Relayer aggregation ism (#2411)

### Description

Adds AggregationISM support to the relayer, by adding the scaffolding,
sub-ism metadata fetching, and custom metadata encoding.

### Drive-by changes

- adds `dry_run_verify(...)` to the `InterchainSecurityModule` trait and
implements it for `EthereumInterchainSecurityModule`
- changes the default ISM in the test environment from
`routingIsm(multisigIsm)` to `routingIsm(aggregationIsm([multisigIsm,
messageIdIsm], threshold = 1))`

### Related issues

- Fixes https://github.com/hyperlane-xyz/hyperlane-monorepo/issues/1757

### Backward compatibility

_Are these changes backward compatible?_

Yes

_Are there any infrastructure implications, e.g. changes that would
prohibit deploying older commits using this infra tooling?_

None


### Testing

The AggregationISM metadata encoding is tested using unit tests whose
input was taken from the tests in `AggregationIsm.t.sol`, by printing
the individual ISM metadatas and the final metadata.

The overall AggregationISM is tested with the `run-locally` script.

.gitignore

@@ -27,4 +27,5 @@ yarn-error.log
 
 .idea
 **/*.ignore
+.vscode
 

rust/agents/relayer/src/msg/metadata/aggregation.rs

@@ -0,0 +1,262 @@
+use async_trait::async_trait;
+use derive_more::Deref;
+use futures_util::future::join_all;
+
+use derive_new::new;
+use eyre::Context;
+use tracing::{info, instrument};
+
+use hyperlane_core::{HyperlaneMessage, InterchainSecurityModule, H256, U256};
+
+use super::{BaseMetadataBuilder, MetadataBuilder};
+
+/// Bytes used to store one member of the (start, end) range tuple
+/// Copied from `AggregationIsmMetadata.sol`
+const METADATA_RANGE_SIZE: usize = 4;
+
+#[derive(Clone, Debug, new, Deref)]
+pub struct AggregationIsmMetadataBuilder {
+    base: BaseMetadataBuilder,
+}
+
+#[derive(Clone, Debug, new, PartialEq, Eq)]
+struct SubModuleMetadata {
+    /// The index of the sub-module (ISM) in the aggregation ISM.
+    index: usize,
+    /// The metadata for the sub-module.
+    metadata: Vec<u8>,
+}
+
+#[derive(Debug)]
+struct IsmAndMetadata {
+    ism: Box<dyn InterchainSecurityModule>,
+    meta: SubModuleMetadata,
+}
+
+impl IsmAndMetadata {
+    fn new(ism: Box<dyn InterchainSecurityModule>, index: usize, metadata: Vec<u8>) -> Self {
+        Self {
+            ism,
+            meta: SubModuleMetadata::new(index, metadata),
+        }
+    }
+}
+
+impl AggregationIsmMetadataBuilder {
+    fn format_metadata(metadatas: &mut [SubModuleMetadata], ism_count: usize) -> Vec<u8> {
+        // See test solidity implementation of this fn at:
+        // https://github.com/hyperlane-xyz/hyperlane-monorepo/blob/445da4fb0d8140a08c4b314e3051b7a934b0f968/solidity/test/isms/AggregationIsm.t.sol#L35
+        fn encode_byte_index(i: usize) -> [u8; 4] {
+            (i as u32).to_be_bytes()
+        }
+        let range_tuples_size = METADATA_RANGE_SIZE * 2 * ism_count;
+        //  Format of metadata:
+        //  [????:????] Metadata start/end uint32 ranges, packed as uint64
+        //  [????:????] ISM metadata, packed encoding
+        // Initialize the range tuple part of the buffer, so the actual metadatas can
+        // simply be appended to it
+        let mut buffer = vec![0; range_tuples_size];
+        for SubModuleMetadata { index, metadata } in metadatas.iter_mut() {
+            let range_start = buffer.len();
+            buffer.append(metadata);
+            let range_end = buffer.len();
+
+            // The new tuple starts at the end of the previous ones.
+            // Also see: https://github.com/hyperlane-xyz/hyperlane-monorepo/blob/445da4fb0d8140a08c4b314e3051b7a934b0f968/solidity/contracts/libs/isms/AggregationIsmMetadata.sol#L49
+            let encoded_range_start = METADATA_RANGE_SIZE * 2 * (*index);
+            // Overwrite the 0-initialized buffer
