internal/

Package cache provides DNS caching functionality for SDNS.

Package contextutil provides context lifecycle helpers shared by transports and middleware.

Package debugenv reads the environment switches that expose sdns's diagnostic surfaces.

Package dnsclient owns SDNS's upstream DNS transport: wire framing, buffer pooling, dialing, deadlines and exchange policy (ID match, question-section guard, UDP->TCP truncation fallback).

Package dnsname walks domain-name labels without allocating.

Package dnsutil provides DNS protocol utilities for SDNS.

Package ecs holds the policy and helpers for EDNS Client Subnet handling (RFC 7871).

Package emptyzones holds the locally-served zones of RFC 6303, the list the AS112 middleware answers for by default.

Package ipset answers one question: is this address inside any of these CIDRs?

Package metric is a thin shim over Prometheus that trades a small amount of staleness for a much faster hot path.

Package rpz is the policy engine for DNS Response Policy Zones (draft-vixie-dnsop-dns-rpz): parsing policy zones into an immutable compiled store, and matching query names against it under the draft's precedence rules.

Package wire provides zero-allocation cursors over packed DNS messages.

Package zonetransfer holds the secondary-zone transfer primitives: strict AXFR over TCP, the SOA serial probe, RFC 1982 serial comparison, schedule jitter, and RFC 5936 duplicate normalization.