Implement query_header_at_height via plain RPC queries (no light client verification)

CHANGELOG.md

@@ -7,10 +7,12 @@
 - [changelog] Added "unreleased" section in `CHANGELOG.MD` to help streamline releases ([#274])
 - [relayer] Integrate relayer spike into relayer crate ([#335])
 - [modules] Implement flexible connection id selection ([#332])
+- [relayer] Implement `query_header_at_height` via plain RPC queries (no light client verification) ([#336])
 
 [#274]: https://github.com/informalsystems/ibc-rs/issues/274
 [#332]: https://github.com/informalsystems/ibc-rs/issues/332
 [#335]: https://github.com/informalsystems/ibc-rs/pulls/335
+[#336]: https://github.com/informalsystems/ibc-rs/issues/336
 
 ### IMPROVEMENTS
 

relayer-cli/tests/fixtures/two_chains.toml

@@ -16,6 +16,9 @@ strategy = "naive"
   gas_price = "0.025stake"
   trusting_period = "336h"
 
+  # TODO: Move to light client config
+  peer_id = "BADFADAD0BEFEEDC0C0ADEADBEEFC0FFEEFACADE"
+
 [[chains]]
   id = "ibc1"
   rpc_addr = "localhost:26557"
@@ -26,4 +29,7 @@ strategy = "naive"
   gas = 200000
   gas_adjustement = 1.3
   gas_price = "0.025stake"
-  trusting_period = "336h"
+  trusting_period = "336h"
+
+  # TODO: Move to light client config
+  peer_id = "DC0C0ADEADBEEFC0FFEEFACADEBADFADAD0BEFEE"

relayer-cli/tests/integration.rs

@@ -36,6 +36,7 @@ fn simd_config() -> Config {
         client_ids: vec!["ethbridge".to_string()],
         gas: 200000,
         trusting_period: Default::default(),
+        peer_id: "BADFADAD0BEFEEDC0C0ADEADBEEFC0FFEEFACADE".parse().unwrap(),
     }];
     config
 }

relayer/src/chain.rs

@@ -15,6 +15,7 @@ use ibc::ics24_host::Path;
 use crate::client::LightClient;
 use crate::config::ChainConfig;
 use crate::error;
+use crate::util::block_on;
 
 use std::error::Error;
 
@@ -79,44 +80,30 @@ pub trait Chain {
     /// Sign message
     /// TODO - waiting for tendermint-rs upgrade to v0.16
     fn sign_tx(&self, _msgs: &[Any]) -> Result<Vec<u8>, Self::Error>;
-}
 
-/// Query the latest height the chain is at via a RPC query
-pub async fn query_latest_height(chain: &impl Chain) -> Result<Height, error::Error> {
-    let status = chain
-        .rpc_client()
-        .status()
-        .await
-        .map_err(|e| error::Kind::Rpc.context(e))?;
-
-    if status.sync_info.catching_up {
-        fail!(
-            error::Kind::LightClient,
-            "node at {} running chain {} not caught up",
-            chain.config().rpc_addr,
-            chain.config().id,
-        );
-    }
+    /// Query a header at the given height via RPC
+    fn query_header_at_height(&self, height: Height) -> Result<Self::LightBlock, error::Error>;
 
-    Ok(status.sync_info.latest_block_height)
-}
+    /// Query the latest height the chain is at via a RPC query
+    fn query_latest_height(&self) -> Result<Height, error::Error> {
+        let status =
+            block_on(self.rpc_client().status()).map_err(|e| error::Kind::Rpc.context(e))?;
 
-/// Query the latest header
-pub async fn query_latest_header<C>(chain: &C) -> Result<C::LightBlock, error::Error>
-where
-    C: Chain,
-{
-    let h = query_latest_height(chain).await?;
-    Ok(query_header_at_height(chain, h).await?)
-}
+        if status.sync_info.catching_up {
+            fail!(
+                error::Kind::LightClient,
+                "node at {} running chain {} not caught up",
+                self.config().rpc_addr,
+                self.config().id,
+            );
+        }
 
-/// Query a header at the given height via the RPC requester
-pub async fn query_header_at_height<C>(
-    chain: &C,
-    height: Height,
-) -> Result<C::LightBlock, error::Error>
-where
-    C: Chain,
-{
-    todo!()
+        Ok(status.sync_info.latest_block_height)
+    }
+
+    /// Query the latest header via RPC
+    fn query_latest_header(&self) -> Result<Self::LightBlock, error::Error> {
+        let height = self.query_latest_height()?;
+        self.query_header_at_height(height)
+    }
 }

relayer/src/chain/cosmos.rs

@@ -1,10 +1,15 @@
+use std::future::Future;
 use std::str::FromStr;
 use std::time::Duration;
 
+use bytes::Bytes;
+use prost::Message;
+use prost_types::Any;
+
 use tendermint::abci::Path as TendermintABCIPath;
 use tendermint::block::Height;
-use tendermint_light_client::types::LightBlock;
-use tendermint_light_client::types::TrustThreshold;
+use tendermint_light_client::types::{LightBlock, ValidatorSet};
+use tendermint_light_client::types::{SignedHeader, TrustThreshold};
 use tendermint_rpc::Client;
 use tendermint_rpc::HttpClient;
 
@@ -16,11 +21,7 @@ use super::Chain;
 use crate::client::tendermint::LightClient;
 use crate::config::ChainConfig;
 use crate::error::{Error, Kind};
-
-use bytes::Bytes;
-use prost::Message;
-use prost_types::Any;
-use std::future::Future;
+use crate::util::block_on;
 
 pub struct CosmosSDKChain {
     config: ChainConfig,
@@ -103,6 +104,25 @@ impl Chain for CosmosSDKChain {
         Duration::from_secs(24 * 7 * 3)
     }
 
