webauthn_rp

bin.rs (15251B)

---

 extern crate alloc;
 use alloc::borrow::Cow;
 use core::str;
 /// Unit error returned from [`Encode::encode_into_buffer`] and
 /// [`Decode::decode_from_buffer`] to simply signal an error occurred.
 pub(super) struct EncDecErr;
 /// Encodes data as a binary format into a passed `Vec` buffer with the possibility
 /// of erring.
 pub(super) trait EncodeBufferFallible {
     /// Error when [`Self::encode_into_buffer`] fails.
     type Err;
     /// Writes `self` into `buffer`.
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err>;
 }
 /// Encodes data as a binary format into a passed `Vec` buffer.
 pub(super) trait EncodeBuffer {
     /// Writes `self` into `buffer`.
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>);
 }
 impl EncodeBuffer for u8 {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.push(*self);
     }
 }
 impl EncodeBuffer for u16 {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.extend_from_slice(self.to_le_bytes().as_slice());
     }
 }
 impl EncodeBuffer for u32 {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.extend_from_slice(self.to_le_bytes().as_slice());
     }
 }
 impl EncodeBuffer for u64 {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.extend_from_slice(self.to_le_bytes().as_slice());
     }
 }
 impl EncodeBuffer for u128 {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.extend_from_slice(self.to_le_bytes().as_slice());
     }
 }
 // `false as u8` is defined as 0.
 /// `false` tag.
 #[expect(clippy::as_conversions, reason = "this is safe, and we want a const")]
 const FALSE: u8 = false as u8;
 // `true as u8` is defined as 1.
 /// `true` tag.
 #[expect(clippy::as_conversions, reason = "this is safe, and we want a const")]
 const TRUE: u8 = true as u8;
 impl EncodeBuffer for bool {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.push(if *self { TRUE } else { FALSE });
     }
 }
 // We don't implement `EncodeBuffer` for `[T]` since we only ever need `[u8]`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl EncodeBufferFallible for [u8] {
     type Err = EncDecErr;
     /// # Errors
     ///
     /// Errors iff `self.len() > usize::from(u16::MAX)`.
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         u16::try_from(self.len())
             .map_err(|_e| EncDecErr)
             .map(|len| {
                 len.encode_into_buffer(buffer);
                 buffer.extend_from_slice(self);
             })
     }
 }
 // We don't implement `EncodeBuffer` for `Box<T>` since we only ever need `Box<[u8]>`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl EncodeBufferFallible for Box<[u8]> {
     type Err = EncDecErr;
     /// # Errors
     ///
     /// See [`[u8]::encode_into_buffer`].
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         (&self).encode_into_buffer(buffer)
     }
 }
 // We don't implement `EncodeBuffer` for `Vec<T>` since we only ever need `Vec<u8>`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl EncodeBufferFallible for Vec<u8> {
     type Err = EncDecErr;
     /// # Errors
     ///
     /// See [`[u8]::encode_into_buffer`].
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         self.as_slice().encode_into_buffer(buffer)
     }
 }
 // We don't implement `EncodeBuffer` for `[T; LEN]` since we only ever need `[u8; LEN]`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl<const LEN: usize> EncodeBuffer for [u8; LEN]
 where
     [u8; LEN]: Default,
 {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         buffer.extend_from_slice(self.as_slice());
     }
 }
 /// [`Option::None`] tag.
 const NONE: u8 = 0;
 /// [`Option::Some`] tag.
 const SOME: u8 = 1;
 impl<T: EncodeBuffer> EncodeBuffer for Option<T> {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         match *self {
             None => {
                 buffer.push(NONE);
             }
             Some(ref val) => {
                 buffer.push(SOME);
                 val.encode_into_buffer(buffer);
             }
         }
     }
 }
 impl<T: EncodeBuffer, T2: EncodeBuffer> EncodeBuffer for (T, T2) {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         self.0.encode_into_buffer(buffer);
         self.1.encode_into_buffer(buffer);
     }
 }
 impl EncodeBufferFallible for str {
     type Err = EncDecErr;
     /// # Errors
     ///
     /// See [`[u8]::encode_into_buffer`].
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         self.as_bytes().encode_into_buffer(buffer)
     }
 }
 impl EncodeBufferFallible for String {
     type Err = EncDecErr;
     /// # Errors
     ///
     /// See [`[u8]::encode_into_buffer`].
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         self.as_str().encode_into_buffer(buffer)
     }
 }
 impl EncodeBufferFallible for Cow<'_, str> {
     type Err = EncDecErr;
     /// # Errors
     ///
     /// See [`[u8]::encode_into_buffer`].
