feat(dns): resolve hostnames asynchronously

3 files changed, 97 insertions, 74 deletions

diff --git a/src/tests/cases/raw_mode.rs b/src/tests/cases/raw_mode.rs
index 3658f28..26a1801 100644
--- a/src/tests/cases/raw_mode.rs
+++ b/src/tests/cases/raw_mode.rs
@@ -1,5 +1,5 @@
 use crate::tests::fakes::{
-    create_fake_lookup_addr, create_fake_on_winch, get_interface, get_open_sockets, KeyboardEvents,
+    create_fake_dns_client, create_fake_on_winch, get_interface, get_open_sockets, KeyboardEvents,
     NetworkFrames, TestBackend,
 };
 
@@ -85,7 +85,7 @@ fn one_packet_of_traffic() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -102,7 +102,7 @@ fn one_packet_of_traffic() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -154,7 +154,7 @@ fn bi_directional_traffic() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -171,7 +171,7 @@ fn bi_directional_traffic() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -225,7 +225,7 @@ fn multiple_packets_of_traffic_from_different_connections() {
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let stdout = Arc::new(Mutex::new(Vec::new()));
     let write_to_stdout = Box::new({
         let stdout = stdout.clone();
@@ -242,7 +242,7 @@ fn multiple_packets_of_traffic_from_different_connections() {
         on_winch,
         cleanup,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         write_to_stdout,
     };
     let opts = Opt {
@@ -292,7 +292,7 @@ fn multiple_packets_of_traffic_from_single_connection() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -309,7 +309,7 @@ fn multiple_packets_of_traffic_from_single_connection() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -361,7 +361,7 @@ fn one_process_with_multiple_connections() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -378,7 +378,7 @@ fn one_process_with_multiple_connections() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -444,7 +444,7 @@ fn multiple_processes_with_multiple_connections() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -461,7 +461,7 @@ fn multiple_processes_with_multiple_connections() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -513,7 +513,7 @@ fn multiple_connections_from_remote_address() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -530,7 +530,7 @@ fn multiple_connections_from_remote_address() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -584,7 +584,7 @@ fn sustained_traffic_from_one_process() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -601,7 +601,7 @@ fn sustained_traffic_from_one_process() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -669,7 +669,7 @@ fn sustained_traffic_from_multiple_processes() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -686,7 +686,7 @@ fn sustained_traffic_from_multiple_processes() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -782,7 +782,7 @@ fn sustained_traffic_from_multiple_processes_bi_directional() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -799,7 +799,7 @@ fn sustained_traffic_from_multiple_processes_bi_directional() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -908,7 +908,7 @@ fn traffic_with_host_names() {
         IpAddr::V4("10.0.0.2".parse().unwrap()),
         String::from("i-like-cheese.com"),
     );
-    let lookup_addr = create_fake_lookup_addr(ips_to_hostnames);
+    let dns_client = create_fake_dns_client(ips_to_hostnames);
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -925,7 +925,7 @@ fn traffic_with_host_names() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1034,7 +1034,7 @@ fn no_resolve_mode() {
         IpAddr::V4("10.0.0.2".parse().unwrap()),
         String::from("i-like-cheese.com"),
     );
-    let lookup_addr = create_fake_lookup_addr(ips_to_hostnames);
+    let dns_client = None;
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let stdout = Arc::new(Mutex::new(Vec::new()));
@@ -1051,7 +1051,7 @@ fn no_resolve_mode() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
diff --git a/src/tests/cases/ui.rs b/src/tests/cases/ui.rs
index 4b81f87..f2f5374 100644
--- a/src/tests/cases/ui.rs
+++ b/src/tests/cases/ui.rs
@@ -1,6 +1,6 @@
 use crate::tests::fakes::TerminalEvent::*;
 use crate::tests::fakes::{
-    create_fake_lookup_addr, create_fake_on_winch, get_interface, get_open_sockets, KeyboardEvents,
+    create_fake_dns_client, create_fake_on_winch, get_interface, get_open_sockets, KeyboardEvents,
     NetworkFrames, TestBackend,
 };
 
@@ -71,7 +71,7 @@ fn basic_startup() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -81,7 +81,7 @@ fn basic_startup() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -130,7 +130,7 @@ fn one_packet_of_traffic() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -140,7 +140,7 @@ fn one_packet_of_traffic() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -201,7 +201,7 @@ fn bi_directional_traffic() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let write_to_stdout = Box::new({ move |_output: String| {} });
     let cleanup = Box::new(|| {});
@@ -211,7 +211,7 @@ fn bi_directional_traffic() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -274,7 +274,7 @@ fn multiple_packets_of_traffic_from_different_connections() {
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let write_to_stdout = Box::new({ move |_output: String| {} });
 
