reth_eth_wire/
capability.rs

1//! All capability related types
2
3use crate::{
4    errors::{P2PHandshakeError, P2PStreamError},
5    p2pstream::MAX_RESERVED_MESSAGE_ID,
6    protocol::{ProtoVersion, Protocol},
7    version::ParseVersionError,
8    Capability, EthMessageID, EthVersion,
9};
10use derive_more::{Deref, DerefMut};
11use std::{
12    borrow::Cow,
13    collections::{BTreeSet, HashMap},
14};
15
16/// This represents a shared capability, its version, and its message id offset.
17///
18/// The [offset](SharedCapability::message_id_offset) is the message ID offset for this shared
19/// capability, determined during the rlpx handshake.
20///
21/// See also [Message-id based multiplexing](https://github.com/ethereum/devp2p/blob/master/rlpx.md#message-id-based-multiplexing)
22#[derive(Debug, Clone, PartialEq, Eq, Hash)]
23pub enum SharedCapability {
24    /// The `eth` capability.
25    Eth {
26        /// (Highest) negotiated version of the eth capability.
27        version: EthVersion,
28        /// The message ID offset for this capability.
29        ///
30        /// This represents the message ID offset for the first message of the eth capability in
31        /// the message id space.
32        offset: u8,
33    },
34    /// Any other unknown capability.
35    UnknownCapability {
36        /// Shared capability.
37        cap: Capability,
38        /// The message ID offset for this capability.
39        ///
40        /// This represents the message ID offset for the first message of the eth capability in
41        /// the message id space.
42        offset: u8,
43        /// The number of messages of this capability. Needed to calculate range of message IDs in
44        /// demuxing.
45        messages: u8,
46    },
47}
48
49impl SharedCapability {
50    /// Creates a new [`SharedCapability`] based on the given name, offset, version (and messages
51    /// if the capability is custom).
52    ///
53    /// Returns an error if the offset is equal or less than [`MAX_RESERVED_MESSAGE_ID`].
54    pub(crate) fn new(
55        name: &str,
56        version: u8,
57        offset: u8,
58        messages: u8,
59    ) -> Result<Self, SharedCapabilityError> {
60        if offset <= MAX_RESERVED_MESSAGE_ID {
61            return Err(SharedCapabilityError::ReservedMessageIdOffset(offset))
62        }
63
64        match name {
65            "eth" => Ok(Self::eth(EthVersion::try_from(version)?, offset)),
66            _ => Ok(Self::UnknownCapability {
67                cap: Capability::new(name.to_string(), version as usize),
68                offset,
69                messages,
70            }),
71        }
72    }
73
74    /// Creates a new [`SharedCapability`] based on the given name, offset, and version.
75    pub(crate) const fn eth(version: EthVersion, offset: u8) -> Self {
76        Self::Eth { version, offset }
77    }
78
79    /// Returns the capability.
80    pub const fn capability(&self) -> Cow<'_, Capability> {
81        match self {
82            Self::Eth { version, .. } => Cow::Owned(Capability::eth(*version)),
83            Self::UnknownCapability { cap, .. } => Cow::Borrowed(cap),
84        }
85    }
86
87    /// Returns the name of the capability.
88    #[inline]
89    pub fn name(&self) -> &str {
90        match self {
91            Self::Eth { .. } => "eth",
92            Self::UnknownCapability { cap, .. } => cap.name.as_ref(),
93        }
94    }
95
96    /// Returns true if the capability is eth.
97    #[inline]
98    pub const fn is_eth(&self) -> bool {
99        matches!(self, Self::Eth { .. })
100    }
101
102    /// Returns the version of the capability.
103    pub const fn version(&self) -> u8 {
104        match self {
105            Self::Eth { version, .. } => *version as u8,
106            Self::UnknownCapability { cap, .. } => cap.version as u8,
107        }
108    }
109
110    /// Returns the eth version if it's the `eth` capability.
111    pub const fn eth_version(&self) -> Option<EthVersion> {
112        match self {
113            Self::Eth { version, .. } => Some(*version),
114            _ => None,
115        }
116    }
117
118    /// Returns the message ID offset of the current capability.
