core: add and implement socket_interface::connect()

include/ftp/detail/socket_base.hpp

@@ -26,6 +26,7 @@
 #define LIBFTP_SOCKET_BASE_HPP
 
 #include <ftp/detail/socket_interface.hpp>
+#include <boost/asio/connect.hpp>
 
 namespace ftp::detail
 {
@@ -34,6 +35,32 @@ template<typename SocketType>
 class socket_base : public socket_interface
 {
 public:
+    void connect(std::string_view hostname, std::uint16_t port, boost::system::error_code & ec) override
+    {
+        SocketType & socket = get_sock();
+
+        boost::asio::ip::tcp::resolver resolver(socket.get_executor());
+        boost::asio::ip::tcp::resolver::results_type endpoints =
+            resolver.resolve(hostname, std::to_string(port), ec);
+
+        if (ec)
+            return;
+
+        boost::asio::connect(socket, endpoints, ec);
+
+        if (ec)
+        {
+            boost::system::error_code ignored;
+
+            /* If the connect fails, and the socket was automatically opened,
+             * the socket is not returned to the closed state.
+             *
+             * https://www.boost.org/doc/libs/1_70_0/doc/html/boost_asio/reference/basic_stream_socket/connect/overload2.html
+             */
+            socket.close(ignored);
+        }
+    }
+
     SocketType & get_socket() override
     {
         return get_sock();

include/ftp/detail/socket_interface.hpp

@@ -35,6 +35,8 @@ namespace ftp::detail
 class socket_interface
 {
 public:
+    virtual void connect(std::string_view hostname, std::uint16_t port, boost::system::error_code & ec) = 0;
+
     // TODO: Remove.
     virtual boost::asio::ip::tcp::socket & get_socket() = 0;
 

src/control_connection.cpp

@@ -26,7 +26,6 @@
 #include <ftp/detail/control_connection.hpp>
 #include <ftp/detail/socket_factory.hpp>
 #include <ftp/detail/utils.hpp>
-#include <boost/asio/connect.hpp>
 #include <boost/asio/read_until.hpp>
 #include <boost/asio/write.hpp>
 
@@ -50,31 +49,12 @@ control_connection::control_connection(net_context & net_context)
 
 void control_connection::connect(std::string_view hostname, std::uint16_t port)
 {
-    boost::asio::ip::tcp::socket & socket = socket_ptr_->get_socket();
-    boost::asio::ip::tcp::resolver resolver(socket.get_executor());
     boost::system::error_code ec;
 
-    boost::asio::ip::tcp::resolver::results_type endpoints =
-            resolver.resolve(hostname, std::to_string(port), ec);
-
-    if (ec)
-    {
-        throw ftp_exception(ec, "Cannot open control connection");
-    }
-
-    boost::asio::connect(socket, endpoints, ec);
+    socket_ptr_->connect(hostname, port, ec);
 
     if (ec)
     {
-        boost::system::error_code ignored;
-
-        /* If the connect fails, and the socket was automatically opened,
-         * the socket is not returned to the closed state.
-         *
-         * https://www.boost.org/doc/libs/1_70_0/doc/html/boost_asio/reference/basic_stream_socket/connect/overload2.html
-         */
-        socket.close(ignored);
-
         throw ftp_exception(ec, "Cannot open control connection");
     }
 }