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OER: improve decoding field presence tracking #375

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merged 1 commit into from
Nov 23, 2024
Merged

OER: improve decoding field presence tracking #375

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2 changes: 1 addition & 1 deletion macros/macros_impl/src/decode.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ pub fn derive_struct_impl(
.constraints
.const_expr(crate_root)
.unwrap_or_else(|| quote!(#crate_root::types::Constraints::default()));
let constraint_name = format_ident!("DELEGATE_DECODE_CONSTRAINT");
let constraint_name = format_ident!("delegate_constraint");
let constraint_def = if generics.params.is_empty() {
quote! {
let #constraint_name: #crate_root::types::Constraints = const {<#ty as #crate_root::AsnType>::CONSTRAINTS.intersect(#constraints)}.intersect(constraints);
Expand Down
121 changes: 74 additions & 47 deletions src/oer/de.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@
// the encoding itself without knowledge of the type being encoded ITU-T X.696 (6.2).

use alloc::{
collections::VecDeque,
string::{String, ToString},
vec::Vec,
};
Expand Down Expand Up @@ -73,9 +72,9 @@ impl DecoderOptions {
pub struct Decoder<'input, const RFC: usize = 0, const EFC: usize = 0> {
input: InputSlice<'input>,
options: DecoderOptions,
fields: VecDeque<(Field, bool)>,
fields: ([Option<Field>; RFC], usize),
extension_fields: Option<Fields<EFC>>,
extensions_present: Option<Option<VecDeque<(Field, bool)>>>,
extensions_present: Option<Option<([Option<Field>; EFC], usize)>>,
}

impl<'input, const RFC: usize, const EFC: usize> Decoder<'input, RFC, EFC> {
Expand All @@ -85,7 +84,7 @@ impl<'input, const RFC: usize, const EFC: usize> Decoder<'input, RFC, EFC> {
Self {
input: input.into(),
options,
fields: <_>::default(),
fields: ([None; RFC], 0),
extension_fields: <_>::default(),
extensions_present: <_>::default(),
}
Expand Down Expand Up @@ -388,30 +387,39 @@ impl<'input, const RFC: usize, const EFC: usize> Decoder<'input, RFC, EFC> {

#[track_caller]
fn require_field(&mut self, tag: Tag) -> Result<bool, DecodeError> {
if self
.fields
.front()
.is_some_and(|field| field.0.tag_tree.smallest_tag() == tag)
{
Ok(self.fields.pop_front().unwrap().1)
} else {
Err(DecodeError::missing_tag_class_or_value_in_sequence_or_set(
let (fields, index) = &mut self.fields;
let Some(field) = fields.get(*index) else {
return Err(DecodeError::missing_tag_class_or_value_in_sequence_or_set(
tag.class,
tag.value,
self.codec(),
))
));
};

*index += 1;
match field {
Some(field) if field.tag_tree.smallest_tag() == tag => Ok(true),
None => Ok(false),
_ => Err(DecodeError::missing_tag_class_or_value_in_sequence_or_set(
tag.class,
tag.value,
self.codec(),
)),
}
}

fn extension_is_present(&mut self) -> Result<Option<(Field, bool)>, DecodeError> {
fn extension_is_present(&mut self) -> Result<Option<&Field>, DecodeError> {
let codec = self.codec();
Ok(self
.extensions_present
.as_mut()
.ok_or_else(|| DecodeError::type_not_extensible(codec))?
.as_mut()
.ok_or_else(|| DecodeError::type_not_extensible(codec))?
.pop_front())
let Some(Some((fields, index))) = self.extensions_present.as_mut() else {
return Err(DecodeError::type_not_extensible(codec));
};

let field = fields
.get(*index)
.ok_or_else(|| DecodeError::type_not_extensible(codec))?;

*index += 1;
Ok(field.as_ref())
}

fn parse_extension_header(&mut self) -> Result<bool, DecodeError> {
Expand All @@ -427,9 +435,11 @@ impl<'input, const RFC: usize, const EFC: usize> Decoder<'input, RFC, EFC> {
"Extension length should be at least 1 byte".to_string(),
));
}
let extension_fields = self
.extension_fields
.ok_or_else(|| DecodeError::type_not_extensible(self.codec()))?;
// Must be at least 8 bits at this point or error is already raised
let bitfield = self.extract_data_by_length(extensions_length)?.to_bitvec();
// let mut missing_bits: bitvec::vec::BitVec<u8, bitvec::order::Msb0>;
let bitfield = self.extract_data_by_length(extensions_length)?;
// Initial octet
let (unused_bits, bitfield) = bitfield.split_at(8);
let unused_bits: usize = unused_bits.load();
Expand All @@ -439,26 +449,23 @@ impl<'input, const RFC: usize, const EFC: usize> Decoder<'input, RFC, EFC> {
"Invalid extension bitfield initial octet".to_string(),
));
}
let (bitfield, _) = bitfield.split_at(bitfield.len() - unused_bits);
let needed = bitfield.len() - unused_bits;
let bitfield = &bitfield[..needed];

