tokio_xmpp/stanzastream/negotiation.rs
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// Copyright (c) 2019 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
use core::ops::ControlFlow::{self, Break, Continue};
use core::pin::Pin;
use core::task::{Context, Poll};
use std::io;
use futures::{ready, Sink, Stream};
use xmpp_parsers::{
bind::{BindQuery, BindResponse},
iq::{Iq, IqType},
jid::{FullJid, Jid},
sm,
stream_error::{DefinedCondition, StreamError},
stream_features::StreamFeatures,
};
use crate::xmlstream::{ReadError, XmppStreamElement};
use crate::Stanza;
use super::queue::{QueueEntry, TransmitQueue};
use super::stream_management::*;
use super::worker::{parse_error_to_stream_error, XmppStream};
static BIND_REQ_ID: &str = "resource-binding";
pub(super) enum NegotiationState {
/// Send request to enable or resume stream management.
SendSmRequest {
/// Stream management state to use. If present, resumption will be
/// attempted. Otherwise, a fresh session will be established.
sm_state: Option<SmState>,
/// If the stream has been freshly bound, we carry the bound JID along
/// with us.
bound_jid: Option<FullJid>,
},
/// Await the response to the SM enable/resume request.
ReceiveSmResponse {
/// State to use.
sm_state: Option<SmState>,
/// If the stream has been freshly bound, we carry the bound JID along
/// with us.
bound_jid: Option<FullJid>,
},
/// Send a new request to bind to a resource.
SendBindRequest { sm_supported: bool },
/// Receive the bind response.
ReceiveBindResponse { sm_supported: bool },
}
/// The ultimate result of a stream negotiation.
pub(super) enum NegotiationResult {
/// An unplanned disconnect happened or a stream error was received from
/// the remote party.
Disconnect {
/// Stream management state for a later resumption attempt.
sm_state: Option<SmState>,
/// I/O error which came along the disconnect.
error: io::Error,
},
/// The negotiation completed successfully, but the stream was reset (i.e.
/// stream management and all session state was lost).
StreamReset {
/// Stream management state. This may still be non-None if the new
/// stream has successfully negotiated stream management.
sm_state: Option<SmState>,
/// The JID to which the stream is now bound.
bound_jid: Jid,
},
/// The negotiation completed successfully and a previous session was
/// resumed.
StreamResumed {
/// Negotiated stream management state.
sm_state: SmState,
},
/// The negotiation failed and we need to emit a stream error.
///
/// **Note:** Stream errors *received* from the peer are signalled using
/// [`Self::Disconnect`] instead, with an I/O error of kind `Other`.
StreamError {
/// Stream error to send to the remote party with details about the
/// failure.
error: StreamError,
},
}
impl NegotiationState {
pub fn new(features: &StreamFeatures, sm_state: Option<SmState>) -> io::Result<Self> {
match sm_state {
Some(sm_state) => {
if features.stream_management.is_some() {
return Ok(Self::SendSmRequest {
sm_state: Some(sm_state),
bound_jid: None,
});
} else {
log::warn!("Peer is not offering stream management anymore. Dropping state.");
}
}
None => (),
}
if !features.can_bind() {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
"Peer is not offering the bind feature. Cannot proceed with stream negotiation.",
));
}
Ok(Self::SendBindRequest {
sm_supported: features.stream_management.is_some(),
})
}
fn flush(stream: Pin<&mut XmppStream>, cx: &mut Context) -> ControlFlow<io::Error, ()> {
match <XmppStream as Sink<&XmppStreamElement>>::poll_flush(stream, cx) {
Poll::Pending | Poll::Ready(Ok(())) => Continue(()),
Poll::Ready(Err(error)) => Break(error),
}
}
pub fn advance(
&mut self,
mut stream: Pin<&mut XmppStream>,
jid: &Jid,
transmit_queue: &mut TransmitQueue<QueueEntry>,
cx: &mut Context<'_>,
) -> Poll<ControlFlow<NegotiationResult, Option<Stanza>>> {
// When sending requests, we need to wait for the stream to become
// ready to send and then send the corresponding request.
// Note that if this wasn't a fresh stream (which it always is!),
// doing it in this kind of simplex fashion could lead to deadlocks
// (because we are blockingly sending without attempting to receive: a
// peer could stop receiving from our side if their tx buffer was too
// full or smth). However, because this stream is fresh, we know that
// our tx buffers are empty enough that this will succeed quickly, so
// that we can proceed.
// TODO: define a deadline for negotiation.
match self {
Self::SendBindRequest { sm_supported } => {
match ready!(<XmppStream as Sink<&Stanza>>::poll_ready(
stream.as_mut(),
cx
)) {
// We can send.
Ok(()) => (),
// Stream broke horribly.
