Added LightClientBootstrap V1 (#3711)

## Issue Addressed

Partially addresses #3651

## Proposed Changes

Adds server-side support for light_client_bootstrap_v1 topic

## Additional Info

This PR, creates each time a bootstrap without using cache, I do not know how necessary a cache is in this case as this topic is not supposed to be called frequently and IMHO we can just prevent abuse by using the limiter, but let me know what you think or if there is any caveat to this, or if it is necessary only for the sake of good practice.


Co-authored-by: Pawan Dhananjay <pawandhananjay@gmail.com>

beacon_node/lighthouse_network/src/rpc/codec/ssz_snappy.rs

@@ -16,8 +16,8 @@ use std::marker::PhantomData;
 use std::sync::Arc;
 use tokio_util::codec::{Decoder, Encoder};
 use types::{
-    EthSpec, ForkContext, ForkName, SignedBeaconBlock, SignedBeaconBlockAltair,
-    SignedBeaconBlockBase, SignedBeaconBlockMerge,
+    light_client_bootstrap::LightClientBootstrap, EthSpec, ForkContext, ForkName, Hash256,
+    SignedBeaconBlock, SignedBeaconBlockAltair, SignedBeaconBlockBase, SignedBeaconBlockMerge,
 };
 use unsigned_varint::codec::Uvi;
 
@@ -70,6 +70,7 @@ impl<TSpec: EthSpec> Encoder<RPCCodedResponse<TSpec>> for SSZSnappyInboundCodec<
                 RPCResponse::Status(res) => res.as_ssz_bytes(),
                 RPCResponse::BlocksByRange(res) => res.as_ssz_bytes(),
                 RPCResponse::BlocksByRoot(res) => res.as_ssz_bytes(),
+                RPCResponse::LightClientBootstrap(res) => res.as_ssz_bytes(),
                 RPCResponse::Pong(res) => res.data.as_ssz_bytes(),
                 RPCResponse::MetaData(res) =>
                 // Encode the correct version of the MetaData response based on the negotiated version.
@@ -230,6 +231,7 @@ impl<TSpec: EthSpec> Encoder<OutboundRequest<TSpec>> for SSZSnappyOutboundCodec<
             OutboundRequest::BlocksByRoot(req) => req.block_roots.as_ssz_bytes(),
             OutboundRequest::Ping(req) => req.as_ssz_bytes(),
             OutboundRequest::MetaData(_) => return Ok(()), // no metadata to encode
+            OutboundRequest::LightClientBootstrap(req) => req.as_ssz_bytes(),
         };
         // SSZ encoded bytes should be within `max_packet_size`
         if bytes.len() > self.max_packet_size {
@@ -472,7 +474,11 @@ fn handle_v1_request<T: EthSpec>(
         Protocol::Ping => Ok(Some(InboundRequest::Ping(Ping {
             data: u64::from_ssz_bytes(decoded_buffer)?,
         }))),
-
+        Protocol::LightClientBootstrap => Ok(Some(InboundRequest::LightClientBootstrap(
+            LightClientBootstrapRequest {
+                root: Hash256::from_ssz_bytes(decoded_buffer)?,
+            },
+        ))),
         // MetaData requests return early from InboundUpgrade and do not reach the decoder.
         // Handle this case just for completeness.
         Protocol::MetaData => {
@@ -544,6 +550,9 @@ fn handle_v1_response<T: EthSpec>(
         Protocol::MetaData => Ok(Some(RPCResponse::MetaData(MetaData::V1(
             MetaDataV1::from_ssz_bytes(decoded_buffer)?,
         )))),
+        Protocol::LightClientBootstrap => Ok(Some(RPCResponse::LightClientBootstrap(
+            LightClientBootstrap::from_ssz_bytes(decoded_buffer)?,
+        ))),
     }
 }
 