let extensions_present: VecDeque<_> = self
.extension_fields
.as_ref()
.unwrap()
.iter()
.zip(bitfield.iter().map(|b| *b))
.collect();

for (field, is_present) in &extensions_present {
if field.is_not_optional_or_default() && !*is_present {
let mut fields: [Option<Field>; EFC] = [None; EFC];
for (i, field) in extension_fields.iter().enumerate() {
if field.is_not_optional_or_default() && !bitfield[i] {
return Err(DecodeError::required_extension_not_present(
field.tag,
self.codec(),
));
} else if bitfield[i] {
fields[i] = Some(field);
} else {
fields[i] = None;
}
}
self.extensions_present = Some(Some(extensions_present));

self.extensions_present = Some(Some((fields, 0)));
Ok(true)
}

Expand All @@ -481,7 +488,7 @@ impl<'input, const RFC: usize, const EFC: usize> Decoder<'input, RFC, EFC> {
} else {
bitmap.len()
};
self.drop_preamble_bits((8 - preamble_length % 8) % 8)?;
self.drop_preamble_bits((8 - (preamble_length & 7)) & 7)?;

debug_assert_eq!(self.input.len() % 8, 0);
Ok((bitmap, extensible_present))
Expand Down Expand Up @@ -608,10 +615,18 @@ impl<'input, const RFC: usize, const EFC: usize> crate::Decoder for Decoder<'inp
// ### PREAMBLE ###
let (bitmap, extensible_present) = self.parse_preamble::<RC, EC, D>()?;
// ### ENDS
let fields = D::FIELDS
let mut fields = ([None; RC], 0);
for (i, (field, is_present)) in D::FIELDS
.optional_and_default_fields()
.zip(bitmap.into_iter().map(|b| *b))
.collect();
.enumerate()
{
if is_present {
fields.0[i] = Some(field);
} else {
fields.0[i] = None;
}
}

let value = {
let mut sequence_decoder = Decoder::new(self.input.0, self.options);
Expand Down Expand Up @@ -841,26 +856,38 @@ impl<'input, const RFC: usize, const EFC: usize> crate::Decoder for Decoder<'inp
{
let (bitmap, extensible_present) = self.parse_preamble::<RC, EC, SET>()?;

let field_map = SET::FIELDS
let mut field_map: ([Option<Field>; RC], usize) = ([None; RC], 0);
for (i, (field, is_present)) in SET::FIELDS
.canonised()
.optional_and_default_fields()
.zip(bitmap.into_iter().map(|b| *b))
.collect::<alloc::collections::BTreeMap<_, _>>();
.enumerate()
{
if is_present {
field_map.0[i] = Some(field);
} else {
field_map.0[i] = None;
}
}

let fields = {
let extended_fields_len = SET::EXTENDED_FIELDS.map_or(0, |fields| fields.len());
let mut fields = Vec::with_capacity(SET::FIELDS.len() + extended_fields_len);
let mut set_decoder = Decoder::new(self.input.0, self.options);
set_decoder.extension_fields = SET::EXTENDED_FIELDS;
set_decoder.extensions_present = extensible_present.then_some(None);
set_decoder.fields = field_map.clone().into_iter().collect();
set_decoder.fields = field_map;

let mut opt_index = 0;
for field in SET::FIELDS.canonised().iter() {
match field_map.get(&field).copied() {
Some(true) | None => {
if field.is_optional_or_default() {
// Safe unwrap, we just created the field_map
if field_map.0.get(opt_index).unwrap().is_some() {
fields.push(decode_fn(&mut set_decoder, field.index, field.tag)?);
}
Some(false) => {}
opt_index += 1;
} else {
fields.push(decode_fn(&mut set_decoder, field.index, field.tag)?);
}
}
for (indice, field) in SET::EXTENDED_FIELDS
Expand Down Expand Up @@ -967,7 +994,7 @@ impl<'input, const RFC: usize, const EFC: usize> crate::Decoder for Decoder<'inp
return Ok(None);
}

let extension_is_present = self.extension_is_present()?.is_some_and(|(_, b)| b);
let extension_is_present = self.extension_is_present()?.is_some();

if !extension_is_present {
return Ok(None);
Expand All @@ -992,7 +1019,7 @@ impl<'input, const RFC: usize, const EFC: usize> crate::Decoder for Decoder<'inp
return Ok(None);
}

let extension_is_present = self.extension_is_present()?.is_some_and(|(_, b)| b);
let extension_is_present = self.extension_is_present()?.is_some();

if !extension_is_present {
return Ok(None);
Expand Down
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