Trait Reader

pub trait Reader<'r>: Sized {
    // Required methods
    fn input_len(&self) -> Length;
    fn peek_byte(&self) -> Option<u8>;
    fn peek_header(&self) -> Result<Header>;
    fn position(&self) -> Length;
    fn read_slice(&mut self, len: Length) -> Result<&'r [u8]>;

    // Provided methods
    fn context_specific<T>(
        &mut self,
        tag_number: TagNumber,
        tag_mode: TagMode,
    ) -> Result<Option<T>>
       where T: DecodeValue<'r> + FixedTag { ... }
    fn decode<T: Decode<'r>>(&mut self) -> Result<T> { ... }
    fn error(&mut self, kind: ErrorKind) -> Error { ... }
    fn finish<T>(self, value: T) -> Result<T> { ... }
    fn is_finished(&self) -> bool { ... }
    fn offset(&self) -> Length { ... }
    fn peek_tag(&self) -> Result<Tag> { ... }
    fn read_byte(&mut self) -> Result<u8> { ... }
    fn read_into<'o>(&mut self, buf: &'o mut [u8]) -> Result<&'o [u8]> { ... }
    fn read_nested<'n, T, F>(&'n mut self, len: Length, f: F) -> Result<T>
       where F: FnOnce(&mut NestedReader<'n, Self>) -> Result<T> { ... }
    fn read_vec(&mut self, len: Length) -> Result<Vec<u8>> { ... }
    fn remaining_len(&self) -> Length { ... }
    fn sequence<'n, F, T>(&'n mut self, f: F) -> Result<T>
       where F: FnOnce(&mut NestedReader<'n, Self>) -> Result<T> { ... }
    fn tlv_bytes(&mut self) -> Result<&'r [u8]> { ... }
}

Reader trait which reads DER-encoded input.

Required Methods

fn input_len(&self) -> Length

Get the length of the input.

fn peek_byte(&self) -> Option<u8>

Peek at the next byte of input without modifying the cursor.

fn peek_header(&self) -> Result<Header>

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 position(&self) -> Length

Get the position within the buffer.

fn read_slice(&mut self, len: Length) -> Result<&'r [u8]>

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

Provided Methods

fn context_specific<T>( &mut self, tag_number: TagNumber, tag_mode: TagMode, ) -> Result<Option<T>>

where T: DecodeValue<'r> + FixedTag,

Attempt to decode an ASN.1 CONTEXT-SPECIFIC field with the provided TagNumber.

fn decode<T: Decode<'r>>(&mut self) -> Result<T>

Decode a value which impls the Decode trait.

fn error(&mut self, kind: ErrorKind) -> Error

Return an error with the given ErrorKind, annotating it with context about where the error occurred.

fn finish<T>(self, value: T) -> Result<T>

Finish decoding, returning the given value if there is no remaining data, or an error otherwise

fn is_finished(&self) -> bool

Have we read all of the input data?

fn offset(&self) -> Length

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 peek_tag(&self) -> Result<Tag>

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 read_byte(&mut self) -> Result<u8>

Read a single byte.

fn read_into<'o>(&mut self, buf: &'o mut [u8]) -> Result<&'o [u8]>

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_nested<'n, T, F>(&'n mut self, len: Length, f: F) -> Result<T>

where F: FnOnce(&mut NestedReader<'n, Self>) -> Result<T>,

Read nested data of the given length.

fn read_vec(&mut self, len: Length) -> Result<Vec<u8>>

Read a byte vector of the given length.

fn remaining_len(&self) -> Length

Get the number of bytes still remaining in the buffer.

fn sequence<'n, F, T>(&'n mut self, f: F) -> Result<T>

where F: FnOnce(&mut NestedReader<'n, Self>) -> Result<T>,

Read an ASN.1 SEQUENCE, creating a nested Reader for the body and calling the provided closure with it.

fn tlv_bytes(&mut self) -> Result<&'r [u8]>

Obtain a slice of bytes contain a complete TLV production suitable for parsing later.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<'a> Reader<'a> for SliceReader<'a>

impl<'i, 'r, R: Reader<'r>> Reader<'r> for NestedReader<'i, R>