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
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
// Copyright 2015-2023 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

//! Lookup result from a resolution of ipv4 and ipv6 records with a Resolver.

use std::{
    cmp::min,
    error::Error,
    pin::Pin,
    slice::Iter,
    sync::Arc,
    task::{Context, Poll},
    time::{Duration, Instant},
};

use futures_util::{
    future::{self, Future},
    stream::Stream,
    FutureExt,
};

use crate::{
    caching_client::CachingClient,
    dns_lru::MAX_TTL,
    error::*,
    lookup_ip::LookupIpIter,
    name_server::{ConnectionProvider, NameServerPool},
    proto::{
        error::ProtoError,
        op::Query,
        rr::{
            rdata::{self, A, AAAA, NS, PTR},
            Name, RData, Record, RecordType,
        },
        xfer::{DnsRequest, DnsRequestOptions, DnsResponse},
        DnsHandle, RetryDnsHandle,
    },
};

#[cfg(feature = "dnssec")]
use proto::DnssecDnsHandle;

/// Result of a DNS query when querying for any record type supported by the Trust-DNS Proto library.
///
/// For IP resolution see LookupIp, as it has more features for A and AAAA lookups.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Lookup {
    query: Query,
    records: Arc<[Record]>,
    valid_until: Instant,
}

impl Lookup {
    /// Return new instance with given rdata and the maximum TTL.
    pub fn from_rdata(query: Query, rdata: RData) -> Self {
        let record = Record::from_rdata(query.name().clone(), MAX_TTL, rdata);
        Self::new_with_max_ttl(query, Arc::from([record]))
    }

    /// Return new instance with given records and the maximum TTL.
    pub fn new_with_max_ttl(query: Query, records: Arc<[Record]>) -> Self {
        let valid_until = Instant::now() + Duration::from_secs(u64::from(MAX_TTL));
        Self {
            query,
            records,
            valid_until,
        }
    }

    /// Return a new instance with the given records and deadline.
    pub fn new_with_deadline(query: Query, records: Arc<[Record]>, valid_until: Instant) -> Self {
        Self {
            query,
            records,
            valid_until,
        }
    }

    /// Returns a reference to the `Query` that was used to produce this result.
    pub fn query(&self) -> &Query {
        &self.query
    }

    /// Returns a borrowed iterator of the returned IPs
    pub fn iter(&self) -> LookupIter<'_> {
        LookupIter(self.records.iter())
    }

    /// Returns a borrowed iterator of the returned IPs
    pub fn record_iter(&self) -> LookupRecordIter<'_> {
        LookupRecordIter(self.records.iter())
    }

    /// Returns the `Instant` at which this `Lookup` is no longer valid.
    pub fn valid_until(&self) -> Instant {
        self.valid_until
    }

    #[doc(hidden)]
    pub fn is_empty(&self) -> bool {
        self.records.is_empty()
    }

    pub(crate) fn len(&self) -> usize {
        self.records.len()
    }

    /// Returns the records list
    pub fn records(&self) -> &[Record] {
        self.records.as_ref()
    }

    /// Clones the inner vec, appends the other vec
    pub(crate) fn append(&self, other: Self) -> Self {
        let mut records = Vec::with_capacity(self.len() + other.len());
        records.extend_from_slice(&self.records);
        records.extend_from_slice(&other.records);

        // Choose the sooner deadline of the two lookups.
        let valid_until = min(self.valid_until(), other.valid_until());
        Self::new_with_deadline(self.query.clone(), Arc::from(records), valid_until)
    }
}

/// Borrowed view of set of [`RData`]s returned from a Lookup
pub struct LookupIter<'a>(Iter<'a, Record>);

impl<'a> Iterator for LookupIter<'a> {
    type Item = &'a RData;

    fn next(&mut self) -> Option<Self::Item> {
        self.0.next().and_then(Record::data)
    }
}

/// Borrowed view of set of [`Record`]s returned from a Lookup
pub struct LookupRecordIter<'a>(Iter<'a, Record>);

impl<'a> Iterator for LookupRecordIter<'a> {
    type Item = &'a Record;

    fn next(&mut self) -> Option<Self::Item> {
        self.0.next()
    }
}

// TODO: consider removing this as it's not a zero-cost abstraction
impl IntoIterator for Lookup {
    type Item = RData;
    type IntoIter = LookupIntoIter;

