forked from seanmonstar/reqwest
/
dns.rs
104 lines (86 loc) · 2.99 KB
/
dns.rs
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use std::future::Future;
use std::io;
use std::net::SocketAddr;
use std::pin::Pin;
use std::sync::Arc;
use std::task::{self, Poll};
use hyper::client::connect::dns as hyper_dns;
use hyper::service::Service;
use once_cell::sync::Lazy;
use tokio::sync::Mutex;
use trust_dns_resolver::{
config::{ResolverConfig, ResolverOpts},
lookup_ip::LookupIpIntoIter,
system_conf, AsyncResolver, TokioConnection, TokioConnectionProvider, TokioHandle,
};
use crate::error::BoxError;
type SharedResolver = Arc<AsyncResolver<TokioConnection, TokioConnectionProvider>>;
static SYSTEM_CONF: Lazy<io::Result<(ResolverConfig, ResolverOpts)>> =
Lazy::new(|| system_conf::read_system_conf().map_err(io::Error::from));
#[derive(Clone)]
pub(crate) struct TrustDnsResolver {
state: Arc<Mutex<State>>,
}
pub(crate) struct SocketAddrs {
iter: LookupIpIntoIter,
}
enum State {
Init,
Ready(SharedResolver),
}
impl TrustDnsResolver {
pub(crate) fn new() -> io::Result<Self> {
SYSTEM_CONF.as_ref().map_err(|e| {
io::Error::new(e.kind(), format!("error reading DNS system conf: {}", e))
})?;
// At this stage, we might not have been called in the context of a
// Tokio Runtime, so we must delay the actual construction of the
// resolver.
Ok(TrustDnsResolver {
state: Arc::new(Mutex::new(State::Init)),
})
}
}
impl Service<hyper_dns::Name> for TrustDnsResolver {
type Response = SocketAddrs;
type Error = BoxError;
type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
fn poll_ready(&mut self, _: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
Poll::Ready(Ok(()))
}
fn call(&mut self, name: hyper_dns::Name) -> Self::Future {
let resolver = self.clone();
Box::pin(async move {
let mut lock = resolver.state.lock().await;
let resolver = match &*lock {
State::Init => {
let resolver = new_resolver().await?;
*lock = State::Ready(resolver.clone());
resolver
}
State::Ready(resolver) => resolver.clone(),
};
// Don't keep lock once the resolver is constructed, otherwise
// only one lookup could be done at a time.
drop(lock);
let lookup = resolver.lookup_ip(name.as_str()).await?;
Ok(SocketAddrs {
iter: lookup.into_iter(),
})
})
}
}
impl Iterator for SocketAddrs {
type Item = SocketAddr;
fn next(&mut self) -> Option<Self::Item> {
self.iter.next().map(|ip_addr| SocketAddr::new(ip_addr, 0))
}
}
async fn new_resolver() -> Result<SharedResolver, BoxError> {
let (config, opts) = SYSTEM_CONF
.as_ref()
.expect("can't construct TrustDnsResolver if SYSTEM_CONF is error")
.clone();
let resolver = AsyncResolver::new(config, opts, TokioHandle)?;
Ok(Arc::new(resolver))
}