mqtt_codec_kit/common/variable_header/
connect_ack_flags.rs

1use std::io::{self, Read, Write};
2
3use byteorder::{ReadBytesExt, WriteBytesExt};
4
5use crate::common::{Decodable, Encodable};
6
7/// Flags in `CONNACK` packet
8#[derive(Debug, Eq, PartialEq, Copy, Clone)]
9pub struct ConnackFlags {
10    pub session_present: bool,
11}
12
13impl ConnackFlags {
14    pub fn empty() -> ConnackFlags {
15        ConnackFlags {
16            session_present: false,
17        }
18    }
19}
20
21impl Encodable for ConnackFlags {
22    fn encode<W: Write>(&self, writer: &mut W) -> Result<(), io::Error> {
23        let code = self.session_present as u8;
24        writer.write_u8(code)
25    }
26
27    fn encoded_length(&self) -> u32 {
28        1
29    }
30}
31
32impl Decodable for ConnackFlags {
33    type Error = ConnectAckFlagsError;
34    type Cond = ();
35
36    fn decode_with<R: Read>(
37        reader: &mut R,
38        _rest: (),
39    ) -> Result<ConnackFlags, ConnectAckFlagsError> {
40        let code = reader.read_u8()?;
41        if code & !1 != 0 {
42            return Err(ConnectAckFlagsError::InvalidReservedFlag);
43        }
44
45        Ok(ConnackFlags {
46            session_present: code == 1,
47        })
48    }
49}
50
51#[derive(Debug, thiserror::Error)]
52#[error(transparent)]
53pub enum ConnectAckFlagsError {
54    IoError(#[from] io::Error),
55    #[error("invalid reserved flag")]
56    InvalidReservedFlag,
57}