RequestServer: Avoid using gethostbyname

Replace gethostbyname with Core::Socket::resolve_host in
RequestServer::ConnectionFromClient::ensure_connection.

Resolved #22199.

Userland/Libraries/LibCore/Socket.h

@@ -20,6 +20,16 @@ namespace Core {
 /// classes. Sockets are non-seekable streams which can be read byte-wise.
 class Socket : public Stream {
 public:
+    enum class PreventSIGPIPE {
+        No,
+        Yes,
+    };
+
+    enum class SocketType {
+        Stream,
+        Datagram,
+    };
+
     Socket(Socket&&) = default;
     Socket& operator=(Socket&&) = default;
 
@@ -46,12 +56,11 @@ public:
     /// Conversely, set_notifications_enabled(true) will re-enable notifications.
     virtual void set_notifications_enabled(bool) { }
 
-    Function<void()> on_ready_to_read;
+    // FIXME: This will need to be updated when IPv6 socket arrives. Perhaps a
+    //        base class for all address types is appropriate.
+    static ErrorOr<IPv4Address> resolve_host(ByteString const&, SocketType);
 
-    enum class PreventSIGPIPE {
+    Function<void()> on_ready_to_read;
-        No,
-        Yes,
-    };
 
 protected:
     enum class SocketDomain {
@@ -59,20 +68,12 @@ protected:
         Inet,
     };
 
-    enum class SocketType {
-        Stream,
-        Datagram,
-    };
-
     Socket(PreventSIGPIPE prevent_sigpipe = PreventSIGPIPE::No)
         : m_prevent_sigpipe(prevent_sigpipe == PreventSIGPIPE::Yes)
     {
     }
 
     static ErrorOr<int> create_fd(SocketDomain, SocketType);
-    // FIXME: This will need to be updated when IPv6 socket arrives. Perhaps a
-    //        base class for all address types is appropriate.
-    static ErrorOr<IPv4Address> resolve_host(ByteString const&, SocketType);
 
     static ErrorOr<void> connect_local(int fd, ByteString const& path);
     static ErrorOr<void> connect_inet(int fd, SocketAddress const&);

Userland/Services/RequestServer/ConnectionFromClient.cpp

@@ -9,6 +9,7 @@
 #include <AK/RefCounted.h>
 #include <AK/Weakable.h>
 #include <LibCore/Proxy.h>
+#include <LibCore/Socket.h>
 #include <RequestServer/ConnectionFromClient.h>
 #include <RequestServer/Protocol.h>
 #include <RequestServer/Request.h>
@@ -159,7 +160,9 @@ void ConnectionFromClient::ensure_connection(URL const& url, ::RequestServer::Ca
     if (cache_level == CacheLevel::ResolveOnly) {
         return Core::deferred_invoke([host = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string()] {
             dbgln("EnsureConnection: DNS-preload for {}", host);
-            (void)gethostbyname(host.characters());
+            auto resolved_host = Core::Socket::resolve_host(host, Core::Socket::SocketType::Stream);
+            if (resolved_host.is_error())
+                dbgln("EnsureConnection: DNS-preload failed for {}", host);
         });
     }