    /// This is most likely not a free conversion, the `RData`s will be cloned if data is
    ///  held behind an Arc with more than one reference (which is most likely the case coming from cache)
    fn into_iter(self) -> Self::IntoIter {
        LookupIntoIter {
            records: Arc::clone(&self.records),
            index: 0,
        }
    }
}

/// Borrowed view of set of [`RData`]s returned from a [`Lookup`].
///
/// This is not usually a zero overhead `Iterator`, it may result in clones of the [`RData`].
pub struct LookupIntoIter {
    // the result of the try_unwrap on Arc
    records: Arc<[Record]>,
    index: usize,
}

impl Iterator for LookupIntoIter {
    type Item = RData;

    fn next(&mut self) -> Option<Self::Item> {
        let rdata = self.records.get(self.index).and_then(Record::data);
        self.index += 1;
        rdata.cloned()
    }
}

/// Different lookup options for the lookup attempts and validation
#[derive(Clone)]
#[doc(hidden)]
pub enum LookupEither<P: ConnectionProvider + Send> {
    Retry(RetryDnsHandle<NameServerPool<P>>),
    #[cfg(feature = "dnssec")]
    #[cfg_attr(docsrs, doc(cfg(feature = "dnssec")))]
    Secure(DnssecDnsHandle<RetryDnsHandle<NameServerPool<P>>>),
}

impl<P: ConnectionProvider> DnsHandle for LookupEither<P> {
    type Response = Pin<Box<dyn Stream<Item = Result<DnsResponse, ResolveError>> + Send>>;
    type Error = ResolveError;

    fn is_verifying_dnssec(&self) -> bool {
        match *self {
            Self::Retry(ref c) => c.is_verifying_dnssec(),
            #[cfg(feature = "dnssec")]
            Self::Secure(ref c) => c.is_verifying_dnssec(),
        }
    }

    fn send<R: Into<DnsRequest> + Unpin + Send + 'static>(&mut self, request: R) -> Self::Response {
        match *self {
            Self::Retry(ref mut c) => c.send(request),
            #[cfg(feature = "dnssec")]
            Self::Secure(ref mut c) => c.send(request),
        }
    }
}

/// The Future returned from [`AsyncResolver`] when performing a lookup.
#[doc(hidden)]
pub struct LookupFuture<C, E>
where
    C: DnsHandle<Error = E> + 'static,
    E: Into<ResolveError> + From<ProtoError> + Error + Clone + Send + Unpin + 'static,
{
    client_cache: CachingClient<C, E>,
    names: Vec<Name>,
    record_type: RecordType,
    options: DnsRequestOptions,
    query: Pin<Box<dyn Future<Output = Result<Lookup, ResolveError>> + Send>>,
}

impl<C, E> LookupFuture<C, E>
where
    C: DnsHandle<Error = E> + 'static,
    E: Into<ResolveError> + From<ProtoError> + Error + Clone + Send + Unpin + 'static,
{
    /// Perform a lookup from a name and type to a set of RDatas
    ///
    /// # Arguments
    ///
    /// * `names` - a set of DNS names to attempt to resolve, they will be attempted in queue order, i.e. the first is `names.pop()`. Upon each failure, the next will be attempted.
    /// * `record_type` - type of record being sought
    /// * `client_cache` - cache with a connection to use for performing all lookups
    #[doc(hidden)]
    pub fn lookup(
        mut names: Vec<Name>,
        record_type: RecordType,
        options: DnsRequestOptions,
        mut client_cache: CachingClient<C, E>,
    ) -> Self {
        let name = names.pop().ok_or_else(|| {
            ResolveError::from(ResolveErrorKind::Message("can not lookup for no names"))
        });

        let query: Pin<Box<dyn Future<Output = Result<Lookup, ResolveError>> + Send>> = match name {
            Ok(name) => client_cache
                .lookup(Query::query(name, record_type), options)
                .boxed(),
            Err(err) => future::err(err).boxed(),
        };

        Self {
            client_cache,
            names,
            record_type,
            options,
            query,
        }
    }
}

impl<C, E> Future for LookupFuture<C, E>
where
    C: DnsHandle<Error = E> + 'static,
    E: Into<ResolveError> + From<ProtoError> + Error + Clone + Send + Unpin + 'static,
{
    type Output = Result<Lookup, ResolveError>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        loop {
            // Try polling the underlying DNS query.
            let query = self.query.as_mut().poll_unpin(cx);

