use tokio::io::{AsyncRead, AsyncWrite};
use tokio::sync::mpsc;
use crate::core::session::decompress::BodyLimit;
use crate::h2::error::{ErrorCode, H2Error};
use crate::h2::stream_state::StreamEvent;
use super::*;
mod frames;
mod headers;
const RECV_WINDOW_VIOLATION_SLACK: i64 = 16 * 1024;
type Failure = (H2Error, ErrorCode);
enum Intake {
NoStream,
Illegal(H2Error),
Taken {
queued: usize,
failure: Option<Failure>,
},
}
fn enforce_odd(sid: u32) -> Result<(), H2Error> {
if sid == 0 || sid.is_multiple_of(2) {
return Err(H2Error::Connection {
code: ErrorCode::ProtocolError,
reason: format!(
"peer used server-initiated stream id {sid} for a client-expected frame"
),
});
}
Ok(())
}
fn forward_chunk(actor: &mut StreamActor, d: &DataFrame) -> Result<usize, Failure> {
let Some(ResponseSink::StreamingEx { body_tx, .. }) = actor.response_tx.as_ref() else {
return Ok(0);
};
if d.data.is_empty() {
return Ok(0);
}
let sent = if actor.stalled.is_empty() {
body_tx.try_send(Ok(d.data.clone()))
} else {
Err(mpsc::error::TrySendError::Full(Ok(d.data.clone())))
};
match sent {
Ok(()) => Ok(0),
Err(mpsc::error::TrySendError::Full(_)) => {
actor.stalled.push_back(d.data.clone());
Ok(1)
}
Err(mpsc::error::TrySendError::Closed(_)) => Err((
H2Error::Stream {
stream_id: d.stream_id,
code: ErrorCode::Cancel,
},
ErrorCode::Cancel,
)),
}
}
fn buffer_chunk(actor: &mut StreamActor, d: &DataFrame, max_body: usize) -> Result<usize, Failure> {
if actor.body.len() + d.data.len() > max_body {
return Err((
H2Error::Io(BodyLimit::session(max_body).into_io()),
ErrorCode::Cancel,
));
}
actor.body.extend_from_slice(&d.data);
Ok(0)
}
fn store_chunk(actor: &mut StreamActor, d: &DataFrame, max_body: usize) -> Result<usize, Failure> {
if actor.drop_body {
Ok(0)
} else if matches!(actor.response_tx, Some(ResponseSink::StreamingEx { .. })) {
forward_chunk(actor, d)
} else {
buffer_chunk(actor, d, max_body)
}
}
fn charge_stream_window(actor: &mut StreamActor, stream_id: u32, len: i64) -> Option<Failure> {
actor.recv_window -= len;
if actor.recv_window >= -RECV_WINDOW_VIOLATION_SLACK {
return None;
}
Some((
H2Error::Stream {
stream_id,
code: ErrorCode::FlowControlError,
},
ErrorCode::FlowControlError,
))
}
fn accept_data(actor: &mut StreamActor, d: &DataFrame, len: i64, max_body: usize) -> Intake {
let event = StreamEvent::RecvData {
end_stream: d.end_stream,
};
if let Err(e) = actor.state.transition(event) {
actor.recv_window -= len;
return Intake::Illegal(map_state_err(d.stream_id, e));
}
actor.recv_len = actor.recv_len.saturating_add(d.data.len() as u64);
let stored = store_chunk(actor, d, max_body);
let overrun = charge_stream_window(actor, d.stream_id, len);
match stored {
Ok(queued) => Intake::Taken {
queued,
failure: overrun,
},
Err(failure) => Intake::Taken {
queued: 0,
failure: Some(failure),
},
}
}
impl<T: AsyncRead + AsyncWrite + Unpin + Send + 'static> Driver<T> {
pub(super) async fn on_inbound_frame(&mut self, frame: Frame) -> Result<(), H2Error> {
match frame {
Frame::Headers(h) => {
enforce_odd(h.stream_id)?;
self.on_headers(h).await
}
Frame::Data(d) => {
enforce_odd(d.stream_id)?;
self.on_data(d).await
}
Frame::Settings(s) => self.on_settings(s).await,
Frame::WindowUpdate(w) => self.on_window(w).await,
Frame::Ping(p) => self.on_ping(p).await,
