{ "number": 36675, "input_hash": "c5806304b7e94cc4", "model": "ledger", "prompt_hash": null, "created": "2026-10-29T01:22:06+00:00", "result": { "summary": "Expands compressed IPv6 addresses into full eight-group notation when sending destination hostnames in SOCKS5 CONNECT requests. This works around an upstream Tor issue where relay exit nodes mistakenly parse `:` as a single IPv6 address if `::` absorbs the port as an eighth group, dropping the connection.", "problem": "Outbound connections routed through Tor SOCKS5 proxies fail with \"general failure\" for IPv6 peers whose addresses contain an inner `::`. Tor exit relays attempt to parse `:` as an address, causing the compressed address to absorb the port number and fail port extraction, dropping roughly 20% of IPv6 peers in addrman and ~29% of DNS seed IPv6 answers.", "card": "Expands shortened IPv6 addresses into full eight-group notation when passing them to SOCKS5 proxies. Nodes using Tor as an outbound proxy fail to connect to IPv6 peers whose addresses contain an inner `::` because Tor exit relays mistake the appended port for an eighth address group and close the stream. This bug prevents connection to an estimated 20% to 30% of reachable IPv6 peers on mainnet. Author verified against Tor 0.4.9.13 that connections failing on master connect and handshake with this change.", "evidence": [ "Author references upstream Tor issue https://gitlab.torproject.org/tpo/core/tor/-/issues/32314: Tor exit's `tor_addr_port_split` parses `2001:db8::1:8333` as a valid IPv6 address without a port and terminates the stream.", "Author measurement: \"About 20% of the IPv6 addresses in a gossip-filled addrman, and 29% of current IPv6 DNS seed answers, have an inner `::`.\"", "Author test against Tor 0.4.9.13 on mainnet: master failed to connect to four seed-provided peers with inner-`::` addresses (30 \"general failure\" errors), whereas this change allowed all four to connect and complete the version handshake." ], "scope_notes": "", "changed_since_previous": "Initial description with diff.", "thread": { "last_event_at": "2026-10-27T15:01:35Z", "events": 3, "head_sha": "721e2f5051142c2194838dd06fe0a86a07621c14", "schema_floor": 2, "schema": 2 }, "waiting_on": [ { "at": "2026-10-27", "id": "c:6445417783", "on": "reviewer", "url": "https://github.com/bitcoin/bitcoin/pull/36675#issuecomment-6445417783", "what": "code review and testing" } ], "risk": { "level": "low", "touches": [ "p2p" ], "why": "A formatting error in SOCKS5 destination names could fail outbound connections over SOCKS5 proxies." }, "discussion": { "author_status": "last statement processed 2026-10-27", "open_concerns": [], "resolved_concerns": [ "darosior: Report the issue upstream to Tor (accepted by darosior 2026-10-27)" ] }, "reviewability": { "state": "Ready", "label": "Ready", "reason": "Nothing known that would invalidate a review now." }, "agreement": { "state": "Positive", "summary": "Positive: support without stated reasons, no open objection (darosior)", "reason": "Initial record: darosior suggested upstreaming the Tor bug report, which instagibbs confirmed was already known and closed upstream, after which darosior Concept ACKed. / Initial record. darosior suggested reporting the issue upstream to Tor, which instagibbs pointed out was already reported and closed; darosior then Concept ACKed.", "evidence": [ "darosior: Concept ACK" ], "objections": [ { "reviewer": "darosior", "association": "MEMBER", "type": "suggestion", "kind": "approach", "harm": "", "request": "Report the issue upstream to Tor", "question": "", "text": "Report the issue upstream to Tor", "clears_with": "answer", "blocking": false, "status": "accepted", "status_note": "author pointed out it is already a known closed upstream issue; reviewer followed up with Concept ACK", "cleared": true, "author_replied": true, "others_replied": false, "fix_pushed": false, "replies": [ "c:6445339269" ], "evidence": "2026-10-27: 'May be worth upstreaming a bug report.'", "url": "https://github.com/bitcoin/bitcoin/pull/36675#pullrequestreview-5669053406", "id": "r:5669053406", "at": "2026-10-27", "status_at": "2026-10-27", "status_by": "darosior", "resolution_evidence": "2026-10-27: darosior: 'Concept ACK'", "pin": null, "from_schema": 2 } ], "support": [ { "reviewer": "darosior", "reason": "", "substantive": false, "verdict": "Concept ACK", "id": "c:6445417783", "url": "https://github.com/bitcoin/bitcoin/pull/36675#issuecomment-6445417783", "at": "2026-10-27", "association": "MEMBER", "evidence": "none", "areas": [] } ], "participants": [ { "login": "darosior", "stance": "support", "note": "supported workaround with Concept ACK after checking upstream Tor status", "association": "MEMBER", "comments": 2, "first": "2026-10-27", "last": "2026-10-27" } ], "derivation": "support without stated reasons, no open objection (darosior)", "model_state": null, "corrections": [], "notes": "Initial record: darosior suggested upstreaming the Tor bug report, which instagibbs confirmed was already known and closed upstream, after which darosior Concept ACKed. / Initial record. darosior suggested reporting the issue upstream to Tor, which instagibbs pointed out was already reported and closed; darosior then Concept ACKed." }, "dependencies": { "depends_on": [], "enables": [] }, "categories": [ { "name": "p2p", "member": true, "evidence": "Touches `src/netbase.cpp` handling proxy connections and SOCKS5 destination address formatting for Tor outbound peer connectivity.", "band": "P2", "reason_tag": "bug fix", "score": 0.65, "factors": { "bug_severity": 2, "leverage": 0, "performance": 0, "security_stability": 1, "user_value": 2 }, "rationale": "Fixes outbound connection failures over Tor SOCKS5 proxies to IPv6 peers with compressed addresses. As measured by the author, roughly 20% of addrman IPv6 addresses and 29% of DNS seed answers have an inner `::`, which previously caused Tor exit nodes to drop connections with general failure errors." } ], "confidence": "high", "uncertainties": [], "needs": [] }, "cost_usd": 0.0, "source": { "record": "2026-10-29T01:22:06+00:00", "code": "2026-10-29T01:26:13+00:00", "judgments": 1 } }