reth_eth_wire/
capability.rs

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
//! All capability related types

use crate::{
    errors::{P2PHandshakeError, P2PStreamError},
    p2pstream::MAX_RESERVED_MESSAGE_ID,
    protocol::{ProtoVersion, Protocol},
    version::ParseVersionError,
    Capability, EthMessageID, EthVersion,
};
use alloy_primitives::bytes::Bytes;
use derive_more::{Deref, DerefMut};
use reth_eth_wire_types::{EthMessage, EthNetworkPrimitives, NetworkPrimitives};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use std::{
    borrow::Cow,
    collections::{BTreeSet, HashMap},
};

/// A Capability message consisting of the message-id and the payload
#[derive(Debug, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct RawCapabilityMessage {
    /// Identifier of the message.
    pub id: usize,
    /// Actual __encoded__ payload
    pub payload: Bytes,
}

impl RawCapabilityMessage {
    /// Creates a new capability message with the given id and payload.
    pub const fn new(id: usize, payload: Bytes) -> Self {
        Self { id, payload }
    }

    /// Creates a raw message for the eth sub-protocol.
    ///
    /// Caller must ensure that the rlp encoded `payload` matches the given `id`.
    ///
    /// See also  [`EthMessage`]
    pub const fn eth(id: EthMessageID, payload: Bytes) -> Self {
        Self::new(id as usize, payload)
    }
}

/// Various protocol related event types bubbled up from a session that need to be handled by the
/// network.
#[derive(Debug)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum CapabilityMessage<N: NetworkPrimitives = EthNetworkPrimitives> {
    /// Eth sub-protocol message.
    #[cfg_attr(
        feature = "serde",
        serde(bound = "EthMessage<N>: Serialize + serde::de::DeserializeOwned")
    )]
    Eth(EthMessage<N>),
    /// Any other or manually crafted eth message.
    Other(RawCapabilityMessage),
}

/// This represents a shared capability, its version, and its message id offset.
///
/// The [offset](SharedCapability::message_id_offset) is the message ID offset for this shared
/// capability, determined during the rlpx handshake.
///
/// See also [Message-id based multiplexing](https://github.com/ethereum/devp2p/blob/master/rlpx.md#message-id-based-multiplexing)
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum SharedCapability {
    /// The `eth` capability.
    Eth {
        /// (Highest) negotiated version of the eth capability.
        version: EthVersion,
        /// The message ID offset for this capability.
        ///
        /// This represents the message ID offset for the first message of the eth capability in
        /// the message id space.
        offset: u8,
    },
    /// Any other unknown capability.
    UnknownCapability {
        /// Shared capability.
        cap: Capability,
        /// The message ID offset for this capability.
        ///
        /// This represents the message ID offset for the first message of the eth capability in
        /// the message id space.
        offset: u8,
        /// The number of messages of this capability. Needed to calculate range of message IDs in
        /// demuxing.
        messages: u8,
    },
}

impl SharedCapability {
    /// Creates a new [`SharedCapability`] based on the given name, offset, version (and messages
    /// if the capability is custom).
    ///
    /// Returns an error if the offset is equal or less than [`MAX_RESERVED_MESSAGE_ID`].
    pub(crate) fn new(
        name: &str,
        version: u8,
        offset: u8,
        messages: u8,
    ) -> Result<Self, SharedCapabilityError> {
        if offset <= MAX_RESERVED_MESSAGE_ID {
            return Err(SharedCapabilityError::ReservedMessageIdOffset(offset))
        }

        match name {
            "eth" => Ok(Self::eth(EthVersion::try_from(version)?, offset)),
            _ => Ok(Self::UnknownCapability {
                cap: Capability::new(name.to_string(), version as usize),
                offset,
                messages,
            }),
        }
    }

    /// Creates a new [`SharedCapability`] based on the given name, offset, and version.
    pub(crate) const fn eth(version: EthVersion, offset: u8) -> Self {
        Self::Eth { version, offset }
    }