Frame::GoAway(g) => self.on_goaway(g),
Frame::RstStream(r) => self.on_rst(r),
Frame::PushPromise(pp) => self.on_push(pp).await,
Frame::Continuation { .. } => Err(H2Error::Connection {
code: ErrorCode::ProtocolError,
reason: "unexpected CONTINUATION".into(),
}),
Frame::Priority | Frame::Unknown => Ok(()),
}
}
pub(super) async fn on_data(&mut self, d: DataFrame) -> Result<(), H2Error> {
let stream_id = d.stream_id;
let len = d.wire_len as i64;
self.charge_conn_window(len)?;
match self.receive_data(&d, len) {
Intake::NoStream => self.maybe_top_up_conn_window().await,
Intake::Illegal(err) => self.reject_data(stream_id, err).await,
Intake::Taken { queued, failure } => {
self.stalled += queued;
match failure {
Some((err, code)) => self.abort_data(stream_id, err, code).await,
None => self.settle_data(stream_id, d.end_stream).await,
}
}
}
}
fn charge_conn_window(&mut self, len: i64) -> Result<(), H2Error> {
self.conn_recv_window -= len;
if self.conn_recv_window < -RECV_WINDOW_VIOLATION_SLACK {
return Err(H2Error::Connection {
code: ErrorCode::FlowControlError,
reason: format!(
"peer overran connection receive window by {} bytes",
-self.conn_recv_window
),
});
}
Ok(())
}
fn receive_data(&mut self, d: &DataFrame, len: i64) -> Intake {
let max_body = self.config.max_response_body_bytes;
match self.streams.get_mut(d.stream_id) {
Some(actor) => accept_data(actor, d, len, max_body),
None => Intake::NoStream,
}
}
async fn reject_data(&mut self, stream_id: u32, err: H2Error) -> Result<(), H2Error> {
self.fail_stream(stream_id, err);
let _ = self
.writer
.write_rst_stream(stream_id, ErrorCode::StreamClosed)
.await;
self.maybe_top_up_conn_window().await
}
async fn abort_data(
&mut self,
stream_id: u32,
err: H2Error,
code: ErrorCode,
) -> Result<(), H2Error> {
let _ = self.writer.write_rst_stream(stream_id, code).await;
self.fail_stream(stream_id, err);
self.maybe_top_up_conn_window().await
}
async fn settle_data(&mut self, stream_id: u32, end_stream: bool) -> Result<(), H2Error> {
self.maybe_top_up_conn_window().await?;
self.maybe_top_up_stream_window(stream_id).await?;
if end_stream {
self.finish_remote(stream_id).await?;
}
Ok(())
}
}
impl<T: AsyncRead + AsyncWrite + Unpin + Send + 'static> Driver<T> {
pub(super) async fn maybe_top_up_conn_window(&mut self) -> Result<(), H2Error> {
let initial = self.config.initial_connection_window_size as i64;
if self.conn_recv_window < initial / 2 {
let increment = (initial - self.conn_recv_window).clamp(1, 0x7FFF_FFFF) as u32;
self.writer
.write_window_update(&WindowUpdateFrame {
stream_id: 0,
increment,
})
.await?;
self.conn_recv_window += increment as i64;
}
Ok(())
}
pub(super) async fn maybe_top_up_stream_window(
&mut self,
stream_id: u32,
) -> Result<(), H2Error> {
let initial = self.config.advertised_initial_window_size() as i64;
let needs_update = self
.streams
.get(stream_id)
.map(|a| a.stalled.is_empty() && a.recv_window < initial / 2)
.unwrap_or(false);
if needs_update {
let current = self
.streams
.get(stream_id)
.map(|a| a.recv_window)
.unwrap_or(0);
let increment = (initial - current).clamp(1, 0x7FFF_FFFF) as u32;
self.writer
.write_window_update(&WindowUpdateFrame {
stream_id,
increment,
})
.await?;
if let Some(actor) = self.streams.get_mut(stream_id) {
actor.recv_window += increment as i64;
}
}
Ok(())
}
}