Merging upstream version 1.70.0+dfsg2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 168 insertions, 0 deletions

diff --git a/vendor/der/src/reader.rs b/vendor/der/src/reader.rs
new file mode 100644
index 000000000..b917323c2
--- /dev/null
+++ b/vendor/der/src/reader.rs
@@ -0,0 +1,168 @@
+//! Reader trait.
+
+mod nested;
+#[cfg(feature = "pem")]
+pub(crate) mod pem;
+pub(crate) mod slice;
+
+pub(crate) use nested::NestedReader;
+
+use crate::{
+    asn1::ContextSpecific, Decode, DecodeValue, Encode, Error, ErrorKind, FixedTag, Header, Length,
+    Result, Tag, TagMode, TagNumber,
+};
+
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
+/// Reader trait which reads DER-encoded input.
+pub trait Reader<'r>: Sized {
+    /// Get the length of the input.
+    fn input_len(&self) -> Length;
+
+    /// Peek at the next byte of input without modifying the cursor.
+    fn peek_byte(&self) -> Option<u8>;
+
+    /// Peek forward in the input data, attempting to decode a [`Header`] from
+    /// the data at the current position in the decoder.
+    ///
+    /// Does not modify the decoder's state.
+    fn peek_header(&self) -> Result<Header>;
+
+    /// Get the position within the buffer.
+    fn position(&self) -> Length;
+
+    /// Attempt to read data borrowed directly from the input as a slice,
+    /// updating the internal cursor position.
+    ///
+    /// # Returns
+    /// - `Ok(slice)` on success
+    /// - `Err(ErrorKind::Incomplete)` if there is not enough data
+    /// - `Err(ErrorKind::Reader)` if the reader can't borrow from the input
+    fn read_slice(&mut self, len: Length) -> Result<&'r [u8]>;
+
+    /// Attempt to decode an ASN.1 `CONTEXT-SPECIFIC` field with the
+    /// provided [`TagNumber`].
+    fn context_specific<T>(&mut self, tag_number: TagNumber, tag_mode: TagMode) -> Result<Option<T>>
+    where
+        T: DecodeValue<'r> + FixedTag,
+    {
+        Ok(match tag_mode {
+            TagMode::Explicit => ContextSpecific::<T>::decode_explicit(self, tag_number)?,
+            TagMode::Implicit => ContextSpecific::<T>::decode_implicit(self, tag_number)?,
+        }
+        .map(|field| field.value))
+    }
+
+    /// Decode a value which impls the [`Decode`] trait.
+    fn decode<T: Decode<'r>>(&mut self) -> Result<T> {
+        T::decode(self).map_err(|e| e.nested(self.position()))
+    }
+
+    /// Return an error with the given [`ErrorKind`], annotating it with
+    /// context about where the error occurred.
+    fn error(&mut self, kind: ErrorKind) -> Error {
+        kind.at(self.position())
+    }
+
+    /// Finish decoding, returning the given value if there is no
+    /// remaining data, or an error otherwise
+    fn finish<T>(self, value: T) -> Result<T> {
+        if !self.is_finished() {
+            Err(ErrorKind::TrailingData {
+                decoded: self.position(),
+                remaining: self.remaining_len(),
+            }
+            .at(self.position()))
+        } else {
+            Ok(value)
+        }
+    }
+
+    /// Have we read all of the input data?
+    fn is_finished(&self) -> bool {
+        self.remaining_len().is_zero()
+    }
+
+    /// Offset within the original input stream.
+    ///
+    /// This is used for error reporting, and doesn't need to be overridden
+    /// by any reader implementations (except for the built-in `NestedReader`,
+    /// which consumes nested input messages)
+    fn offset(&self) -> Length {
+        self.position()
+    }
+
+    /// Peek at the next byte in the decoder and attempt to decode it as a
+    /// [`Tag`] value.
+    ///
+    /// Does not modify the decoder's state.
+    fn peek_tag(&self) -> Result<Tag> {
+        match self.peek_byte() {
+            Some(byte) => byte.try_into(),
+            None => Err(Error::incomplete(self.input_len())),
+        }
+    }
+
+    /// Read a single byte.
+    fn read_byte(&mut self) -> Result<u8> {
+        let mut buf = [0];
+        self.read_into(&mut buf)?;
+        Ok(buf[0])
+    }
+
+    /// Attempt to read input data, writing it into the provided buffer, and
+    /// returning a slice on success.
+    ///
+    /// # Returns
+    /// - `Ok(slice)` if there is sufficient data
+    /// - `Err(ErrorKind::Incomplete)` if there is not enough data
+    fn read_into<'o>(&mut self, buf: &'o mut [u8]) -> Result<&'o [u8]> {
+        let input = self.read_slice(buf.len().try_into()?)?;
+        buf.copy_from_slice(input);
+        Ok(buf)
+    }
+
+    /// Read nested data of the given length.
+    fn read_nested<'n, T, F>(&'n mut self, len: Length, f: F) -> Result<T>
+    where
+        F: FnOnce(&mut NestedReader<'n, Self>) -> Result<T>,
+    {
+        let mut reader = NestedReader::new(self, len)?;
+        let ret = f(&mut reader)?;
+        reader.finish(ret)
+    }
+
+    /// Read a byte vector of the given length.
+    #[cfg(feature = "alloc")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
+    fn read_vec(&mut self, len: Length) -> Result<Vec<u8>> {
+        let mut bytes = vec![0u8; usize::try_from(len)?];
+        self.read_into(&mut bytes)?;
+        Ok(bytes)
+    }
+
+    /// Get the number of bytes still remaining in the buffer.
+    fn remaining_len(&self) -> Length {
+        debug_assert!(self.position() <= self.input_len());
+        self.input_len().saturating_sub(self.position())
+    }
+
+    /// Read an ASN.1 `SEQUENCE`, creating a nested [`Reader`] for the body and
+    /// calling the provided closure with it.
+    fn sequence<'n, F, T>(&'n mut self, f: F) -> Result<T>
+    where
+        F: FnOnce(&mut NestedReader<'n, Self>) -> Result<T>,
+    {
+        let header = Header::decode(self)?;
+        header.tag.assert_eq(Tag::Sequence)?;
+        self.read_nested(header.length, f)
+    }
+
+    /// Obtain a slice of bytes contain a complete TLV production suitable for parsing later.
+    fn tlv_bytes(&mut self) -> Result<&'r [u8]> {
+        let header = self.peek_header()?;
+        let header_len = header.encoded_len()?;
+        self.read_slice((header_len + header.length)?)
+    }
+}