Check if ClientStatePath is empty during client creation (#605)

* Check if ClientStatePath is empty during client creation

* Rewrite ClientState present check with is_ok

.changelog/unreleased/breaking-changes/604-fix-unchecked-clientstatepath.md

@@ -0,0 +1,2 @@
+- Check if `ClientStatePath` is empty during client creation process
+  ([#604](https://github.com/cosmos/ibc-rs/issues/604))

crates/ibc/src/core/ics02_client/error.rs

@@ -19,10 +19,12 @@ pub enum ClientError {
         counter: u64,
         validation_error: ValidationError,
     },
-    /// client not found: `{client_id}`
-    ClientNotFound { client_id: ClientId },
     /// client is frozen with description: `{description}`
     ClientFrozen { description: String },
+    /// client state not found: `{client_id}`
+    ClientStateNotFound { client_id: ClientId },
+    /// client state already exists: `{client_id}`
+    ClientStateAlreadyExists { client_id: ClientId },
     /// consensus state not found at: `{client_id}` at height `{height}`
     ConsensusStateNotFound { client_id: ClientId, height: Height },
     /// implementation specific error

crates/ibc/src/core/ics02_client/handler/create_client.rs

@@ -37,14 +37,18 @@ where
 
     let client_type = client_state.client_type();
 
-    let _client_id = ClientId::new(client_type, id_counter).map_err(|e| {
+    let client_id = ClientId::new(client_type, id_counter).map_err(|e| {
         ClientError::ClientIdentifierConstructor {
             client_type: client_state.client_type(),
             counter: id_counter,
             validation_error: e,
         }
     })?;
 
+    if ctx.client_state(&client_id).is_ok() {
+        return Err(ClientError::ClientStateAlreadyExists { client_id }.into());
+    };
+
     Ok(())
 }
 

crates/ibc/src/mock/context.rs

@@ -715,11 +715,11 @@ impl ValidationContext for MockContext {
                 client_record
                     .client_state
                     .clone()
-                    .ok_or_else(|| ClientError::ClientNotFound {
+                    .ok_or_else(|| ClientError::ClientStateNotFound {
                         client_id: client_id.clone(),
                     })
             }
-            None => Err(ClientError::ClientNotFound {
+            None => Err(ClientError::ClientStateNotFound {
                 client_id: client_id.clone(),
             }),
         }
@@ -771,7 +771,7 @@ impl ValidationContext for MockContext {
             ibc_store
                 .clients
                 .get(client_id)
-                .ok_or_else(|| ClientError::ClientNotFound {
+                .ok_or_else(|| ClientError::ClientStateNotFound {
                     client_id: client_id.clone(),
                 })?;
 
@@ -801,7 +801,7 @@ impl ValidationContext for MockContext {
             ibc_store
                 .clients
                 .get(client_id)
-                .ok_or_else(|| ClientError::ClientNotFound {
+                .ok_or_else(|| ClientError::ClientStateNotFound {
                     client_id: client_id.clone(),
                 })?;