1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
//! DNS high level transit implimentations.
//!
//! Primarily there are two types in this module of interest, the `DnsMultiplexer` type and the `DnsHandle` type. `DnsMultiplexer` can be thought of as the state machine responsible for sending and receiving DNS messages. `DnsHandle` is the type given to API users of the `trust-dns-proto` library to send messages into the `DnsMultiplexer` for delivery. Finally there is the `DnsRequest` type. This allows for customizations, through `DnsRequestOptions`, to the delivery of messages via a `DnsMultiplexer`.
//!
//! TODO: this module needs some serious refactoring and normalization.

use std::fmt::{Debug, Display};
use std::net::SocketAddr;
use std::pin::Pin;
use std::task::{Context, Poll};

use futures::channel::mpsc::{TrySendError, UnboundedSender};
use futures::channel::oneshot::{self, Receiver, Sender};
use futures::{ready, Future, Stream};
use log::{debug, warn};

use crate::error::*;
use crate::Time;

mod dns_exchange;
pub mod dns_handle;
pub mod dns_multiplexer;
pub mod dns_request;
pub mod dns_response;
#[cfg(feature = "dnssec")]
pub mod dnssec_dns_handle;
pub mod retry_dns_handle;
mod serial_message;

pub use self::dns_exchange::{
    DnsExchange, DnsExchangeBackground, DnsExchangeConnect, DnsExchangeSend,
};
pub use self::dns_handle::{DnsHandle, DnsStreamHandle, StreamHandle};
pub use self::dns_multiplexer::{
    DnsMultiplexer, DnsMultiplexerConnect, DnsMultiplexerSerialResponse,
};
pub use self::dns_request::{DnsRequest, DnsRequestOptions};
pub use self::dns_response::DnsResponse;
#[cfg(feature = "dnssec")]
pub use self::dnssec_dns_handle::DnssecDnsHandle;
pub use self::retry_dns_handle::RetryDnsHandle;
pub use self::serial_message::SerialMessage;

/// Ignores the result of a send operation and logs and ignores errors
fn ignore_send<M, E: Debug>(result: Result<M, E>) {
    if let Err(error) = result {
        warn!("error notifying wait, possible future leak: {:?}", error);
    }
}

/// A non-multiplexed stream of Serialized DNS messages
pub trait DnsClientStream:
    Stream<Item = Result<SerialMessage, ProtoError>> + Display + Send
{
    /// The remote name server address
    fn name_server_addr(&self) -> SocketAddr;
}

// TODO: change to Sink
/// A sender to which serialized DNS Messages can be sent
#[derive(Clone)]
pub struct BufStreamHandle {
    sender: UnboundedSender<SerialMessage>,
}

impl BufStreamHandle {
    /// Constructs a new BufStreamHandle with the associated ProtoError
    pub fn new(sender: UnboundedSender<SerialMessage>) -> Self {
        BufStreamHandle { sender }
    }

    /// see [`futures::sync::mpsc::UnboundedSender`]
    pub fn unbounded_send(&self, msg: SerialMessage) -> Result<(), TrySendError<SerialMessage>> {
        self.sender.unbounded_send(msg)
    }
}

/// A buffering stream bound to a `SocketAddr`
pub struct BufDnsStreamHandle {
    name_server: SocketAddr,
    sender: BufStreamHandle,
}

impl BufDnsStreamHandle {
    /// Constructs a new Buffered Stream Handle, used for sending data to the DNS peer.
    ///
    /// # Arguments
    ///
    /// * `name_server` - the address of the DNS server
    /// * `sender` - the handle being used to send data to the server
    pub fn new(name_server: SocketAddr, sender: BufStreamHandle) -> Self {
        BufDnsStreamHandle {
            name_server,
            sender,
        }
    }
}

impl DnsStreamHandle for BufDnsStreamHandle {
    fn send(&mut self, buffer: SerialMessage) -> Result<(), ProtoError> {
        let name_server: SocketAddr = self.name_server;
        let sender: &mut _ = &mut self.sender;
        sender
            .sender
            .unbounded_send(SerialMessage::new(buffer.unwrap().0, name_server))
            .map_err(|e| ProtoError::from(format!("mpsc::SendError {}", e)))
    }
}

// TODO: expose the Sink trait for this?
/// A sender to which serialized DNS Messages can be sent
pub struct DnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    sender: UnboundedSender<OneshotDnsRequest<F>>,
}

impl<F> DnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    /// Constructs a new BufStreamHandle with the associated ProtoError
    pub fn new(sender: UnboundedSender<OneshotDnsRequest<F>>) -> Self {
        DnsRequestStreamHandle { sender }
    }

    /// see [`futures::sync::mpsc::UnboundedSender`]
    pub fn unbounded_send(
        &self,
        msg: OneshotDnsRequest<F>,
    ) -> Result<(), TrySendError<OneshotDnsRequest<F>>> {
        self.sender.unbounded_send(msg)
    }
}

impl<F> Clone for DnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    fn clone(&self) -> Self {
        DnsRequestStreamHandle {
            sender: self.sender.clone(),
        }
    }
}

