From 68f7627d778d71a9683dc0be431c6f489f8f13bb Mon Sep 17 00:00:00 2001
From: plaidfinch <finch@starlingcyber.net>
Date: Fri, 3 May 2024 21:46:52 +0000
Subject: [PATCH] Add stateful checks for chain ID and expiry height

---
 .../app/src/action_handler/transaction.rs     |  9 +++-
 .../action_handler/transaction/stateful.rs    | 42 +++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/crates/core/app/src/action_handler/transaction.rs b/crates/core/app/src/action_handler/transaction.rs
index 9219a8350b..5e5db3fcf0 100644
--- a/crates/core/app/src/action_handler/transaction.rs
+++ b/crates/core/app/src/action_handler/transaction.rs
@@ -13,7 +13,10 @@ use super::AppActionHandler;
 mod stateful;
 mod stateless;
 
-use self::stateful::{claimed_anchor_is_valid, fee_greater_than_base_fee, fmd_parameters_valid};
+use self::stateful::{
+    chain_id_is_correct, claimed_anchor_is_valid, expiry_height_is_valid,
+    fee_greater_than_base_fee, fmd_parameters_valid,
+};
 use stateless::{
     check_memo_exists_if_outputs_absent_if_not, num_clues_equal_to_num_outputs,
     valid_binding_signature,
@@ -58,6 +61,10 @@ impl AppActionHandler for Transaction {
 
         // TODO: these could be pushed into the action checks and run concurrently if needed
 
+        // SAFETY: chain ID never changes during a transaction execution.
+        chain_id_is_correct(state.clone(), self).await?;
+        // SAFETY: height never changes during a transaction execution.
+        expiry_height_is_valid(state.clone(), self).await?;
         // SAFETY: anchors are historical data and cannot change during transaction execution.
         claimed_anchor_is_valid(state.clone(), self).await?;
         // SAFETY: FMD parameters cannot change during transaction execution.
diff --git a/crates/core/app/src/action_handler/transaction/stateful.rs b/crates/core/app/src/action_handler/transaction/stateful.rs
index 7241d1a6a6..ea5a490b86 100644
--- a/crates/core/app/src/action_handler/transaction/stateful.rs
+++ b/crates/core/app/src/action_handler/transaction/stateful.rs
@@ -8,8 +8,50 @@ use penumbra_shielded_pool::fmd;
 use penumbra_transaction::gas::GasCost;
 use penumbra_transaction::Transaction;
 
+use crate::app::StateReadExt;
+
 const FMD_GRACE_PERIOD_BLOCKS: u64 = 10;
 
+pub async fn chain_id_is_correct<S: StateRead>(state: S, transaction: &Transaction) -> Result<()> {
+    let chain_id = state.get_chain_id().await?;
+    let tx_chain_id = &transaction.transaction_body.transaction_parameters.chain_id;
+
+    // The chain ID in the transaction must exactly match the current chain ID.
+    ensure!(
+        *tx_chain_id == chain_id,
+        "transaction chain ID '{}' must match the current chain ID '{}'",
+        tx_chain_id,
+        chain_id
+    );
+    Ok(())
+}
+
+pub async fn expiry_height_is_valid<S: StateRead>(
+    state: S,
+    transaction: &Transaction,
+) -> Result<()> {
+    let current_height = state.get_block_height().await?;
+    let expiry_height = transaction
+        .transaction_body
+        .transaction_parameters
+        .expiry_height;
+
+    // A zero expiry height means that the transaction is valid indefinitely.
+    if expiry_height == 0 {
+        return Ok(());
+    }
+
+    // Otherwise, the expiry height must be greater than or equal to the current block height.
+    ensure!(
+        expiry_height >= current_height,
+        "transaction expiry height '{}' must be greater than or equal to the current block height '{}'",
+        expiry_height,
+        current_height
+    );
+
+    Ok(())
+}
+
 pub async fn fmd_parameters_valid<S: StateRead>(state: S, transaction: &Transaction) -> Result<()> {
     let previous_fmd_parameters = state
         .get_previous_fmd_parameters()