Use ConnectEx where available.

N.B. This change conservatively limits the use of ConnectEx to
connection-oriented IP sockets.

asio/include/asio/detail/impl/socket_ops.ipp

@@ -520,6 +520,22 @@ void sync_connect(socket_type s, const socket_addr_type* addr,
       asio::error::get_system_category());
 }
 
+#if defined(ASIO_HAS_IOCP)
+
+void complete_iocp_connect(socket_type s, asio::error_code& ec)
+{
+  if (!ec)
+  {
+    // Need to set the SO_UPDATE_CONNECT_CONTEXT option so that getsockname
+    // and getpeername will work on the connected socket.
+    socket_ops::state_type state = 0;
+    socket_ops::setsockopt(s, state, SOL_SOCKET,
+        SO_UPDATE_CONNECT_CONTEXT, 0, 0, ec);
+  }
+}
+
+#endif // defined(ASIO_HAS_IOCP)
+
 bool non_blocking_connect(socket_type s, asio::error_code& ec)
 {
   // Check if the connect operation has finished. This is required since we may

asio/include/asio/detail/impl/win_iocp_socket_service_base.ipp

@@ -31,6 +31,7 @@ win_iocp_socket_service_base::win_iocp_socket_service_base(
   : io_service_(io_service),
     iocp_service_(use_service<win_iocp_io_service>(io_service)),
     reactor_(0),
+    connect_ex_(0),
     mutex_(),
     impl_list_(0)
 {
@@ -544,8 +545,51 @@ void win_iocp_socket_service_base::start_reactor_op(
 
 void win_iocp_socket_service_base::start_connect_op(
     win_iocp_socket_service_base::base_implementation_type& impl,
-    reactor_op* op, const socket_addr_type* addr, std::size_t addrlen)
+    int family, int type, const socket_addr_type* addr,
+    std::size_t addrlen, win_iocp_socket_connect_op_base* op)
 {
+  // If ConnectEx is available, use that.
+  if (family == ASIO_OS_DEF(AF_INET)
+      || family == ASIO_OS_DEF(AF_INET6))
+  {
+    if (connect_ex_fn connect_ex = get_connect_ex(impl, type))
+    {
+      union address_union
+      {
+        socket_addr_type base;
+        sockaddr_in4_type v4;
+        sockaddr_in6_type v6;
+      } a;
+
+      using namespace std; // For memset.
+      memset(&a, 0, sizeof(a));
+      a.base.sa_family = family;
+
+      socket_ops::bind(impl.socket_, &a.base,
+          family == ASIO_OS_DEF(AF_INET)
+          ? sizeof(a.v4) : sizeof(a.v6), op->ec_);
+      if (op->ec_ && op->ec_ != asio::error::invalid_argument)
+      {
+        iocp_service_.post_immediate_completion(op, false);
+        return;
+      }
+
+      op->connect_ex_ = true;
+      update_cancellation_thread_id(impl);
+      iocp_service_.work_started();
+
+      BOOL result = connect_ex(impl.socket_,
+          addr, static_cast<int>(addrlen), 0, 0, 0, op);
+      DWORD last_error = ::WSAGetLastError();
+      if (!result && last_error != WSA_IO_PENDING)
+        iocp_service_.on_completion(op, last_error);
+      else
+        iocp_service_.on_pending(op);
+      return;
+    }
+  }
+
+  // Otherwise, fall back to a reactor-based implementation.
   reactor& r = get_reactor();
   update_cancellation_thread_id(impl);
 
@@ -622,6 +666,35 @@ reactor& win_iocp_socket_service_base::get_reactor()
   return *r;
 }
 
+win_iocp_socket_service_base::connect_ex_fn
+win_iocp_socket_service_base::get_connect_ex(
+    win_iocp_socket_service_base::base_implementation_type& impl, int type)
+{
+  if (type != ASIO_OS_DEF(SOCK_STREAM)
+      && type != ASIO_OS_DEF(SOCK_SEQPACKET))
+    return 0;
+
+  void* ptr = interlocked_compare_exchange_pointer(&connect_ex_, 0, 0);
+  if (!ptr)
+  {
+    GUID guid = { 0x25a207b9, 0xddf3, 0x4660,
+      { 0x8e, 0xe9, 0x76, 0xe5, 0x8c, 0x74, 0x06, 0x3e } };
+
+    DWORD bytes = 0;
+    if (::WSAIoctl(impl.socket_, SIO_GET_EXTENSION_FUNCTION_POINTER,
+          &guid, sizeof(guid), &ptr, sizeof(ptr), &bytes, 0, 0) != 0)
+    {
+      // Set connect_ex_ to a special value to indicate that ConnectEx is
+      // unavailable. That way we won't bother trying to look it up again.
+      ptr = this;
+    }
+
+    interlocked_exchange_pointer(&connect_ex_, ptr);
+  }
+
+  return reinterpret_cast<connect_ex_fn>(ptr == this ? 0 : ptr);
+}
+
 void* win_iocp_socket_service_base::interlocked_compare_exchange_pointer(
     void** dest, void* exch, void* cmp)
 {

