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use std::io::{BufRead, Read as _};
use crate::{
body_parser::{BodyParseError, BodyParseOutput, BodyParser},
CR, CRLF, LF,
};
const LENGTH_MAX_LEN: usize = 4; const DATA_DEFAULT_LEN: usize = 512;
#[derive(Default)]
pub struct ChunkedBodyParser {
state: State,
length_buf: Vec<u8>,
length: u16,
data_buf: Vec<u8>,
}
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
enum State {
Idle,
WaitLengthParse,
WaitDataParse,
WaitDataParsing,
WaitCRLFParse(ActionAfterCRLFParsed),
}
impl Default for State {
fn default() -> Self {
Self::Idle
}
}
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
enum ActionAfterCRLFParsed {
Continue,
Break,
}
impl ChunkedBodyParser {
pub fn new() -> Self {
Self {
length_buf: Vec::with_capacity(LENGTH_MAX_LEN),
data_buf: vec![0u8; DATA_DEFAULT_LEN],
..Default::default()
}
}
pub fn with_data_buf(data_buf: Vec<u8>) -> Self {
Self {
length_buf: Vec::with_capacity(LENGTH_MAX_LEN),
data_buf,
..Default::default()
}
}
}
impl BodyParser for ChunkedBodyParser {
fn parse<R: BufRead>(
&mut self,
r: &mut R,
body_buf: &mut Vec<u8>,
) -> Result<BodyParseOutput, BodyParseError> {
let mut take = r.take(0);
let mut parsed_num_bytes = 0_usize;
loop {
if self.state <= State::WaitLengthParse {
let end_bytes_len = 2_usize;
take.set_limit(LENGTH_MAX_LEN as u64 + end_bytes_len as u64);
self.length_buf.clear();
let n = take
.read_until(LF, &mut self.length_buf)
.map_err(BodyParseError::ReadError)?;
if n < end_bytes_len {
return Ok(BodyParseOutput::Partial(parsed_num_bytes));
}
if !self.length_buf[..n].ends_with(&[LF]) {
if n >= LENGTH_MAX_LEN {
return Err(BodyParseError::TooLongChunksOfLength);
} else {
return Ok(BodyParseOutput::Partial(parsed_num_bytes));
}
}
if !self.length_buf[..n - 1].ends_with(&[CR]) {
return Err(BodyParseError::InvalidCRLF);
}
let length_bytes = &self.length_buf[..n - end_bytes_len];
let length_str = core::str::from_utf8(length_bytes)
.map_err(|_| BodyParseError::InvalidChunksOfLength(None))?;
let length = u16::from_str_radix(length_str, 16)
.map_err(|err| BodyParseError::InvalidChunksOfLength(Some(err)))?;
self.length = length;
parsed_num_bytes += n;
if length == 0 {
self.state = State::WaitCRLFParse(ActionAfterCRLFParsed::Break);
} else {
self.state = State::WaitDataParse;
}
}
if self.state <= State::WaitDataParsing {
take.set_limit(self.length as u64);
let n = take
.read(&mut self.data_buf)
.map_err(BodyParseError::ReadError)?;
body_buf.extend_from_slice(&self.data_buf[..n]);
self.length -= n as u16;
parsed_num_bytes += n;
if self.length == 0 {
self.state = State::WaitCRLFParse(ActionAfterCRLFParsed::Continue);
} else {
self.state = State::WaitDataParsing;
return Ok(BodyParseOutput::Partial(parsed_num_bytes));
}
}
if let State::WaitCRLFParse(action) = &self.state {
let end_bytes_len = 2_usize;
take.set_limit(end_bytes_len as u64);
self.length_buf.clear();
let n = take
.read_until(LF, &mut self.length_buf)
.map_err(BodyParseError::ReadError)?;
if n < end_bytes_len {
return Ok(BodyParseOutput::Partial(parsed_num_bytes));
}
if &self.length_buf[..n] != CRLF {
return Err(BodyParseError::InvalidCRLF);
}
parsed_num_bytes += n;
match action {
ActionAfterCRLFParsed::Continue => {
self.state = State::WaitLengthParse;
continue;
}
ActionAfterCRLFParsed::Break => {
self.state = State::Idle;
break Ok(BodyParseOutput::Completed(parsed_num_bytes));
}
}
}
unreachable!()
}
}
}