From 45970c298b3c440d49f3a6f40be64ed6ef2e877f Mon Sep 17 00:00:00 2001
From: Romain Ruetschi <romain@informal.systems>
Date: Wed, 18 Sep 2024 10:56:38 +0200
Subject: [PATCH] fix(rust): Interpret `max_depth` in proof specs as 128 if
 left to 0

---
 rust/src/lib.rs    |  4 ++++
 rust/src/verify.rs | 11 +++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 4799357b..aff96078 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -14,6 +14,10 @@ mod verify;
 mod ics23 {
     include!("cosmos.ics23.v1.rs");
 
+    impl ProofSpec {
+        pub const DEFAULT_MAX_DEPTH: i32 = 128;
+    }
+
     #[cfg(feature = "serde")]
     include!("cosmos.ics23.v1.serde.rs");
 }
diff --git a/rust/src/verify.rs b/rust/src/verify.rs
index ade0b93a..c3b138f9 100644
--- a/rust/src/verify.rs
+++ b/rust/src/verify.rs
@@ -9,9 +9,9 @@ use anyhow::{bail, ensure};
 use crate::api::{ensure_inner_prefix, ensure_leaf_prefix};
 use crate::helpers::Result;
 use crate::host_functions::HostFunctionsProvider;
-use crate::ics23;
 use crate::ops::do_hash;
 use crate::ops::{apply_inner, apply_leaf};
+use crate::{ics23, ProofSpec};
 
 pub type CommitmentRoot = Vec<u8>;
 
@@ -118,6 +118,13 @@ fn check_existence_spec(proof: &ics23::ExistenceProof, spec: &ics23::ProofSpec)
     if let (Some(leaf), Some(leaf_spec)) = (&proof.leaf, &spec.leaf_spec) {
         ensure_leaf_prefix(&leaf.prefix, spec)?;
         ensure_leaf(leaf, leaf_spec)?;
+
+        let max_depth = if spec.max_depth == 0 {
+            ProofSpec::DEFAULT_MAX_DEPTH
+        } else {
+            spec.max_depth
+        };
+
         // ensure min/max depths
         if spec.min_depth != 0 {
             ensure!(
@@ -126,7 +133,7 @@ fn check_existence_spec(proof: &ics23::ExistenceProof, spec: &ics23::ProofSpec)
                 proof.path.len(),
             );
             ensure!(
-                proof.path.len() <= spec.max_depth as usize,
+                proof.path.len() <= max_depth as usize,
                 "Too many InnerOps: {}",
                 proof.path.len(),
             );