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use crate::codec::UserError;
use crate::error::Reason;
use crate::frame;
use crate::proto::*;
use std::task::{Context, Poll};
#[derive(Debug)]
pub(crate) struct Settings {
/// Our local SETTINGS sync state with the remote.
local: Local,
/// Received SETTINGS frame pending processing. The ACK must be written to
/// the socket first then the settings applied **before** receiving any
/// further frames.
remote: Option<frame::Settings>,
}
#[derive(Debug)]
enum Local {
/// We want to send these SETTINGS to the remote when the socket is ready.
ToSend(frame::Settings),
/// We have sent these SETTINGS and are waiting for the remote to ACK
/// before we apply them.
WaitingAck(frame::Settings),
/// Our local settings are in sync with the remote.
Synced,
}
impl Settings {
pub(crate) fn new(local: frame::Settings) -> Self {
Settings {
// We assume the initial local SETTINGS were flushed during
// the handshake process.
local: Local::WaitingAck(local),
remote: None,
}
}
pub(crate) fn recv_settings<T, B, C, P>(
&mut self,
frame: frame::Settings,
codec: &mut Codec<T, B>,
streams: &mut Streams<C, P>,
) -> Result<(), Error>
where
T: AsyncWrite + Unpin,
B: Buf,
C: Buf,
P: Peer,
{
if frame.is_ack() {
match &self.local {
Local::WaitingAck(local) => {
tracing::debug!("received settings ACK; applying {:?}", local);
if let Some(max) = local.max_frame_size() {
codec.set_max_recv_frame_size(max as usize);
}
if let Some(max) = local.max_header_list_size() {
codec.set_max_recv_header_list_size(max as usize);
}
if let Some(val) = local.header_table_size() {
codec.set_recv_header_table_size(val as usize);
}
streams.apply_local_settings(local)?;
self.local = Local::Synced;
Ok(())
}
Local::ToSend(..) | Local::Synced => {
// We haven't sent any SETTINGS frames to be ACKed, so
// this is very bizarre! Remote is either buggy or malicious.
proto_err!(conn: "received unexpected settings ack");
Err(Error::library_go_away(Reason::PROTOCOL_ERROR))
}
}
} else {
// We always ACK before reading more frames, so `remote` should
// always be none!
assert!(self.remote.is_none());
self.remote = Some(frame);
Ok(())
}
}
pub(crate) fn send_settings(&mut self, frame: frame::Settings) -> Result<(), UserError> {
assert!(!frame.is_ack());
match &self.local {
Local::ToSend(..) | Local::WaitingAck(..) => Err(UserError::SendSettingsWhilePending),
Local::Synced => {
tracing::trace!("queue to send local settings: {:?}", frame);
self.local = Local::ToSend(frame);
Ok(())
}
}
}
pub(crate) fn poll_send<T, B, C, P>(
&mut self,
cx: &mut Context,
dst: &mut Codec<T, B>,
streams: &mut Streams<C, P>,
) -> Poll<Result<(), Error>>
where
T: AsyncWrite + Unpin,
B: Buf,
C: Buf,
P: Peer,
{
if let Some(settings) = &self.remote {
if !dst.poll_ready(cx)?.is_ready() {
return Poll::Pending;
}
// Create an ACK settings frame
let frame = frame::Settings::ack();
// Buffer the settings frame
dst.buffer(frame.into()).expect("invalid settings frame");
tracing::trace!("ACK sent; applying settings");
streams.apply_remote_settings(settings)?;
if let Some(val) = settings.header_table_size() {
dst.set_send_header_table_size(val as usize);
}
if let Some(val) = settings.max_frame_size() {
dst.set_max_send_frame_size(val as usize);
}
}
self.remote = None;
match &self.local {
Local::ToSend(settings) => {
if !dst.poll_ready(cx)?.is_ready() {
return Poll::Pending;
}
// Buffer the settings frame
dst.buffer(settings.clone().into())
.expect("invalid settings frame");
tracing::trace!("local settings sent; waiting for ack: {:?}", settings);
self.local = Local::WaitingAck(settings.clone());
}
Local::WaitingAck(..) | Local::Synced => {}
}
Poll::Ready(Ok(()))
}
}