119    ///
120    /// This represents the message ID offset for the first message of the eth capability in the
121    /// message id space.
122    pub const fn message_id_offset(&self) -> u8 {
123        match self {
124            Self::Eth { offset, .. } | Self::UnknownCapability { offset, .. } => *offset,
125        }
126    }
127
128    /// Returns the message ID offset of the current capability relative to the start of the
129    /// reserved message id space: [`MAX_RESERVED_MESSAGE_ID`].
130    pub const fn relative_message_id_offset(&self) -> u8 {
131        self.message_id_offset() - MAX_RESERVED_MESSAGE_ID - 1
132    }
133
134    /// Returns the number of protocol messages supported by this capability.
135    pub const fn num_messages(&self) -> u8 {
136        match self {
137            Self::Eth { version, .. } => EthMessageID::message_count(*version),
138            Self::UnknownCapability { messages, .. } => *messages,
139        }
140    }
141}
142
143/// Non-empty,ordered list of recognized shared capabilities.
144///
145/// Shared capabilities are ordered alphabetically by case sensitive name.
146#[derive(Debug, Clone, Deref, DerefMut, PartialEq, Eq)]
147pub struct SharedCapabilities(Vec<SharedCapability>);
148
149impl SharedCapabilities {
150    /// Merges the local and peer capabilities and returns a new [`SharedCapabilities`] instance.
151    #[inline]
152    pub fn try_new(
153        local_protocols: Vec<Protocol>,
154        peer_capabilities: Vec<Capability>,
155    ) -> Result<Self, P2PStreamError> {
156        shared_capability_offsets(local_protocols, peer_capabilities).map(Self)
157    }
158
159    /// Iterates over the shared capabilities.
160    #[inline]
161    pub fn iter_caps(&self) -> impl Iterator<Item = &SharedCapability> {
162        self.0.iter()
163    }
164
165    /// Returns the eth capability if it is shared.
166    #[inline]
167    pub fn eth(&self) -> Result<&SharedCapability, P2PStreamError> {
168        self.iter_caps().find(|c| c.is_eth()).ok_or(P2PStreamError::CapabilityNotShared)
169    }
170
171    /// Returns the negotiated eth version if it is shared.
172    #[inline]
173    pub fn eth_version(&self) -> Result<EthVersion, P2PStreamError> {
174        self.iter_caps()
175            .find_map(SharedCapability::eth_version)
176            .ok_or(P2PStreamError::CapabilityNotShared)
177    }
178
179    /// Returns true if the shared capabilities contain the given capability.
180    #[inline]
181    pub fn contains(&self, cap: &Capability) -> bool {
182        self.find(cap).is_some()
183    }
184
185    /// Returns the shared capability for the given capability.
186    #[inline]
187    pub fn find(&self, cap: &Capability) -> Option<&SharedCapability> {
188        self.0.iter().find(|c| c.version() == cap.version as u8 && c.name() == cap.name)
189    }
190
191    /// Converts a capability-local message ID into the relative `RLPx` message ID used by
192    /// [`P2PStream`](crate::P2PStream).
193    ///
194    /// `P2PStream` strips the reserved p2p message ID range before yielding subprotocol messages,
195    /// so the returned ID is relative to the first shared capability, not the absolute wire ID.
196    #[inline]
197    pub fn relative_message_id(&self, cap: &Capability, message_id: u8) -> Option<u8> {
198        let shared = self.find(cap)?;
199        if message_id >= shared.num_messages() {
200            return None
201        }
202
203        shared.relative_message_id_offset().checked_add(message_id)
204    }
205
206    /// Converts a relative `RLPx` message ID back into the message ID local to `cap`.
207    ///
208    /// Returns `None` if `cap` is not shared, if the relative ID belongs to a different
209    /// capability, or if it is outside the capability's negotiated message range.
