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use bytes::{buf::Buf, BytesMut};
use ntex_codec::{Decoder, Encoder};
use super::{decode, encode, Packet, Publish};
use crate::error::{DecodeError, EncodeError};
use crate::types::{FixedHeader, QoS};
use crate::utils::decode_variable_length;
#[derive(Debug)]
pub struct Codec {
state: DecodeState,
max_size: u32,
}
#[derive(Debug, Clone, Copy)]
enum DecodeState {
FrameHeader,
Frame(FixedHeader),
}
impl Codec {
pub fn new() -> Self {
Codec {
state: DecodeState::FrameHeader,
max_size: 0,
}
}
pub fn max_size(mut self, size: u32) -> Self {
self.max_size = size;
self
}
pub fn set_max_size(&mut self, size: u32) {
self.max_size = size;
}
}
impl Default for Codec {
fn default() -> Self {
Self::new()
}
}
impl Decoder for Codec {
type Item = Packet;
type Error = DecodeError;
fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, DecodeError> {
loop {
match self.state {
DecodeState::FrameHeader => {
if src.len() < 2 {
return Ok(None);
}
let src_slice = src.as_ref();
let first_byte = src_slice[0];
match decode_variable_length(&src_slice[1..])? {
Some((remaining_length, consumed)) => {
if self.max_size != 0 && self.max_size < remaining_length {
return Err(DecodeError::MaxSizeExceeded);
}
src.advance(consumed + 1);
self.state = DecodeState::Frame(FixedHeader {
first_byte,
remaining_length,
});
let remaining_length = remaining_length as usize;
if src.len() < remaining_length {
src.reserve(remaining_length);
return Ok(None);
}
}
None => {
return Ok(None);
}
}
}
DecodeState::Frame(fixed) => {
if src.len() < fixed.remaining_length as usize {
return Ok(None);
}
let packet_buf = src.split_to(fixed.remaining_length as usize);
let packet = decode::decode_packet(packet_buf.freeze(), fixed.first_byte)?;
self.state = DecodeState::FrameHeader;
src.reserve(2);
return Ok(Some(packet));
}
}
}
}
}
impl Encoder for Codec {
type Item = Packet;
type Error = EncodeError;
fn encode(&mut self, item: Self::Item, dst: &mut BytesMut) -> Result<(), EncodeError> {
if let Packet::Publish(Publish { qos, packet_id, .. }) = item {
if (qos == QoS::AtLeastOnce || qos == QoS::ExactlyOnce) && packet_id.is_none() {
return Err(EncodeError::PacketIdRequired);
}
}
let content_size = encode::get_encoded_size(&item);
dst.reserve(content_size + 5);
encode::encode(&item, dst, content_size as u32)?;
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use bytes::Bytes;
use bytestring::ByteString;
#[test]
fn test_max_size() {
let mut codec = Codec::new().max_size(5);
let mut buf = BytesMut::new();
buf.extend_from_slice(b"\0\x09");
assert_eq!(codec.decode(&mut buf), Err(DecodeError::MaxSizeExceeded));
}
#[test]
fn test_packet() {
let mut codec = Codec::new();
let mut buf = BytesMut::new();
let pkt = Publish {
dup: false,
retain: false,
qos: QoS::AtMostOnce,
topic: ByteString::from_static("/test"),
packet_id: None,
payload: Bytes::from(Vec::from("a".repeat(260 * 1024))),
};
codec
.encode(Packet::Publish(pkt.clone()), &mut buf)
.unwrap();
let pkt2 = if let Packet::Publish(v) = codec.decode(&mut buf).unwrap().unwrap() {
v
} else {
panic!()
};
assert_eq!(pkt, pkt2);
}
}