Struct ResolverOpts

#[non_exhaustive]
pub struct ResolverOpts {

    pub ndots: usize,
    pub timeout: Duration,
    pub attempts: usize,
    pub rotate: bool,
    pub check_names: bool,
    pub edns0: bool,
    pub validate: bool,
    pub ip_strategy: LookupIpStrategy,
    pub cache_size: usize,
    pub use_hosts_file: ResolveHosts,
    pub positive_min_ttl: Option<Duration>,
    pub negative_min_ttl: Option<Duration>,
    pub positive_max_ttl: Option<Duration>,
    pub negative_max_ttl: Option<Duration>,
    pub num_concurrent_reqs: usize,
    pub preserve_intermediates: bool,
    pub try_tcp_on_error: bool,
    pub server_ordering_strategy: ServerOrderingStrategy,
    pub recursion_desired: bool,
    pub authentic_data: bool,
    pub shuffle_dns_servers: bool,
    pub avoid_local_udp_ports: Arc<HashSet<u16>>,
}

Available on crate feature dns only.

Configuration for the Resolver

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

ndots: usize

Sets the number of dots that must appear (unless it’s a final dot representing the root) before a query is assumed to include the TLD. The default is one, which means that www would never be assumed to be a TLD, and would always be appended to either the search

timeout: Duration

Specify the timeout for a request. Defaults to 5 seconds

attempts: usize

Number of retries after lookup failure before giving up. Defaults to 2

rotate: bool

Rotate through the resource records in the response (if there is more than one for a given name)

check_names: bool

Validate the names in the response, not implemented don’t really see the point unless you need to support badly configured DNS

edns0: bool

Enable edns, for larger records

validate: bool

Use DNSSEC to validate the request

ip_strategy: LookupIpStrategy

The ip_strategy for the Resolver to use when lookup Ipv4 or Ipv6 addresses

cache_size: usize

Cache size is in number of records (some records can be large)

use_hosts_file: ResolveHosts

Check /etc/hosts file before dns requery (only works for unix like OS)

positive_min_ttl: Option<Duration>

Optional minimum TTL for positive responses.

If this is set, any positive responses with a TTL lower than this value will have a TTL of positive_min_ttl instead. Otherwise, this will default to 0 seconds.

negative_min_ttl: Option<Duration>

Optional minimum TTL for negative (NXDOMAIN) responses.

If this is set, any negative responses with a TTL lower than this value will have a TTL of negative_min_ttl instead. Otherwise, this will default to 0 seconds.

positive_max_ttl: Option<Duration>

Optional maximum TTL for positive responses.

If this is set, any positive responses with a TTL higher than this value will have a TTL of positive_max_ttl instead. Otherwise, this will default to MAX_TTL seconds.

negative_max_ttl: Option<Duration>

Optional maximum TTL for negative (NXDOMAIN) responses.

If this is set, any negative responses with a TTL higher than this value will have a TTL of negative_max_ttl instead. Otherwise, this will default to MAX_TTL seconds.

num_concurrent_reqs: usize

Number of concurrent requests per query

Where more than one nameserver is configured, this configures the resolver to send queries to a number of servers in parallel. Defaults to 2; 0 or 1 will execute requests serially.

preserve_intermediates: bool

Preserve all intermediate records in the lookup response, such as CNAME records

try_tcp_on_error: bool

Try queries over TCP if they fail over UDP.

server_ordering_strategy: ServerOrderingStrategy

The server ordering strategy that the resolver should use.

recursion_desired: bool

Request upstream recursive resolvers to not perform any recursion.

This is true by default, disabling this is useful for requesting single records, but may prevent successful resolution.

authentic_data: bool

This is true by default, disabling this is useful for requesting single records, but may prevent successful resolution.

shuffle_dns_servers: bool

Shuffle DNS servers before each query.

avoid_local_udp_ports: Arc<HashSet<u16>>

Local UDP ports to avoid when making outgoing queries

Trait Implementations

impl Clone for ResolverOpts

fn clone(&self) -> ResolverOpts

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ResolverOpts

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

Formats the value using the given formatter.

impl Default for ResolverOpts

fn default() -> ResolverOpts

Default values for the Resolver configuration.

This follows the resolv.conf defaults as defined in the Linux man pages