Struct Codec 

pub struct Codec { /* private fields */ }

A pea2pea codec that constrains every frame on the wire to a single, fixed payload size, regardless of the actual payload contents.

Wire format

+--------+------------+
| length |  payload   |
| (4 B)  | (frame_size)|
+--------+------------+

• length: a 4-byte big-endian unsigned integer. Always equal to frame_size for a well-formed frame; any other value causes the connection to be torn down by the decoder.
• payload: exactly frame_size bytes of frame data. The application is free to lay them out however it likes — random padding, structured records, or anything in between — because an observer cannot tell “what” is being sent, only “when”, “to whom”, and “how big” (and the last is constant).

Implementations

impl Codec

pub fn new(frame_size: usize, max_frame_size: usize) -> Self

Creates a codec that accepts frames of exactly frame_size payload bytes and rejects any frame larger than max_frame_size bytes (defensive DoS bound).

Panics

Panics if frame_size == 0 (the resulting codec would never produce a useful message).

pub fn frame_size(&self) -> usize

Returns the on-the-wire payload size this codec expects.

Trait Implementations

impl Decoder for Codec

type Item = BytesMut

The type of decoded frames.

type Error = Error

The type of unrecoverable frame decoding errors.

fn decode( &mut self, src: &mut BytesMut, ) -> Result<Option<Self::Item>, Self::Error>

Attempts to decode a frame from the provided buffer of bytes.

fn decode_eof( &mut self, buf: &mut BytesMut, ) -> Result<Option<Self::Item>, Self::Error>

A default method available to be called when there are no more bytes available to be read from the underlying I/O.

fn framed<T>(self, io: T) -> Framed<T, Self>

where T: AsyncRead + AsyncWrite, Self: Sized,

Provides a Stream and Sink interface for reading and writing to this Io object, using Decode and Encode to read and write the raw data.

impl Encoder<BytesMut> for Codec

type Error = Error

The type of encoding errors.

fn encode( &mut self, item: BytesMut, dst: &mut BytesMut, ) -> Result<(), Self::Error>

Encodes a frame into the buffer provided.