210    #[inline]
211    pub fn capability_message_id(&self, cap: &Capability, relative_message_id: u8) -> Option<u8> {
212        let shared = self.find(cap)?;
213        let start = shared.relative_message_id_offset();
214        let end = start.checked_add(shared.num_messages())?;
215
216        (start..end).contains(&relative_message_id).then(|| relative_message_id - start)
217    }
218
219    /// Returns the matching shared capability for the given capability offset.
220    ///
221    /// `offset` is the multiplexed message id offset of the capability relative to the reserved
222    /// message id space. In other words, counting starts at [`MAX_RESERVED_MESSAGE_ID`] + 1, which
223    /// corresponds to the first non-reserved message id.
224    ///
225    /// For example: `offset == 0` corresponds to the first shared message across the shared
226    /// capabilities and will return the first shared capability that supports messages.
227    #[inline]
228    pub fn find_by_relative_offset(&self, offset: u8) -> Option<&SharedCapability> {
229        self.find_by_offset(offset.saturating_add(MAX_RESERVED_MESSAGE_ID + 1))
230    }
231
232    /// Returns the matching shared capability for the given capability offset.
233    ///
234    /// `offset` is the multiplexed message id offset of the capability that includes the reserved
235    /// message id space.
236    ///
237    /// This will always return None if `offset` is less than or equal to
238    /// [`MAX_RESERVED_MESSAGE_ID`] because the reserved message id space is not shared.
239    #[inline]
240    pub fn find_by_offset(&self, offset: u8) -> Option<&SharedCapability> {
241        let mut iter = self.0.iter();
242        let mut cap = iter.next()?;
243        if offset < cap.message_id_offset() {
244            // reserved message id space
245            return None
246        }
247
248        for next in iter {
249            if offset < next.message_id_offset() {
250                return Some(cap)
251            }
252            cap = next
253        }
254
255        Some(cap)
256    }
257
258    /// Returns the shared capability for the given capability or an error if it's not compatible.
259    #[inline]
260    pub fn ensure_matching_capability(
261        &self,
262        cap: &Capability,
263    ) -> Result<&SharedCapability, UnsupportedCapabilityError> {
264        self.find(cap).ok_or_else(|| UnsupportedCapabilityError { capability: cap.clone() })
265    }
266
267    /// Returns the number of shared capabilities.
268    #[inline]
269    pub const fn len(&self) -> usize {
270        self.0.len()
271    }
272
273    /// Returns true if there are no shared capabilities.
274    #[inline]
275    pub const fn is_empty(&self) -> bool {
276        self.0.is_empty()
277    }
278}
279
280/// Determines the offsets for each shared capability between the input list of peer
281/// capabilities and the input list of locally supported [Protocol].
282///
283/// Additionally, the `p2p` capability version 5 is supported, but is
284/// expected _not_ to be in neither `local_protocols` or `peer_capabilities`.
285///
286/// **Note**: For `local_protocols` this takes [Protocol] because we need to know the number of
287/// messages per versioned capability. From the remote we only get the plain [Capability].
288#[inline]
289pub fn shared_capability_offsets(
290    local_protocols: Vec<Protocol>,
291    peer_capabilities: Vec<Capability>,
292) -> Result<Vec<SharedCapability>, P2PStreamError> {
293    // find intersection of capabilities
294    let our_capabilities =
295        local_protocols.into_iter().map(Protocol::split).collect::<HashMap<_, _>>();
296
297    // map of capability name to version
298    let mut shared_capabilities: HashMap<_, ProtoVersion> = HashMap::default();
299
300    // The `Ord` implementation for capability names should be equivalent to geth (and every other
301    // client), since geth uses golang's default string comparison, which orders strings
302    // lexicographically.
303    // https://golang.org/pkg/strings/#Compare
304    //
305    // This is important because the capability name is used to determine the message id offset, so
306    // if the sorting is not identical, offsets for connected peers could be inconsistent.
307    // This would cause the peers to send messages with the wrong message id, which is usually a
308    // protocol violation.
309    //
310    // The `Ord` implementation for `str` orders strings lexicographically.