    /// Returns the capability.
    pub const fn capability(&self) -> Cow<'_, Capability> {
        match self {
            Self::Eth { version, .. } => Cow::Owned(Capability::eth(*version)),
            Self::UnknownCapability { cap, .. } => Cow::Borrowed(cap),
        }
    }

    /// Returns the name of the capability.
    #[inline]
    pub fn name(&self) -> &str {
        match self {
            Self::Eth { .. } => "eth",
            Self::UnknownCapability { cap, .. } => cap.name.as_ref(),
        }
    }

    /// Returns true if the capability is eth.
    #[inline]
    pub const fn is_eth(&self) -> bool {
        matches!(self, Self::Eth { .. })
    }

    /// Returns the version of the capability.
    pub const fn version(&self) -> u8 {
        match self {
            Self::Eth { version, .. } => *version as u8,
            Self::UnknownCapability { cap, .. } => cap.version as u8,
        }
    }

    /// Returns the eth version if it's the `eth` capability.
    pub const fn eth_version(&self) -> Option<EthVersion> {
        match self {
            Self::Eth { version, .. } => Some(*version),
            _ => None,
        }
    }

    /// Returns the message ID offset of the current capability.
    ///
    /// This represents the message ID offset for the first message of the eth capability in the
    /// message id space.
    pub const fn message_id_offset(&self) -> u8 {
        match self {
            Self::Eth { offset, .. } | Self::UnknownCapability { offset, .. } => *offset,
        }
    }

    /// Returns the message ID offset of the current capability relative to the start of the
    /// reserved message id space: [`MAX_RESERVED_MESSAGE_ID`].
    pub const fn relative_message_id_offset(&self) -> u8 {
        self.message_id_offset() - MAX_RESERVED_MESSAGE_ID - 1
    }

    /// Returns the number of protocol messages supported by this capability.
    pub const fn num_messages(&self) -> u8 {
        match self {
            Self::Eth { version: _version, .. } => EthMessageID::max() + 1,
            Self::UnknownCapability { messages, .. } => *messages,
        }
    }
}

/// Non-empty,ordered list of recognized shared capabilities.
///
/// Shared capabilities are ordered alphabetically by case sensitive name.
#[derive(Debug, Clone, Deref, DerefMut, PartialEq, Eq)]
pub struct SharedCapabilities(Vec<SharedCapability>);

impl SharedCapabilities {
    /// Merges the local and peer capabilities and returns a new [`SharedCapabilities`] instance.
    #[inline]
    pub fn try_new(
        local_protocols: Vec<Protocol>,
        peer_capabilities: Vec<Capability>,
    ) -> Result<Self, P2PStreamError> {
        shared_capability_offsets(local_protocols, peer_capabilities).map(Self)
    }

    /// Iterates over the shared capabilities.
    #[inline]
    pub fn iter_caps(&self) -> impl Iterator<Item = &SharedCapability> {
        self.0.iter()
    }

    /// Returns the eth capability if it is shared.
    #[inline]
    pub fn eth(&self) -> Result<&SharedCapability, P2PStreamError> {
        self.iter_caps().find(|c| c.is_eth()).ok_or(P2PStreamError::CapabilityNotShared)
    }

    /// Returns the negotiated eth version if it is shared.
    #[inline]
    pub fn eth_version(&self) -> Result<EthVersion, P2PStreamError> {
        self.iter_caps()
            .find_map(SharedCapability::eth_version)
            .ok_or(P2PStreamError::CapabilityNotShared)
    }

    /// Returns true if the shared capabilities contain the given capability.
    #[inline]
    pub fn contains(&self, cap: &Capability) -> bool {
        self.find(cap).is_some()
    }

    /// Returns the shared capability for the given capability.
    #[inline]
    pub fn find(&self, cap: &Capability) -> Option<&SharedCapability> {
        self.0.iter().find(|c| c.version() == cap.version as u8 && c.name() == cap.name)
    }

