foundry_evm_traces/identifier/
local.rs

1use super::{IdentifiedAddress, TraceIdentifier};
2use alloy_dyn_abi::JsonAbiExt;
3use alloy_json_abi::JsonAbi;
4use alloy_primitives::{Address, Bytes, map::HashMap};
5use foundry_common::contracts::{ContractsByArtifact, bytecode_diff_score};
6use foundry_compilers::ArtifactId;
7use revm_inspectors::tracing::types::CallTraceNode;
8use std::borrow::Cow;
9
10/// A trace identifier that tries to identify addresses using local contracts.
11pub struct LocalTraceIdentifier<'a> {
12    /// Known contracts to search through.
13    known_contracts: &'a ContractsByArtifact,
14    /// Vector of pairs of artifact ID and the runtime code length of the given artifact.
15    ordered_ids: Vec<(&'a ArtifactId, usize)>,
16    /// The contracts bytecode.
17    contracts_bytecode: Option<&'a HashMap<Address, Bytes>>,
18}
19
20impl<'a> LocalTraceIdentifier<'a> {
21    /// Creates a new local trace identifier.
22    pub fn new(known_contracts: &'a ContractsByArtifact) -> Self {
23        let mut ordered_ids = known_contracts
24            .iter()
25            .filter_map(|(id, contract)| Some((id, contract.deployed_bytecode()?)))
26            .map(|(id, bytecode)| (id, bytecode.len()))
27            .collect::<Vec<_>>();
28        ordered_ids.sort_by_key(|(_, len)| *len);
29        Self { known_contracts, ordered_ids, contracts_bytecode: None }
30    }
31
32    pub fn with_bytecodes(mut self, contracts_bytecode: &'a HashMap<Address, Bytes>) -> Self {
33        self.contracts_bytecode = Some(contracts_bytecode);
34        self
35    }
36
37    /// Returns the known contracts.
38    #[inline]
39    pub fn contracts(&self) -> &'a ContractsByArtifact {
40        self.known_contracts
41    }
42
43    /// Identifies the artifact based on score computed for both creation and deployed bytecodes.
44    pub fn identify_code(
45        &self,
46        runtime_code: &[u8],
47        creation_code: &[u8],
48    ) -> Option<(&'a ArtifactId, &'a JsonAbi)> {
49        let len = runtime_code.len();
50
51        let mut min_score = f64::MAX;
52        let mut min_score_id = None;
53
54        let mut check = |id, is_creation, min_score: &mut f64| {
55            let contract = self.known_contracts.get(id)?;
56            // Select bytecodes to compare based on `is_creation` flag.
57            let (contract_bytecode, current_bytecode) = if is_creation {
58                (contract.bytecode_without_placeholders(), creation_code)
59            } else {
60                (contract.deployed_bytecode_without_placeholders(), runtime_code)
61            };
62
63            if let Some(bytecode) = contract_bytecode {
64                let mut current_bytecode = current_bytecode;
65                if is_creation && current_bytecode.len() > bytecode.len() {
66                    // Try to decode ctor args with contract abi.
67                    if let Some(constructor) = contract.abi.constructor() {
68                        let constructor_args = &current_bytecode[bytecode.len()..];
69                        if constructor.abi_decode_input(constructor_args).is_ok() {
70                            // If we can decode args with current abi then remove args from
71                            // code to compare.
72                            current_bytecode = &current_bytecode[..bytecode.len()]
73                        }
74                    }
75                }
76
77                let score = bytecode_diff_score(&bytecode, current_bytecode);
78                if score == 0.0 {
79                    trace!(target: "evm::traces::local", "found exact match");
80                    return Some((id, &contract.abi));
81                }
82                if score < *min_score {
83                    *min_score = score;
84                    min_score_id = Some((id, &contract.abi));
85                }
86            }
87            None
88        };
89
90        // Check `[len * 0.9, ..., len * 1.1]`.
91        let max_len = (len * 11) / 10;
92
93        // Start at artifacts with the same code length: `len..len*1.1`.
94        let same_length_idx = self.find_index(len);
95        for idx in same_length_idx..self.ordered_ids.len() {
96            let (id, len) = self.ordered_ids[idx];
97            if len > max_len {
98                break;
99            }
100            if let found @ Some(_) = check(id, true, &mut min_score) {
101                return found;
102            }
103        }
104
105        // Iterate over the remaining artifacts with less code length: `len*0.9..len`.
106        let min_len = (len * 9) / 10;
107        let idx = self.find_index(min_len);
108        for i in idx..same_length_idx {
109            let (id, _) = self.ordered_ids[i];
110            if let found @ Some(_) = check(id, true, &mut min_score) {
111                return found;
112            }
113        }
114
115        // Fallback to comparing deployed code if min score greater than threshold.
116        if min_score >= 0.85 {
117            for (artifact, _) in &self.ordered_ids {
118                if let found @ Some(_) = check(artifact, false, &mut min_score) {
119                    return found;
120                }
121            }
122        }
123
124        trace!(target: "evm::traces::local", %min_score, "no exact match found");
125
126        // Note: the diff score can be inaccurate for small contracts so we're using a relatively
127        // high threshold here to avoid filtering out too many contracts.
128        if min_score < 0.85 { min_score_id } else { None }
129    }
130
131    /// Returns the index of the artifact with the given code length, or the index of the first
132    /// artifact with a greater code length if the exact code length is not found.
133    fn find_index(&self, len: usize) -> usize {
134        let (Ok(mut idx) | Err(mut idx)) =
135            self.ordered_ids.binary_search_by_key(&len, |(_, probe)| *probe);
136
137        // In case of multiple artifacts with the same code length, we need to find the first one.
138        while idx > 0 && self.ordered_ids[idx - 1].1 == len {
139            idx -= 1;
140        }
141
142        idx
143    }
144}
145
146impl TraceIdentifier for LocalTraceIdentifier<'_> {
147    fn identify_addresses(&mut self, nodes: &[&CallTraceNode]) -> Vec<IdentifiedAddress<'_>> {
148        if nodes.is_empty() {
149            return Vec::new();
150        }
151
152        trace!(target: "evm::traces::local", "identify {} addresses", nodes.len());
153
154        nodes
155            .iter()
156            .map(|&node| {
157                (
158                    node.trace.address,
159                    node.trace.kind.is_any_create().then_some(&node.trace.output[..]),
160                    node.trace.kind.is_any_create().then_some(&node.trace.data[..]),
161                )
162            })
163            .filter_map(|(address, runtime_code, creation_code)| {
164                let _span =
165                    trace_span!(target: "evm::traces::local", "identify", %address).entered();
166
167                // In order to identify the addresses, we need at least the runtime code. It can be
168                // obtained from the trace itself (if it's a CREATE* call), or from the fetched
169                // bytecodes.
170                let (runtime_code, creation_code) = match (runtime_code, creation_code) {
171                    (Some(runtime_code), Some(creation_code)) => (runtime_code, creation_code),
172                    (Some(runtime_code), _) => (runtime_code, &[] as &[u8]),
173                    _ => {
174                        let code = self.contracts_bytecode?.get(&address)?;
175                        (code.as_ref(), &[] as &[u8])
176                    }
177                };
178                let (id, abi) = self.identify_code(runtime_code, creation_code)?;
179                trace!(target: "evm::traces::local", id=%id.identifier(), "identified");
180
181                Some(IdentifiedAddress {
182                    address,
183                    contract: Some(id.identifier()),
184                    label: Some(id.name.clone()),
185                    abi: Some(Cow::Borrowed(abi)),
186                    artifact_id: Some(id.clone()),
187                })
188            })
189            .collect()
190    }
191}