311    let mut shared_capability_names = BTreeSet::new();
312
313    // find highest shared version of each shared capability
314    for peer_capability in peer_capabilities {
315        // if we contain this specific capability both peers share it
316        if let Some(messages) = our_capabilities.get(&peer_capability).copied() {
317            // If multiple versions are shared of the same (equal name) capability, the numerically
318            // highest wins, others are ignored
319            if shared_capabilities
320                .get(&peer_capability.name)
321                .is_none_or(|v| peer_capability.version > v.version)
322            {
323                shared_capabilities.insert(
324                    peer_capability.name.clone(),
325                    ProtoVersion { version: peer_capability.version, messages },
326                );
327                shared_capability_names.insert(peer_capability.name);
328            }
329        }
330    }
331
332    // disconnect if we don't share any capabilities
333    if shared_capabilities.is_empty() {
334        return Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
335    }
336
337    // order versions based on capability name (alphabetical) and select offsets based on
338    // BASE_OFFSET + prev_total_message
339    let mut shared_with_offsets = Vec::new();
340
341    // Message IDs are assumed to be compact from ID 0x10 onwards (0x00-0x0f is reserved for the
342    // "p2p" capability) and given to each shared (equal-version, equal-name) capability in
343    // alphabetic order.
344    let mut offset = MAX_RESERVED_MESSAGE_ID + 1;
345    for name in shared_capability_names {
346        let proto_version = &shared_capabilities[&name];
347        let shared_capability = SharedCapability::new(
348            &name,
349            proto_version.version as u8,
350            offset,
351            proto_version.messages,
352        )?;
353        offset += shared_capability.num_messages();
354        shared_with_offsets.push(shared_capability);
355    }
356
357    if shared_with_offsets.is_empty() {
358        return Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
359    }
360
361    Ok(shared_with_offsets)
362}
363
364/// An error that may occur while creating a [`SharedCapability`].
365#[derive(Debug, thiserror::Error)]
366pub enum SharedCapabilityError {
367    /// Unsupported `eth` version.
368    #[error(transparent)]
369    UnsupportedVersion(#[from] ParseVersionError),
370    /// Thrown when the message id for a [`SharedCapability`] overlaps with the reserved p2p
371    /// message id space [`MAX_RESERVED_MESSAGE_ID`].
372    #[error("message id offset `{0}` is reserved")]
373    ReservedMessageIdOffset(u8),
374}
375
376/// An error thrown when capabilities mismatch.
377#[derive(Debug, thiserror::Error)]
378#[error("unsupported capability {capability}")]
379pub struct UnsupportedCapabilityError {
380    capability: Capability,
381}
382
383impl UnsupportedCapabilityError {
384    /// Creates a new error with the given capability
385    pub const fn new(capability: Capability) -> Self {
386        Self { capability }
387    }
388}
389
390#[cfg(test)]
391mod tests {
392    use super::*;
393    use crate::{Capabilities, Capability, SnapVersion};
394    use alloy_primitives::bytes::Bytes;
395    use alloy_rlp::{Decodable, Encodable};
396    use reth_eth_wire_types::RawCapabilityMessage;
397
398    #[test]
399    fn from_eth_68() {
400        let capability = SharedCapability::new("eth", 68, MAX_RESERVED_MESSAGE_ID + 1, 13).unwrap();
401
402        assert_eq!(capability.name(), "eth");
403        assert_eq!(capability.version(), 68);
404        assert_eq!(
405            capability,
406            SharedCapability::Eth {
407                version: EthVersion::Eth68,
408                offset: MAX_RESERVED_MESSAGE_ID + 1
409            }
410        );
411    }
412
413    #[test]
414    fn from_eth_67() {
415        let capability = SharedCapability::new("eth", 67, MAX_RESERVED_MESSAGE_ID + 1, 13).unwrap();
416
417        assert_eq!(capability.name(), "eth");
