RequestServer: Implement preconnect for CreateConnection cache level

This uses the share mechanism in curl to cache connection and DNS information. The multi handle already does some caching, but in order to use that, we would also need to construct an `ActiveRequest` here. That isn't necessary, and we gain some explicitness+flexibility this way :^)
rmg-x · Nov 2, 2024 · cef3009 · cef3009
1 parent bd41902
commit cef3009
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Showing 2 changed files with 46 additions and 3 deletions.
diff --git a/Userland/Services/RequestServer/ConnectionFromClient.cpp b/Userland/Services/RequestServer/ConnectionFromClient.cpp
@@ -21,8 +21,10 @@
 namespace RequestServer {
 
 ByteString g_default_certificate_path;
+
 static HashMap<int, RefPtr<ConnectionFromClient>> s_connections;
 static IDAllocator s_client_ids;
+static long s_connect_timeout_seconds = 90L;
 
 struct ConnectionFromClient::ActiveRequest {
     CURLM* multi { nullptr };
@@ -199,6 +201,10 @@ ConnectionFromClient::ConnectionFromClient(IPC::Transport transport)
     s_connections.set(client_id(), *this);
 
     m_curl_multi = curl_multi_init();
+    m_curl_share = curl_share_init();
+
+    curl_share_setopt(m_curl_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_CONNECT);
+    curl_share_setopt(m_curl_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_DNS);
 
     auto set_option = [this](auto option, auto value) {
         auto result = curl_multi_setopt(m_curl_multi, option, value);
@@ -305,7 +311,8 @@ void ConnectionFromClient::start_request(i32 request_id, ByteString const& metho
     set_option(CURLOPT_ACCEPT_ENCODING, "gzip, deflate, br");
     set_option(CURLOPT_URL, url.to_string().value().to_byte_string().characters());
     set_option(CURLOPT_PORT, url.port_or_default());
-    set_option(CURLOPT_CONNECTTIMEOUT, 90L);
+    set_option(CURLOPT_CONNECTTIMEOUT, s_connect_timeout_seconds);
+    set_option(CURLOPT_SHARE, m_curl_share);
 
     if (method == "GET"sv) {
         set_option(CURLOPT_HTTPGET, 1L);
@@ -440,8 +447,38 @@ void ConnectionFromClient::ensure_connection(URL::URL const& url, ::RequestServe
         return;
     }
 
-    (void)cache_level;
-    dbgln("FIXME: EnsureConnection: Pre-connect to {}", url);
+    auto const url_string_value = url.to_string().value();
+
+    if (cache_level == CacheLevel::CreateConnection) {
+        auto* easy = curl_easy_init();
+        if (!easy) {
+            dbgln("EnsureConnection: Failed to initialize curl easy handle");
+            return;
+        }
+
+        auto set_option = [easy](auto option, auto value) {
+            auto result = curl_easy_setopt(easy, option, value);
+            if (result != CURLE_OK) {
+                dbgln("EnsureConnection: Failed to set curl option: {}", curl_easy_strerror(result));
+                return false;
+            }
+            return true;
+        };
+
+        set_option(CURLOPT_URL, url_string_value.to_byte_string().characters());
+        set_option(CURLOPT_PORT, url.port_or_default());
+        set_option(CURLOPT_CONNECTTIMEOUT, s_connect_timeout_seconds);
+        set_option(CURLOPT_CONNECT_ONLY, 1L);
+        set_option(CURLOPT_SHARE, m_curl_share);
+
+        curl_easy_perform(easy);
+        curl_easy_cleanup(easy);
+        return;
+    }
+
+    if (cache_level == CacheLevel::ResolveOnly) {
+        dbgln("FIXME: EnsureConnection: Implement ResolveOnly cache level");
+    }
 }
 
 void ConnectionFromClient::websocket_connect(i64 websocket_id, URL::URL const& url, ByteString const& origin, Vector<ByteString> const& protocols, Vector<ByteString> const& extensions, HTTP::HeaderMap const& additional_request_headers)

diff --git a/Userland/Services/RequestServer/ConnectionFromClient.h b/Userland/Services/RequestServer/ConnectionFromClient.h
@@ -58,6 +58,12 @@ class ConnectionFromClient final
 
     void check_active_requests();
     void* m_curl_multi { nullptr };
+
+    // NOTE: m_curl_multi already caches some information about DNS and connections,
+    //       but using a share is more explicit and allows us flexibility when making "connect only" requests.
+    //       See https://everything.curl.dev/helpers/sharing.html and https://everything.curl.dev/internals/caches.html
+    void* m_curl_share { nullptr };
+
     RefPtr<Core::Timer> m_timer;
     HashMap<int, NonnullRefPtr<Core::Notifier>> m_read_notifiers;
     HashMap<int, NonnullRefPtr<Core::Notifier>> m_write_notifiers;