fix(dns): unify provider resolution and bound SMTP and tunnel egress

Share provider DNS policy across WebSocket and connection probes, handle bracketed IPv6 literals, and preserve bounded address sets for outbound clients.

Bound SMTP DNS and TCP setup with multi-address fallback. Add opt-in trusted proxy DNS for tunnel upstreams while retaining default IP ACLs and origin isolation.

Document DNS policy boundaries and verify 809 gateway, tunnel, and HTTP regression tests.

apps/aether-gateway/src/bark_push.rs

@@ -23,7 +23,6 @@ const MAX_BARK_TEMPLATE_BYTES: usize = 256 * 1024;
 const MAX_BARK_TITLE_BYTES: usize = 512;
 const MAX_BARK_BODY_BYTES: usize = 2 * 1024 * 1024;
 const MAX_BARK_RENDERED_BODY_BYTES: usize = 2 * 1024 * 1024;
-const MAX_BARK_RESOLVED_ADDRESSES: usize = 32;
 
 #[derive(Clone)]
 pub(crate) struct BarkPushConfig {
@@ -208,19 +207,20 @@ async fn build_bark_push_client_and_url(
     let port = push_url
         .port_or_known_default()
         .ok_or_else(|| GatewayError::Internal("Bark 服务器地址缺少端口".to_string()))?;
-    let addresses = if let Ok(ip) = host.parse::<IpAddr>() {
-        vec![SocketAddr::new(ip, port)]
-    } else {
-        tokio::time::timeout(
-            std::time::Duration::from_millis(BARK_CONNECT_TIMEOUT_MS),
-            tokio::net::lookup_host((host.as_str(), port)),
-        )
-        .await
-        .map_err(|_| GatewayError::Internal("Bark 服务器 DNS 解析超时".to_string()))?
-        .map_err(|_| GatewayError::Internal("Bark 服务器 DNS 解析失败".to_string()))?
-        .take(MAX_BARK_RESOLVED_ADDRESSES)
-        .collect::<Vec<_>>()
-    };
+    let addresses = aether_http::lookup_host_with_limits(
+        host.as_str(),
+        port,
+        std::time::Duration::from_millis(BARK_CONNECT_TIMEOUT_MS),
+    )
+    .await
+    .map_err(|error| {
+        let message = match error.kind() {
+            std::io::ErrorKind::TimedOut => "Bark 服务器 DNS 解析超时",
+            std::io::ErrorKind::InvalidData => "Bark 服务器 DNS 解析返回过多地址",
+            _ => "Bark 服务器 DNS 解析失败",
+        };
+        GatewayError::Internal(message.to_string())
+    })?;
     let allow_benchmarking_ip = push_url.scheme() == "https"
         && push_url.port_or_known_default() == Some(443)
         && host.eq_ignore_ascii_case("api.day.app");