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         self.as_ref().encode_into_buffer(buffer)
     }
 }
 impl<T: EncodeBuffer + ?Sized> EncodeBuffer for &T {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         (**self).encode_into_buffer(buffer);
     }
 }
 impl<T: EncodeBuffer + ?Sized> EncodeBuffer for &mut T {
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) {
         (**self).encode_into_buffer(buffer);
     }
 }
 impl<T: EncodeBufferFallible + ?Sized> EncodeBufferFallible for &T {
     type Err = T::Err;
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         (**self).encode_into_buffer(buffer)
     }
 }
 impl<T: EncodeBufferFallible + ?Sized> EncodeBufferFallible for &mut T {
     type Err = T::Err;
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         (**self).encode_into_buffer(buffer)
     }
 }
 impl<T: EncodeBufferFallible> EncodeBufferFallible for Option<T> {
     type Err = T::Err;
     fn encode_into_buffer(&self, buffer: &mut Vec<u8>) -> Result<(), Self::Err> {
         match *self {
             None => {
                 buffer.push(NONE);
                 Ok(())
             }
             Some(ref val) => {
                 buffer.push(SOME);
                 val.encode_into_buffer(buffer)
             }
         }
     }
 }
 /// Decodes binary data generated by [`EncodeBuffer::encode_into_buffer`].
 pub(super) trait DecodeBuffer<'a>: Sized {
     /// Error returned from [`Self::decode_from_buffer`].
     type Err;
     /// Transforms a sub-`slice` of `data` into `Self`; and upon success,
     /// mutates `data` to be the remaining portion.
     ///
     /// # Errors
     ///
     /// Errors iff `data` cannot be decoded into `Self`.
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err>;
 }
 impl<'a> DecodeBuffer<'a> for u8 {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         data.split_first().ok_or(EncDecErr).map(|(&val, rem)| {
             *data = rem;
             val
         })
     }
 }
 impl<'a> DecodeBuffer<'a> for u16 {
     type Err = EncDecErr;
     #[expect(
         clippy::little_endian_bytes,
         reason = "we must standardize the endianness to remove ambiguity"
     )]
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         /// Number of bytes `u16` is made of.
         const SIZE: usize = 2;
         data.split_at_checked(SIZE)
             .ok_or(EncDecErr)
             .map(|(le_bytes, rem)| {
                 *data = rem;
                 let mut val = [0; SIZE];
                 val.copy_from_slice(le_bytes);
                 Self::from_le_bytes(val)
             })
     }
 }
 impl<'a> DecodeBuffer<'a> for u32 {
     type Err = EncDecErr;
     #[expect(
         clippy::little_endian_bytes,
         reason = "we must standardize the endianness to remove ambiguity"
     )]
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         /// Number of bytes `u32` is made of.
         const SIZE: usize = 4;
         data.split_at_checked(SIZE)
             .ok_or(EncDecErr)
             .map(|(le_bytes, rem)| {
                 *data = rem;
                 let mut val = [0; SIZE];
                 val.copy_from_slice(le_bytes);
                 Self::from_le_bytes(val)
             })
     }
 }
 impl<'a> DecodeBuffer<'a> for u64 {
     type Err = EncDecErr;
     #[expect(
         clippy::little_endian_bytes,
         reason = "we must standardize the endianness to remove ambiguity"
     )]
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         /// Number of bytes `u64` is made of.
         const SIZE: usize = 8;
         data.split_at_checked(SIZE)
             .ok_or(EncDecErr)
             .map(|(le_bytes, rem)| {
                 *data = rem;
                 let mut val = [0; SIZE];
                 val.copy_from_slice(le_bytes);
                 Self::from_le_bytes(val)
             })
     }
 }
 impl<'a> DecodeBuffer<'a> for u128 {
     type Err = EncDecErr;
     #[expect(
         clippy::little_endian_bytes,
         reason = "we must standardize the endianness to remove ambiguity"
     )]
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         /// Number of bytes `u128` is made of.
