Fix BSC gas price issues by treating chains with a base fee of 0 as n…

…on-1559 (#3462)

### Description

- Fixes #3396 
- See v2 backport here #3463 

So turns out this is because:
- BSC nodes tend to enforce a minimum gas price of 3 gwei when you
submit a tx
- it's possible for validators to include privileged txs at a lower gas
price, so in practice (probably some mev stuff ?) there are a bunch of
txs in blocks with transactions lower than 3 gwei
- BSC's 1559 situation is they have a base fee of zero, so it's
basically like they just use legacy txs
- when we try to figure out what to pay in prio fees, we are suggested a
1 gwei priority fee:
```
$ cast rpc eth_feeHistory 10 latest "[5.0]" --rpc-url https://rpc.ankr.com/bsc
{"oldestBlock":"0x23706f7","reward":[["0x3b9aca00"]],"baseFeePerGas":["0x0","0x0"],"gasUsedRatio":[0.1149265]}

$ cast td 0x3b9aca00
1000000000
```

So options are:
1. tx overrides for bsc, set it to 3 gwei

2. use a different eip 1559 estimator and set the percentile used in
eth_feeHistory to something higher. Atm the percentile is 5%, if you
change this to 50% we seem to get 3 gwei. This would have consequences
for other chains tho

3. another heuristic, to fall back to legacy txs (where we can trust the
eth_gasPrice to give us an accurate price) whenever the base fee is 0


I'm a tx override hater and we don't have this in the agents so far so
I'm gonna go with 3. It's the least intrusive change

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

@@ -5,10 +5,17 @@ use std::time::Duration;
 use ethers::{
     abi::Detokenize,
     prelude::{NameOrAddress, TransactionReceipt},
+    providers::ProviderError,
     types::Eip1559TransactionRequest,
 };
 use ethers_contract::builders::ContractCall;
-use ethers_core::types::BlockNumber;
+use ethers_core::{
+    types::{BlockNumber, U256 as EthersU256},
+    utils::{
+        eip1559_default_estimator, EIP1559_FEE_ESTIMATION_PAST_BLOCKS,
+        EIP1559_FEE_ESTIMATION_REWARD_PERCENTILE,
+    },
+};
 use hyperlane_core::{utils::bytes_to_hex, ChainCommunicationError, ChainResult, H256, U256};
 use tracing::{error, info};
 
@@ -84,10 +91,22 @@ where
             .saturating_add(U256::from(GAS_ESTIMATE_BUFFER).into())
             .into()
     };
-    let Ok((max_fee, max_priority_fee)) = provider.estimate_eip1559_fees(None).await else {
+
+    let Ok((base_fee, max_fee, max_priority_fee)) = estimate_eip1559_fees(provider, None).await
+    else {
         // Is not EIP 1559 chain
         return Ok(tx.gas(gas_limit));
     };
+
+    // If the base fee is zero, just treat the chain as a non-EIP-1559 chain.
+    // This is useful for BSC, where the base fee is zero, there's a minimum gas price
+    // generally enforced by nodes of 3 gwei, but EIP 1559 estimation suggests a priority
+    // fee lower than 3 gwei because of privileged transactions being included by block
+    // producers that have a lower priority fee.
+    if base_fee.is_zero() {
+        return Ok(tx.gas(gas_limit));
+    }
+
     // Is EIP 1559 chain
     let mut request = Eip1559TransactionRequest::new();
     if let Some(from) = tx.tx.from() {
@@ -109,6 +128,46 @@ where
     Ok(eip_1559_tx.gas(gas_limit))
 }
 
+type FeeEstimator = fn(EthersU256, Vec<Vec<EthersU256>>) -> (EthersU256, EthersU256);
+
+/// Pretty much a copy of the logic in ethers-rs (https://github.com/hyperlane-xyz/ethers-rs/blob/c9ced035628da59376c369be035facda1648577a/ethers-providers/src/provider.rs#L478)
+/// but returns the base fee as well as the max fee and max priority fee.
+/// Gets a heuristic recommendation of max fee per gas and max priority fee per gas for
+/// EIP-1559 compatible transactions.
+async fn estimate_eip1559_fees<M>(
+    provider: Arc<M>,
+    estimator: Option<FeeEstimator>,
+) -> ChainResult<(EthersU256, EthersU256, EthersU256)>
+where
+    M: Middleware + 'static,
+{
+    let base_fee_per_gas = provider
+        .get_block(BlockNumber::Latest)
+        .await
+        .map_err(ChainCommunicationError::from_other)?
+        .ok_or_else(|| ProviderError::CustomError("Latest block not found".into()))?
+        .base_fee_per_gas
+        .ok_or_else(|| ProviderError::CustomError("EIP-1559 not activated".into()))?;
+
+    let fee_history = provider
+        .fee_history(
+            EIP1559_FEE_ESTIMATION_PAST_BLOCKS,
+            BlockNumber::Latest,
+            &[EIP1559_FEE_ESTIMATION_REWARD_PERCENTILE],
+        )
+        .await
+        .map_err(ChainCommunicationError::from_other)?;
+
+    // use the provided fee estimator function, or fallback to the default implementation.
+    let (max_fee_per_gas, max_priority_fee_per_gas) = if let Some(es) = estimator {
+        es(base_fee_per_gas, fee_history.reward)
+    } else {
+        eip1559_default_estimator(base_fee_per_gas, fee_history.reward)
+    };
+
+    Ok((base_fee_per_gas, max_fee_per_gas, max_priority_fee_per_gas))
+}
+
 pub(crate) async fn call_with_lag<M, T>(
     call: ethers::contract::builders::ContractCall<M, T>,
     provider: &M,

typescript/infra/config/environments/mainnet3/agent.ts

@@ -137,7 +137,7 @@ const hyperlane: RootAgentConfig = {
     docker: {
       repo,
       // Includes Cosmos block-by-block indexing.
-      tag: 'a72c3cf-20240314-173418',
+      tag: '39df4ca-20240321-100543',
     },
     gasPaymentEnforcement: [
       // Temporary measure to ensure all inEVM warp route messages are delivered -