+            buffer.splice(
+                encoded_range_start..(encoded_range_start + METADATA_RANGE_SIZE * 2),
+                [encode_byte_index(range_start), encode_byte_index(range_end)].concat(),
+            );
+        }
+        buffer
+    }
+
+    fn n_cheapest_metas(
+        mut metas_and_gas: Vec<(SubModuleMetadata, U256)>,
+        n: usize,
+    ) -> Vec<SubModuleMetadata> {
+        // Sort by gas cost in ascending order
+        metas_and_gas.sort_by(|(_, gas_1), (_, gas_2)| gas_1.cmp(gas_2));
+        // Take the cheapest n (the aggregation ISM threshold)
+        let mut cheapest: Vec<_> = metas_and_gas[..n].into();
+        // Sort by index in ascending order, to match the order expected by the smart contract
+        cheapest.sort_by(|(meta_1, _), (meta_2, _)| meta_1.index.cmp(&meta_2.index));
+        cheapest.into_iter().map(|(meta, _)| meta).collect()
+    }
+
+    async fn cheapest_valid_metas(
+        sub_modules: Vec<IsmAndMetadata>,
+        message: &HyperlaneMessage,
+        threshold: usize,
+    ) -> Option<Vec<SubModuleMetadata>> {
+        let gas_cost_results: Vec<_> = join_all(
+            sub_modules
+                .iter()
+                .map(|module| module.ism.dry_run_verify(message, &(module.meta.metadata))),
+        )
+        .await;
+
+        // Filter out the ISMs without a gas cost estimate
+        let metas_and_gas: Vec<_> = sub_modules
+            .into_iter()
+            .zip(gas_cost_results.into_iter())
+            .filter_map(|(module, gas_cost)| gas_cost.ok().flatten().map(|gc| (module.meta, gc)))
+            .collect();
+
+        let metas_and_gas_count = metas_and_gas.len();
+        if metas_and_gas_count < threshold {
+            info!("Could not fetch all metadata: Found {metas_and_gas_count} of the {threshold} required ISM metadata pieces");
+            return None;
+        }
+        Some(Self::n_cheapest_metas(metas_and_gas, threshold))
+    }
+}
+
+#[async_trait]
+impl MetadataBuilder for AggregationIsmMetadataBuilder {
+    #[instrument(err, skip(self))]
+    async fn build(
+        &self,
+        ism_address: H256,
+        message: &HyperlaneMessage,
+    ) -> eyre::Result<Option<Vec<u8>>> {
+        const CTX: &str = "When fetching AggregationIsm metadata";
+        let ism = self.build_aggregation_ism(ism_address).await.context(CTX)?;
+        let (ism_addresses, threshold) = ism.modules_and_threshold(message).await.context(CTX)?;
+        let threshold = threshold as usize;
+
+        let metas = join_all(
+            ism_addresses
+                .iter()
+                .map(|ism_address| self.base.build(*ism_address, message)),
+        )
+        .await;
+
+        let sub_modules = join_all(
+            ism_addresses
+                .iter()
+                .map(|ism_address| self.base.build_ism(*ism_address)),
+        )
+        .await;
+
+        let filtered_sub_module_metas = metas
+            .into_iter()
+            .enumerate()
+            .zip(sub_modules.into_iter())
+            .filter_map(|((index, meta_result), sub_module_result)| {
+                match (meta_result, sub_module_result) {
+                    (Ok(Some(meta)), Ok(ism)) => Some(IsmAndMetadata::new(ism, index, meta)),
+                    _ => None,
+                }
+            })
+            .collect();
+
+        let maybe_aggregation_metadata =
+            Self::cheapest_valid_metas(filtered_sub_module_metas, message, threshold)
+                .await
+                .map(|mut metas| Self::format_metadata(&mut metas, ism_addresses.len()));
+        Ok(maybe_aggregation_metadata)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use ethers::utils::hex::FromHex;
+
+    use super::*;
+
+    #[test]