asio/include/asio/detail/socket_ops.hpp

@@ -107,6 +107,13 @@ ASIO_DECL int connect(socket_type s, const socket_addr_type* addr,
 ASIO_DECL void sync_connect(socket_type s, const socket_addr_type* addr,
     std::size_t addrlen, asio::error_code& ec);
 
+#if defined(ASIO_HAS_IOCP)
+
+ASIO_DECL void complete_iocp_connect(socket_type s,
+    asio::error_code& ec);
+
+#endif // defined(ASIO_HAS_IOCP)
+
 ASIO_DECL bool non_blocking_connect(socket_type s,
     asio::error_code& ec);
 

asio/include/asio/detail/win_iocp_socket_connect_op.hpp

@@ -0,0 +1,123 @@
+//
+// detail/win_iocp_socket_connect_op.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2014 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ASIO_DETAIL_WIN_IOCP_SOCKET_CONNECT_OP_HPP
+#define ASIO_DETAIL_WIN_IOCP_SOCKET_CONNECT_OP_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+
+#if defined(ASIO_HAS_IOCP)
+
+#include "asio/detail/addressof.hpp"
+#include "asio/detail/bind_handler.hpp"
+#include "asio/detail/fenced_block.hpp"
+#include "asio/detail/handler_alloc_helpers.hpp"
+#include "asio/detail/handler_invoke_helpers.hpp"
+#include "asio/detail/reactor_op.hpp"
+#include "asio/detail/socket_ops.hpp"
+#include "asio/error.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+class win_iocp_socket_connect_op_base : public reactor_op
+{
+public:
+  win_iocp_socket_connect_op_base(socket_type socket, func_type complete_func)
+    : reactor_op(&win_iocp_socket_connect_op_base::do_perform, complete_func),
+      socket_(socket),
+      connect_ex_(false)
+  {
+  }
+
+  static bool do_perform(reactor_op* base)
+  {
+    win_iocp_socket_connect_op_base* o(
+        static_cast<win_iocp_socket_connect_op_base*>(base));
+
+    return socket_ops::non_blocking_connect(o->socket_, o->ec_);
+  }
+
+  socket_type socket_;
+  bool connect_ex_;
+};
+
+template <typename Handler>
+class win_iocp_socket_connect_op : public win_iocp_socket_connect_op_base
+{
+public:
+  ASIO_DEFINE_HANDLER_PTR(win_iocp_socket_connect_op);
+
+  win_iocp_socket_connect_op(socket_type socket, Handler& handler)
+    : win_iocp_socket_connect_op_base(socket,
+        &win_iocp_socket_connect_op::do_complete),
+      handler_(ASIO_MOVE_CAST(Handler)(handler))
+  {
+  }
+
+  static void do_complete(io_service_impl* owner, operation* base,
+      const asio::error_code& result_ec,
+      std::size_t /*bytes_transferred*/)
+  {
+    asio::error_code ec(result_ec);
+
+    // Take ownership of the operation object.
+    win_iocp_socket_connect_op* o(static_cast<win_iocp_socket_connect_op*>(base));
+    ptr p = { asio::detail::addressof(o->handler_), o, o };
+
+    if (owner)
+    {
+      if (o->connect_ex_)
+        socket_ops::complete_iocp_connect(o->socket_, ec);
+      else
+        ec = o->ec_;
+    }
+
+    ASIO_HANDLER_COMPLETION((o));
+
+    // Make a copy of the handler so that the memory can be deallocated before
+    // the upcall is made. Even if we're not about to make an upcall, a
+    // sub-object of the handler may be the true owner of the memory associated
+    // with the handler. Consequently, a local copy of the handler is required
+    // to ensure that any owning sub-object remains valid until after we have
+    // deallocated the memory here.
+    detail::binder1<Handler, asio::error_code>
+      handler(o->handler_, ec);
+    p.h = asio::detail::addressof(handler.handler_);
+    p.reset();
+
+    // Make the upcall if required.
+    if (owner)
+    {
+      fenced_block b(fenced_block::half);
+      ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
+      asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      ASIO_HANDLER_INVOCATION_END;
+    }
+  }
+
+private:
+  Handler handler_;
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // defined(ASIO_HAS_IOCP)
+
+#endif // ASIO_DETAIL_WIN_IOCP_SOCKET_CONNECT_OP_HPP