@@ -867,6 +876,9 @@ mod tests {
                 OutboundRequest::MetaData(metadata) => {
                     assert_eq!(decoded, InboundRequest::MetaData(metadata))
                 }
+                OutboundRequest::LightClientBootstrap(bootstrap) => {
+                    assert_eq!(decoded, InboundRequest::LightClientBootstrap(bootstrap))
+                }
             }
         }
     }

beacon_node/lighthouse_network/src/rpc/methods.rs

@@ -12,7 +12,9 @@ use std::ops::Deref;
 use std::sync::Arc;
 use strum::IntoStaticStr;
 use superstruct::superstruct;
-use types::{Epoch, EthSpec, Hash256, SignedBeaconBlock, Slot};
+use types::{
+    light_client_bootstrap::LightClientBootstrap, Epoch, EthSpec, Hash256, SignedBeaconBlock, Slot,
+};
 
 /// Maximum number of blocks in a single request.
 pub type MaxRequestBlocks = U1024;
@@ -243,6 +245,9 @@ pub enum RPCResponse<T: EthSpec> {
     /// A response to a get BLOCKS_BY_ROOT request.
     BlocksByRoot(Arc<SignedBeaconBlock<T>>),
 
+    /// A response to a get LIGHTCLIENT_BOOTSTRAP request.
+    LightClientBootstrap(LightClientBootstrap<T>),
+
     /// A PONG response to a PING request.
     Pong(Ping),
 
@@ -273,6 +278,12 @@ pub enum RPCCodedResponse<T: EthSpec> {
     StreamTermination(ResponseTermination),
 }
 
+/// Request a light_client_bootstrap for lightclients peers.
+#[derive(Encode, Decode, Clone, Debug, PartialEq)]
+pub struct LightClientBootstrapRequest {
+    pub root: Hash256,
+}
+
 /// The code assigned to an erroneous `RPCResponse`.
 #[derive(Debug, Clone, Copy, PartialEq, IntoStaticStr)]
 #[strum(serialize_all = "snake_case")]
@@ -321,6 +332,7 @@ impl<T: EthSpec> RPCCodedResponse<T> {
                 RPCResponse::BlocksByRoot(_) => true,
                 RPCResponse::Pong(_) => false,
                 RPCResponse::MetaData(_) => false,
+                RPCResponse::LightClientBootstrap(_) => false,
             },
             RPCCodedResponse::Error(_, _) => true,
             // Stream terminations are part of responses that have chunks
@@ -355,6 +367,7 @@ impl<T: EthSpec> RPCResponse<T> {
             RPCResponse::BlocksByRoot(_) => Protocol::BlocksByRoot,
             RPCResponse::Pong(_) => Protocol::Ping,
             RPCResponse::MetaData(_) => Protocol::MetaData,
+            RPCResponse::LightClientBootstrap(_) => Protocol::LightClientBootstrap,
         }
     }
 }
@@ -390,6 +403,9 @@ impl<T: EthSpec> std::fmt::Display for RPCResponse<T> {
             }
             RPCResponse::Pong(ping) => write!(f, "Pong: {}", ping.data),
             RPCResponse::MetaData(metadata) => write!(f, "Metadata: {}", metadata.seq_number()),
+            RPCResponse::LightClientBootstrap(bootstrap) => {
+                write!(f, "LightClientBootstrap Slot: {}", bootstrap.header.slot)
+            }
         }
     }
 }

beacon_node/lighthouse_network/src/rpc/mod.rs

@@ -26,8 +26,8 @@ pub(crate) use protocol::{InboundRequest, RPCProtocol};
 
 pub use handler::SubstreamId;
 pub use methods::{
-    BlocksByRangeRequest, BlocksByRootRequest, GoodbyeReason, MaxRequestBlocks,
-    RPCResponseErrorCode, ResponseTermination, StatusMessage, MAX_REQUEST_BLOCKS,
+    BlocksByRangeRequest, BlocksByRootRequest, GoodbyeReason, LightClientBootstrapRequest,
+    MaxRequestBlocks, RPCResponseErrorCode, ResponseTermination, StatusMessage, MAX_REQUEST_BLOCKS,
 };
 pub(crate) use outbound::OutboundRequest;
 pub use protocol::{max_rpc_size, Protocol, RPCError};
@@ -108,18 +108,24 @@ pub struct RPC<Id: ReqId, TSpec: EthSpec> {
     /// Queue of events to be processed.
     events: Vec<NetworkBehaviourAction<RPCMessage<Id, TSpec>, RPCHandler<Id, TSpec>>>,
     fork_context: Arc<ForkContext>,
+    enable_light_client_server: bool,
     /// Slog logger for RPC behaviour.
     log: slog::Logger,
 }
 