            // Determine whether or not we will attempt to retry the query.
            let should_retry = match query {
                // If the query is NotReady, yield immediately.
                Poll::Pending => return Poll::Pending,
                // If the query returned a successful lookup, we will attempt
                // to retry if the lookup is empty. Otherwise, we will return
                // that lookup.
                Poll::Ready(Ok(ref lookup)) => lookup.records.len() == 0,
                // If the query failed, we will attempt to retry.
                Poll::Ready(Err(_)) => true,
            };

            if should_retry {
                if let Some(name) = self.names.pop() {
                    let record_type = self.record_type;
                    let options = self.options;

                    // If there's another name left to try, build a new query
                    // for that next name and continue looping.
                    self.query = self
                        .client_cache
                        .lookup(Query::query(name, record_type), options);
                    // Continue looping with the new query. It will be polled
                    // on the next iteration of the loop.
                    continue;
                }
            }
            // If we didn't have to retry the query, or we weren't able to
            // retry because we've exhausted the names to search, return the
            // current query.
            return query;
            // If we skipped retrying the  query, this will return the
            // successful lookup, otherwise, if the retry failed, this will
            // return the last  query result --- either an empty lookup or the
            // last error we saw.
        }
    }
}

/// The result of an SRV lookup
#[derive(Debug, Clone)]
pub struct SrvLookup(Lookup);

impl SrvLookup {
    /// Returns an iterator over the SRV RData
    pub fn iter(&self) -> SrvLookupIter<'_> {
        SrvLookupIter(self.0.iter())
    }

    /// Returns a reference to the Query that was used to produce this result.
    pub fn query(&self) -> &Query {
        self.0.query()
    }

    /// Returns the list of IPs associated with the SRV record.
    ///
    /// *Note*: That Trust-DNS performs a recursive lookup on SRV records for IPs if they were not included in the original request. If there are no IPs associated to the result, a subsequent query for the IPs via the `srv.target()` should not resolve to the IPs.
    pub fn ip_iter(&self) -> LookupIpIter<'_> {
        LookupIpIter(self.0.iter())
    }

    /// Return a reference to the inner lookup
    ///
    /// This can be useful for getting all records from the request
    pub fn as_lookup(&self) -> &Lookup {
        &self.0
    }
}

impl From<Lookup> for SrvLookup {
    fn from(lookup: Lookup) -> Self {
        Self(lookup)
    }
}

/// An iterator over the Lookup type
pub struct SrvLookupIter<'i>(LookupIter<'i>);

impl<'i> Iterator for SrvLookupIter<'i> {
    type Item = &'i rdata::SRV;

    fn next(&mut self) -> Option<Self::Item> {
        let iter: &mut _ = &mut self.0;
        iter.filter_map(|rdata| match *rdata {
            RData::SRV(ref data) => Some(data),
            _ => None,
        })
        .next()
    }
}

impl IntoIterator for SrvLookup {
    type Item = rdata::SRV;
    type IntoIter = SrvLookupIntoIter;

    /// This is most likely not a free conversion, the RDatas will be cloned if data is
    ///  held behind an Arc with more than one reference (which is most likely the case coming from cache)
    fn into_iter(self) -> Self::IntoIter {
        SrvLookupIntoIter(self.0.into_iter())
    }
}

/// Borrowed view of set of RDatas returned from a Lookup
pub struct SrvLookupIntoIter(LookupIntoIter);

impl Iterator for SrvLookupIntoIter {
    type Item = rdata::SRV;

    fn next(&mut self) -> Option<Self::Item> {
        let iter: &mut _ = &mut self.0;
        iter.filter_map(|rdata| match rdata {
            RData::SRV(data) => Some(data),
            _ => None,
        })
        .next()
    }
}

/// Creates a Lookup result type from the specified components
macro_rules! lookup_type {
    ($l:ident, $i:ident, $ii:ident, $r:path, $t:path) => {
        /// Contains the results of a lookup for the associated RecordType
        #[derive(Debug, Clone)]
        pub struct $l(Lookup);

        impl $l {
            /// Returns an iterator over the RData
            pub fn iter(&self) -> $i<'_> {
                $i(self.0.iter())
            }

