refactor/feat: DnsClient as IP resolver in Client

src/client/builder.rs

@@ -7,6 +7,9 @@ use crate::{
     Client,
 };
 
+#[cfg(feature = "hickory")]
+use crate::dns::DnsClient;
+
 use tokio_rustls::rustls::{self, client::danger::ServerCertVerifier, SupportedProtocolVersion};
 
 #[cfg(feature = "webpki")]
@@ -18,6 +21,8 @@ pub struct ClientBuilder {
     ss_verifier: Option<Box<dyn SelfsignedCertVerifier>>,
     custom_verifier: Option<Arc<dyn ServerCertVerifier + 'static>>,
     tls_versions: Option<&'static [&'static SupportedProtocolVersion]>,
+    #[cfg(feature = "hickory")]
+    dns: Option<DnsClient>,
 }
 
 impl Default for ClientBuilder {
@@ -36,6 +41,8 @@ impl ClientBuilder {
             ss_verifier: None,
             custom_verifier: None,
             tls_versions: None,
+            #[cfg(feature = "hickory")]
+            dns: None,
         }
     }
 
@@ -92,6 +99,11 @@ impl ClientBuilder {
         // TODO
         let tls_config = tls_config.with_no_client_auth();
 
+        #[cfg(feature = "hickory")]
+        if let Some(dns) = self.dns {
+            return Client::from((tls_config, dns));
+        }
+
         Client::from(tls_config)
     }
 
@@ -149,4 +161,10 @@ impl ClientBuilder {
         self.custom_verifier = Some(Arc::new(custom_verifier));
         self
     }
+
+    #[cfg(feature = "hickory")]
+    pub fn with_dns_client(mut self, dns: DnsClient) -> Self {
+        self.dns = Some(dns);
+        self
+    }
 }

src/client/mod.rs

@@ -5,9 +5,18 @@ pub mod response;
 
 pub use response::Response;
 
+#[cfg(feature = "hickory")]
+use crate::dns::DnsClient;
+
+#[cfg(feature = "hickory")]
+use hickory_client::rr::IntoName;
+
 use crate::{error::*, status::*};
 use builder::ClientBuilder;
 
+#[cfg(feature = "hickory")]
+use std::net::SocketAddr;
+
 use std::sync::Arc;
 
 use tokio::{
@@ -22,6 +31,8 @@ use url::Url;
 
 pub struct Client {
     connector: TlsConnector,
+    #[cfg(feature = "hickory")]
+    dns: Option<DnsClient>,
 }
 
 impl From<rustls::ClientConfig> for Client {
@@ -30,6 +41,19 @@ impl From<rustls::ClientConfig> for Client {
     fn from(config: rustls::ClientConfig) -> Self {
         Client {
             connector: TlsConnector::from(Arc::new(config)),
+            #[cfg(feature = "hickory")]
+            dns: None,
+        }
+    }
+}
+
+#[cfg(feature = "hickory")]
+impl From<(rustls::ClientConfig, DnsClient)> for Client {
+    #[inline]
+    fn from(value: (rustls::ClientConfig, DnsClient)) -> Self {
+        Client {
+            connector: TlsConnector::from(Arc::new(value.0)),
+            dns: Some(value.1),
         }
     }
 }
@@ -93,16 +117,11 @@ impl Client {
         host: &str,
         port: u16,
     ) -> Result<Response, LibError> {
-        let addr = tokio::net::lookup_host((host, port))
-            .await?
-            .next()
-            .ok_or(InvalidUrl::ConvertError)?;
-
         let domain = pki_types::ServerName::try_from(host)
             .map_err(|_| InvalidUrl::ConvertError)?
             .to_owned();
 
-        let stream = TcpStream::connect(&addr).await?;
+        let stream = self.try_connect(host, port).await?;
         let mut stream = self.connector.connect(domain, stream).await?;
 
         // Write URL, then CRLF
@@ -150,4 +169,59 @@ impl Client {
 
         Ok(Response::new(status, message, stream))
     }
+
+    pub async fn try_connect(&self, host: &str, port: u16) -> Result<TcpStream, LibError> {
+        let mut last_err: Option<std::io::Error> = None;
+
+        #[cfg(feature = "hickory")]
+        if let Some(dns) = &self.dns {
+            let mut dns = dns.clone();
+            let name = host.into_name()?;
+
+            for ip_addr in dns.query_ipv4(name.clone()).await? {
+                match TcpStream::connect(SocketAddr::new(ip_addr, port)).await {
+                    Ok(stream) => {
+                        return Ok(stream);
+                    }
+                    Err(err) => {
+                        last_err = Some(err);
+                    }
+                }
+            }
+
+            for ip_addr in dns.query_ipv6(name).await? {
+                match TcpStream::connect(SocketAddr::new(ip_addr, port)).await {
+                    Ok(stream) => {
+                        return Ok(stream);
+                    }
+                    Err(err) => {
+                        last_err = Some(err);
+                    }
+                }
+            }
+
+            if let Some(err) = last_err {
+                return Err(err.into());
+            }
+
+            return Err(LibError::HostLookupError);
+        }
+
+        for addr in tokio::net::lookup_host((host, port)).await? {
+            match TcpStream::connect(addr).await {
+                Ok(stream) => {
+                    return Ok(stream);
+                }
+                Err(err) => {
+                    last_err = Some(err);
+                }
+            }
+        }
+
+        if let Some(err) = last_err {
+            return Err(err.into());
+        }
+
+        Err(LibError::HostLookupError)
+    }
 }

src/dns.rs

@@ -13,6 +13,7 @@ use tokio::net::ToSocketAddrs;
 
 use crate::{certs::fingerprint::CertFingerprint, LibError};
 
+#[derive(Clone)]
 pub struct DnsClient(AsyncClient);
 
 impl DnsClient {
@@ -34,14 +35,14 @@ impl DnsClient {
 
     pub async fn query_ipv4(
         &mut self,
-        name: &str,
+        name: impl IntoName,
     ) -> Result<impl Iterator<Item = IpAddr>, LibError> {
         self.query_ip(name, RecordType::A).await
     }
 
     pub async fn query_ipv6(
         &mut self,
-        name: &str,
+        name: impl IntoName,
     ) -> Result<impl Iterator<Item = IpAddr>, LibError> {
         self.query_ip(name, RecordType::AAAA).await
     }
@@ -49,7 +50,7 @@ impl DnsClient {
     #[inline]
     async fn query_ip(
         &mut self,
-        name: &str,
+        name: impl IntoName,
         rtype: RecordType,
     ) -> Result<impl Iterator<Item = IpAddr>, LibError> {
         let answers = self