From ca351ecf7ee062f531cb27357bd8d4f2d64d6c55 Mon Sep 17 00:00:00 2001
From: Christian Ebner <c.ebner@proxmox.com>
Date: Wed, 9 Apr 2025 13:05:15 +0200
Subject: [PATCH] http: client: make https connector generic over resolver

Allow to instantiate a `HttpsConnector` not using the default
`getaddrinfo` based `GaiResolver` for domain name resolution, but
rather a custom resolver implementing the required traits.

The usecase for this is to swap out the DNS resolver for the
statically linked proxmox-backup-client binary, where the glibc
dependency is problematic because of possible ABI incompatibility.

However, set the generic type on `HttpsConnector` to default to
`GaiResolver` to limit inconvenience for implementations using it.

Adds tower-service as cargo workspace dependency and build dependency
to debian/control.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
---
 proxmox-http/Cargo.toml              |  1 +
 proxmox-http/src/client/connector.rs | 17 ++++++++++++-----
 proxmox-http/src/client/simple.rs    |  3 ++-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/proxmox-http/Cargo.toml b/proxmox-http/Cargo.toml
index c8c963f7..6bfb1413 100644
--- a/proxmox-http/Cargo.toml
+++ b/proxmox-http/Cargo.toml
@@ -22,6 +22,7 @@ openssl =  { version = "0.10", optional = true }
 serde_json = { workspace = true, optional = true }
 tokio = { workspace = true, features = [], optional = true }
 tokio-openssl = { workspace = true, optional = true }
+tower-service.workspace = true
 ureq = { version = "2.4", features = ["native-certs", "native-tls"], optional = true, default-features = false }
 url = { workspace = true, optional = true }
 
diff --git a/proxmox-http/src/client/connector.rs b/proxmox-http/src/client/connector.rs
index 63b9d10c..2e04680f 100644
--- a/proxmox-http/src/client/connector.rs
+++ b/proxmox-http/src/client/connector.rs
@@ -6,6 +6,7 @@ use std::task::{Context, Poll};
 
 use futures::*;
 use http::Uri;
+use hyper::client::connect::dns::{GaiResolver, Name};
 use hyper::client::HttpConnector;
 use openssl::ssl::SslConnector;
 use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
@@ -23,8 +24,8 @@ use crate::{RateLimitedStream, ShareableRateLimit};
 type SharedRateLimit = Arc<dyn ShareableRateLimit>;
 
 #[derive(Clone)]
-pub struct HttpsConnector {
-    connector: HttpConnector,
+pub struct HttpsConnector<T = GaiResolver> {
+    connector: HttpConnector<T>,
     ssl_connector: Arc<SslConnector>,
     proxy: Option<ProxyConfig>,
     tcp_keepalive: u32,
@@ -32,9 +33,9 @@ pub struct HttpsConnector {
     write_limiter: Option<SharedRateLimit>,
 }
 
-impl HttpsConnector {
+impl<T> HttpsConnector<T> {
     pub fn with_connector(
-        mut connector: HttpConnector,
+        mut connector: HttpConnector<T>,
         ssl_connector: SslConnector,
         tcp_keepalive: u32,
     ) -> Self {
@@ -122,7 +123,13 @@ impl HttpsConnector {
     }
 }
 
-impl hyper::service::Service<Uri> for HttpsConnector {
+impl<T> hyper::service::Service<Uri> for HttpsConnector<T>
+where
+    T: tower_service::Service<Name> + Clone + Send + Sync + 'static,
+    T::Future: Send,
+    T::Error: Into<Box<(dyn std::error::Error + Send + Sync + 'static)>>,
+    T::Response: std::iter::Iterator<Item = std::net::SocketAddr>,
+{
     type Response = MaybeTlsStream<RateLimitedStream<TcpStream>>;
     type Error = Error;
     #[allow(clippy::type_complexity)]
diff --git a/proxmox-http/src/client/simple.rs b/proxmox-http/src/client/simple.rs
index 062889ac..cb8bb777 100644
--- a/proxmox-http/src/client/simple.rs
+++ b/proxmox-http/src/client/simple.rs
@@ -8,6 +8,7 @@ use futures::*;
 #[cfg(all(feature = "client-trait", feature = "proxmox-async"))]
 use http::header::HeaderName;
 use http::{HeaderValue, Request, Response};
+use hyper::client::connect::dns::GaiResolver;
 use hyper::client::Client as HyperClient;
 use hyper::client::HttpConnector;
 use hyper::Body;
@@ -18,7 +19,7 @@ use crate::HttpOptions;
 
 /// Asynchronous HTTP client implementation
 pub struct Client {
-    client: HyperClient<HttpsConnector, Body>,
+    client: HyperClient<HttpsConnector<GaiResolver>, Body>,
     options: HttpOptions,
 }