+    fn test_format_n_of_n_metadata_works_correctly() {
+        let mut metadatas = vec![
+            SubModuleMetadata::new(
+                0,
+                Vec::from_hex("290decd9548b62a8d60345a988386fc84ba6bc95484008f6362f93160ef3e563")
+                    .unwrap(),
+            ),
+            SubModuleMetadata::new(
+                1,
+                Vec::from_hex("510e4e770828ddbf7f7b00ab00a9f6adaf81c0dc9cc85f1f8249c256942d61d9")
+                    .unwrap(),
+            ),
+            SubModuleMetadata::new(
+                2,
+                Vec::from_hex("356e5a2cc1eba076e650ac7473fccc37952b46bc2e419a200cec0c451dce2336")
+                    .unwrap(),
+            ),
+        ];
+        let expected = Vec::from_hex("000000180000003800000038000000580000005800000078290decd9548b62a8d60345a988386fc84ba6bc95484008f6362f93160ef3e563510e4e770828ddbf7f7b00ab00a9f6adaf81c0dc9cc85f1f8249c256942d61d9356e5a2cc1eba076e650ac7473fccc37952b46bc2e419a200cec0c451dce2336").unwrap();
+        assert_eq!(
+            AggregationIsmMetadataBuilder::format_metadata(&mut metadatas, 3),
+            expected
+        );
+    }
+
+    #[test]
+    fn test_format_n_of_m_metadata_works_correctly() {
+        // We're passing the metadatas of 4 ISMs (indexes 0, 1, 2, 4) out of 5
+        let mut metadatas = vec![
+            SubModuleMetadata::new(
+                0,
+                Vec::from_hex("290decd9548b62a8d60345a988386fc84ba6bc95484008f6362f93160ef3e563")
+                    .unwrap(),
+            ),
+            SubModuleMetadata::new(
+                1,
+                Vec::from_hex("510e4e770828ddbf7f7b00ab00a9f6adaf81c0dc9cc85f1f8249c256942d61d9")
+                    .unwrap(),
+            ),
+            SubModuleMetadata::new(
+                2,
+                Vec::from_hex("356e5a2cc1eba076e650ac7473fccc37952b46bc2e419a200cec0c451dce2336")
+                    .unwrap(),
+            ),
+            SubModuleMetadata::new(
+                4,
+                Vec::from_hex("f2e59013a0a379837166b59f871b20a8a0d101d1c355ea85d35329360e69c000")
+                    .unwrap(),
+            ),
+        ];
+        let expected = Vec::from_hex("000000280000004800000048000000680000006800000088000000000000000000000088000000a8290decd9548b62a8d60345a988386fc84ba6bc95484008f6362f93160ef3e563510e4e770828ddbf7f7b00ab00a9f6adaf81c0dc9cc85f1f8249c256942d61d9356e5a2cc1eba076e650ac7473fccc37952b46bc2e419a200cec0c451dce2336f2e59013a0a379837166b59f871b20a8a0d101d1c355ea85d35329360e69c000").unwrap();
+        assert_eq!(
+            AggregationIsmMetadataBuilder::format_metadata(&mut metadatas, 5),
+            expected
+        );
+    }
+
+    #[test]
+    fn test_format_empty_metadata_works_correctly() {
+        let mut metadatas = vec![SubModuleMetadata::new(0, Vec::from_hex("").unwrap())];
+        let expected = Vec::from_hex("0000000800000008").unwrap();
+        assert_eq!(
+            AggregationIsmMetadataBuilder::format_metadata(&mut metadatas, 1),
+            expected
+        );
+    }
+
+    #[test]
+    fn test_n_cheapest_metas_works() {
+        let metas_and_gas = vec![
+            (
+                SubModuleMetadata::new(3, vec![]),
+                U256::from_dec_str("3").unwrap(),
+            ),
+            (
+                SubModuleMetadata::new(2, vec![]),
+                U256::from_dec_str("2").unwrap(),
+            ),
+            (
+                SubModuleMetadata::new(1, vec![]),
+                U256::from_dec_str("1").unwrap(),
+            ),
+        ];
+        assert_eq!(
+            AggregationIsmMetadataBuilder::n_cheapest_metas(metas_and_gas, 2),
+            vec![
+                SubModuleMetadata::new(1, vec![]),
+                SubModuleMetadata::new(2, vec![])
+            ]
+        )
+    }
+}

