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fix: reject standalone TreeLookup node at eval to match the reference interpreter #893

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fix: reject standalone TreeLookup node at eval to match the reference interpreter #893

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132 changes: 30 additions & 102 deletions ergotree-interpreter/src/eval/tree_lookup.rs
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Original file line number Diff line number Diff line change
@@ -1,151 +1,79 @@
use alloc::boxed::Box;
use alloc::vec::Vec;
use bytes::Bytes;
use alloc::string::ToString;
use ergotree_ir::mir::tree_lookup::TreeLookup;
use ergotree_ir::mir::value::Value;

use crate::eval::env::Env;
use crate::eval::Context;
use crate::eval::EvalError;
use crate::eval::Evaluable;
use ergo_avltree_rust::batch_avl_verifier::BatchAVLVerifier;
use ergo_avltree_rust::batch_node::{AVLTree, Node, NodeHeader};
use ergo_avltree_rust::operation::Operation;
use ergotree_ir::mir::avl_tree_data::AvlTreeData;
use ergotree_ir::mir::constant::TryExtractInto;
use sigma_util::AsVecU8;

impl Evaluable for TreeLookup {
fn eval<'ctx>(
&self,
env: &mut Env<'ctx>,
ctx: &Context<'ctx>,
_env: &mut Env<'ctx>,
_ctx: &Context<'ctx>,
) -> Result<Value<'ctx>, EvalError> {
let normalized_tree_val = self
.tree
.eval(env, ctx)?
.try_extract_into::<AvlTreeData>()?;
let normalized_key_val = self.key.eval(env, ctx)?.try_extract_into::<Vec<i8>>()?;
let normalized_proof_val = self.proof.eval(env, ctx)?.try_extract_into::<Vec<i8>>()?;

let starting_digest = Bytes::from(normalized_tree_val.digest.0.to_vec());
let proof = Bytes::from(normalized_proof_val.as_vec_u8());

let mut bv = BatchAVLVerifier::new(
&starting_digest,
&proof,
AVLTree::new(
|digest| Node::LabelOnly(NodeHeader::new(Some(*digest), None)),
normalized_tree_val.key_length as usize,
normalized_tree_val
.value_length_opt
.as_ref()
.map(|v| **v as usize),
),
None,
None,
)
.map_err(map_eval_err)?;

match bv.perform_one_operation(&Operation::Lookup(Bytes::from(
normalized_key_val.as_vec_u8(),
))) {
Ok(opt) => match opt {
Some(v) => Ok(Value::Opt(Some(Box::new(v.to_vec().into())))),
_ => Ok(Value::Opt(None)),
},
Err(_) => Err(EvalError::AvlTree(format!(
"Tree proof is incorrect {:?}",
normalized_tree_val
))),
}
// The reference interpreter has no eval override for the standalone
// `TreeLookup` node (opcode `AvlTreeGet`): its `costKind` is
// `notSupportedError`, so the default `Value.eval` raises ("Should be
// overriden"). The ErgoScript compiler emits an `AvlTree.get` MethodCall,
// never this node, so mainnet never reaches it — but a hand-crafted tree
// using the opcode directly must error to match the oracle rather than
// evaluate (it would be a consensus split otherwise).
Err(EvalError::UnexpectedExpr(
"TreeLookup (AvlTreeGet) node is not supported for evaluation".to_string(),
))
}
}

fn map_eval_err<T: core::fmt::Debug>(e: T) -> EvalError {
EvalError::AvlTree(format!("{:?}", e))
}

#[allow(clippy::unwrap_used, clippy::panic, clippy::unreachable)]
#[cfg(test)]
mod tests {

use super::*;
use crate::eval::test_util::eval_out_wo_ctx;
use crate::eval::test_util::try_eval_out_wo_ctx;

use alloc::boxed::Box;
use alloc::vec;
use alloc::vec::Vec;
use bytes::Bytes;
use ergo_avltree_rust::authenticated_tree_ops::AuthenticatedTreeOps;
use ergo_avltree_rust::batch_avl_prover::BatchAVLProver;
use ergo_avltree_rust::operation::KeyValue;
use ergo_avltree_rust::batch_node::{AVLTree, Node, NodeHeader};
use ergo_avltree_rust::operation::{KeyValue, Operation};
use ergo_chain_types::ADDigest;
use ergotree_ir::mir::{
avl_tree_data::{AvlTreeData, AvlTreeFlags},
expr::Expr,
value::{CollKind, NativeColl},
};
use ergotree_ir::mir::avl_tree_data::{AvlTreeData, AvlTreeFlags};
use ergotree_ir::mir::expr::Expr;
use sigma_ser::ScorexSerializable;
use sigma_util::AsVecI8;

#[test]
fn eval_tree_lookup() {
fn tree_lookup_eval_is_unsupported() {
// A well-formed TreeLookup over a real tree and a valid proof: the
// reference interpreter still refuses to evaluate the standalone node, so
// eval must error rather than return the looked-up value.
let mut prover = populate_tree(vec![(vec![1u8], 10u64.to_be_bytes().to_vec())]);
let initial_digest =
ADDigest::scorex_parse_bytes(&prover.digest().unwrap().into_iter().collect::<Vec<_>>())
.unwrap();

let key1 = Bytes::from(vec![1u8]);
let key2 = Bytes::from(vec![2u8]);
let op1 = Operation::Lookup(key1);
let op2 = Operation::Lookup(key2);
let lookup_found = prover.perform_one_operation(&op1).unwrap();
let lookup_not_found = prover.perform_one_operation(&op2).unwrap();
let proof = prover.generate_proof().to_vec().as_vec_i8();

let tree_flags = AvlTreeFlags::new(false, false, false);
let obj = Expr::Const(
AvlTreeData {
digest: initial_digest,
tree_flags,
tree_flags: AvlTreeFlags::new(false, false, false),
key_length: 1,
value_length_opt: None,
}
.into(),
);

let search_key_found = vec![1i8];
let search_key_not_found = vec![2i8];

let expr_found = TreeLookup {
tree: Box::new(obj.clone()),
key: Box::new(search_key_found.into()),
proof: Box::new(proof.clone().into()),
}
.into();
let expr_not_found = TreeLookup {
let expr: Expr = TreeLookup {
tree: Box::new(obj),
key: Box::new(search_key_not_found.into()),
key: Box::new(vec![1i8].into()),
proof: Box::new(proof.into()),
}
.into();

let res_found: Value = eval_out_wo_ctx(&expr_found);
let res_not_found: Value = eval_out_wo_ctx(&expr_not_found);

if let Value::Opt(opt) = res_found {
if let Some(Value::Coll(CollKind::NativeColl(NativeColl::CollByte(b)))) = opt.as_deref()
{
assert!(lookup_found.unwrap().eq(&b.as_vec_u8()));
} else {
unreachable!();
}
} else {
unreachable!();
}

if let Value::Opt(opt) = res_not_found {
assert!(lookup_not_found.is_none() && opt.is_none())
} else {
unreachable!();
}
assert!(try_eval_out_wo_ctx::<Value>(&expr).is_err());
}

fn populate_tree(entries: Vec<(Vec<u8>, Vec<u8>)>) -> BatchAVLProver {
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