 impl<Id: ReqId, TSpec: EthSpec> RPC<Id, TSpec> {
-    pub fn new(fork_context: Arc<ForkContext>, log: slog::Logger) -> Self {
+    pub fn new(
+        fork_context: Arc<ForkContext>,
+        enable_light_client_server: bool,
+        log: slog::Logger,
+    ) -> Self {
         let log = log.new(o!("service" => "libp2p_rpc"));
         let limiter = RPCRateLimiterBuilder::new()
             .n_every(Protocol::MetaData, 2, Duration::from_secs(5))
             .n_every(Protocol::Ping, 2, Duration::from_secs(10))
             .n_every(Protocol::Status, 5, Duration::from_secs(15))
             .one_every(Protocol::Goodbye, Duration::from_secs(10))
+            .one_every(Protocol::LightClientBootstrap, Duration::from_secs(10))
             .n_every(
                 Protocol::BlocksByRange,
                 methods::MAX_REQUEST_BLOCKS,
@@ -132,6 +138,7 @@ impl<Id: ReqId, TSpec: EthSpec> RPC<Id, TSpec> {
             limiter,
             events: Vec::new(),
             fork_context,
+            enable_light_client_server,
             log,
         }
     }
@@ -188,6 +195,7 @@ where
                 RPCProtocol {
                     fork_context: self.fork_context.clone(),
                     max_rpc_size: max_rpc_size(&self.fork_context),
+                    enable_light_client_server: self.enable_light_client_server,
                     phantom: PhantomData,
                 },
                 (),

beacon_node/lighthouse_network/src/rpc/outbound.rs

@@ -38,6 +38,7 @@ pub enum OutboundRequest<TSpec: EthSpec> {
     Goodbye(GoodbyeReason),
     BlocksByRange(OldBlocksByRangeRequest),
     BlocksByRoot(BlocksByRootRequest),
+    LightClientBootstrap(LightClientBootstrapRequest),
     Ping(Ping),
     MetaData(PhantomData<TSpec>),
 }
@@ -84,9 +85,12 @@ impl<TSpec: EthSpec> OutboundRequest<TSpec> {
                 ProtocolId::new(Protocol::MetaData, Version::V2, Encoding::SSZSnappy),
                 ProtocolId::new(Protocol::MetaData, Version::V1, Encoding::SSZSnappy),
             ],
+            // Note: This match arm is technically unreachable as we only respond to light client requests
+            // that we generate from the beacon state.
+            // We do not make light client rpc requests from the beacon node
+            OutboundRequest::LightClientBootstrap(_) => vec![],
         }
     }
-
     /* These functions are used in the handler for stream management */
 
     /// Number of responses expected for this request.
@@ -98,6 +102,7 @@ impl<TSpec: EthSpec> OutboundRequest<TSpec> {
             OutboundRequest::BlocksByRoot(req) => req.block_roots.len() as u64,
             OutboundRequest::Ping(_) => 1,
             OutboundRequest::MetaData(_) => 1,
+            OutboundRequest::LightClientBootstrap(_) => 1,
         }
     }
 
@@ -110,6 +115,7 @@ impl<TSpec: EthSpec> OutboundRequest<TSpec> {
             OutboundRequest::BlocksByRoot(_) => Protocol::BlocksByRoot,
             OutboundRequest::Ping(_) => Protocol::Ping,
             OutboundRequest::MetaData(_) => Protocol::MetaData,
+            OutboundRequest::LightClientBootstrap(_) => Protocol::LightClientBootstrap,
         }
     }
 