Err(error) => {
return Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: None,
error,
}))
}
};
let resource = jid.resource().map(|x| x.as_str().to_owned());
let stanza = Iq::from_set(BIND_REQ_ID, BindQuery::new(resource));
match stream.start_send(&stanza) {
Ok(()) => (),
Err(e) => panic!("failed to serialize BindQuery: {}", e),
};
*self = Self::ReceiveBindResponse {
sm_supported: *sm_supported,
};
Poll::Ready(Continue(None))
}
Self::ReceiveBindResponse { sm_supported } => {
match Self::flush(stream.as_mut(), cx) {
Break(error) => {
return Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: None,
error,
}))
}
Continue(()) => (),
}
let item = ready!(stream.poll_next(cx));
let item = item.unwrap_or_else(|| {
Err(ReadError::HardError(io::Error::new(
io::ErrorKind::UnexpectedEof,
"eof before stream footer",
)))
});
match item {
Ok(XmppStreamElement::Stanza(data)) => match data {
Stanza::Iq(iq) if iq.id == BIND_REQ_ID => {
let error = match iq.payload {
IqType::Result(Some(payload)) => {
match BindResponse::try_from(payload) {
Ok(v) => {
let bound_jid = v.into();
if *sm_supported {
*self = Self::SendSmRequest {
sm_state: None,
bound_jid: Some(bound_jid),
};
return Poll::Ready(Continue(None));
} else {
return Poll::Ready(Break(
NegotiationResult::StreamReset {
sm_state: None,
bound_jid: Jid::from(bound_jid),
},
));
}
}
Err(e) => e.to_string(),
}
}
IqType::Result(None) => "Bind response has no payload".to_owned(),
_ => "Unexpected IQ type in response to bind request".to_owned(),
};
log::warn!("Received IQ matching the bind request, but parsing failed ({error})! Emitting stream error.");
Poll::Ready(Break(NegotiationResult::StreamError {
error: StreamError {
condition: DefinedCondition::UndefinedCondition,
text: Some((None, error)),
application_specific: vec![super::error::ParseError.into()],
},
}))
}
st => {
log::warn!("Received unexpected stanza before response to bind request: {st:?}. Dropping.");
Poll::Ready(Continue(None))
}
},
Ok(XmppStreamElement::StreamError(error)) => {
log::debug!("Received stream:error, failing stream and discarding any stream management state.");
let error = io::Error::new(io::ErrorKind::Other, error);
transmit_queue.fail(&(&error).into());
Poll::Ready(Break(NegotiationResult::Disconnect {
error,
sm_state: None,
}))
}
Ok(other) => {
log::warn!("Received unsupported stream element during bind: {other:?}. Emitting stream error.");
Poll::Ready(Break(NegotiationResult::StreamError {
error: StreamError {
condition: DefinedCondition::UnsupportedStanzaType,
text: None,
application_specific: vec![],
},
}))
}
// Soft timeouts during negotiation are a bad sign
// (because we already prompted the server to send
// something and are waiting for it), but also nothing
// to write home about.
Err(ReadError::SoftTimeout) => Poll::Ready(Continue(None)),
// Parse errors during negotiation cause an unconditional
// stream error.
Err(ReadError::ParseError(e)) => {
Poll::Ready(Break(NegotiationResult::StreamError {
error: parse_error_to_stream_error(e),
}))
}
// I/O errors cause the stream to be considered
// broken; we drop it and send a Disconnect event with
// the error embedded.
Err(ReadError::HardError(error)) => {
Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: None,
error,
}))
}
// Stream footer during negotation is really weird.
// We kill the stream immediately with an error
// (but allow preservation of the SM state).
Err(ReadError::StreamFooterReceived) => {
Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: None,
error: io::Error::new(
io::ErrorKind::InvalidData,
"stream footer received during negotation",
),
}))
}
}
}
Self::SendSmRequest {
sm_state,
bound_jid,
} => {
match ready!(<XmppStream as Sink<&XmppStreamElement>>::poll_ready(
stream.as_mut(),
cx
)) {
// We can send.
Ok(()) => (),
// Stream broke horribly.
Err(error) => {
return Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: sm_state.take(),
error,
}))
}
};
let nonza = if let Some((id, inbound_ctr)) =
sm_state.as_ref().and_then(|x| x.resume_info())
{
// Attempt resumption
sm::Nonza::Resume(sm::Resume {
h: inbound_ctr,
previd: sm::StreamId(id.to_owned()),
})
} else {
// Attempt enabling
sm::Nonza::Enable(sm::Enable {
max: None,
resume: true,
})
};
match stream.start_send(&XmppStreamElement::SM(nonza)) {
Ok(()) => (),
Err(e) => {
// We panic here, instead of returning an
// error, because after we confirmed via
// poll_ready that the stream is ready to
// send, the only error returned by start_send
// can be caused by our data.
panic!("Failed to send SM nonza: {}", e);
}
}
*self = Self::ReceiveSmResponse {
sm_state: sm_state.take(),
bound_jid: bound_jid.take(),
};
// Ask caller to poll us again immediately in order to
// start flushing the stream.