rust/agents/relayer/src/msg/metadata/base.rs

@@ -13,8 +13,8 @@ use hyperlane_base::{
 };
 use hyperlane_core::accumulator::merkle::Proof;
 use hyperlane_core::{
-    Checkpoint, HyperlaneDomain, HyperlaneMessage, ModuleType, MultisigIsm, RoutingIsm,
-    ValidatorAnnounce, H160, H256,
+    AggregationIsm, Checkpoint, HyperlaneDomain, HyperlaneMessage, InterchainSecurityModule,
+    ModuleType, MultisigIsm, RoutingIsm, ValidatorAnnounce, H160, H256,
 };
 
 use crate::merkle_tree_builder::MerkleTreeBuilder;
@@ -22,7 +22,7 @@ use crate::msg::metadata::multisig::{
     LegacyMultisigMetadataBuilder, MerkleRootMultisigMetadataBuilder,
     MessageIdMultisigMetadataBuilder,
 };
-use crate::msg::metadata::RoutingIsmMetadataBuilder;
+use crate::msg::metadata::{AggregationIsmMetadataBuilder, RoutingIsmMetadataBuilder};
 
 #[derive(Debug, thiserror::Error)]
 pub enum MetadataBuilderError {
@@ -72,11 +72,7 @@ impl MetadataBuilder for BaseMetadataBuilder {
         message: &HyperlaneMessage,
     ) -> Result<Option<Vec<u8>>> {
         const CTX: &str = "When fetching module type";
-        let ism = self
-            .destination_chain_setup
-            .build_ism(ism_address, &self.metrics)
-            .await
-            .context(CTX)?;
+        let ism = self.build_ism(ism_address).await.context(CTX)?;
         let module_type = ism.module_type().await.context(CTX)?;
         let base = self.clone_with_incremented_depth()?;
 
@@ -87,6 +83,7 @@ impl MetadataBuilder for BaseMetadataBuilder {
             }
             ModuleType::MessageIdMultisig => Box::new(MessageIdMultisigMetadataBuilder::new(base)),
             ModuleType::Routing => Box::new(RoutingIsmMetadataBuilder::new(base)),
+            ModuleType::Aggregation => Box::new(AggregationIsmMetadataBuilder::new(base)),
             _ => return Err(MetadataBuilderError::UnsupportedModuleType(module_type).into()),
         };
         metadata_builder
@@ -138,6 +135,12 @@ impl BaseMetadataBuilder {
         self.origin_prover_sync.read().await.count() - 1
     }
 
+    pub async fn build_ism(&self, address: H256) -> Result<Box<dyn InterchainSecurityModule>> {
+        self.destination_chain_setup
+            .build_ism(address, &self.metrics)
+            .await
+    }
+
     pub async fn build_routing_ism(&self, address: H256) -> Result<Box<dyn RoutingIsm>> {
         self.destination_chain_setup
             .build_routing_ism(address, &self.metrics)
@@ -150,6 +153,12 @@ impl BaseMetadataBuilder {
             .await
     }
 
+    pub async fn build_aggregation_ism(&self, address: H256) -> Result<Box<dyn AggregationIsm>> {
+        self.destination_chain_setup
+            .build_aggregation_ism(address, &self.metrics)
+            .await
+    }
+
     pub async fn build_checkpoint_syncer(
         &self,
         validators: &[H256],

rust/agents/relayer/src/msg/metadata/mod.rs

@@ -1,7 +1,9 @@
+mod aggregation;
 mod base;
 mod multisig;
 mod routing;
 
+use aggregation::AggregationIsmMetadataBuilder;
 pub(crate) use base::BaseMetadataBuilder;
 pub(crate) use base::MetadataBuilder;
 use routing::RoutingIsmMetadataBuilder;

rust/chains/hyperlane-ethereum/Cargo.toml

@@ -15,6 +15,7 @@ ethers-contract.workspace = true
 ethers-core.workspace = true
 ethers-signers.workspace = true
 ethers.workspace = true
+futures-util.workspace = true
 hex = "0.4.3"
 num = "0.4"
 reqwest.workspace = true

