# rsdns - DNS Client Library
**rsdns** is a Rust library for interacting with DNS servers.
Its main goal is to query the Domain Name System and return the results in easily
consumable Rust types.
*rsdns* strives to be simple and fast. To be simple *rsdns* keeps a minimal API.
To be fast *rsdns* aims to allow DNS message parsing with minimal overhead.
There are crates which implement asynchronous DNS clients, but are built for a single
async runtime. This somewhat blocks usage of such client in an application built around
another runtime. *rsdns* closes this gap and genuinely supports three different async
runtimes. Moreover, *rsdns* has an independent synchronous client as well.
[![crates.io][crates-badge]][crates-url]
[![docs.rs][docs-badge]][docs-url]
[crates-badge]: https://img.shields.io/crates/v/rsdns.svg
[crates-url]: https://crates.io/crates/rsdns
[docs-badge]: https://img.shields.io/docsrs/rsdns
[docs-url]: https://docs.rs/rsdns/latest/rsdns
## Notable Features
* Minimal API
* Asynchronous DNS clients for `tokio`, `async-std` and `smol`
* Blocking client implemented with `std::net`
* Zero memory allocations when parsing records with no variable size fields
* Sockets can be bound to network interfaces by name (available on operating
systems with `SO_BINDTODEVICE` support)
* Minimal set of dependencies
## ch4
*rsdns* comes with a small command-line tool [ch4](https://github.com/r-bk/ch4).
*ch4* uses *rsdns* to query the Domain Name System,
and shows the results in a zone-file format.
It can be used as a simple substitute for [dig](https://en.wikipedia.org/wiki/Dig_(command)),
especially on platforms where *dig* is not originally supported.
## Supported RFCs
* [RFC 1035] - the foundation of DNS protocol: `A`, `NS`, `TXT`, `CNAME`, `SOA`, `MX`, `PTR`, `ANY` etc.
* [RFC 1101], [RFC 1123] - allow leading digits in domain name labels
* [RFC 2181] - RRSet definition and TTL handling
* [RFC 2671], [RFC 6891] - EDNS0
* [RFC 3596] - `AAAA`
* [RFC 7766] - DNS Transport over TCP, TCP message length field handling
[RFC 1035]: https://www.rfc-editor.org/rfc/rfc1035.html
[RFC 1101]: https://www.rfc-editor.org/rfc/rfc1101.html
[RFC 1123]: https://www.rfc-editor.org/rfc/rfc1123.html
[RFC 2181]: https://www.rfc-editor.org/rfc/rfc2181#section-5
[RFC 2671]: https://www.rfc-editor.org/rfc/rfc2671.html
[RFC 3596]: https://www.rfc-editor.org/rfc/rfc3596.html
[RFC 6891]: https://www.rfc-editor.org/rfc/rfc6891.html
[RFC 7766]: https://www.rfc-editor.org/rfc/rfc7766.html
## Roadmap
The next planned features are:
* [RFC 2782](https://www.rfc-editor.org/rfc/rfc2782.html) - `SRV`
* [RFC 6844](https://www.rfc-editor.org/rfc/rfc6844.html) - `CAA`
* [RFC 7208](https://www.rfc-editor.org/rfc/rfc7208.html) - `SPF`
## Changelog
The changelog is maintained in [CHANGELOG.md](CHANGELOG.md)
## License
Licensed under either of
* Apache License, Version 2.0
([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
* MIT license
([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
at your option.
## Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.