dnssec_resolver

On-device DNSSEC validation over a caller-supplied DohWireTransport. The validator is a native Rust crate built by the package's build hook; the Dart side performs no networking of its own.

Usage

import 'package:dnssec_resolver/dnssec_resolver.dart';
import 'package:doh_transport/doh_transport_io.dart';

final transport = IoDohTransport();
try {
  final resolver = DnssecResolver(transport: transport);
  for (final record in await resolver.lookupTxt('example.com')) {
    print(record.text);
  }
} on DnssecException catch (error) {
  print('${error.code.name}: ${error.message}');
} finally {
  await transport.close();
}

lookup returns a DnssecResult with its status (secure, insecure, bogus, indeterminate), records and CNAME aliases. lookupTxt and DnssecResult.secureTxt() return TXT records from a secure answer and throw DnssecException otherwise. Record types: A, CNAME, TXT and AAAA.

Trust model

Every answer is validated locally from the trust anchors down to the queried owner. The DoH endpoint is only a transport: it can withhold or delay answers but cannot forge a secure one. Answers are scoped to the queried owner; additional-section data is ignored and expanded records are rejected. RRSIGs using SHA-1 based algorithms are ignored. The endpoint sees every query the validator makes, from the root keys down, and, without a proxy, your address. DnssecResolver.validator identifies this package to consumers that check a TxtAnswer.validator, such as openalias.

Configuration

• endpoint: an RFC 8484 URI, https://dns.google/dns-query by default.
• timeout 20 s (at most 2 minutes) for a whole lookup, including its sub-queries.
• maxQueries 64 (at most 128) per lookup.
• trustAnchors: DNSKEY records in zone presentation format; the IANA root keys by default.
• Proxy, fixed destination, connection reuse and transport deadlines belong to the transport; see doh_transport.

Building

The build hook compiles native/ with cargo build --locked. Building needs rustup with the toolchain in native/rust-toolchain.toml and the Rust target for each platform you build for. Dart SDK 3.10 or later.

Development

doh_transport is not on pub.dev yet: clone it beside this repository and add pubspec_overrides.yaml:

dependency_overrides:
  doh_transport:
    path: ../doh_transport

bash tool/check.sh runs format, analyze, the cargo checks and the tests. tool/notices.py regenerates NOTICES from the crate licenses.

License

MIT; see LICENSE. NOTICES lists the licenses of the bundled Rust crates. test/support/LICENSE covers the test support files.