rust/chains/hyperlane-ethereum/abis/IAggregationIsm.abi.json

@@ -0,0 +1,63 @@
+[
+  {
+    "inputs": [],
+    "name": "moduleType",
+    "outputs": [
+      {
+        "internalType": "uint8",
+        "name": "",
+        "type": "uint8"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "bytes",
+        "name": "_message",
+        "type": "bytes"
+      }
+    ],
+    "name": "modulesAndThreshold",
+    "outputs": [
+      {
+        "internalType": "address[]",
+        "name": "modules",
+        "type": "address[]"
+      },
+      {
+        "internalType": "uint8",
+        "name": "threshold",
+        "type": "uint8"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "bytes",
+        "name": "_metadata",
+        "type": "bytes"
+      },
+      {
+        "internalType": "bytes",
+        "name": "_message",
+        "type": "bytes"
+      }
+    ],
+    "name": "verify",
+    "outputs": [
+      {
+        "internalType": "bool",
+        "name": "",
+        "type": "bool"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  }
+]

rust/chains/hyperlane-ethereum/src/aggregation_ism.rs

@@ -0,0 +1,117 @@
+#![allow(clippy::enum_variant_names)]
+#![allow(missing_docs)]
+
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use async_trait::async_trait;
+use ethers::providers::Middleware;
+use tracing::instrument;
+
+use hyperlane_core::{
+    AggregationIsm, ChainResult, ContractLocator, HyperlaneAbi, HyperlaneChain, HyperlaneContract,
+    HyperlaneDomain, HyperlaneMessage, HyperlaneProvider, RawHyperlaneMessage, H256,
+};
+
+use crate::contracts::i_aggregation_ism::{
+    IAggregationIsm as EthereumAggregationIsmInternal, IAGGREGATIONISM_ABI,
+};
+use crate::trait_builder::BuildableWithProvider;
+use crate::EthereumProvider;
+
+pub struct AggregationIsmBuilder {}
+
+#[async_trait]
+impl BuildableWithProvider for AggregationIsmBuilder {
+    type Output = Box<dyn AggregationIsm>;
+
+    async fn build_with_provider<M: Middleware + 'static>(
+        &self,
+        provider: M,
+        locator: &ContractLocator,
+    ) -> Self::Output {
+        Box::new(EthereumAggregationIsm::new(Arc::new(provider), locator))
+    }
+}
+
+/// A reference to an AggregationIsm contract on some Ethereum chain
+#[derive(Debug)]
+pub struct EthereumAggregationIsm<M>
+where
+    M: Middleware,
+{
+    contract: Arc<EthereumAggregationIsmInternal<M>>,
+    domain: HyperlaneDomain,
+}
+
+impl<M> EthereumAggregationIsm<M>
+where
+    M: Middleware + 'static,
+{
+    /// Create a reference to a mailbox at a specific Ethereum address on some
+    /// chain
+    pub fn new(provider: Arc<M>, locator: &ContractLocator) -> Self {
+        Self {
+            contract: Arc::new(EthereumAggregationIsmInternal::new(
+                locator.address,
+                provider,
+            )),
+            domain: locator.domain.clone(),
+        }
+    }
+}
+
+impl<M> HyperlaneChain for EthereumAggregationIsm<M>
+where
+    M: Middleware + 'static,
+{
+    fn domain(&self) -> &HyperlaneDomain {
+        &self.domain
+    }
+
+    fn provider(&self) -> Box<dyn HyperlaneProvider> {
+        Box::new(EthereumProvider::new(
+            self.contract.client(),
+            self.domain.clone(),
+        ))
+    }
+}
+
+impl<M> HyperlaneContract for EthereumAggregationIsm<M>
+where
+    M: Middleware + 'static,
+{
+    fn address(&self) -> H256 {
+        self.contract.address().into()
+    }
+}
+
+#[async_trait]
+impl<M> AggregationIsm for EthereumAggregationIsm<M>
+where
+    M: Middleware + 'static,
+{
+    #[instrument(err)]
+    async fn modules_and_threshold(
+        &self,
+        message: &HyperlaneMessage,
+    ) -> ChainResult<(Vec<H256>, u8)> {
+        let (isms, threshold) = self
+            .contract
+            .modules_and_threshold(RawHyperlaneMessage::from(message).to_vec().into())
+            .call()
+            .await?;
+        let isms_h256 = isms.iter().map(|address| (*address).into()).collect();
+        Ok((isms_h256, threshold))
+    }
+}
+
+pub struct EthereumRoutingIsmAbi;
+
+impl HyperlaneAbi for EthereumRoutingIsmAbi {
+    const SELECTOR_SIZE_BYTES: usize = 4;
+
+    fn fn_map() -> HashMap<Vec<u8>, &'static str> {
+        super::extract_fn_map(&IAGGREGATIONISM_ABI)
+    }
+}

