Struct hickory_resolver::AsyncResolver

pub struct AsyncResolver<P: ConnectionProvider> { /* private fields */ }

An asynchronous resolver for DNS generic over async Runtimes.

Creating a AsyncResolver returns a new handle and a future that should be spawned on an executor to drive the background work. The lookup methods on AsyncResolver request lookups from the background task.

The futures returned by a AsyncResolver and the corresponding background task need not be spawned on the same executor, or be in the same thread. Additionally, one background task may have any number of handles; calling clone() on a handle will create a new handle linked to the same background task.

NOTE If lookup futures returned by a AsyncResolver and the background future are spawned on two separate CurrentThread executors, one thread cannot run both executors simultaneously, so the run or block_on functions will cause the thread to deadlock. If both the background work and the lookup futures are intended to be run on the same thread, they should be spawned on the same executor.

The background task manages the name server pool and other state used to drive lookups. When this future is spawned on an executor, it will first construct and configure the necessary client state, before checking for any incoming lookup requests, handling them, and yielding. It will continue to do so as long as there are still any AsyncResolver handle linked to it. When all of its AsyncResolvers have been dropped, the background future will finish.

Implementations

impl AsyncResolver<GenericConnector<TokioRuntimeProvider>>

pub fn tokio(config: ResolverConfig, options: ResolverOpts) -> Self

Available on crate feature tokio-runtime only.

Construct a new Tokio based AsyncResolver with the provided configuration.

Arguments

• config - configuration, name_servers, etc. for the Resolver
• options - basic lookup options for the resolver

Returns

A tuple containing the new AsyncResolver and a future that drives the background task that runs resolutions for the AsyncResolver. See the documentation for AsyncResolver for more information on how to use the background future.

pub fn tokio_from_system_conf() -> Result<Self, ResolveError>

Available on crate feature system-config and (Unix or Windows) and crate feature tokio-runtime only.

Constructs a new Tokio based Resolver with the system configuration.

This will use /etc/resolv.conf on Unix OSes and the registry on Windows.

impl<R: ConnectionProvider> AsyncResolver<R>

pub fn new(config: ResolverConfig, options: ResolverOpts, provider: R) -> Self

Construct a new generic AsyncResolver with the provided configuration.

see [TokioAsyncResolver::tokio(..)] instead.

Arguments

• config - configuration, name_servers, etc. for the Resolver
• options - basic lookup options for the resolver

Returns

A tuple containing the new AsyncResolver and a future that drives the background task that runs resolutions for the AsyncResolver. See the documentation for AsyncResolver for more information on how to use the background future.

pub fn from_system_conf(runtime: R) -> Result<Self, ResolveError>

Available on crate feature system-config and (Unix or Windows) only.

Constructs a new Resolver with the system configuration.

see [TokioAsyncResolver::tokio_from_system_conf(..)] instead.

This will use /etc/resolv.conf on Unix OSes and the registry on Windows.

pub fn clear_cache(&self)

Flushes/Removes all entries from the cache

pub fn config(&self) -> &ResolverConfig

Read the config for this resolver.

pub fn options(&self) -> &ResolverOpts

Read the options for this resolver.

impl<P: ConnectionProvider> AsyncResolver<P>

pub fn new_with_conn( config: ResolverConfig, options: ResolverOpts, conn_provider: P, ) -> Self

Construct a new AsyncResolver with the provided configuration.

Arguments

• config - configuration, name_servers, etc. for the Resolver
• options - basic lookup options for the resolver

Returns

A tuple containing the new AsyncResolver and a future that drives the background task that runs resolutions for the AsyncResolver. See the documentation for AsyncResolver for more information on how to use the background future.

pub fn from_system_conf_with_provider( conn_provider: P, ) -> Result<Self, ResolveError>

Available on crate feature system-config and (Unix or Windows) only.

Constructs a new Resolver with the system configuration.

This will use /etc/resolv.conf on Unix OSes and the registry on Windows.

pub async fn lookup<N: IntoName>( &self, name: N, record_type: RecordType, ) -> Result<Lookup, ResolveError>

Generic lookup for any RecordType

WARNING this interface may change in the future, see if one of the specializations would be better.

Arguments

• name - name of the record to lookup, if name is not a valid domain name, an error will be returned
• record_type - type of record to lookup, all RecordData responses will be filtered to this type

Returns

pub async fn lookup_ip<N: IntoName + TryParseIp>( &self, host: N, ) -> Result<LookupIp, ResolveError>

Performs a dual-stack DNS lookup for the IP for the given hostname.

See the configuration and options parameters for controlling the way in which A(Ipv4) and AAAA(Ipv6) lookups will be performed. For the least expensive query a fully-qualified-domain-name, FQDN, which ends in a final ., e.g. www.example.com., will only issue one query. Anything else will always incur the cost of querying the ResolverConfig::domain and ResolverConfig::search.

Arguments

• host - string hostname, if this is an invalid hostname, an error will be returned.

pub fn set_hosts(&mut self, hosts: Option<Hosts>)

Customizes the static hosts used in this resolver.

pub async fn reverse_lookup( &self, query: IpAddr, ) -> Result<ReverseLookup, ResolveError>

Performs a lookup for the associated type.

Arguments

• query - a type which can be converted to Name via From.

pub async fn ipv4_lookup<N: IntoName>( &self, query: N, ) -> Result<Ipv4Lookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn ipv6_lookup<N: IntoName>( &self, query: N, ) -> Result<Ipv6Lookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn mx_lookup<N: IntoName>( &self, query: N, ) -> Result<MxLookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn ns_lookup<N: IntoName>( &self, query: N, ) -> Result<NsLookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn soa_lookup<N: IntoName>( &self, query: N, ) -> Result<SoaLookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn srv_lookup<N: IntoName>( &self, query: N, ) -> Result<SrvLookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn tlsa_lookup<N: IntoName>( &self, query: N, ) -> Result<TlsaLookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

pub async fn txt_lookup<N: IntoName>( &self, query: N, ) -> Result<TxtLookup, ResolveError>

Performs a lookup for the associated type.

hint queries that end with a ‘.’ are fully qualified names and are cheaper lookups

Arguments

• query - a string which parses to a domain name, failure to parse will return an error

Trait Implementations

impl<P: Clone + ConnectionProvider> Clone for AsyncResolver<P>

fn clone(&self) -> AsyncResolver<P>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<P: ConnectionProvider> Debug for AsyncResolver<P>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.