            /// Returns a reference to the Query that was used to produce this result.
            pub fn query(&self) -> &Query {
                self.0.query()
            }

            /// Returns the `Instant` at which this result is no longer valid.
            pub fn valid_until(&self) -> Instant {
                self.0.valid_until()
            }

            /// Return a reference to the inner lookup
            ///
            /// This can be useful for getting all records from the request
            pub fn as_lookup(&self) -> &Lookup {
                &self.0
            }
        }

        impl From<Lookup> for $l {
            fn from(lookup: Lookup) -> Self {
                $l(lookup)
            }
        }

        impl From<$l> for Lookup {
            fn from(revlookup: $l) -> Self {
                revlookup.0
            }
        }

        /// An iterator over the Lookup type
        pub struct $i<'i>(LookupIter<'i>);

        impl<'i> Iterator for $i<'i> {
            type Item = &'i $t;

            fn next(&mut self) -> Option<Self::Item> {
                let iter: &mut _ = &mut self.0;
                iter.filter_map(|rdata| match *rdata {
                    $r(ref data) => Some(data),
                    _ => None,
                })
                .next()
            }
        }

        impl IntoIterator for $l {
            type Item = $t;
            type IntoIter = $ii;

            /// This is most likely not a free conversion, the RDatas will be cloned if data is
            ///  held behind an Arc with more than one reference (which is most likely the case coming from cache)
            fn into_iter(self) -> Self::IntoIter {
                $ii(self.0.into_iter())
            }
        }

        /// Borrowed view of set of RDatas returned from a Lookup
        pub struct $ii(LookupIntoIter);

        impl Iterator for $ii {
            type Item = $t;

            fn next(&mut self) -> Option<Self::Item> {
                let iter: &mut _ = &mut self.0;
                iter.filter_map(|rdata| match rdata {
                    $r(data) => Some(data),
                    _ => None,
                })
                .next()
            }
        }
    };
}

// Generate all Lookup record types
lookup_type!(
    ReverseLookup,
    ReverseLookupIter,
    ReverseLookupIntoIter,
    RData::PTR,
    PTR
);
lookup_type!(Ipv4Lookup, Ipv4LookupIter, Ipv4LookupIntoIter, RData::A, A);
lookup_type!(
    Ipv6Lookup,
    Ipv6LookupIter,
    Ipv6LookupIntoIter,
    RData::AAAA,
    AAAA
);
lookup_type!(
    MxLookup,
    MxLookupIter,
    MxLookupIntoIter,
    RData::MX,
    rdata::MX
);
lookup_type!(
    TlsaLookup,
    TlsaLookupIter,
    TlsaLookupIntoIter,
    RData::TLSA,
    rdata::TLSA
);
lookup_type!(
    TxtLookup,
    TxtLookupIter,
    TxtLookupIntoIter,
    RData::TXT,
    rdata::TXT
);
lookup_type!(
    SoaLookup,
    SoaLookupIter,
    SoaLookupIntoIter,
    RData::SOA,
    rdata::SOA
);
lookup_type!(NsLookup, NsLookupIter, NsLookupIntoIter, RData::NS, NS);

#[cfg(test)]
pub mod tests {
    use std::net::{IpAddr, Ipv4Addr};
    use std::str::FromStr;
    use std::sync::{Arc, Mutex};

    use futures_executor::block_on;
    use futures_util::future;
    use futures_util::stream::once;

    use proto::op::{Message, Query};
    use proto::rr::{Name, RData, Record, RecordType};
    use proto::xfer::{DnsRequest, DnsRequestOptions};

    use super::*;
    use crate::error::ResolveError;