+    fn query_header_at_height(&self, height: Height) -> Result<LightBlock, Error> {
+        let client = self.rpc_client();
+
+        let signed_header = fetch_signed_header(client, height)?;
+        assert_eq!(height, signed_header.header.height);
+
+        let validator_set = fetch_validator_set(client, height)?;
+        let next_validator_set = fetch_validator_set(client, height.increment())?;
+
+        let light_block = LightBlock::new(
+            signed_header,
+            validator_set,
+            next_validator_set,
+            self.config().peer_id,
+        );
+
+        Ok(light_block)
+    }
+
     fn sign_tx(&self, _msgs: &[Any]) -> Result<Vec<u8>, Error> {
         unimplemented!()
 
@@ -249,12 +269,20 @@ async fn abci_query(
     Ok(response.value)
 }
 
-/// block on future
-pub fn block_on<F: Future>(future: F) -> F::Output {
-    tokio::runtime::Builder::new()
-        .basic_scheduler()
-        .enable_all()
-        .build()
-        .unwrap()
-        .block_on(future)
+fn fetch_signed_header(client: &HttpClient, height: Height) -> Result<SignedHeader, Error> {
+    let res = block_on(client.commit(height));
+
+    match res {
+        Ok(response) => Ok(response.signed_header),
+        Err(err) => Err(Kind::Rpc.context(err).into()),
+    }
+}
+
+fn fetch_validator_set(client: &HttpClient, height: Height) -> Result<ValidatorSet, Error> {
+    let res = block_on(client.validators(height));
+
+    match res {
+        Ok(response) => Ok(ValidatorSet::new(response.validators)),
+        Err(err) => Err(Kind::Rpc.context(err).into()),
+    }
 }

relayer/src/config.rs

@@ -80,6 +80,9 @@ pub struct ChainConfig {
     pub gas: u64,
     #[serde(default = "default::trusting_period", with = "humantime_serde")]
     pub trusting_period: Duration,
+
+    // TODO: Move the light client config
+    pub peer_id: node::Id,
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]

relayer/src/tx/client.rs

@@ -8,10 +8,10 @@ use ibc::ics24_host::identifier::{ChainId, ClientId};
 use ibc::ics24_host::Path::ClientState as ClientStatePath;
 use ibc::tx_msg::Msg;
 
-use crate::chain::cosmos::block_on;
-use crate::chain::{query_latest_header, Chain, CosmosSDKChain};
+use crate::chain::{Chain, CosmosSDKChain};
 use crate::config::ChainConfig;
 use crate::error::{Error, Kind};
+use crate::util::block_on;
 use ibc::ics02_client::height::Height;
 
 #[derive(Clone, Debug)]
@@ -41,14 +41,13 @@ pub fn create_client(opts: CreateClientOptions) -> Result<(), Error> {
 
     // Get the latest header from the source chain and build the consensus state.
     let src_chain = CosmosSDKChain::from_config(opts.clone().src_chain_config)?;
-    let tm_latest_header =
-        block_on(query_latest_header::<CosmosSDKChain>(&src_chain)).map_err(|e| {
-            Kind::CreateClient(
-                opts.dest_client_id.clone(),
-                "failed to get the latest header".into(),
-            )
-            .context(e)
-        })?;
+    let tm_latest_header = src_chain.query_latest_header().map_err(|e| {
+        Kind::CreateClient(
+            opts.dest_client_id.clone(),
+            "failed to get the latest header".into(),
+        )
+        .context(e)
+    })?;
 
     let height = u64::from(tm_latest_header.signed_header.header.height);
     let version = tm_latest_header.signed_header.header.chain_id.to_string();

relayer/src/util.rs

@@ -1 +1,4 @@
+mod block_on;
+pub use block_on::block_on;
+
 pub mod sled;

relayer/src/util/block_on.rs

@@ -0,0 +1,13 @@
+//! Utility function to execute a future synchronously
+
+use futures::Future;
+
+/// Spawns a new tokio runtime and use it to block on the given future.
+pub fn block_on<F: Future>(future: F) -> F::Output {
+    tokio::runtime::Builder::new()
+        .basic_scheduler()
+        .enable_all()
+        .build()
+        .unwrap()
+        .block_on(future)
+}

relayer/tests/config/fixtures/relayer_conf_example.toml

@@ -17,6 +17,9 @@ strategy = "naive"
   gas_price = "0.025stake"
   trusting_period = "336h"
 
+  # TODO: Move to light client config
+  peer_id = "BADFADAD0BEFEEDC0C0ADEADBEEFC0FFEEFACADE"
+
 [[chains]]
   id = "chain_B"
   rpc_addr = "localhost:26557"
@@ -29,6 +32,9 @@ strategy = "naive"
   gas_price = "0.025stake"
   trusting_period = "336h"
 
+  # TODO: Move to light client config
+  peer_id = "DC0C0ADEADBEEFC0FFEEFACADEBADFADAD0BEFEE"
+
 [[connections]]
 
 [connections.src]

relayer/tests/config/fixtures/simple_config.toml

@@ -18,6 +18,9 @@ strategy = "naive"
   gas_price = "0.025stake"
   trusting_period = "336h"
 
+  # TODO: Move to light client config
+  peer_id = "BADFADAD0BEFEEDC0C0ADEADBEEFC0FFEEFACADE"
+
 [[chains]]
   id = "chain_B"
   rpc_addr = "localhost:26557"
@@ -30,6 +33,9 @@ strategy = "naive"
   gas_price = "0.025stake"
   trusting_period = "336h"
 
+  # TODO: Move to light client config
+  peer_id = "DC0C0ADEADBEEFC0FFEEFACADEBADFADAD0BEFEE"
+
 [[connections]]
 
 [connections.src]