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use crate::crypto::aes::MicSize;
use crate::crypto::{AID, MIC};
use crate::lower::{BlockAck, SegN, SegO, SegmentedAccessPDU, SegmentedControlPDU};
use crate::control::{ControlOpcode, ControlPayload};
use crate::upper;
use crate::upper::EncryptedAppPayload;
use alloc::vec::Vec;
#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug, Hash)]
pub enum ReassembleError {
DataTooLong,
SegmentOutOfBounds,
Timeout,
}
#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug, Hash)]
pub enum LowerHeader {
ControlOpcode(ControlOpcode),
AID(Option<AID>),
}
impl LowerHeader {
pub fn is_control(&self) -> bool {
match self {
LowerHeader::ControlOpcode(_) => true,
LowerHeader::AID(_) => false,
}
}
pub fn is_access(&self) -> bool {
!self.is_control()
}
pub fn opcode(&self) -> Option<ControlOpcode> {
match self {
LowerHeader::ControlOpcode(opcode) => Some(*opcode),
LowerHeader::AID(_) => None,
}
}
pub fn aid(&self) -> Option<AID> {
match self {
LowerHeader::ControlOpcode(_) => None,
LowerHeader::AID(aid) => *aid,
}
}
}
#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug, Hash)]
pub struct ContextHeader {
flag: bool,
seg_o: SegO,
block_ack: BlockAck,
lower_header: LowerHeader,
}
impl ContextHeader {
pub fn new(lower_header: LowerHeader, seg_o: SegO, flag: bool) -> Self {
Self {
lower_header,
seg_o,
flag,
block_ack: Default::default(),
}
}
#[must_use]
pub fn all_acked(&self) -> bool {
self.block_ack.all_acked(self.seg_o)
}
#[must_use]
pub fn seg_o(&self) -> SegO {
self.seg_o
}
#[must_use]
pub fn seg_count(&self) -> usize {
usize::from(u8::from(self.seg_o)) + 1usize
}
#[must_use]
pub const fn block_ack(&self) -> BlockAck {
self.block_ack
}
#[must_use]
pub fn mic_size(&self) -> Option<MicSize> {
if self.lower_header.is_access() {
if self.flag {
Some(MicSize::Big)
} else {
Some(MicSize::Small)
}
} else {
None
}
}
#[must_use]
pub fn lower_header(&self) -> LowerHeader {
self.lower_header
}
#[must_use]
pub fn max_seg_len(&self) -> usize {
if self.lower_header.is_control() {
SegmentedControlPDU::max_seg_len()
} else {
SegmentedAccessPDU::max_seg_len()
}
}
#[must_use]
pub fn seg_pos(&self, seg_n: SegN) -> Option<usize> {
let pos = usize::from(u8::from(seg_n)) * self.max_seg_len();
if pos > self.max_len() {
None
} else {
Some(pos)
}
}
#[must_use]
pub fn max_len(&self) -> usize {
self.max_seg_len() * self.seg_count()
}
#[must_use]
pub fn mic_size_bytes(&self) -> usize {
self.mic_size().map(MicSize::byte_size).unwrap_or(0)
}
}
#[derive(Clone, Debug)]
pub struct Context {
storage: Vec<u8>,
data_len: usize,
header: ContextHeader,
}
impl Context {
pub fn new(header: ContextHeader) -> Self {
let mut storage = Vec::with_capacity(header.max_len());
storage.resize_with(header.max_len(), u8::default);
Self {
storage,
data_len: 0,
header,
}
}
pub fn data(&self) -> &[u8] {
self.storage.as_ref()
}
pub fn is_ready(&self) -> bool {
self.header.all_acked()
}
pub fn header(&self) -> ContextHeader {
self.header
}
pub fn mic_size(&self) -> Option<MicSize> {
self.header.mic_size()
}
pub fn mic(&self) -> Option<MIC> {
if !self.is_ready() || self.header.lower_header.is_control() {
None
} else {
Some(
MIC::try_from_bytes_le(
&self.data()[self.data_len..][..self.mic_size()?.byte_size()],
)
.expect("MIC should be here"),
)
}
}
pub fn insert_data(&mut self, seg_n: SegN, data: &[u8]) -> Result<(), ReassembleError> {
if data.len() > self.header.max_seg_len() {
Err(ReassembleError::DataTooLong)
} else {
let pos = self
.header
.seg_pos(seg_n)
.ok_or(ReassembleError::SegmentOutOfBounds)?;
self.storage[pos..pos + data.len()].copy_from_slice(data);
self.header.block_ack.set(seg_n.into());
if u8::from(seg_n) == u8::from(self.header.seg_o) {
self.data_len = pos + data.len() - self.header.mic_size_bytes();
}
Ok(())
}
}
pub fn finish(mut self) -> Result<upper::PDU<Box<[u8]>>, Context> {
if !self.is_ready() {
Err(self)
} else {
let len = self.data_len;
self.storage.truncate(len);
let mic = self.mic();
let header = self.header;
let storage = self.storage.into_boxed_slice();
match header.lower_header {
LowerHeader::ControlOpcode(opcode) => Ok(upper::PDU::Control(ControlPayload {
opcode,
payload: storage,
})),
LowerHeader::AID(aid) => Ok(upper::PDU::Access(EncryptedAppPayload {
data: storage,
mic: mic.expect("mic exists if PDU is ready and access"),
aid,
})),
}
}
}
}