    #[derive(Clone)]
    pub struct MockDnsHandle {
        messages: Arc<Mutex<Vec<Result<DnsResponse, ResolveError>>>>,
    }

    impl DnsHandle for MockDnsHandle {
        type Response = Pin<Box<dyn Stream<Item = Result<DnsResponse, ResolveError>> + Send>>;
        type Error = ResolveError;

        fn send<R: Into<DnsRequest>>(&mut self, _: R) -> Self::Response {
            Box::pin(once(
                future::ready(self.messages.lock().unwrap().pop().unwrap_or_else(empty)).boxed(),
            ))
        }
    }

    pub fn v4_message() -> Result<DnsResponse, ResolveError> {
        let mut message = Message::new();
        message.add_query(Query::query(Name::root(), RecordType::A));
        message.insert_answers(vec![Record::from_rdata(
            Name::root(),
            86400,
            RData::A(A::new(127, 0, 0, 1)),
        )]);

        let resp = DnsResponse::from_message(message).unwrap();
        assert!(resp.contains_answer());
        Ok(resp)
    }

    pub fn empty() -> Result<DnsResponse, ResolveError> {
        Ok(DnsResponse::from_message(Message::new()).unwrap())
    }

    pub fn error() -> Result<DnsResponse, ResolveError> {
        Err(ResolveError::from(ProtoError::from(std::io::Error::from(
            std::io::ErrorKind::Other,
        ))))
    }

    pub fn mock(messages: Vec<Result<DnsResponse, ResolveError>>) -> MockDnsHandle {
        MockDnsHandle {
            messages: Arc::new(Mutex::new(messages)),
        }
    }

    #[test]
    fn test_lookup() {
        assert_eq!(
            block_on(LookupFuture::lookup(
                vec![Name::root()],
                RecordType::A,
                DnsRequestOptions::default(),
                CachingClient::new(0, mock(vec![v4_message()]), false),
            ))
            .unwrap()
            .iter()
            .map(|r| r.ip_addr().unwrap())
            .collect::<Vec<IpAddr>>(),
            vec![Ipv4Addr::new(127, 0, 0, 1)]
        );
    }

    #[test]
    fn test_lookup_slice() {
        assert_eq!(
            Record::data(
                &block_on(LookupFuture::lookup(
                    vec![Name::root()],
                    RecordType::A,
                    DnsRequestOptions::default(),
                    CachingClient::new(0, mock(vec![v4_message()]), false),
                ))
                .unwrap()
                .records()[0]
            )
            .unwrap()
            .ip_addr()
            .unwrap(),
            Ipv4Addr::new(127, 0, 0, 1)
        );
    }

    #[test]
    fn test_lookup_into_iter() {
        assert_eq!(
            block_on(LookupFuture::lookup(
                vec![Name::root()],
                RecordType::A,
                DnsRequestOptions::default(),
                CachingClient::new(0, mock(vec![v4_message()]), false),
            ))
            .unwrap()
            .into_iter()
            .map(|r| r.ip_addr().unwrap())
            .collect::<Vec<IpAddr>>(),
            vec![Ipv4Addr::new(127, 0, 0, 1)]
        );
    }

    #[test]
    fn test_error() {
        assert!(block_on(LookupFuture::lookup(
            vec![Name::root()],
            RecordType::A,
            DnsRequestOptions::default(),
            CachingClient::new(0, mock(vec![error()]), false),
        ))
        .is_err());
    }

    #[test]
    fn test_empty_no_response() {
        if let ResolveErrorKind::NoRecordsFound {
            query,
            negative_ttl,
            ..
        } = block_on(LookupFuture::lookup(
            vec![Name::root()],
            RecordType::A,
            DnsRequestOptions::default(),
            CachingClient::new(0, mock(vec![empty()]), false),
        ))
        .unwrap_err()
        .kind()
        {
            assert_eq!(**query, Query::query(Name::root(), RecordType::A));
            assert_eq!(*negative_ttl, None);
        } else {
            panic!("wrong error received");
        }
    }

    #[test]
    fn test_lookup_into_iter_arc() {
        let mut lookup = LookupIntoIter {
            records: Arc::from([
                Record::from_rdata(
                    Name::from_str("www.example.com.").unwrap(),
                    80,
                    RData::A(A::new(127, 0, 0, 1)),
                ),
                Record::from_rdata(
                    Name::from_str("www.example.com.").unwrap(),
                    80,
                    RData::A(A::new(127, 0, 0, 2)),
                ),
            ]),
            index: 0,
        };

        assert_eq!(lookup.next().unwrap(), RData::A(A::new(127, 0, 0, 1)));
        assert_eq!(lookup.next().unwrap(), RData::A(A::new(127, 0, 0, 2)));
        assert_eq!(lookup.next(), None);
    }
}