every.channel/evolution/proposals/ECP-0017-dht-mdns-discovery.md

ECP-0017: opt-in DHT + mDNS discovery (DNS off by default)

Status

Draft

Context

The current iroh endpoint setup uses default DNS-based discovery implicitly. We want discovery to be explicit and privacy-preserving by default, while still supporting decentralized discovery when users opt in. DHT discovery provides global, decentralized rendezvous; mDNS handles local networks without external infrastructure.

Decision

Switch endpoint construction to Endpoint::empty_builder with no discovery providers by default. Add opt-in discovery modes for DHT and mDNS. DNS discovery is disabled unless explicitly added in a future ECP.

Details

• Add a discovery config that can be set via EVERY_CHANNEL_IROH_DISCOVERY (comma-separated: dht, mdns, dns).
• Use iroh address lookup providers: DhtAddressLookup for dht, MdnsAddressLookup for mdns, and PkarrPublisher + DnsAddressLookup for dns (when explicitly enabled).
• Keep existing mDNS peer discovery (address-lookup) for LAN gossip bootstrapping.
• If discovery is disabled, peer addresses must include relay/address info (e.g., share bundle JSON).

Consequences

• DNS-based discovery is no longer automatic; opt-in discovery is required for ID-only dialing.
• Privacy improves by default (no implicit DNS publishing).
• Operators can enable decentralized DHT discovery when they want global reach.

Follow-ups

• Consider an explicit dns discovery mode if needed.
• Add UI toggles for discovery modes (for non-CLI users).