rust/chains/hyperlane-ethereum/src/interchain_security_module.rs

@@ -8,9 +8,11 @@ use async_trait::async_trait;
 use ethers::providers::Middleware;
 use tracing::{instrument, warn};
 
+use futures_util::future::try_join;
 use hyperlane_core::{
     ChainResult, ContractLocator, HyperlaneAbi, HyperlaneChain, HyperlaneContract, HyperlaneDomain,
-    HyperlaneProvider, InterchainSecurityModule, ModuleType, H256,
+    HyperlaneMessage, HyperlaneProvider, InterchainSecurityModule, ModuleType, RawHyperlaneMessage,
+    H256, U256,
 };
 use num_traits::cast::FromPrimitive;
 
@@ -106,6 +108,24 @@ where
             Ok(ModuleType::Unused)
         }
     }
+
+    #[instrument]
+    async fn dry_run_verify(
+        &self,
+        message: &HyperlaneMessage,
+        metadata: &[u8],
+    ) -> ChainResult<Option<U256>> {
+        let tx = self.contract.verify(
+            metadata.to_owned().into(),
+            RawHyperlaneMessage::from(message).to_vec().into(),
+        );
+        let (verifies, gas_estimate) = try_join(tx.call(), tx.estimate_gas()).await?;
+        if verifies {
+            Ok(Some(gas_estimate))
+        } else {
+            Ok(None)
+        }
+    }
 }
 
 pub struct EthereumInterchainSecurityModuleAbi;

rust/chains/hyperlane-ethereum/src/lib.rs

@@ -10,9 +10,9 @@ use ethers::prelude::{abi, Lazy, Middleware};
 
 #[cfg(not(doctest))]
 pub use self::{
-    config::*, interchain_gas::*, interchain_security_module::*, mailbox::*, multisig_ism::*,
-    provider::*, routing_ism::*, rpc_clients::*, signers::*, singleton_signer::*, trait_builder::*,
-    validator_announce::*,
+    aggregation_ism::*, config::*, interchain_gas::*, interchain_security_module::*, mailbox::*,
+    multisig_ism::*, provider::*, routing_ism::*, rpc_clients::*, signers::*, singleton_signer::*,
+    trait_builder::*, validator_announce::*,
 };
 
 #[cfg(not(doctest))]
@@ -49,6 +49,10 @@ mod routing_ism;
 #[cfg(not(doctest))]
 mod validator_announce;
 
+/// AggregationIsm abi
+#[cfg(not(doctest))]
+mod aggregation_ism;
+
 /// Generated contract bindings.
 #[cfg(not(doctest))]
 mod contracts;

rust/hyperlane-base/src/settings/chains.rs

@@ -8,10 +8,10 @@ use ethers_prometheus::middleware::{
     ChainInfo, ContractInfo, PrometheusMiddlewareConf, WalletInfo,
 };
 use hyperlane_core::{
-    config::*, ContractLocator, HyperlaneAbi, HyperlaneDomain, HyperlaneDomainProtocol,
-    HyperlaneProvider, HyperlaneSigner, Indexer, InterchainGasPaymaster, InterchainGasPayment,
-    InterchainSecurityModule, Mailbox, MessageIndexer, MultisigIsm, RoutingIsm, ValidatorAnnounce,
-    H160, H256,
+    config::*, AggregationIsm, ContractLocator, HyperlaneAbi, HyperlaneDomain,
+    HyperlaneDomainProtocol, HyperlaneProvider, HyperlaneSigner, Indexer, InterchainGasPaymaster,
+    InterchainGasPayment, InterchainSecurityModule, Mailbox, MessageIndexer, MultisigIsm,
+    RoutingIsm, ValidatorAnnounce, H160, H256,
 };
 use hyperlane_ethereum::{
     self as h_eth, BuildableWithProvider, EthereumInterchainGasPaymasterAbi, EthereumMailboxAbi,
@@ -529,6 +529,29 @@ impl ChainConf {
         .context(ctx)
     }
 
