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use crate::body::common::length_from_headers;
use futures::prelude::*;
use pin_project::pin_project;
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
#[pin_project]
pub struct BodyDecode<IO: AsyncRead + Unpin> {
transport: IO,
state: BodyDecodeState,
}
impl<IO: AsyncRead + Unpin> BodyDecode<IO> {
pub fn from_headers(headers: &http::header::HeaderMap, transport: IO) -> anyhow::Result<Self> {
Ok(BodyDecodeState::from_headers(headers)?.restore(transport))
}
pub fn new(transport: IO, length: Option<u64>) -> Self {
BodyDecodeState::new(length).restore(transport)
}
pub fn checkpoint(self) -> (IO, BodyDecodeState) {
(self.transport, self.state)
}
}
impl<IO: AsyncRead + Unpin> AsyncRead for BodyDecode<IO> {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
let this = self.project();
this.state.poll_read(this.transport, cx, buf)
}
}
pub struct BodyDecodeState {
parser_state: Parser,
_compression_state: (),
remaining: u64,
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum Parser {
FixedLength,
Chunked(ChunkState),
Failed,
Done,
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum ChunkState {
Size,
SizeLF,
Content,
ContentCR,
ContentLF,
EndCR,
EndLF,
}
fn err_kind<T>(kind: io::ErrorKind) -> Poll<io::Result<T>> {
Poll::Ready(Err(kind.into()))
}
impl BodyDecodeState {
pub fn from_headers(headers: &http::header::HeaderMap) -> anyhow::Result<Self> {
Ok(Self::new(length_from_headers(headers)?))
}
pub fn new(length: Option<u64>) -> Self {
let (parser_state, remaining) = match length {
Some(0) => (Parser::Done, 0),
Some(length) => (Parser::FixedLength, length),
None => (Parser::Chunked(ChunkState::Size), 0),
};
Self {
parser_state,
_compression_state: (),
remaining,
}
}
pub fn restore<IO: AsyncRead + Unpin>(self, transport: IO) -> BodyDecode<IO> {
BodyDecode {
transport,
state: self,
}
}
fn poll_read<IO: AsyncRead + Unpin>(
&mut self,
mut transport: IO,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
loop {
let max_read_size = match self.parser_state {
Parser::Failed => return err_kind(io::ErrorKind::BrokenPipe),
Parser::Done => return Poll::Ready(Ok(0)),
Parser::FixedLength | Parser::Chunked(ChunkState::Content) => {
if buf.len() as u64 > self.remaining {
self.remaining as usize
} else {
buf.len()
}
}
Parser::Chunked(chunked_state) => {
let mut next = [0u8];
match Pin::new(&mut transport).poll_read(cx, &mut next) {
Poll::Ready(Err(err)) => {
self.parser_state = Parser::Failed;
return Poll::Ready(Err(err));
}
Poll::Pending => return Poll::Pending,
Poll::Ready(Ok(0)) => {
self.parser_state = Parser::Failed;
return err_kind(io::ErrorKind::UnexpectedEof);
}
Poll::Ready(Ok(_)) => {
self.parser_state = match (chunked_state, next[0]) {
(ChunkState::Size, b'\r') => Parser::Chunked(ChunkState::SizeLF),
(ChunkState::Size, hex_digit) => {
self.remaining *= 16;
self.remaining += match hex_digit {
b'0'..=b'9' => 0 + hex_digit - b'0',
b'a'..=b'f' => 10 + hex_digit - b'a',
b'A'..=b'F' => 10 + hex_digit - b'A',
_ => {
self.parser_state = Parser::Failed;
return err_kind(io::ErrorKind::InvalidData);
}
} as u64;
Parser::Chunked(ChunkState::Size)
}
(ChunkState::SizeLF, b'\n') => match self.remaining {
0 => Parser::Chunked(ChunkState::EndCR),
_ => Parser::Chunked(ChunkState::Content),
},
(ChunkState::Content, _) => unreachable!(),
(ChunkState::ContentCR, b'\r') => {
Parser::Chunked(ChunkState::ContentLF)
}
(ChunkState::ContentLF, b'\n') => Parser::Chunked(ChunkState::Size),
(ChunkState::EndCR, b'\r') => Parser::Chunked(ChunkState::EndLF),
(ChunkState::EndLF, b'\n') => Parser::Done,
(_, _) => return err_kind(io::ErrorKind::InvalidData),
}
}
}
continue;
}
};
return match Pin::new(&mut transport).poll_read(cx, &mut buf[0..max_read_size]) {
Poll::Ready(Err(err)) => {
self.parser_state = Parser::Failed;
Poll::Ready(Err(err))
}
Poll::Ready(Ok(0)) => {
self.parser_state = Parser::Failed;
err_kind(io::ErrorKind::UnexpectedEof)
}
Poll::Ready(Ok(n)) => {
self.remaining -= n as u64;
if self.remaining == 0 {
self.parser_state = match self.parser_state {
Parser::FixedLength => Parser::Done,
Parser::Chunked(ChunkState::Content) => {
Parser::Chunked(ChunkState::ContentCR)
}
_ => unreachable!(),
}
}
Poll::Ready(Ok(n))
}
Poll::Pending => Poll::Pending,
};
}
}
}