/// Types that implement this are capable of sending a serialized DNS message on a stream
///
/// The underlying Stream implementation should yield `Some(())` whenever it is ready to send a message,
///   NotReady, if it is not ready to send a message, and `Err` or `None` in the case that the stream is
///   done, and should be shutdown.
pub trait DnsRequestSender: Stream<Item = Result<(), ProtoError>> + Send + Unpin + 'static {
    /// A future that resolves to a response serial message
    type DnsResponseFuture: Future<Output = Result<DnsResponse, ProtoError>>
        + 'static
        + Send
        + Unpin;

    /// Send a message, and return a future of the response
    ///
    /// # Return
    ///
    /// A future which will resolve to a SerialMessage response
    fn send_message<TE: Time>(
        &mut self,
        message: DnsRequest,
        cx: &mut Context,
    ) -> Self::DnsResponseFuture;

    /// Constructs an error response
    fn error_response<TE: Time>(error: ProtoError) -> Self::DnsResponseFuture;

    /// Allows the upstream user to inform the underling stream that it should shutdown.
    ///
    /// After this is called, the next time `poll` is called on the stream it would be correct to return `Poll::Ready(Ok(()))`. This is not required though, if there are say outstanding requests that are not yet complete, then it would be correct to first wait for those results.
    fn shutdown(&mut self);

    /// Returns true if the stream has been shutdown with `shutdown`
    fn is_shutdown(&self) -> bool;
}

/// Used for associating a name_server to a DnsRequestStreamHandle
pub struct BufDnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    sender: DnsRequestStreamHandle<F>,
}

impl<F> BufDnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    /// Construct a new BufDnsRequestStreamHandle
    pub fn new(sender: DnsRequestStreamHandle<F>) -> Self {
        BufDnsRequestStreamHandle { sender }
    }
}

impl<F> Clone for BufDnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    fn clone(&self) -> Self {
        BufDnsRequestStreamHandle {
            sender: self.sender.clone(),
        }
    }
}

macro_rules! try_oneshot {
    ($expr:expr) => {{
        use std::result::Result;

        match $expr {
            Result::Ok(val) => val,
            Result::Err(err) => {
                return OneshotDnsResponseReceiver::Err(Some(ProtoError::from(err)))
            }
        }
    }};
    ($expr:expr,) => {
        $expr?
    };
}

impl<F> DnsHandle for BufDnsRequestStreamHandle<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send + Unpin + 'static,
{
    type Response = OneshotDnsResponseReceiver<F>;

    fn send<R: Into<DnsRequest>>(&mut self, request: R) -> Self::Response {
        let request: DnsRequest = request.into();
        debug!("enqueueing message: {:?}", request.queries());

        let (request, oneshot) = OneshotDnsRequest::oneshot(request);
        try_oneshot!(self.sender.unbounded_send(request).map_err(|_| {
            debug!("unable to enqueue message");
            ProtoError::from("could not send request")
        }));

        OneshotDnsResponseReceiver::Receiver(oneshot)
    }
}

// TODO: this future should return the origin message in the response on errors
/// A OneshotDnsRequest creates a channel for a response to message
pub struct OneshotDnsRequest<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    dns_request: DnsRequest,
    sender_for_response: Sender<F>,
}

impl<F> OneshotDnsRequest<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    fn oneshot(dns_request: DnsRequest) -> (OneshotDnsRequest<F>, oneshot::Receiver<F>) {
        let (sender_for_response, receiver) = oneshot::channel();

        (
            OneshotDnsRequest {
                dns_request,
                sender_for_response,
            },
            receiver,
        )
    }

    fn unwrap(self) -> (DnsRequest, OneshotDnsResponse<F>) {
        (
            self.dns_request,
            OneshotDnsResponse(self.sender_for_response),
        )
    }
}

struct OneshotDnsResponse<F>(oneshot::Sender<F>)
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send;

impl<F> OneshotDnsResponse<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send,
{
    fn send_response(self, serial_response: F) -> Result<(), F> {
        self.0.send(serial_response)
    }
}

/// A Future that wraps a oneshot::Receiver and resolves to the final value
pub enum OneshotDnsResponseReceiver<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send + Unpin,
{
    /// The receiver
    Receiver(Receiver<F>),
    /// The future once received
    Received(F),
    /// Error during the send operation
    Err(Option<ProtoError>),
}

impl<F> Future for OneshotDnsResponseReceiver<F>
where
    F: Future<Output = Result<DnsResponse, ProtoError>> + Send + Unpin,
{
    type Output = <F as Future>::Output;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
        loop {
            *self = match *self.as_mut() {
                OneshotDnsResponseReceiver::Receiver(ref mut receiver) => {
                    let receiver = Pin::new(receiver);
                    let future = ready!(receiver
                        .poll(cx)
                        .map_err(|_| ProtoError::from("receiver was canceled")))?;
                    OneshotDnsResponseReceiver::Received(future)
                }
                OneshotDnsResponseReceiver::Received(ref mut future) => {
                    let future = Pin::new(future);
                    return future.poll(cx);
                }
                OneshotDnsResponseReceiver::Err(ref mut err) => {
                    return Poll::Ready(Err(err
                        .take()
                        .expect("futures should not be polled after complete")))
                }
            };
        }
    }
}