+    /// Try to convert the chain setting into an AggregationIsm Ism contract
+    pub async fn build_aggregation_ism(
+        &self,
+        address: H256,
+        metrics: &CoreMetrics,
+    ) -> Result<Box<dyn AggregationIsm>> {
+        let ctx = "Building aggregation ISM";
+        let locator = ContractLocator {
+            domain: &self.domain,
+            address,
+        };
+
+        match &self.connection()? {
+            ChainConnectionConf::Ethereum(conf) => {
+                self.build_ethereum(conf, &locator, metrics, h_eth::AggregationIsmBuilder {})
+                    .await
+            }
+
+            ChainConnectionConf::Fuel(_) => todo!(),
+        }
+        .context(ctx)
+    }
+
     async fn signer<S: BuildableWithSignerConf>(&self) -> Result<Option<S>> {
         if let Some(conf) = &self.signer {
             Ok(Some(conf.build::<S>().await?))

rust/hyperlane-core/src/traits/aggregation_ism.rs

@@ -0,0 +1,18 @@
+use std::fmt::Debug;
+
+use async_trait::async_trait;
+use auto_impl::auto_impl;
+
+use crate::{ChainResult, HyperlaneContract, HyperlaneMessage, H256};
+
+/// Interface for the AggregationIsm chain contract. Allows abstraction over
+/// different chains
+#[async_trait]
+#[auto_impl(&, Box, Arc)]
+pub trait AggregationIsm: HyperlaneContract + Send + Sync + Debug {
+    /// Returns the `m` ISMs and `n` threshold needed to n-of-m verify the message
+    async fn modules_and_threshold(
+        &self,
+        message: &HyperlaneMessage,
+    ) -> ChainResult<(Vec<H256>, u8)>;
+}

rust/hyperlane-core/src/traits/interchain_security_module.rs

@@ -3,9 +3,10 @@ use std::fmt::Debug;
 use async_trait::async_trait;
 use auto_impl::auto_impl;
 use num_derive::FromPrimitive;
+use primitive_types::U256;
 use strum::Display;
 
-use crate::{ChainResult, HyperlaneContract};
+use crate::{ChainResult, HyperlaneContract, HyperlaneMessage};
 
 /// Enumeration of all known module types
 #[derive(FromPrimitive, Clone, Debug, Default, Display, Copy, PartialEq, Eq)]
@@ -33,4 +34,12 @@ pub trait InterchainSecurityModule: HyperlaneContract + Send + Sync + Debug {
     /// Returns the module type of the ISM compliant with the corresponding
     /// metadata offchain fetching and onchain formatting standard.
     async fn module_type(&self) -> ChainResult<ModuleType>;
+
+    /// Dry runs the `verify()` ISM call and returns `Some(gas_estimate)` if the call
+    /// succeeds.
+    async fn dry_run_verify(
+        &self,
+        message: &HyperlaneMessage,
+        metadata: &[u8],
+    ) -> ChainResult<Option<U256>>;
 }

rust/hyperlane-core/src/traits/mod.rs

@@ -1,3 +1,4 @@
+pub use aggregation_ism::*;
 pub use cursor::*;
 pub use db::*;
 pub use deployed::*;
@@ -12,6 +13,7 @@ pub use routing_ism::*;
 pub use signing::*;
 pub use validator_announce::*;
 