     let os_input = OsInputOutput {
@@ -284,7 +284,7 @@ fn multiple_packets_of_traffic_from_different_connections() {
         on_winch,
         cleanup,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         write_to_stdout,
     };
     let opts = Opt {
@@ -343,7 +343,7 @@ fn multiple_packets_of_traffic_from_single_connection() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -353,7 +353,7 @@ fn multiple_packets_of_traffic_from_single_connection() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -414,7 +414,7 @@ fn one_process_with_multiple_connections() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -424,7 +424,7 @@ fn one_process_with_multiple_connections() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -499,7 +499,7 @@ fn multiple_processes_with_multiple_connections() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -509,7 +509,7 @@ fn multiple_processes_with_multiple_connections() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -570,7 +570,7 @@ fn multiple_connections_from_remote_address() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -580,7 +580,7 @@ fn multiple_connections_from_remote_address() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -643,7 +643,7 @@ fn sustained_traffic_from_one_process() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -653,7 +653,7 @@ fn sustained_traffic_from_one_process() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -730,7 +730,7 @@ fn sustained_traffic_from_multiple_processes() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -740,7 +740,7 @@ fn sustained_traffic_from_multiple_processes() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -845,7 +845,7 @@ fn sustained_traffic_from_multiple_processes_bi_directional() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -855,7 +855,7 @@ fn sustained_traffic_from_multiple_processes_bi_directional() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -973,7 +973,7 @@ fn traffic_with_host_names() {
         IpAddr::V4("10.0.0.2".parse().unwrap()),
         String::from("i-like-cheese.com"),
     );
-    let lookup_addr = create_fake_lookup_addr(ips_to_hostnames);
+    let dns_client = create_fake_dns_client(ips_to_hostnames);
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -983,7 +983,7 @@ fn traffic_with_host_names() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1101,7 +1101,7 @@ fn no_resolve_mode() {
         IpAddr::V4("10.0.0.2".parse().unwrap()),
         String::from("i-like-cheese.com"),
     );
-    let lookup_addr = create_fake_lookup_addr(ips_to_hostnames);
+    let dns_client = None;
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1111,7 +1111,7 @@ fn no_resolve_mode() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1163,7 +1163,7 @@ fn traffic_with_winch_event() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(true);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1173,7 +1173,7 @@ fn traffic_with_winch_event() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1249,7 +1249,7 @@ fn layout_full_width_under_30_height() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1259,7 +1259,7 @@ fn layout_full_width_under_30_height() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1334,7 +1334,7 @@ fn layout_under_150_width_full_height() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1344,7 +1344,7 @@ fn layout_under_150_width_full_height() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1419,7 +1419,7 @@ fn layout_under_150_width_under_30_height() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1429,7 +1429,7 @@ fn layout_under_150_width_under_30_height() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1504,7 +1504,7 @@ fn layout_under_120_width_full_height() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1514,7 +1514,7 @@ fn layout_under_120_width_full_height() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
@@ -1589,7 +1589,7 @@ fn layout_under_120_width_under_30_height() {
         terminal_height,
     );
     let network_interface = get_interface();
-    let lookup_addr = create_fake_lookup_addr(HashMap::new());
+    let dns_client = create_fake_dns_client(HashMap::new());
     let on_winch = create_fake_on_winch(false);
     let cleanup = Box::new(|| {});
     let write_to_stdout = Box::new({ move |_output: String| {} });
@@ -1599,7 +1599,7 @@ fn layout_under_120_width_under_30_height() {
         network_frames,
         get_open_sockets,
         keyboard_events,
-        lookup_addr,
+        dns_client,
         on_winch,
         cleanup,
         write_to_stdout,
diff --git a/src/tests/fakes/fake_input.rs b/src/tests/fakes/fake_input.rs
index d11d974..454924e 100644
--- a/src/tests/fakes/fake_input.rs
+++ b/src/tests/fakes/fake_input.rs
@@ -1,12 +1,19 @@
+use ::async_trait::async_trait;
 use ::ipnetwork::IpNetwork;
 use ::pnet::datalink::DataLinkReceiver;
 use ::pnet::datalink::NetworkInterface;
 use ::std::collections::HashMap;
+use ::std::future::Future;
 use ::std::net::{IpAddr, Ipv4Addr, SocketAddr};
+use ::std::pin::Pin;
+use ::std::task::{Context, Poll};
 use ::std::{thread, time};
 use ::termion::event::Event;
 
-use crate::network::{Connection, Protocol};
+use crate::network::{
+    dns::{self, Lookup},
+    Connection, Protocol,
+};
 
 pub struct KeyboardEvents {
     pub events: Vec<Option<Event>>,
@@ -135,15 +142,6 @@ pub fn get_interface() -> NetworkInterface {
     }
 }
 
-pub fn create_fake_lookup_addr(
-    ips_to_hosts: HashMap<IpAddr, String>,
-) -> Box<dyn Fn(&IpAddr) -> Option<String> + Send> {
-    Box::new(move |ip| match ips_to_hosts.get(ip) {
-        Some(host) => Some(host.clone()),
-        None => None,
-    })
-}
-
 pub fn create_fake_on_winch(should_send_winch_event: bool) -> Box<dyn Fn(Box<dyn Fn()>) + Send> {
     Box::new(move |cb| {
         if should_send_winch_event {
@@ -152,3 +150,28 @@ pub fn create_fake_on_winch(should_send_winch_event: bool) -> Box<dyn Fn(Box<dyn
         }
     })
 }
+
+pub fn create_fake_dns_client(ips_to_hosts: HashMap<IpAddr, String>) -> Option<dns::Client> {
+    let dns_client = dns::Client::new(FakeResolver(ips_to_hosts), FakeBackground {}).unwrap();
+    Some(dns_client)
+}
+
+struct FakeResolver(HashMap<IpAddr, String>);
+
+#[async_trait]
+impl Lookup for FakeResolver {
+    async fn lookup(&self, ip: Ipv4Addr) -> Option<String> {
+        let ip = IpAddr::from(ip);
+        self.0.get(&ip).map(|host| host.clone())
+    }
+}
+
+struct FakeBackground {}
+
+impl Future for FakeBackground {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+        Poll::Ready(())
+    }
+}