418        assert_eq!(capability.version(), 67);
419        assert_eq!(
420            capability,
421            SharedCapability::Eth {
422                version: EthVersion::Eth67,
423                offset: MAX_RESERVED_MESSAGE_ID + 1
424            }
425        );
426    }
427
428    #[test]
429    fn from_eth_66() {
430        let capability = SharedCapability::new("eth", 66, MAX_RESERVED_MESSAGE_ID + 1, 15).unwrap();
431
432        assert_eq!(capability.name(), "eth");
433        assert_eq!(capability.version(), 66);
434        assert_eq!(
435            capability,
436            SharedCapability::Eth {
437                version: EthVersion::Eth66,
438                offset: MAX_RESERVED_MESSAGE_ID + 1
439            }
440        );
441    }
442
443    #[test]
444    fn capabilities_supports_eth() {
445        let capabilities: Capabilities = vec![
446            Capability::new_static("eth", 66),
447            Capability::new_static("eth", 67),
448            Capability::new_static("eth", 68),
449            Capability::new_static("eth", 69),
450            Capability::new_static("eth", 70),
451        ]
452        .into();
453
454        assert!(capabilities.supports_eth());
455        assert!(capabilities.supports_eth_v66());
456        assert!(capabilities.supports_eth_v67());
457        assert!(capabilities.supports_eth_v68());
458        assert!(capabilities.supports_eth_v69());
459        assert!(capabilities.supports_eth_v70());
460    }
461
462    #[test]
463    fn test_peer_capability_version_zero() {
464        let cap = Capability::new_static("TestName", 0);
465        let local_capabilities: Vec<Protocol> =
466            vec![Protocol::new(cap.clone(), 0), EthVersion::Eth67.into(), EthVersion::Eth68.into()];
467        let peer_capabilities = vec![cap.clone()];
468
469        let shared = shared_capability_offsets(local_capabilities, peer_capabilities).unwrap();
470        assert_eq!(shared.len(), 1);
471        assert_eq!(shared[0], SharedCapability::UnknownCapability { cap, offset: 16, messages: 0 })
472    }
473
474    #[test]
475    fn test_peer_lower_capability_version() {
476        let local_capabilities: Vec<Protocol> =
477            vec![EthVersion::Eth66.into(), EthVersion::Eth67.into(), EthVersion::Eth68.into()];
478        let peer_capabilities: Vec<Capability> = vec![EthVersion::Eth66.into()];
479
480        let shared_capability =
481            shared_capability_offsets(local_capabilities, peer_capabilities).unwrap()[0].clone();
482
483        assert_eq!(
484            shared_capability,
485            SharedCapability::Eth {
486                version: EthVersion::Eth66,
487                offset: MAX_RESERVED_MESSAGE_ID + 1
488            }
489        )
490    }
491
492    #[test]
493    fn test_peer_capability_version_too_low() {
494        let local: Vec<Protocol> = vec![EthVersion::Eth67.into()];
495        let peer_capabilities: Vec<Capability> = vec![EthVersion::Eth66.into()];
496
497        let shared_capability = shared_capability_offsets(local, peer_capabilities);
498
499        assert!(matches!(
500            shared_capability,
501            Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
502        ))
503    }
504
505    #[test]
506    fn test_peer_capability_version_too_high() {
507        let local_capabilities = vec![EthVersion::Eth66.into()];
508        let peer_capabilities = vec![EthVersion::Eth67.into()];
509
510        let shared_capability = shared_capability_offsets(local_capabilities, peer_capabilities);
511
512        assert!(matches!(
513            shared_capability,
514            Err(P2PStreamError::HandshakeError(P2PHandshakeError::NoSharedCapabilities))
515        ))
516    }
517
518    #[test]
519    fn test_find_by_offset() {
520        let local_capabilities = vec![EthVersion::Eth66.into()];
521        let peer_capabilities = vec![EthVersion::Eth66.into()];
522
523        let shared = SharedCapabilities::try_new(local_capabilities, peer_capabilities).unwrap();
524
525        let shared_eth = shared.find_by_relative_offset(0).unwrap();
