espresso_node/state_signature/relay_server/
lcv2_relay.rs

1use std::{
2    collections::{BTreeSet, HashMap, hash_map::Entry},
3    sync::Arc,
4};
5
6use alloy::primitives::U256;
7use axum::http::StatusCode;
8use hotshot_types::{
9    light_client::{
10        LCV2StateSignatureRequestBody, LCV2StateSignaturesBundle, LightClientState, StateVerKey,
11    },
12    traits::signature_key::LCV2StateSignatureKey,
13};
14
15use super::{RelayError, stake_table_tracker::StakeTableTracker};
16
17#[async_trait::async_trait]
18pub trait LCV2StateRelayServerDataSource {
19    /// Get the latest available signatures bundle.
20    /// # Errors
21    /// Errors if there's no available signatures bundle.
22    fn get_latest_signature_bundle(&self) -> Result<LCV2StateSignaturesBundle, RelayError>;
23
24    /// Post a signature to the relay server
25    /// # Errors
26    /// Errors if the signature is invalid, already posted, or no longer needed.
27    async fn post_signature(
28        &mut self,
29        req: LCV2StateSignatureRequestBody,
30    ) -> Result<(), RelayError>;
31}
32
33/// Server state that tracks the light client V2 state and signatures
34pub struct LCV2StateRelayServerState {
35    /// Bundles for light client V2
36    bundles: HashMap<u64, HashMap<LightClientState, LCV2StateSignaturesBundle>>,
37
38    /// The latest state signatures bundle for LCV2 light client
39    latest_available_bundle: Option<LCV2StateSignaturesBundle>,
40    /// The block height of the latest available LCV2 state signature bundle
41    latest_block_height: Option<u64>,
42
43    /// A ordered queue of block heights for V2 light client state, used for garbage collection.
44    gc_queue: BTreeSet<u64>,
45
46    /// Stake table tracker
47    stake_table_tracker: Arc<StakeTableTracker>,
48}
49
50#[async_trait::async_trait]
51impl LCV2StateRelayServerDataSource for LCV2StateRelayServerState {
52    fn get_latest_signature_bundle(&self) -> Result<LCV2StateSignaturesBundle, RelayError> {
53        self.latest_available_bundle
54            .clone()
55            .ok_or(RelayError::catch_all(
56                StatusCode::NOT_FOUND,
57                "The light client V2 state signatures are not ready.".to_owned(),
58            ))
59    }
60
61    async fn post_signature(
62        &mut self,
63        req: LCV2StateSignatureRequestBody,
64    ) -> Result<(), RelayError> {
65        let block_height = req.state.block_height;
66        if block_height <= self.latest_block_height.unwrap_or(0) {
67            // This signature is no longer needed
68            return Ok(());
69        }
70        let stake_table = self
71            .stake_table_tracker
72            .stake_table_info_for_block(block_height)
73            .await
74            .map_err(|e| RelayError::catch_all(StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
75        let Some(weight) = stake_table.known_nodes.get(&req.key) else {
76            tracing::warn!("Received LCV2 signature from unknown node: {req}");
77            return Err(RelayError::catch_all(
78                StatusCode::UNAUTHORIZED,
79                "LCV2 signature posted by nodes not on the stake table".to_owned(),
80            ));
81        };
82
83        // sanity check the signature validity first before adding in
84        if !<StateVerKey as LCV2StateSignatureKey>::verify_state_sig(
85            &req.key,
86            &req.signature,
87            &req.state,
88            &req.next_stake,
89        ) {
90            tracing::warn!("Couldn't verify the received LCV2 signature: {req}");
91            return Err(RelayError::catch_all(
92                StatusCode::BAD_REQUEST,
93                "The posted LCV2 signature is not valid.".to_owned(),
94            ));
95        }
96
97        let bundles_at_height = self.bundles.entry(block_height).or_default();
98        self.gc_queue.insert(block_height);
99
100        let bundle = bundles_at_height
101            .entry(req.state)
102            .or_insert(LCV2StateSignaturesBundle {
103                state: req.state,
104                next_stake: req.next_stake,
105                signatures: Default::default(),
106                accumulated_weight: U256::from(0),
107            });
108        tracing::debug!(
109            "Accepting new LCV2 signature for block height {} from {}.",
110            block_height,
111            req.key
112        );
113        match bundle.signatures.entry(req.key) {
114            Entry::Occupied(_) => {
115                // A signature is already posted for this key with this state
116                return Err(RelayError::catch_all(
117                    StatusCode::BAD_REQUEST,
118                    "A LCV2 signature of this light client state is already posted at this block \
119                     height for this key."
120                        .to_owned(),
121                ));
122            },
123            Entry::Vacant(entry) => {
124                entry.insert(req.signature);
125                bundle.accumulated_weight += *weight;
126            },
127        }
128
129        if bundle.accumulated_weight >= stake_table.threshold {
130            tracing::info!(
131                "Light client V2 state signature bundle at block height {} is ready to serve.",
132                block_height
133            );
134            self.latest_block_height = Some(block_height);
135            self.latest_available_bundle = Some(bundle.clone());
136
137            // garbage collect
138            self.prune(block_height);
139        }
140
141        Ok(())
142    }
143}
144
145impl LCV2StateRelayServerState {
146    /// Centralizing all garbage-collection logic, won't panic, won't error, simply do nothing if nothing to prune.
147    /// `until_height` is inclusive, meaning that would also be pruned.
148    pub fn prune(&mut self, until_height: u64) {
149        while let Some(&height) = self.gc_queue.first() {
150            if height > until_height {
151                return;
152            }
153            self.bundles.remove(&height);
154            self.gc_queue.pop_first();
155            tracing::debug!(%height, "garbage collected for ");
156        }
157    }
158
159    pub fn new(stake_table_tracker: Arc<StakeTableTracker>) -> Self {
160        Self {
161            bundles: HashMap::new(),
162            latest_available_bundle: None,
163            latest_block_height: None,
164            gc_queue: BTreeSet::new(),
165            stake_table_tracker,
166        }
167    }
168}
espresso_node/state_signature/relay_server/lcv2_relay.rs

espresso_node/state_signature/relay_server/
lcv2_relay.rs