    /// Returns the matching shared capability for the given capability offset.
    ///
    /// `offset` is the multiplexed message id offset of the capability relative to the reserved
    /// message id space. In other words, counting starts at [`MAX_RESERVED_MESSAGE_ID`] + 1, which
    /// corresponds to the first non-reserved message id.
    ///
    /// For example: `offset == 0` corresponds to the first shared message across the shared
    /// capabilities and will return the first shared capability that supports messages.
    #[inline]
    pub fn find_by_relative_offset(&self, offset: u8) -> Option<&SharedCapability> {
        self.find_by_offset(offset.saturating_add(MAX_RESERVED_MESSAGE_ID + 1))
    }

    /// Returns the matching shared capability for the given capability offset.
    ///
    /// `offset` is the multiplexed message id offset of the capability that includes the reserved
    /// message id space.
    ///
    /// This will always return None if `offset` is less than or equal to
    /// [`MAX_RESERVED_MESSAGE_ID`] because the reserved message id space is not shared.
    #[inline]
    pub fn find_by_offset(&self, offset: u8) -> Option<&SharedCapability> {
        let mut iter = self.0.iter();
        let mut cap = iter.next()?;
        if offset < cap.message_id_offset() {
            // reserved message id space
            return None
        }

        for next in iter {
            if offset < next.message_id_offset() {
                return Some(cap)
            }
            cap = next
        }

        Some(cap)
    }

    /// Returns the shared capability for the given capability or an error if it's not compatible.
    #[inline]
    pub fn ensure_matching_capability(
        &self,
        cap: &Capability,
    ) -> Result<&SharedCapability, UnsupportedCapabilityError> {
        self.find(cap).ok_or_else(|| UnsupportedCapabilityError { capability: cap.clone() })
    }

    /// Returns the number of shared capabilities.
    #[inline]
    pub fn len(&self) -> usize {
        self.0.len()
    }

    /// Returns true if there are no shared capabilities.
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.0.is_empty()
    }
}

/// Determines the offsets for each shared capability between the input list of peer
/// capabilities and the input list of locally supported [Protocol].
///
/// Additionally, the `p2p` capability version 5 is supported, but is
/// expected _not_ to be in neither `local_protocols` or `peer_capabilities`.
///
/// **Note**: For `local_protocols` this takes [Protocol] because we need to know the number of
/// messages per versioned capability. From the remote we only get the plain [Capability].
#[inline]
pub fn shared_capability_offsets(
    local_protocols: Vec<Protocol>,
    peer_capabilities: Vec<Capability>,
) -> Result<Vec<SharedCapability>, P2PStreamError> {
    // find intersection of capabilities
    let our_capabilities =
        local_protocols.into_iter().map(Protocol::split).collect::<HashMap<_, _>>();

    // map of capability name to version
    let mut shared_capabilities: HashMap<_, ProtoVersion> = HashMap::default();

    // The `Ord` implementation for capability names should be equivalent to geth (and every other
    // client), since geth uses golang's default string comparison, which orders strings
    // lexicographically.
    // https://golang.org/pkg/strings/#Compare
    //
    // This is important because the capability name is used to determine the message id offset, so
    // if the sorting is not identical, offsets for connected peers could be inconsistent.
    // This would cause the peers to send messages with the wrong message id, which is usually a
    // protocol violation.
    //
    // The `Ord` implementation for `str` orders strings lexicographically.
    let mut shared_capability_names = BTreeSet::new();

    // find highest shared version of each shared capability
    for peer_capability in peer_capabilities {
        // if we contain this specific capability both peers share it
        if let Some(messages) = our_capabilities.get(&peer_capability).copied() {
            // If multiple versions are shared of the same (equal name) capability, the numerically
            // highest wins, others are ignored
            if shared_capabilities
                .get(&peer_capability.name)
                .is_none_or(|v| peer_capability.version > v.version)
            {
                shared_capabilities.insert(
                    peer_capability.name.clone(),
                    ProtoVersion { version: peer_capability.version, messages },
                );
                shared_capability_names.insert(peer_capability.name);
            }
        }
    }