526        assert_eq!(shared_eth.name(), "eth");
527
528        let shared_eth = shared.find_by_offset(MAX_RESERVED_MESSAGE_ID + 1).unwrap();
529        assert_eq!(shared_eth.name(), "eth");
530
531        // reserved message id space
532        assert!(shared.find_by_offset(MAX_RESERVED_MESSAGE_ID).is_none());
533    }
534
535    #[test]
536    fn test_find_by_offset_many() {
537        let cap = Capability::new_static("aaa", 1);
538        let proto = Protocol::new(cap.clone(), 5);
539        let local_capabilities = vec![proto.clone(), EthVersion::Eth66.into()];
540        let peer_capabilities = vec![cap, EthVersion::Eth66.into()];
541
542        let shared = SharedCapabilities::try_new(local_capabilities, peer_capabilities).unwrap();
543
544        let shared_eth = shared.find_by_relative_offset(0).unwrap();
545        assert_eq!(shared_eth.name(), proto.cap.name);
546
547        let shared_eth = shared.find_by_offset(MAX_RESERVED_MESSAGE_ID + 1).unwrap();
548        assert_eq!(shared_eth.name(), proto.cap.name);
549
550        // the 5th shared message (0,1,2,3,4) is the last message of the aaa capability
551        let shared_eth = shared.find_by_relative_offset(4).unwrap();
552        assert_eq!(shared_eth.name(), proto.cap.name);
553        let shared_eth = shared.find_by_offset(MAX_RESERVED_MESSAGE_ID + 5).unwrap();
554        assert_eq!(shared_eth.name(), proto.cap.name);
555
556        // the 6th shared message is the first message of the eth capability
557        let shared_eth = shared.find_by_relative_offset(1 + proto.messages()).unwrap();
558        assert_eq!(shared_eth.name(), "eth");
559    }
560
561    #[test]
562    fn relative_message_id_accounts_for_intermediate_capabilities() {
563        let intermediate_cap = Capability::new_static("foo", 1);
564        let intermediate = Protocol::new(intermediate_cap.clone(), 3);
565        let snap = Capability::snap(SnapVersion::V1);
566        let eth = Capability::eth(EthVersion::Eth69);
567        let local_capabilities =
568            vec![EthVersion::Eth69.into(), intermediate, Protocol::snap(SnapVersion::V1)];
569        let peer_capabilities = vec![eth, intermediate_cap, snap.clone()];
570
571        let shared = SharedCapabilities::try_new(local_capabilities, peer_capabilities).unwrap();
572        let snap_id = shared.relative_message_id(&snap, 2).unwrap();
573
574        assert_eq!(snap_id, EthMessageID::message_count(EthVersion::Eth69) + 3 + 2);
575        assert_eq!(shared.capability_message_id(&snap, snap_id), Some(2));
576    }
577
578    #[test]
579    fn capability_message_id_rejects_other_capability_range() {
580        let intermediate_cap = Capability::new_static("foo", 1);
581        let intermediate = Protocol::new(intermediate_cap.clone(), 3);
582        let snap = Capability::snap(SnapVersion::V1);
583        let local_capabilities =
584            vec![EthVersion::Eth69.into(), intermediate, Protocol::snap(SnapVersion::V1)];
585        let peer_capabilities =
586            vec![Capability::eth(EthVersion::Eth69), intermediate_cap.clone(), snap.clone()];
587
588        let shared = SharedCapabilities::try_new(local_capabilities, peer_capabilities).unwrap();
589        let intermediate_id = shared.relative_message_id(&intermediate_cap, 1).unwrap();
590
591        assert_eq!(shared.capability_message_id(&snap, intermediate_id), None);
592        assert_eq!(shared.relative_message_id(&snap, SnapVersion::V1.message_count()), None);
593    }
594
595    #[test]
596    fn test_raw_capability_rlp() {
597        let msg = RawCapabilityMessage { id: 1, payload: Bytes::from(vec![0x01, 0x02, 0x03]) };
598
599        // Encode the message into bytes
600        let mut encoded = Vec::new();
601        msg.encode(&mut encoded);
602
603        // Decode the bytes back into RawCapabilityMessage
604        let decoded = RawCapabilityMessage::decode(&mut &encoded[..]).unwrap();
605
606        // Verify that the decoded message matches the original
607        assert_eq!(msg, decoded);
608    }
609}
reth_eth_wire/capability.rs

reth_eth_wire/
capability.rs
