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|
// -*- coding: utf-8 -*-
//
// Simple CMS
//
// Copyright (C) 2011-2024 Michael Büsch <m@bues.ch>
//
// Licensed under the Apache License version 2.0
// or the MIT license, at your option.
// SPDX-License-Identifier: Apache-2.0 OR MIT
use anyhow as ah;
use bincode::Options as _;
use serde::{Deserialize, Serialize};
pub const MSG_HDR_LEN: usize = 8;
pub const MAX_RX_BUF: usize = 1024 * 1024 * 64;
#[derive(Clone, Debug)]
pub enum DeserializeResult<M> {
Ok(M),
Pending(usize),
}
pub trait MsgSerde<M> {
fn msg_serialize(&self) -> ah::Result<Vec<u8>>;
fn try_msg_deserialize(buf: &[u8]) -> ah::Result<DeserializeResult<M>>;
}
#[inline]
pub fn bincode_config() -> impl bincode::Options {
bincode::DefaultOptions::new()
.with_limit(MAX_RX_BUF.try_into().unwrap())
.with_native_endian()
.with_fixint_encoding()
.reject_trailing_bytes()
}
/// Generic message header.
#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct MsgHdr {
magic: u32,
payload_len: u32,
}
impl MsgHdr {
#[inline]
pub fn new(magic: u32, payload_len: usize) -> Self {
Self {
magic,
payload_len: payload_len
.try_into()
.expect("MsgHdr: Payload length too long"),
}
}
#[inline]
pub fn magic(&self) -> u32 {
self.magic
}
#[inline]
pub fn len() -> usize {
debug_assert_eq!(
MSG_HDR_LEN,
bincode_config()
.serialized_size(&MsgHdr {
magic: 0,
payload_len: 0,
})
.unwrap()
.try_into()
.unwrap()
);
MSG_HDR_LEN
}
#[inline]
pub fn payload_len(&self) -> usize {
self.payload_len.try_into().unwrap()
}
}
#[macro_export]
macro_rules! impl_msg_serde {
($struct:ty, $magic:literal) => {
impl $crate::MsgSerde<$struct> for $struct {
fn msg_serialize(&self) -> anyhow::Result<Vec<u8>> {
use anyhow::Context as _;
use bincode::Options as _;
use $crate::{bincode_config, MsgHdr};
let mut payload = bincode_config().serialize(self)?;
let mut ret = bincode_config().serialize(&MsgHdr::new($magic, payload.len()))?;
ret.append(&mut payload);
Ok(ret)
}
fn try_msg_deserialize(buf: &[u8]) -> anyhow::Result<$crate::DeserializeResult<Msg>> {
use anyhow::Context as _;
use bincode::Options as _;
use $crate::{bincode_config, MsgHdr};
let hdr_len = MsgHdr::len();
if buf.len() < hdr_len {
Ok($crate::DeserializeResult::Pending(hdr_len - buf.len()))
} else {
let hdr: MsgHdr = bincode_config()
.deserialize(&buf[0..hdr_len])
.context("Deserialize MsgHdr")?;
if hdr.magic() != $magic {
return Err(anyhow::format_err!("Deserialize: Invalid magic code."));
}
let full_len = hdr_len
.checked_add(hdr.payload_len())
.context("Msg length overflow")?;
if buf.len() < full_len {
Ok($crate::DeserializeResult::Pending(full_len - buf.len()))
} else {
let msg = bincode_config()
.deserialize(&buf[hdr_len..full_len])
.context("Deserialize Msg")?;
Ok($crate::DeserializeResult::Ok(msg))
}
}
}
}
};
}
// vim: ts=4 sw=4 expandtab
|
