fix(client): Interop bugfixes (#1006)

bin/client/src/interop/mod.rs

@@ -9,7 +9,7 @@ use kona_executor::{ExecutorError, KonaHandleRegister};
 use kona_preimage::{HintWriterClient, PreimageOracleClient};
 use kona_proof::{errors::OracleProviderError, l2::OracleL2ChainProvider, CachingOracle};
 use kona_proof_interop::{
-    BootInfo, ConsolidationError, PreState, INVALID_TRANSITION_HASH, TRANSITION_STATE_MAX_STEPS,
+    boot::BootstrapError, BootInfo, ConsolidationError, PreState, TRANSITION_STATE_MAX_STEPS,
 };
 use thiserror::Error;
 use tracing::{error, info};
@@ -31,18 +31,18 @@ pub enum FaultProofProgramError {
     /// An error occurred in the driver.
     #[error(transparent)]
     Driver(#[from] DriverError<ExecutorError>),
-    /// An error occurred during RLP decoding.
-    #[error("RLP decoding error: {0}")]
-    Rlp(alloy_rlp::Error),
+    /// Consolidation error.
+    #[error(transparent)]
+    Consolidation(#[from] ConsolidationError),
+    /// Bootstrap error
+    #[error(transparent)]
+    Bootstrap(#[from] BootstrapError),
     /// State transition failed.
     #[error("Critical state transition failure")]
     StateTransitionFailed,
     /// Missing a rollup configuration.
     #[error("Missing rollup configuration for chain ID {0}")]
     MissingRollupConfig(u64),
-    /// Consolidation error.
-    #[error(transparent)]
-    Consolidation(#[from] ConsolidationError),
 }
 
 /// Executes the interop fault proof program with the given [PreimageOracleClient] and
@@ -68,20 +68,16 @@ where
     let oracle = Arc::new(CachingOracle::new(ORACLE_LRU_SIZE, oracle_client, hint_client));
     let boot = match BootInfo::load(oracle.as_ref()).await {
         Ok(boot) => boot,
+        Err(BootstrapError::NoOpTransition) => {
+            info!(target: "client_interop", "No-op transition, short-circuiting.");
+            return Ok(());
+        }
         Err(e) => {
-            error!(target: "client_interop", "Failed to load boot info: {:?}", e);
+            error!(target: "client_interop", "Failed to load boot info: {}", e);
             return Err(e.into());
         }
     };
 
-    // If the pre state is invalid, short-circuit and check if the post-state claim is also invalid.
-    if boot.agreed_pre_state_commitment == INVALID_TRANSITION_HASH &&
-        boot.claimed_post_state == INVALID_TRANSITION_HASH
-    {
-        info!(target: "client_interop", "Invalid pre and post state, short-circuiting.");
-        return Ok(());
-    }
-
     // Load in the agreed pre-state from the preimage oracle in order to determine the active
     // sub-problem.
     match boot.agreed_pre_state {

bin/host/src/interop/cfg.rs

@@ -158,7 +158,7 @@ impl InteropHost {
         let preimage = BidirectionalChannel::new()?;
 
         let server_task = self.start_server(hint.host, preimage.host).await?;
-        let client_task = task::spawn(kona_client::single::run(
+        let client_task = task::spawn(kona_client::interop::run(
             OracleReader::new(preimage.client),
             HintWriter::new(hint.client),
             None,

bin/host/src/interop/handler.rs

@@ -362,7 +362,7 @@ impl HintHandler for InteropHintHandler {
 
                 let block_number = u64::from_be_bytes(hint.data.as_ref()[..8].try_into()?);
                 let address = Address::from_slice(&hint.data.as_ref()[8..28]);
-                let slot = B256::from_slice(&hint.data.as_ref()[28..]);
+                let slot = B256::from_slice(&hint.data.as_ref()[28..60]);
                 let chain_id = u64::from_be_bytes(hint.data[60..].try_into()?);
 
                 let mut proof_response = providers

crates/proof-sdk/proof-interop/src/boot.rs

@@ -1,7 +1,7 @@
 //! This module contains the prologue phase of the client program, pulling in the boot information
 //! through the `PreimageOracle` ABI as local keys.
 
