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//! Declare a type for streams that do hostname lookups
use crate::stream::StreamReader;
use crate::{Error, Result};
use tor_cell::relaycell::msg::Resolved;
use tor_cell::relaycell::RelayCmd;
use tor_cell::restricted_msg;
use super::AnyCmdChecker;
/// A ResolveStream represents a pending DNS request made with a RESOLVE
/// cell.
pub struct ResolveStream {
/// The underlying RawCellStream.
s: StreamReader,
}
restricted_msg! {
/// An allowable reply for a RESOLVE message.
enum ResolveResponseMsg : RelayMsg {
End,
Resolved,
}
}
impl ResolveStream {
/// Wrap a RawCellStream into a ResolveStream.
///
/// Call only after sending a RESOLVE cell.
pub(crate) fn new(s: StreamReader) -> Self {
ResolveStream { s }
}
/// Read a message from this stream telling us the answer to our
/// name lookup request.
pub async fn read_msg(&mut self) -> Result<Resolved> {
use ResolveResponseMsg::*;
let cell = self.s.recv().await?;
let msg = match cell.decode::<ResolveResponseMsg>() {
Ok(cell) => cell.into_msg(),
Err(e) => {
self.s.protocol_error();
return Err(Error::from_bytes_err(e, "response on a resolve stream"));
}
};
match msg {
End(e) => Err(Error::EndReceived(e.reason())),
Resolved(r) => Ok(r),
}
}
}
/// A `CmdChecker` that enforces correctness for incoming commands on an
/// outbound resolve stream.
#[derive(Debug, Default)]
pub(crate) struct ResolveCmdChecker {}
impl super::CmdChecker for ResolveCmdChecker {
fn check_msg(
&mut self,
msg: &tor_cell::relaycell::UnparsedRelayCell,
) -> Result<super::StreamStatus> {
use super::StreamStatus::Closed;
match msg.cmd() {
RelayCmd::RESOLVED => Ok(Closed),
RelayCmd::END => Ok(Closed),
_ => Err(Error::StreamProto(format!(
"Unexpected {} on resolve stream",
msg.cmd()
))),
}
}
fn consume_checked_msg(&mut self, msg: tor_cell::relaycell::UnparsedRelayCell) -> Result<()> {
let _ = msg
.decode::<ResolveResponseMsg>()
.map_err(|err| Error::from_bytes_err(err, "message on resolve stream."))?;
Ok(())
}
}
impl ResolveCmdChecker {
/// Return a new boxed `DataCmdChecker` in a state suitable for a newly
/// constructed connection.
pub(crate) fn new_any() -> AnyCmdChecker {
Box::<Self>::default()
}
}
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