@@ -121,6 +127,7 @@ impl<TSpec: EthSpec> OutboundRequest<TSpec> {
             // variants that have `multiple_responses()` can have values.
             OutboundRequest::BlocksByRange(_) => ResponseTermination::BlocksByRange,
             OutboundRequest::BlocksByRoot(_) => ResponseTermination::BlocksByRoot,
+            OutboundRequest::LightClientBootstrap(_) => unreachable!(),
             OutboundRequest::Status(_) => unreachable!(),
             OutboundRequest::Goodbye(_) => unreachable!(),
             OutboundRequest::Ping(_) => unreachable!(),
@@ -178,6 +185,9 @@ impl<TSpec: EthSpec> std::fmt::Display for OutboundRequest<TSpec> {
             OutboundRequest::BlocksByRoot(req) => write!(f, "Blocks by root: {:?}", req),
             OutboundRequest::Ping(ping) => write!(f, "Ping: {}", ping.data),
             OutboundRequest::MetaData(_) => write!(f, "MetaData request"),
+            OutboundRequest::LightClientBootstrap(bootstrap) => {
+                write!(f, "Lightclient Bootstrap: {}", bootstrap.root)
+            }
         }
     }
 }

beacon_node/lighthouse_network/src/rpc/protocol.rs

@@ -153,6 +153,8 @@ pub enum Protocol {
     Ping,
     /// The `MetaData` protocol name.
     MetaData,
+    /// The `LightClientBootstrap` protocol name.
+    LightClientBootstrap,
 }
 
 /// RPC Versions
@@ -179,6 +181,7 @@ impl std::fmt::Display for Protocol {
             Protocol::BlocksByRoot => "beacon_blocks_by_root",
             Protocol::Ping => "ping",
             Protocol::MetaData => "metadata",
+            Protocol::LightClientBootstrap => "light_client_bootstrap",
         };
         f.write_str(repr)
     }
@@ -207,6 +210,7 @@ impl std::fmt::Display for Version {
 pub struct RPCProtocol<TSpec: EthSpec> {
     pub fork_context: Arc<ForkContext>,
     pub max_rpc_size: usize,
+    pub enable_light_client_server: bool,
     pub phantom: PhantomData<TSpec>,
 }
 
@@ -216,7 +220,7 @@ impl<TSpec: EthSpec> UpgradeInfo for RPCProtocol<TSpec> {
 
     /// The list of supported RPC protocols for Lighthouse.
     fn protocol_info(&self) -> Self::InfoIter {
-        vec![
+        let mut supported_protocols = vec![
             ProtocolId::new(Protocol::Status, Version::V1, Encoding::SSZSnappy),
             ProtocolId::new(Protocol::Goodbye, Version::V1, Encoding::SSZSnappy),
             // V2 variants have higher preference then V1
@@ -227,7 +231,15 @@ impl<TSpec: EthSpec> UpgradeInfo for RPCProtocol<TSpec> {
             ProtocolId::new(Protocol::Ping, Version::V1, Encoding::SSZSnappy),
             ProtocolId::new(Protocol::MetaData, Version::V2, Encoding::SSZSnappy),
             ProtocolId::new(Protocol::MetaData, Version::V1, Encoding::SSZSnappy),
-        ]
+        ];
+        if self.enable_light_client_server {
+            supported_protocols.push(ProtocolId::new(
+                Protocol::LightClientBootstrap,
+                Version::V1,
+                Encoding::SSZSnappy,
+            ));
+        }
+        supported_protocols
     }
 }
 