asio/include/asio/detail/win_iocp_socket_service.hpp

@@ -31,7 +31,6 @@
 #include "asio/detail/handler_invoke_helpers.hpp"
 #include "asio/detail/mutex.hpp"
 #include "asio/detail/operation.hpp"
-#include "asio/detail/reactive_socket_connect_op.hpp"
 #include "asio/detail/reactor.hpp"
 #include "asio/detail/reactor_op.hpp"
 #include "asio/detail/socket_holder.hpp"
@@ -40,6 +39,7 @@
 #include "asio/detail/win_iocp_io_service.hpp"
 #include "asio/detail/win_iocp_null_buffers_op.hpp"
 #include "asio/detail/win_iocp_socket_accept_op.hpp"
+#include "asio/detail/win_iocp_socket_connect_op.hpp"
 #include "asio/detail/win_iocp_socket_recvfrom_op.hpp"
 #include "asio/detail/win_iocp_socket_send_op.hpp"
 #include "asio/detail/win_iocp_socket_service_base.hpp"
@@ -501,7 +501,7 @@ public:
       const endpoint_type& peer_endpoint, Handler& handler)
   {
     // Allocate and construct an operation to wrap the handler.
-    typedef reactive_socket_connect_op<Handler> op;
+    typedef win_iocp_socket_connect_op<Handler> op;
     typename op::ptr p = { asio::detail::addressof(handler),
       asio_handler_alloc_helpers::allocate(
         sizeof(op), handler), 0 };
@@ -509,8 +509,8 @@ public:
 
     ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_connect"));
 
-    start_connect_op(impl, p.p, peer_endpoint.data(),
-        static_cast<int>(peer_endpoint.size()));
+    start_connect_op(impl, impl.protocol_.family(), impl.protocol_.type(),
+        peer_endpoint.data(), static_cast<int>(peer_endpoint.size()), p.p);
     p.v = p.p = 0;
   }
 };

asio/include/asio/detail/win_iocp_socket_service_base.hpp

@@ -37,6 +37,7 @@
 #include "asio/detail/socket_types.hpp"
 #include "asio/detail/win_iocp_io_service.hpp"
 #include "asio/detail/win_iocp_null_buffers_op.hpp"
+#include "asio/detail/win_iocp_socket_connect_op.hpp"
 #include "asio/detail/win_iocp_socket_send_op.hpp"
 #include "asio/detail/win_iocp_socket_recv_op.hpp"
 #include "asio/detail/win_iocp_socket_recvmsg_op.hpp"
@@ -450,7 +451,8 @@ protected:
 
   // Start the asynchronous connect operation using the reactor.
   ASIO_DECL void start_connect_op(base_implementation_type& impl,
-      reactor_op* op, const socket_addr_type* addr, std::size_t addrlen);
+      int family, int type, const socket_addr_type* remote_addr,
+      std::size_t remote_addrlen, win_iocp_socket_connect_op_base* op);
 
   // Helper function to close a socket when the associated object is being
   // destroyed.
@@ -465,6 +467,16 @@ protected:
   // this service.
   ASIO_DECL reactor& get_reactor();
 
+  // The type of a ConnectEx function pointer, as old SDKs may not provide it.
+  typedef BOOL (PASCAL *connect_ex_fn)(SOCKET,
+      const socket_addr_type*, int, void*, DWORD, DWORD*, OVERLAPPED*);
+
+  // Helper function to get the ConnectEx pointer. If no ConnectEx pointer has
+  // been obtained yet, one is obtained using WSAIoctl and the pointer is
+  // cached. Returns a null pointer if ConnectEx is not available.
+  ASIO_DECL connect_ex_fn get_connect_ex(
+      base_implementation_type& impl, int type);
+
   // Helper function to emulate InterlockedCompareExchangePointer functionality
   // for:
   // - very old Platform SDKs; and
@@ -488,6 +500,9 @@ protected:
   // only if needed.
   reactor* reactor_;
 
+  // Pointer to ConnectEx implementation.
+  void* connect_ex_;
+
   // Mutex to protect access to the linked list of implementations. 
   asio::detail::mutex mutex_;