.len() as u8;
+        buf[MIN_TLV_LEN..self.data.len() + MIN_TLV_LEN].copy_from_slice(self.data);
+        Ok(MIN_TLV_LEN + self.data.len())
+    }
+
+    pub fn from_be_bytes(buf: &'a [u8]) -> Result<Tlv<'a>, TlvError> {
+        if buf.len() < MIN_TLV_LEN {
+            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: MIN_TLV_LEN,
+            })
+            .into());
+        }
+        let tlv_type_res = TlvType::try_from(buf[0]);
+        if tlv_type_res.is_err() {
+            return Err(TlvError::UnknownTlvType(buf[1]));
+        }
+        let value_len = buf[1] as usize;
+        if buf.len() < value_len {
+            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: MIN_TLV_LEN + value_len,
+            })
+            .into());
+        }
+        Ok(Self {
+            tlv_type: tlv_type_res.unwrap(),
+            data: &buf[MIN_TLV_LEN..MIN_TLV_LEN + value_len],
+        })
+    }
+}