    // disconnect if we don't share any capabilities
    if shared_capabilities.is_empty() {
        return Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
    }

    // order versions based on capability name (alphabetical) and select offsets based on
    // BASE_OFFSET + prev_total_message
    let mut shared_with_offsets = Vec::new();

    // Message IDs are assumed to be compact from ID 0x10 onwards (0x00-0x0f is reserved for the
    // "p2p" capability) and given to each shared (equal-version, equal-name) capability in
    // alphabetic order.
    let mut offset = MAX_RESERVED_MESSAGE_ID + 1;
    for name in shared_capability_names {
        let proto_version = &shared_capabilities[&name];
        let shared_capability = SharedCapability::new(
            &name,
            proto_version.version as u8,
            offset,
            proto_version.messages,
        )?;
        offset += shared_capability.num_messages();
        shared_with_offsets.push(shared_capability);
    }

    if shared_with_offsets.is_empty() {
        return Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
    }

    Ok(shared_with_offsets)
}

/// An error that may occur while creating a [`SharedCapability`].
#[derive(Debug, thiserror::Error)]
pub enum SharedCapabilityError {
    /// Unsupported `eth` version.
    #[error(transparent)]
    UnsupportedVersion(#[from] ParseVersionError),
    /// Thrown when the message id for a [`SharedCapability`] overlaps with the reserved p2p
    /// message id space [`MAX_RESERVED_MESSAGE_ID`].
    #[error("message id offset `{0}` is reserved")]
    ReservedMessageIdOffset(u8),
}

/// An error thrown when capabilities mismatch.
#[derive(Debug, thiserror::Error)]
#[error("unsupported capability {capability}")]
pub struct UnsupportedCapabilityError {
    capability: Capability,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{Capabilities, Capability};

    #[test]
    fn from_eth_68() {
        let capability = SharedCapability::new("eth", 68, MAX_RESERVED_MESSAGE_ID + 1, 13).unwrap();

        assert_eq!(capability.name(), "eth");
        assert_eq!(capability.version(), 68);
        assert_eq!(
            capability,
            SharedCapability::Eth {
                version: EthVersion::Eth68,
                offset: MAX_RESERVED_MESSAGE_ID + 1
            }
        );
    }

    #[test]
    fn from_eth_67() {
        let capability = SharedCapability::new("eth", 67, MAX_RESERVED_MESSAGE_ID + 1, 13).unwrap();

        assert_eq!(capability.name(), "eth");
        assert_eq!(capability.version(), 67);
        assert_eq!(
            capability,
            SharedCapability::Eth {
                version: EthVersion::Eth67,
                offset: MAX_RESERVED_MESSAGE_ID + 1
            }
        );
    }

    #[test]
    fn from_eth_66() {
        let capability = SharedCapability::new("eth", 66, MAX_RESERVED_MESSAGE_ID + 1, 15).unwrap();

        assert_eq!(capability.name(), "eth");
        assert_eq!(capability.version(), 66);
        assert_eq!(
            capability,
            SharedCapability::Eth {
                version: EthVersion::Eth66,
                offset: MAX_RESERVED_MESSAGE_ID + 1
            }
        );
    }

    #[test]
    fn capabilities_supports_eth() {
        let capabilities: Capabilities = vec![
            Capability::new_static("eth", 66),
            Capability::new_static("eth", 67),
            Capability::new_static("eth", 68),
        ]
        .into();

        assert!(capabilities.supports_eth());
        assert!(capabilities.supports_eth_v66());
        assert!(capabilities.supports_eth_v67());
        assert!(capabilities.supports_eth_v68());
    }