-use crate::{HintType, PreState};
+use crate::{HintType, PreState, INVALID_TRANSITION, INVALID_TRANSITION_HASH};
 use alloc::{string::ToString, vec::Vec};
 use alloy_primitives::{Bytes, B256, U256};
 use alloy_rlp::Decodable;
@@ -13,6 +13,7 @@ use kona_proof::errors::OracleProviderError;
 use maili_genesis::RollupConfig;
 use maili_registry::{HashMap, ROLLUP_CONFIGS};
 use serde::{Deserialize, Serialize};
+use thiserror::Error;
 use tracing::warn;
 
 /// The local key ident for the L1 head hash.
@@ -56,7 +57,7 @@ impl BootInfo {
     /// ## Returns
     /// - `Ok(BootInfo)`: The boot information.
     /// - `Err(_)`: Failed to load the boot information.
-    pub async fn load<O>(oracle: &O) -> Result<Self, OracleProviderError>
+    pub async fn load<O>(oracle: &O) -> Result<Self, BootstrapError>
     where
         O: PreimageOracleClient + HintWriterClient + Clone + Send,
     {
@@ -88,9 +89,22 @@ impl BootInfo {
                 .map_err(OracleProviderError::SliceConversion)?,
         );
 
+        let raw_pre_state = read_raw_pre_state(oracle, l2_pre).await?;
+        if raw_pre_state == INVALID_TRANSITION {
+            warn!(
+                target: "boot-loader",
+                "Invalid pre-state, short-circuiting to check post-state claim."
+            );
+
+            if l2_post == INVALID_TRANSITION_HASH {
+                return Err(BootstrapError::NoOpTransition);
+            } else {
+                return Err(BootstrapError::InvalidPostState(l2_post));
+            }
+        }
+
         let agreed_pre_state =
-            PreState::decode(&mut read_raw_pre_state(oracle, l2_pre).await?.as_ref())
-                .map_err(OracleProviderError::Rlp)?;
+            PreState::decode(&mut raw_pre_state.as_ref()).map_err(OracleProviderError::Rlp)?;
 
         let chain_ids: Vec<_> = match agreed_pre_state {
             PreState::SuperRoot(ref super_root) => {
@@ -135,6 +149,20 @@ impl BootInfo {
     }
 }
 
+/// An error that occurred during the bootstrapping phase.
+#[derive(Debug, Error)]
+pub enum BootstrapError {
+    /// An error occurred while reading from the preimage oracle.
+    #[error(transparent)]
+    Oracle(#[from] OracleProviderError),
+    /// The pre-state is invalid and the post-state claim is not invalid.
+    #[error("`INVALID` pre-state claim; Post-state {0} unexpected.")]
+    InvalidPostState(B256),
+    /// The pre-state is invalid and the post-state claim is also invalid.
+    #[error("No-op state transition detected; both pre and post states are `INVALID`.")]
+    NoOpTransition,
+}
+
 /// Reads the raw pre-state from the preimage oracle.
 pub(crate) async fn read_raw_pre_state<O>(
     caching_oracle: &O,

crates/proof-sdk/proof-interop/src/lib.rs

@@ -9,7 +9,8 @@ extern crate alloc;
 
 mod pre_state;
 pub use pre_state::{
-    OptimisticBlock, PreState, TransitionState, INVALID_TRANSITION_HASH, TRANSITION_STATE_MAX_STEPS,
+    OptimisticBlock, PreState, TransitionState, INVALID_TRANSITION, INVALID_TRANSITION_HASH,
+    TRANSITION_STATE_MAX_STEPS,
 };
 
 mod hint;

crates/proof-sdk/proof-interop/src/pre_state.rs

@@ -12,6 +12,9 @@ pub(crate) const TRANSITION_STATE_VERSION: u8 = 255;
 /// The maximum number of steps allowed in a [TransitionState].
 pub const TRANSITION_STATE_MAX_STEPS: u64 = 2u64.pow(10) - 1;
 
+/// The [Bytes] representation of the string "invalid".
+pub const INVALID_TRANSITION: Bytes = Bytes::from_static(b"invalid");
+
 /// `keccak256("invalid")`
 pub const INVALID_TRANSITION_HASH: B256 =
     b256!("ffd7db0f9d5cdeb49c4c9eba649d4dc6d852d64671e65488e57f58584992ac68");

crates/proof-sdk/proof/src/hint.rs

@@ -42,8 +42,8 @@ where
         }
 
         let mut hint_data = Vec::with_capacity(self.data.len() + data.as_ref().len());
-        hint_data[..self.data.len()].copy_from_slice(self.data.as_ref());
-        hint_data[self.data.len()..].copy_from_slice(data.as_ref());
+        hint_data.extend_from_slice(self.data.as_ref());
+        hint_data.extend_from_slice(data.as_ref());
 
         Self { data: hint_data.into(), ..self }
     }