net: v2-only peer discovery (Q-49) - #132
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take_dial_candidates ranked last-resort last but still filled max with known-v1 IPs. A mixed book now omits INCOMPATIBLE until that set is the only leftover (FAILED_LAST_CONNECT stays retryable).
Gossip without the v2 bit is v1-only. We already disconnect those after handshake; keeping them in the book just starves outbound. Filter is (NETWORK || NETWORK_LIMITED) && P2P_V2.
BIP324 v2-only nodes should ask seeds for NETWORK|WITNESS|P2P_V2
(0x809), matching Core strprintf("x%x.%s", bits, seed). The hostname
helper is pure; resolve still uses the bare seed list.
Each DNS seed is queried as x809.<host> (NETWORK|WITNESS|P2P_V2). If that name is empty, the bare seed is tried so operators still bootstrap when a seed does not implement the x-filter. First success wins per seed; regtest stays empty.
OPERATOR owns the discovery contract (x809 seeds, P2P_V2 gossip, skip known-v1 while better addrs remain). Seed host list stays in seeds.rs. experimental-mainnet peer-scarcity points there.
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Why
Tip-follow and IBD were starved by v1-only DNS/
addrgossip. We advertiseNETWORK|WITNESS|P2P_V2and disconnect v1 after handshake, but discoverystill treated the network as dual-stack: bare seed names,
NETWORKgossipwith service bits dropped, and
take_dial_candidates(N)filling outboundwith known-
INCOMPATIBLEIPs.Closes Q-49.
What
INCOMPATIBLEwhile any other candidate remains(
FAILED_LAST_CONNECTstays retryable; all-incompat book is last-resort).addr/addrv2only when(NETWORK || NETWORK_LIMITED) && P2P_V2.dns_seed_query_host= Corex%x.<seed>for0x809.x809.<seed>first per seed; unfiltered name only if thatis empty. No live DNS in the default suite.
OPERATOR.md§ P2P owns the contract; seed host list stays inseeds.rs.quality.mdQ-49 → Completed.Test plan
cargo test -p rbitcoin-net --lib take_dial_cargo test -p rbitcoin-net --lib socket_addrs_from_addr_and_addrv2_filtercargo test -p rbitcoin-net --lib dns_seed_query_hostcargo test -p rbitcoin-net --lib seed_lookup_namescargo test -p rbitcoin-net --lib pick_seed_resultsfmt,deny,clippy,test,multinode,coverage)Not a
core-functional/static-binarieschange.