fix(flashloan): correct Aave V3 BSC PoolDataProvider + tolerate truncated getReserveData (closes #419)

config/default.toml

@@ -75,7 +75,12 @@ chain = "bnb"
 pool  = "0x6807dc923806fe8fd134338eabca509979a7e0cb"
 # Aave V3 PoolDataProvider on BSC — resolves aTokens and reserve
 # configuration bitmaps (paused / frozen flags) for the adapter.
-data_provider = "0x41393e5e337606dc3821075Af65AeE84D7688CBD"
+# Sourced from IPoolAddressesProvider.getPoolDataProvider() — the
+# previous baked-in 0x41393e5e337606dc3821075Af65AeE84D7688CBD has no
+# code on BSC mainnet, which made every Aave reserve probe revert with
+# `buffer overrun` and silently disqualified the only flash-loan
+# source. See #419.
+data_provider = "0xc90Df74A7c16245c5F5C5870327Ceb38Fe5d5328"
 # Aave V3 IPoolAddressesProvider on BSC — `getPool()` is called at
 # startup and the result is compared against `pool` above. Mismatch
 # fails the boot before the bot can burn RPC budget on a stale pool.

config/fork.toml

@@ -72,9 +72,13 @@ comptroller = "0xfd36e2c2a6789db23113685031d7f16329158384"
 [flashloan.aave_v3_bsc]
 chain = "bnb"
 pool  = "0x6807dc923806fe8fd134338eabca509979a7e0cb"
-# Aave V3 PoolDataProvider on BSC — matches default.toml. Resolves
-# aTokens and reserve configuration bitmaps for the adapter.
-data_provider = "0x41393e5e337606dc3821075Af65AeE84D7688CBD"
+# Aave V3 PoolDataProvider on BSC — resolves aTokens and reserve
+# configuration bitmaps for the adapter. The previous value
+# 0x41393e5e337606dc3821075Af65AeE84D7688CBD has no code on BSC
+# mainnet (cast code returns 0x); the live address comes from
+# IPoolAddressesProvider.getPoolDataProvider() and is the one below.
+# See #419.
+data_provider = "0xc90Df74A7c16245c5F5C5870327Ceb38Fe5d5328"
 # Aave V3 IPoolAddressesProvider — startup check is bypassed under
 # profile_tag = "fork" but kept here so the fork profile mirrors the
 # mainnet TOML structure 1:1.

crates/charon-flashloan/src/aave.rs

@@ -283,18 +283,59 @@ impl AaveFlashLoan {
         }
         // Paused is not exposed via the typed accessor, so read the
         // packed bitmap and check bit 60 ourselves.
-        let data = dp
-            .getReserveData(asset)
-            .call()
-            .await
-            .map_err(|e| FlashLoanError::rpc(format!("getReserveData: {e}")))?;
-        if bitmap_says_paused(data.configuration) || bitmap_says_frozen(data.configuration) {
+        //
+        // Aave V3 BSC's PoolDataProvider returns 12 fields here, not
+        // the 15 our `sol!` ABI declares (newer-Aave fields like
+        // `accruedToTreasury`, `unbacked`, `isolationModeTotalDebt`
+        // are absent on BSC's deploy). The strict typed decoder
+        // reports `buffer overrun while deserializing` on every
+        // quote, which silently disqualifies the only flash-loan
+        // source. We only need the leading `configuration` word for
+        // the paused/frozen bitmap check anyway, so issue the call
+        // ourselves and lift the first 32 bytes. See #419.
+        let configuration = read_uint256_first_word(self.provider.as_ref(), self.data_provider, {
+            IAaveV3DataProvider::getReserveDataCall { asset }
+                .abi_encode()
+                .into()
+        })
+        .await
+        .map_err(|e| FlashLoanError::rpc(format!("getReserveData: {e}")))?;
+        if bitmap_says_paused(configuration) || bitmap_says_frozen(configuration) {
             return Err(FlashLoanError::ReservePaused { asset });
         }
         Ok(())
     }
 }
 
+/// Issue an `eth_call` to `target` with `calldata` and decode the
+/// first 32 bytes of the response as a `U256`. Used to read the
+/// leading word of a tuple return when the on-chain ABI has more or
+/// fewer fields than the workspace's `sol!` declaration would tolerate
+/// — alloy's strict decoder rejects any mismatch with `buffer overrun`
+/// or `ReserveMismatch`, but for paused/frozen-bitmap checks we only
+/// need the first word and can safely drop the tail. See #419.
+async fn read_uint256_first_word(
+    provider: &RootProvider<PubSubFrontend>,
+    target: Address,
+    calldata: alloy::primitives::Bytes,
+) -> Result<U256> {
+    use alloy::rpc::types::TransactionRequest;
+    let tx = TransactionRequest::default()
+        .to(target)
+        .input(calldata.into());
+    let bytes = provider.call(&tx).await.context("eth_call failed")?;
+    if bytes.len() < 32 {
+        anyhow::bail!(
+            "expected at least 32 bytes from tuple return, got {} (target={})",
+            bytes.len(),
+            target
+        );
+    }
+    let mut buf = [0u8; 32];
+    buf.copy_from_slice(&bytes[..32]);
+    Ok(U256::from_be_bytes(buf))
+}
+
 /// Return true when bit `index` is set in the Aave packed
 /// configuration `U256`.
 fn bit_is_set(bitmap: U256, index: u32) -> bool {