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java-topology/defects/tor/patch/CLEAN.md
russell@unturf.com a7b08c7e05 blockchain-p2p: solang/tor/bitcoin/transmission/libtorrent/solc CWE-407 scan 
solang-0001: add_external_functions emits_events Vec::contains O(F×E²) MEDIUM
  src/sema/external_functions.rs:93-103 — dedup accumulator Vec uses linear scan
  for each event per function; fix: IndexSet (already a dependency) for O(1) dedup

tor/bitcoin/transmission/libtorrent/solc: CLEAN markers added after full scan
  Tor: nodes_have_common_family_id F=1-3 IDs, O(N×F²) ≈ O(9N), not scalable issue
  Bitcoin: TxGraph/sets throughout, no linear scan in hot paths
  Transmission: bitfields for piece tracking, sorted binary search for string table
  libtorrent: sorted vectors with lower_bound, DHT uses binary search on results
  solc: unordered_set/set throughout OverrideChecker, SMTEncoder, FunctionCallGraph
2026-03-29 19:49:57 -04:00

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CLEAN — Tor Anonymity Network

Scanned 2026-03-29 for CWE-407 (algorithmic complexity: O(N²) linear membership tests, O(2^D) diamond recursion).

Scope

  • src/feature/client/entrynodes.c — guard node selection, sampled/confirmed guard lists
  • src/feature/client/circpathbias.c — circuit path bias tracking
  • src/feature/nodelist/node_select.c — node selection with exclusion lists
  • src/feature/nodelist/nodelist.c — family membership, nodes_have_common_family_id
  • src/feature/nodelist/routerlist.c — router descriptor ingestion
  • src/feature/hs/hs_service.c — hidden service hsdir tracking
  • src/feature/relay/dns.c — DNS wildcard detection

Findings

  • nodelist_subtract (node_select.c:890) — explicitly noted in comments as "delivers linear performance when smartlist_subtract would be quadratic." Uses bitarray_t indexed by node->nodelist_idx. O(N+M). CLEAN.
  • nodes_have_common_family_id (nodelist.c:2190) — O(|ids_a| × |ids_b|) nested loop over family certificate IDs. Both lists are tiny (typically 1–3 IDs per relay). Outer loop in nodelist_add_node_and_family iterates all ~7000 relays but inner product is O(F²) where F≪1. Not a scalable O(N²). CLEAN.
  • entrynodes.c guard lists — smartlist_contains on primary_entry_guards and confirmed_entry_guards: bounded by MAX_SAMPLE_THRESHOLD (dozens), called in setup/error paths (BUG assertions), not hot per-circuit. CLEAN.
  • hs_service.c previous_hsdirs — smartlist_contains_string on a list bounded by REND_NUMBER_OF_CONSECUTIVE_REPLICAS (6). CLEAN.
  • dns.c dns_wildcard_list — linear scan on a list of hijacked IPs. In practice contains 0–10 entries; called once per DNS response. CLEAN.
  • Router descriptor ingestion — requested_fingerprints shrinks as each router is processed (O(N) total). CLEAN.

Result: No actionable CWE-407 defects. Tor's hot node-selection paths use bitarray-indexed O(N) exclusion; all family/guard list scans operate on constant-bounded collections.