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use bytes::{Buf, BufMut, Bytes, BytesMut};
use std::io;
use tokio_util::codec::{Decoder, Encoder};
#[derive(Debug, Clone, Copy)]
pub struct BytesCodec {
state: DecodeState,
raw: bool,
max_packet_length: usize,
}
#[derive(Debug, Clone, Copy)]
enum DecodeState {
Head,
Data(usize),
}
impl Default for BytesCodec {
fn default() -> Self {
Self::new()
}
}
impl BytesCodec {
pub fn new() -> Self {
Self {
state: DecodeState::Head,
raw: false,
max_packet_length: usize::MAX,
}
}
pub fn set_raw(&mut self) {
self.raw = true;
}
pub fn set_max_packet_length(&mut self, n: usize) {
self.max_packet_length = n;
}
fn decode_head(&mut self, src: &mut BytesMut) -> io::Result<Option<usize>> {
if src.is_empty() {
return Ok(None);
}
let head_len = ((src[0] & 0x3) + 1) as usize;
if src.len() < head_len {
return Ok(None);
}
let mut n = src[0] as usize;
if head_len > 1 {
n |= (src[1] as usize) << 8;
}
if head_len > 2 {
n |= (src[2] as usize) << 16;
}
if head_len > 3 {
n |= (src[3] as usize) << 24;
}
n >>= 2;
if n > self.max_packet_length {
return Err(io::Error::new(io::ErrorKind::InvalidData, "Too big packet"));
}
src.advance(head_len);
src.reserve(n);
Ok(Some(n))
}
fn decode_data(&self, n: usize, src: &mut BytesMut) -> io::Result<Option<BytesMut>> {
if src.len() < n {
return Ok(None);
}
Ok(Some(src.split_to(n)))
}
}
impl Decoder for BytesCodec {
type Item = BytesMut;
type Error = io::Error;
fn decode(&mut self, src: &mut BytesMut) -> Result<Option<BytesMut>, io::Error> {
if self.raw {
if !src.is_empty() {
let len = src.len();
return Ok(Some(src.split_to(len)));
} else {
return Ok(None);
}
}
let n = match self.state {
DecodeState::Head => match self.decode_head(src)? {
Some(n) => {
self.state = DecodeState::Data(n);
n
}
None => return Ok(None),
},
DecodeState::Data(n) => n,
};
match self.decode_data(n, src)? {
Some(data) => {
self.state = DecodeState::Head;
Ok(Some(data))
}
None => Ok(None),
}
}
}
impl Encoder<Bytes> for BytesCodec {
type Error = io::Error;
fn encode(&mut self, data: Bytes, buf: &mut BytesMut) -> Result<(), io::Error> {
if self.raw {
buf.reserve(data.len());
buf.put(data);
return Ok(());
}
if data.len() <= 0x3F {
buf.put_u8((data.len() << 2) as u8);
} else if data.len() <= 0x3FFF {
buf.put_u16_le((data.len() << 2) as u16 | 0x1);
} else if data.len() <= 0x3FFFFF {
let h = (data.len() << 2) as u32 | 0x2;
buf.put_u16_le((h & 0xFFFF) as u16);
buf.put_u8((h >> 16) as u8);
} else if data.len() <= 0x3FFFFFFF {
buf.put_u32_le((data.len() << 2) as u32 | 0x3);
} else {
return Err(io::Error::new(io::ErrorKind::InvalidInput, "Overflow"));
}
buf.extend(data);
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_codec1() {
let mut codec = BytesCodec::new();
let mut buf = BytesMut::new();
let mut bytes: Vec<u8> = Vec::new();
bytes.resize(0x3F, 1);
assert!(!codec.encode(bytes.into(), &mut buf).is_err());
let buf_saved = buf.clone();
assert_eq!(buf.len(), 0x3F + 1);
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0x3F);
assert_eq!(res[0], 1);
} else {
assert!(false);
}
let mut codec2 = BytesCodec::new();
let mut buf2 = BytesMut::new();
if let Ok(None) = codec2.decode(&mut buf2) {
} else {
assert!(false);
}
buf2.extend(&buf_saved[0..1]);
if let Ok(None) = codec2.decode(&mut buf2) {
} else {
assert!(false);
}
buf2.extend(&buf_saved[1..]);
if let Ok(Some(res)) = codec2.decode(&mut buf2) {
assert_eq!(res.len(), 0x3F);
assert_eq!(res[0], 1);
} else {
assert!(false);
}
}
#[test]
fn test_codec2() {
let mut codec = BytesCodec::new();
let mut buf = BytesMut::new();
let mut bytes: Vec<u8> = Vec::new();
assert!(!codec.encode("".into(), &mut buf).is_err());
assert_eq!(buf.len(), 1);
bytes.resize(0x3F + 1, 2);
assert!(!codec.encode(bytes.into(), &mut buf).is_err());
assert_eq!(buf.len(), 0x3F + 2 + 2);
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0);
} else {
assert!(false);
}
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0x3F + 1);
assert_eq!(res[0], 2);
} else {
assert!(false);
}
}
#[test]
fn test_codec3() {
let mut codec = BytesCodec::new();
let mut buf = BytesMut::new();
let mut bytes: Vec<u8> = Vec::new();
bytes.resize(0x3F - 1, 3);
assert!(!codec.encode(bytes.into(), &mut buf).is_err());
assert_eq!(buf.len(), 0x3F + 1 - 1);
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0x3F - 1);
assert_eq!(res[0], 3);
} else {
assert!(false);
}
}
#[test]
fn test_codec4() {
let mut codec = BytesCodec::new();
let mut buf = BytesMut::new();
let mut bytes: Vec<u8> = Vec::new();
bytes.resize(0x3FFF, 4);
assert!(!codec.encode(bytes.into(), &mut buf).is_err());
assert_eq!(buf.len(), 0x3FFF + 2);
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0x3FFF);
assert_eq!(res[0], 4);
} else {
assert!(false);
}
}
#[test]
fn test_codec5() {
let mut codec = BytesCodec::new();
let mut buf = BytesMut::new();
let mut bytes: Vec<u8> = Vec::new();
bytes.resize(0x3FFFFF, 5);
assert!(!codec.encode(bytes.into(), &mut buf).is_err());
assert_eq!(buf.len(), 0x3FFFFF + 3);
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0x3FFFFF);
assert_eq!(res[0], 5);
} else {
assert!(false);
}
}
#[test]
fn test_codec6() {
let mut codec = BytesCodec::new();
let mut buf = BytesMut::new();
let mut bytes: Vec<u8> = Vec::new();
bytes.resize(0x3FFFFF + 1, 6);
assert!(!codec.encode(bytes.into(), &mut buf).is_err());
let buf_saved = buf.clone();
assert_eq!(buf.len(), 0x3FFFFF + 4 + 1);
if let Ok(Some(res)) = codec.decode(&mut buf) {
assert_eq!(res.len(), 0x3FFFFF + 1);
assert_eq!(res[0], 6);
} else {
assert!(false);
}
let mut codec2 = BytesCodec::new();
let mut buf2 = BytesMut::new();
buf2.extend(&buf_saved[0..1]);
if let Ok(None) = codec2.decode(&mut buf2) {
} else {
assert!(false);
}
buf2.extend(&buf_saved[1..6]);
if let Ok(None) = codec2.decode(&mut buf2) {
} else {
assert!(false);
}
buf2.extend(&buf_saved[6..]);
if let Ok(Some(res)) = codec2.decode(&mut buf2) {
assert_eq!(res.len(), 0x3FFFFF + 1);
assert_eq!(res[0], 6);
} else {
assert!(false);
}
}
}
|