@@ -289,6 +301,10 @@ impl ProtocolId {
                 <Ping as Encode>::ssz_fixed_len(),
                 <Ping as Encode>::ssz_fixed_len(),
             ),
+            Protocol::LightClientBootstrap => RpcLimits::new(
+                <LightClientBootstrapRequest as Encode>::ssz_fixed_len(),
+                <LightClientBootstrapRequest as Encode>::ssz_fixed_len(),
+            ),
             Protocol::MetaData => RpcLimits::new(0, 0), // Metadata requests are empty
         }
     }
@@ -312,6 +328,10 @@ impl ProtocolId {
                 <MetaDataV1<T> as Encode>::ssz_fixed_len(),
                 <MetaDataV2<T> as Encode>::ssz_fixed_len(),
             ),
+            Protocol::LightClientBootstrap => RpcLimits::new(
+                <LightClientBootstrapRequest as Encode>::ssz_fixed_len(),
+                <LightClientBootstrapRequest as Encode>::ssz_fixed_len(),
+            ),
         }
     }
 
@@ -417,57 +437,13 @@ pub enum InboundRequest<TSpec: EthSpec> {
     Goodbye(GoodbyeReason),
     BlocksByRange(OldBlocksByRangeRequest),
     BlocksByRoot(BlocksByRootRequest),
+    LightClientBootstrap(LightClientBootstrapRequest),
     Ping(Ping),
     MetaData(PhantomData<TSpec>),
 }
 
-impl<TSpec: EthSpec> UpgradeInfo for InboundRequest<TSpec> {
-    type Info = ProtocolId;
-    type InfoIter = Vec<Self::Info>;
-
-    // add further protocols as we support more encodings/versions
-    fn protocol_info(&self) -> Self::InfoIter {
-        self.supported_protocols()
-    }
-}
-
 /// Implements the encoding per supported protocol for `RPCRequest`.
 impl<TSpec: EthSpec> InboundRequest<TSpec> {
-    pub fn supported_protocols(&self) -> Vec<ProtocolId> {
-        match self {
-            // add more protocols when versions/encodings are supported
-            InboundRequest::Status(_) => vec![ProtocolId::new(
-                Protocol::Status,
-                Version::V1,
-                Encoding::SSZSnappy,
-            )],
-            InboundRequest::Goodbye(_) => vec![ProtocolId::new(
-                Protocol::Goodbye,
-                Version::V1,
-                Encoding::SSZSnappy,
-            )],
-            InboundRequest::BlocksByRange(_) => vec![
-                // V2 has higher preference when negotiating a stream
-                ProtocolId::new(Protocol::BlocksByRange, Version::V2, Encoding::SSZSnappy),
-                ProtocolId::new(Protocol::BlocksByRange, Version::V1, Encoding::SSZSnappy),
-            ],
-            InboundRequest::BlocksByRoot(_) => vec![
-                // V2 has higher preference when negotiating a stream
-                ProtocolId::new(Protocol::BlocksByRoot, Version::V2, Encoding::SSZSnappy),
-                ProtocolId::new(Protocol::BlocksByRoot, Version::V1, Encoding::SSZSnappy),
-            ],
-            InboundRequest::Ping(_) => vec![ProtocolId::new(
-                Protocol::Ping,
-                Version::V1,
-                Encoding::SSZSnappy,
-            )],
-            InboundRequest::MetaData(_) => vec![
-                ProtocolId::new(Protocol::MetaData, Version::V2, Encoding::SSZSnappy),
-                ProtocolId::new(Protocol::MetaData, Version::V1, Encoding::SSZSnappy),
-            ],
-        }
-    }
-
     /* These functions are used in the handler for stream management */
 
     /// Number of responses expected for this request.
@@ -479,6 +455,7 @@ impl<TSpec: EthSpec> InboundRequest<TSpec> {
             InboundRequest::BlocksByRoot(req) => req.block_roots.len() as u64,
             InboundRequest::Ping(_) => 1,
             InboundRequest::MetaData(_) => 1,
+            InboundRequest::LightClientBootstrap(_) => 1,
         }
     }
 
@@ -491,6 +468,7 @@ impl<TSpec: EthSpec> InboundRequest<TSpec> {
             InboundRequest::BlocksByRoot(_) => Protocol::BlocksByRoot,
             InboundRequest::Ping(_) => Protocol::Ping,
             InboundRequest::MetaData(_) => Protocol::MetaData,
+            InboundRequest::LightClientBootstrap(_) => Protocol::LightClientBootstrap,
         }
     }
 