         const SIZE: usize = 16;
         data.split_at_checked(SIZE)
             .ok_or(EncDecErr)
             .map(|(le_bytes, rem)| {
                 *data = rem;
                 let mut val = [0; SIZE];
                 val.copy_from_slice(le_bytes);
                 Self::from_le_bytes(val)
             })
     }
 }
 impl<'a> DecodeBuffer<'a> for bool {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         u8::decode_from_buffer(data).and_then(|val| match val {
             FALSE => Ok(false),
             TRUE => Ok(true),
             _ => Err(EncDecErr),
         })
     }
 }
 // We don't implement `DecodeBuffer` for `&'a [T]` since we only ever need `&[u8]`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl<'a> DecodeBuffer<'a> for &'a [u8] {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         u16::decode_from_buffer(data).and_then(|len| {
             data.split_at_checked(usize::from(len))
                 .ok_or(EncDecErr)
                 .map(|(val, rem)| {
                     *data = rem;
                     val
                 })
         })
     }
 }
 // We don't implement `DecodeBuffer` for `Box<T>` since we only ever need `Box<[u8]>`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl<'a> DecodeBuffer<'a> for Box<[u8]> {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         <&[u8]>::decode_from_buffer(data).map(Self::from)
     }
 }
 // We don't implement `DecodeBuffer` for `Vec<T>` since we only ever need `Vec<u8>`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl<'a> DecodeBuffer<'a> for Vec<u8> {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         <&[u8]>::decode_from_buffer(data).map(ToOwned::to_owned)
     }
 }
 // We don't implement `DecodeBuffer` for `[T; LEN]` since we only ever need `[u8; LEN]`; and one can specialize
 // the implementation such that it's _a lot_ faster than a generic `T`.
 impl<'a, const LEN: usize> DecodeBuffer<'a> for [u8; LEN]
 where
     [u8; LEN]: Default,
 {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         data.split_at_checked(LEN)
             .ok_or(EncDecErr)
             .map(|(val_slice, rem)| {
                 *data = rem;
                 let mut val = Self::default();
                 val.copy_from_slice(val_slice);
                 val
             })
     }
 }
 impl<'a, T> DecodeBuffer<'a> for Option<T>
 where
     T: DecodeBuffer<'a, Err = EncDecErr>,
 {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         u8::decode_from_buffer(data).and_then(|tag| match tag {
             NONE => Ok(None),
             SOME => T::decode_from_buffer(data).map(Some),
             _ => Err(EncDecErr),
         })
     }
 }
 impl<'a, T, T2> DecodeBuffer<'a> for (T, T2)
 where
     T: DecodeBuffer<'a, Err = EncDecErr>,
     T2: DecodeBuffer<'a, Err = EncDecErr>,
 {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         T::decode_from_buffer(data)
             .and_then(|val| T2::decode_from_buffer(data).map(|val2| (val, val2)))
     }
 }
 impl<'a> DecodeBuffer<'a> for &'a str {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         <&[u8]>::decode_from_buffer(data)
             .and_then(|utf8| str::from_utf8(utf8).map_err(|_e| EncDecErr))
     }
 }
 impl<'a> DecodeBuffer<'a> for String {
     type Err = EncDecErr;
     fn decode_from_buffer(data: &mut &'a [u8]) -> Result<Self, Self::Err> {
         <&str>::decode_from_buffer(data).map(ToOwned::to_owned)
     }
 }
 /// Encodes `self` into a "primitive"-like type that can be saved to persistent storage
 /// and later decoded via [`Decode::decode`].
 ///
 /// The purpose of this trait is to transform `Self` into something "easily" consumable by persistent
 /// storage which already has some form of inherent metadata (e.g., a column in a relational database (RDB)).
 pub trait Encode {
     /// "Primitive"-like type that `self` will be converted into. This should be one of the following:
     /// * [`u8`]
     /// * [`i8`]
     /// * [`u16`]
     /// * [`i16`]
     /// * [`u32`]
     /// * [`i32`]
     /// * [`u64`]
     /// * [`i64`]
     /// * [`u128`]
     /// * [`i128`]
     /// * [`f32`]
     /// * [`f64`]
     /// * [`bool`]
     /// * `&[u8]`
     /// * [`&str`](prim@str)
     /// * `[u8; N]`
     /// * `Vec<u8>`
     /// * [`String`]
     type Output<'a>
     where
         Self: 'a;
     /// Error returned when encoding fails.
     type Err;
     /// Transforms `self` into a "primitive"-like type.
     ///
     /// # Errors
     ///
     /// Errors iff `self` cannot be encoded into [`Self::Output`].
     fn encode(&self) -> Result<Self::Output<'_>, Self::Err>;
 }
 /// Decodes a "primitive"-like instance that was created via [`Encode::encode`]
 /// into `Self`.
 pub trait Decode: Sized {
     /// "Primitive"-like input to be decoded.
     ///
     /// This should be the same as or the "owned" version of the corresponding [`Encode::Output`]. For example if
     /// `Encode::Output` is `&[u8]`, then this should be `&[u8]` or `Vec<u8>`.
     type Input<'a>;
     /// Error returned when decoding fails.
     type Err;
     /// Decodes `input` into `Self`. Note `input` must not have any trailing data.
     ///
     /// # Errors
     ///
     /// Errors iff `input` cannot be decoded into `Self`.
     fn decode(input: Self::Input<'_>) -> Result<Self, Self::Err>;
 }