+mod aggregation_ism;
 mod cursor;
 mod db;
 mod deployed;

solidity/update_abis.sh

@@ -14,4 +14,5 @@ copy interfaces/IInterchainGasPaymaster && \
 copy interfaces/IValidatorAnnounce && \
 copy interfaces/IInterchainSecurityModule && \
 copy interfaces/isms/IMultisigIsm && \
-copy interfaces/isms/IRoutingIsm
+copy interfaces/isms/IRoutingIsm && \
+copy interfaces/isms/IAggregationIsm

typescript/infra/config/environments/test/aggregationIsm.ts

@@ -0,0 +1,14 @@
+import { AggregationIsmConfig, ModuleType } from '@hyperlane-xyz/sdk';
+
+import { merkleRootMultisig, messageIdMultisig } from './multisigIsm';
+
+export const aggregationIsm = (validatorKey: string): AggregationIsmConfig => {
+  return {
+    type: ModuleType.AGGREGATION,
+    modules: [
+      merkleRootMultisig(validatorKey),
+      messageIdMultisig(validatorKey),
+    ],
+    threshold: 1,
+  };
+};

typescript/infra/config/environments/test/core.ts

@@ -6,7 +6,8 @@ import {
   objMap,
 } from '@hyperlane-xyz/sdk';
 
-import { multisigIsm } from './multisigIsm';
+import { aggregationIsm } from './aggregationIsm';
+import { chainToValidator } from './multisigIsm';
 import { owners } from './owners';
 
 export const core: ChainMap<CoreConfig> = objMap(owners, (local, owner) => {
@@ -14,7 +15,9 @@ export const core: ChainMap<CoreConfig> = objMap(owners, (local, owner) => {
     type: ModuleType.ROUTING,
     owner,
     domains: Object.fromEntries(
-      Object.entries(multisigIsm).filter(([chain]) => chain !== local),
+      Object.entries(chainToValidator)
+        .filter(([chain, _]) => chain !== local)
+        .map(([chain, validatorKey]) => [chain, aggregationIsm(validatorKey)]),
     ),
   };
 

typescript/infra/config/environments/test/multisigIsm.ts

@@ -1,21 +1,41 @@
 import { ChainMap, ModuleType, MultisigIsmConfig } from '@hyperlane-xyz/sdk';
 
 // the addresses here must line up with the e2e test's validator addresses
-export const multisigIsm: ChainMap<MultisigIsmConfig> = {
 // Validators are anvil accounts 4-6
-  test1: {
+export const chainToValidator: Record<string, string> = {
+  test1: '0x15d34AAf54267DB7D7c367839AAf71A00a2C6A65',
+  test2: '0x9965507D1a55bcC2695C58ba16FB37d819B0A4dc',
+  test3: '0x976EA74026E726554dB657fA54763abd0C3a0aa9',
+};
+
+export const legacyMultisig = (validatorKey: string): MultisigIsmConfig => {
+  return {
     type: ModuleType.LEGACY_MULTISIG,
-    validators: ['0x15d34AAf54267DB7D7c367839AAf71A00a2C6A65'],
+    validators: [chainToValidator[validatorKey]],
     threshold: 1,
-  },
-  test2: {
+  };
+};
+
+export const merkleRootMultisig = (validatorKey: string): MultisigIsmConfig => {
+  return {
     type: ModuleType.MERKLE_ROOT_MULTISIG,
-    validators: ['0x9965507D1a55bcC2695C58ba16FB37d819B0A4dc'],
+    validators: [validatorKey],
     threshold: 1,
-  },
-  test3: {
+  };
+};
+
+export const messageIdMultisig = (validatorKey: string): MultisigIsmConfig => {
+  return {
     type: ModuleType.MESSAGE_ID_MULTISIG,
-    validators: ['0x976EA74026E726554dB657fA54763abd0C3a0aa9'],
+    validators: [validatorKey],
     threshold: 1,
-  },
+  };
+};
+
+// the addresses here must line up with the e2e test's validator addresses
+export const multisigIsm: ChainMap<MultisigIsmConfig> = {
+  // Validators are anvil accounts 4-6
+  test1: legacyMultisig('test1'),
+  test2: merkleRootMultisig('test2'),
+  test3: messageIdMultisig('test3'),
 };

typescript/infra/config/environments/test/routingIsm.ts

@@ -0,0 +1,16 @@
+import { ModuleType, RoutingIsmConfig } from '@hyperlane-xyz/sdk';
+
+import { multisigIsm } from './multisigIsm';
+
+export const routingIsm = (
+  local_chain: string,
+  owner: string,
+): RoutingIsmConfig => {
+  return {
+    type: ModuleType.ROUTING,
+    owner,
+    domains: Object.fromEntries(
+      Object.entries(multisigIsm).filter(([chain]) => chain !== local_chain),
+    ),
+  };
+};