@@ -506,6 +484,7 @@ impl<TSpec: EthSpec> InboundRequest<TSpec> {
             InboundRequest::Goodbye(_) => unreachable!(),
             InboundRequest::Ping(_) => unreachable!(),
             InboundRequest::MetaData(_) => unreachable!(),
+            InboundRequest::LightClientBootstrap(_) => unreachable!(),
         }
     }
 }
@@ -609,6 +588,9 @@ impl<TSpec: EthSpec> std::fmt::Display for InboundRequest<TSpec> {
             InboundRequest::BlocksByRoot(req) => write!(f, "Blocks by root: {:?}", req),
             InboundRequest::Ping(ping) => write!(f, "Ping: {}", ping.data),
             InboundRequest::MetaData(_) => write!(f, "MetaData request"),
+            InboundRequest::LightClientBootstrap(bootstrap) => {
+                write!(f, "LightClientBootstrap: {}", bootstrap.root)
+            }
         }
     }
 }

beacon_node/lighthouse_network/src/rpc/rate_limiter.rs

@@ -73,6 +73,8 @@ pub struct RPCRateLimiter {
     bbrange_rl: Limiter<PeerId>,
     /// BlocksByRoot rate limiter.
     bbroots_rl: Limiter<PeerId>,
+    /// LightClientBootstrap rate limiter.
+    lcbootstrap_rl: Limiter<PeerId>,
 }
 
 /// Error type for non conformant requests
@@ -98,6 +100,8 @@ pub struct RPCRateLimiterBuilder {
     bbrange_quota: Option<Quota>,
     /// Quota for the BlocksByRoot protocol.
     bbroots_quota: Option<Quota>,
+    /// Quota for the LightClientBootstrap protocol.
+    lcbootstrap_quota: Option<Quota>,
 }
 
 impl RPCRateLimiterBuilder {
@@ -116,6 +120,7 @@ impl RPCRateLimiterBuilder {
             Protocol::Goodbye => self.goodbye_quota = q,
             Protocol::BlocksByRange => self.bbrange_quota = q,
             Protocol::BlocksByRoot => self.bbroots_quota = q,
+            Protocol::LightClientBootstrap => self.lcbootstrap_quota = q,
         }
         self
     }
@@ -155,6 +160,9 @@ impl RPCRateLimiterBuilder {
         let bbrange_quota = self
             .bbrange_quota
             .ok_or("BlocksByRange quota not specified")?;
+        let lcbootstrap_quote = self
+            .lcbootstrap_quota
+            .ok_or("LightClientBootstrap quota not specified")?;
 
         // create the rate limiters
         let ping_rl = Limiter::from_quota(ping_quota)?;
@@ -163,6 +171,7 @@ impl RPCRateLimiterBuilder {
         let goodbye_rl = Limiter::from_quota(goodbye_quota)?;
         let bbroots_rl = Limiter::from_quota(bbroots_quota)?;
         let bbrange_rl = Limiter::from_quota(bbrange_quota)?;
+        let lcbootstrap_rl = Limiter::from_quota(lcbootstrap_quote)?;
 
         // check for peers to prune every 30 seconds, starting in 30 seconds
         let prune_every = tokio::time::Duration::from_secs(30);
@@ -176,6 +185,7 @@ impl RPCRateLimiterBuilder {
             goodbye_rl,
             bbroots_rl,
             bbrange_rl,
+            lcbootstrap_rl,
             init_time: Instant::now(),
         })
     }
@@ -199,6 +209,7 @@ impl RPCRateLimiter {
             Protocol::Goodbye => &mut self.goodbye_rl,
             Protocol::BlocksByRange => &mut self.bbrange_rl,
             Protocol::BlocksByRoot => &mut self.bbroots_rl,
+            Protocol::LightClientBootstrap => &mut self.lcbootstrap_rl,
         };
         check(limiter)
     }