Poll::Ready(Continue(None))
}
Self::ReceiveSmResponse {
sm_state,
bound_jid,
} => {
match Self::flush(stream.as_mut(), cx) {
Break(error) => {
return Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: sm_state.take(),
error,
}))
}
Continue(()) => (),
}
// So the difficulty here is that there's a possibility
// that we receive non-SM data while the SM negotiation
// is going on.
let item = ready!(stream.poll_next(cx));
let item = item.unwrap_or_else(|| {
Err(ReadError::HardError(io::Error::new(
io::ErrorKind::UnexpectedEof,
"eof before stream footer",
)))
});
match item {
// Pre-SM data. Note that we mustn't count this while we
// are still in negotiating state: we transit to
// [`Self::Ready`] immediately after we got the
// `<resumed/>` or `<enabled/>`, and before we got that,
// counting inbound stanzas is definitely wrong (see e.g.
// aioxmpp commit 796aa32).
Ok(XmppStreamElement::Stanza(data)) => Poll::Ready(Continue(Some(data))),
Ok(XmppStreamElement::SM(sm::Nonza::Enabled(enabled))) => {
if sm_state.is_some() {
// Okay, the peer violated the stream management
// protocol here (or we have a bug).
log::warn!(
"Received <enabled/>, but we also have previous SM state. One of us has a bug here (us or the peer) and I'm not sure which it is. If you can reproduce this, please re-run with trace loglevel and provide the logs. Attempting to proceed with a fresh session.",
);
}
// We must emit Reset here because this is a
// fresh stream and we did not resume.
Poll::Ready(Break(NegotiationResult::StreamReset {
sm_state: Some(enabled.into()),
bound_jid: bound_jid.take().expect("State machine error: no bound_jid available in SM negotiation.").into(),
}))
}
Ok(XmppStreamElement::SM(sm::Nonza::Resumed(resumed))) => match sm_state.take()
{
Some(mut sm_state) => {
// Yay!
match sm_state.resume(resumed.h) {
Ok(to_retransmit) => transmit_queue.requeue_all(to_retransmit),
Err(e) => {
// We kill the stream with an error
log::error!("Resumption failed: {e}");
return Poll::Ready(Break(NegotiationResult::StreamError {
error: e.into(),
}));
}
}
Poll::Ready(Break(NegotiationResult::StreamResumed { sm_state }))
}
None => {
// Okay, the peer violated the stream management
// protocol here (or we have a bug).
// Unlike the
// received-enabled-but-attempted-to-resume
// situation, we do not have enough information to
// proceed without having the stream break soon.
// (If we proceeded without a SM state, we would
// have the stream die as soon as the peer
// requests our counters).
// We thus terminate the stream with an error.
// We must emit Reset here because this is a fresh
// stream and we did not resume.
Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: None,
error: io::Error::new(io::ErrorKind::InvalidData, "Peer replied to <sm:enable/> request with <sm:resumed/> response"),
}))
}
},
Ok(XmppStreamElement::SM(sm::Nonza::Failed(failed))) => match sm_state {
Some(sm_state) => {
log::debug!("Received <sm:failed/> in response to resumption request. Discarding SM data and attempting to renegotiate.");
if let Some(h) = failed.h {
// This is only an optimization anyway, so
// we can also just ignore this.
let _: Result<_, _> = sm_state.remote_acked(h);
}
*self = Self::SendBindRequest { sm_supported: true };
Poll::Ready(Continue(None))
}
None => {
log::warn!("Received <sm:failed/> in response to enable request. Proceeding without stream management.");
// We must emit Reset here because this is a
// fresh stream and we did not resume.
Poll::Ready(Break(NegotiationResult::StreamReset {
bound_jid: bound_jid.take().expect("State machine error: no bound_jid available in SM negotiation.").into(),
sm_state: None,
}))
}
},
Ok(XmppStreamElement::StreamError(error)) => {
log::debug!("Received stream error, failing stream and discarding any stream management state.");
let error = io::Error::new(io::ErrorKind::Other, error);
transmit_queue.fail(&(&error).into());
Poll::Ready(Break(NegotiationResult::Disconnect {
error,
sm_state: None,
}))
}
Ok(other) => {
log::warn!("Received unsupported stream element during negotiation: {other:?}. Emitting stream error.");
Poll::Ready(Break(NegotiationResult::StreamError {
error: StreamError {
condition: DefinedCondition::UnsupportedStanzaType,
text: None,
application_specific: vec![],
},
}))
}
// Soft timeouts during negotiation are a bad sign
// (because we already prompted the server to send
// something and are waiting for it), but also nothing
// to write home about.
Err(ReadError::SoftTimeout) => Poll::Ready(Continue(None)),
// Parse errors during negotiation cause an unconditional
// stream error.
Err(ReadError::ParseError(e)) => {
Poll::Ready(Break(NegotiationResult::StreamError {
error: parse_error_to_stream_error(e),
}))
}
// I/O errors cause the stream to be considered
// broken; we drop it and send a Disconnect event with
// the error embedded.
Err(ReadError::HardError(error)) => {
Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: sm_state.take(),
error,
}))
}
// Stream footer during negotation is really weird.
// We kill the stream immediately with an error
// (but allow preservation of the SM state).
Err(ReadError::StreamFooterReceived) => {
Poll::Ready(Break(NegotiationResult::Disconnect {
sm_state: sm_state.take(),
error: io::Error::new(
io::ErrorKind::InvalidData,
"stream footer received during negotation",
),
}))
}
}
}
}
}
}