libp2p

Crate dns

Available on crate feature dns only.
Expand description

§DNS name resolution

Transport for libp2p.

This crate provides the type tokio::Transport based on [hickory_resolver::TokioResolver].

A Transport is an address-rewriting libp2p_core::Transport wrapper around an inner Transport. The composed transport behaves like the inner transport, except that libp2p_core::Transport::dial resolves /dns/..., /dns4/..., /dns6/... and /dnsaddr/... components of the given Multiaddr through a DNS, replacing them with the resolved protocols (typically TCP/IP).

The tokio::Transport is enabled by default under the tokio feature. Tokio users can furthermore opt-in to the tokio-dns-over-rustls and tokio-dns-over-https-rustls features. For more information about these features, please refer to the documentation of trust-dns-resolver. Alternative runtimes or resolvers can be used though a manual implementation of [Resolver].

On Unix systems, if no custom configuration is given, trust-dns-resolver will try to parse the /etc/resolv.conf file. This approach comes with a few caveats to be aware of:

  1. This fails (panics even!) if /etc/resolv.conf does not exist. This is the case on all versions of Android.
  2. DNS configuration is only evaluated during startup. Runtime changes are thus ignored.
  3. DNS resolution is obviously done in process and consequently not using any system APIs (like libc’s gethostbyname). Again this is problematic on platforms like Android, where there’s a lot of complexity hidden behind the system APIs.

If the implementation requires different characteristics, one should consider providing their own implementation of Transport or use platform specific APIs to extract the host’s DNS configuration (if possible) and provide a custom ResolverConfig.

Modules§

tokio

Structs§

ResolveError
The error type for errors that get returned in the crate
ResolverConfig
Configuration for the upstream nameservers to use for resolution
ResolverOpts
Configuration for the Resolver
Transport
A Transport for performing DNS lookups when dialing Multiaddresses. You shouldn’t need to use this type directly. Use tokio::Transport instead.

Enums§

Error
The possible errors of a Transport wrapped transport.
ResolveErrorKind
The error kind for errors that get returned in the crate