embedded-mqtt 0.1.0

no_std encoder/decoder for MQTT 3.1.1 protocol packets for embedded devices.
Documentation 
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#![allow(warnings)]

use core::result::Result;

use crate::{
    status::Status,
    error::{DecodeError, EncodeError},
    codec::{self, Decodable, Encodable},
    variable_header::connect::Flags,
};

#[derive(Debug)]
pub struct Will<'buf> {
    topic: &'buf str,
    message: &'buf [u8],
}

impl<'buf> Decodable<'buf> for Will<'buf> {
    fn decode(bytes: &'buf [u8]) -> Result<Status<(usize, Will<'buf>)>, DecodeError> {
        let offset = 0;
        let (offset, topic) = read!(codec::string::parse_string, bytes, offset);
        let (offset, message) = read!(codec::values::parse_bytes, bytes, offset);

        Ok(Status::Complete((offset, Will {
            topic,
            message,
        })))
    }
}

impl<'buf> Encodable for Will<'buf> {
    fn encoded_len(&self) -> usize {
        2 + self.topic.len() + 2 + self.message.len()
    }

    fn encode(&self, bytes: &mut [u8]) -> Result<usize, EncodeError> {
        let offset = 0;
        let offset = codec::string::encode_string(self.topic, &mut bytes[offset..])?;
        let offset = codec::values::encode_bytes(self.message, &mut bytes[offset..])?;
        Ok(offset)
    }
}

impl<'buf> Will<'buf> {
    pub fn new(topic: &'buf str, message: &'buf [u8]) -> Self {
        Will {
            topic,
            message,
        }
    }
}

#[derive(Debug)]
pub struct Connect<'buf> {
    client_id: &'buf str,
    will: Option<Will<'buf>>,
    username: Option<&'buf str>,
    password: Option<&'buf [u8]>,
}

impl<'buf> Connect<'buf> {
    pub fn new(client_id: &'buf str, will: Option<Will<'buf>>, username: Option<&'buf str>, password: Option<&'buf [u8]>) -> Self {
        Connect {
            client_id,
            will,
            username,
            password,
        }
    }
}

impl<'buf> Connect<'buf> {
    pub fn decode(flags: Flags, bytes: &'buf [u8]) -> Result<Status<(usize, Self)>, DecodeError> {
        let offset = 0;

        let (offset, client_id) = read!(codec::string::parse_string, bytes, offset);

        let (offset, will) = if flags.has_will() {
            let (offset, will) = read!(Will::decode, bytes, offset);
            (offset, Some(will))
        } else {
            (offset, None)
        };

        let (offset, username) = if flags.has_username() {
            let (offset, username) = read!(codec::string::parse_string, bytes, offset);
            (offset, Some(username))
        } else {
            (offset, None)
        };

        let (offset, password) = if flags.has_password() {
            let (offset, password) = read!(codec::values::parse_bytes, bytes, offset);
            (offset, Some(bytes))
        } else {
            (offset, None)
        };

        Ok(Status::Complete((offset, Connect {
            client_id,
            will,
            username,
            password,
        })))
    }
}

impl<'buf> Encodable for Connect<'buf> {
    fn encoded_len(&self) -> usize {
        self.client_id.encoded_len() +
            self.will.as_ref().map(|w| w.encoded_len()).unwrap_or(0) +
            self.username.as_ref().map(|u| u.encoded_len()).unwrap_or(0) +
            self.password.as_ref().map(|p| p.encoded_len()).unwrap_or(0)
    }

    fn encode(&self, bytes: &mut [u8]) -> Result<usize, EncodeError> {
        let offset = 0;

        let offset = codec::string::encode_string(self.client_id, &mut bytes[offset..])?;
        let offset = if let Some(ref will) = self.will {
            will.encode(&mut bytes[offset..])?
        } else {
            offset
        };

        let offset = if let Some(username) = self.username {
            codec::string::encode_string(username, &mut bytes[offset..])?
        } else {
            offset
        };

        let offset = if let Some(password) = self.password {
            codec::values::encode_bytes(password, &mut bytes[offset..])?
        } else {
            offset
        };

        Ok(offset)
    }
}