    #[test]
    fn test_peer_capability_version_zero() {
        let cap = Capability::new_static("TestName", 0);
        let local_capabilities: Vec<Protocol> =
            vec![Protocol::new(cap.clone(), 0), EthVersion::Eth67.into(), EthVersion::Eth68.into()];
        let peer_capabilities = vec![cap.clone()];

        let shared = shared_capability_offsets(local_capabilities, peer_capabilities).unwrap();
        assert_eq!(shared.len(), 1);
        assert_eq!(shared[0], SharedCapability::UnknownCapability { cap, offset: 16, messages: 0 })
    }

    #[test]
    fn test_peer_lower_capability_version() {
        let local_capabilities: Vec<Protocol> =
            vec![EthVersion::Eth66.into(), EthVersion::Eth67.into(), EthVersion::Eth68.into()];
        let peer_capabilities: Vec<Capability> = vec![EthVersion::Eth66.into()];

        let shared_capability =
            shared_capability_offsets(local_capabilities, peer_capabilities).unwrap()[0].clone();

        assert_eq!(
            shared_capability,
            SharedCapability::Eth {
                version: EthVersion::Eth66,
                offset: MAX_RESERVED_MESSAGE_ID + 1
            }
        )
    }

    #[test]
    fn test_peer_capability_version_too_low() {
        let local: Vec<Protocol> = vec![EthVersion::Eth67.into()];
        let peer_capabilities: Vec<Capability> = vec![EthVersion::Eth66.into()];

        let shared_capability = shared_capability_offsets(local, peer_capabilities);

        assert!(matches!(
            shared_capability,
            Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
        ))
    }

    #[test]
    fn test_peer_capability_version_too_high() {
        let local_capabilities = vec![EthVersion::Eth66.into()];
        let peer_capabilities = vec![EthVersion::Eth67.into()];

        let shared_capability = shared_capability_offsets(local_capabilities, peer_capabilities);

        assert!(matches!(
            shared_capability,
            Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
        ))
    }

    #[test]
    fn test_find_by_offset() {
        let local_capabilities = vec![EthVersion::Eth66.into()];
        let peer_capabilities = vec![EthVersion::Eth66.into()];

        let shared = SharedCapabilities::try_new(local_capabilities, peer_capabilities).unwrap();

        let shared_eth = shared.find_by_relative_offset(0).unwrap();
        assert_eq!(shared_eth.name(), "eth");

        let shared_eth = shared.find_by_offset(MAX_RESERVED_MESSAGE_ID + 1).unwrap();
        assert_eq!(shared_eth.name(), "eth");

        // reserved message id space
        assert!(shared.find_by_offset(MAX_RESERVED_MESSAGE_ID).is_none());
    }

    #[test]
    fn test_find_by_offset_many() {
        let cap = Capability::new_static("aaa", 1);
        let proto = Protocol::new(cap.clone(), 5);
        let local_capabilities = vec![proto.clone(), EthVersion::Eth66.into()];
        let peer_capabilities = vec![cap, EthVersion::Eth66.into()];

        let shared = SharedCapabilities::try_new(local_capabilities, peer_capabilities).unwrap();

        let shared_eth = shared.find_by_relative_offset(0).unwrap();
        assert_eq!(shared_eth.name(), proto.cap.name);

        let shared_eth = shared.find_by_offset(MAX_RESERVED_MESSAGE_ID + 1).unwrap();
        assert_eq!(shared_eth.name(), proto.cap.name);

        // the 5th shared message (0,1,2,3,4) is the last message of the aaa capability
        let shared_eth = shared.find_by_relative_offset(4).unwrap();
        assert_eq!(shared_eth.name(), proto.cap.name);
        let shared_eth = shared.find_by_offset(MAX_RESERVED_MESSAGE_ID + 5).unwrap();
        assert_eq!(shared_eth.name(), proto.cap.name);

        // the 6th shared message is the first message of the eth capability
        let shared_eth = shared.find_by_relative_offset(1 + proto.messages()).unwrap();
        assert_eq!(shared_eth.name(), "eth");
    }
}