Enforce outbound policy at each HTTP connection

crates/remora-outbound/src/resolver.rs

@@ -0,0 +1,25 @@
+use std::{future::Future, io, net::IpAddr};
+
+pub trait Resolver: Send + Sync {
+    fn resolve(
+        &self,
+        host: &str,
+        port: u16,
+    ) -> impl Future<Output = io::Result<Vec<IpAddr>>> + Send;
+}
+
+#[derive(Clone, Copy, Debug, Default)]
+pub struct SystemResolver;
+
+impl Resolver for SystemResolver {
+    async fn resolve(&self, host: &str, port: u16) -> io::Result<Vec<IpAddr>> {
+        let addresses = tokio::net::lookup_host((host, port)).await?;
+        let mut unique = Vec::new();
+        for address in addresses {
+            if !unique.contains(&address.ip()) {
+                unique.push(address.ip());
+            }
+        }
+        Ok(unique)
+    }
+}