commit 7b0a61e30021fc3d85375507c0f06e8dfc2bc8fb
author Christopher Kohlhoff <chris@kohlhoff.com> Wed Sep 14 09:21:31 2016 +1000
committer Christopher Kohlhoff <chris@kohlhoff.com> Fri Sep 16 07:57:56 2016 +1000
tree b2d353edcc495af1ce84fd76cb0f4180b150f3d3
parent a2e070a79eedae07bf6e7357c1428f98078d4993

Defer assigning accepted socket until immediately before handler.

Fixes a problem in the reactor-based async_accept, if the
basic_socket::assign() operation throws due to an out-of-memory
condition.

asio/include/asio/detail/reactive_socket_accept_op.hpp

diff --git a/asio/include/asio/detail/reactive_socket_accept_op.hpp b/asio/include/asio/detail/reactive_socket_accept_op.hpp
index 2a6fe75..11b81d5 100644
--- a/asio/include/asio/detail/reactive_socket_accept_op.hpp
+++ b/asio/include/asio/detail/reactive_socket_accept_op.hpp
@@ -41,7 +41,8 @@
       state_(state),
       peer_(peer),
       protocol_(protocol),
-      peer_endpoint_(peer_endpoint)
+      peer_endpoint_(peer_endpoint),
+      addrlen_(peer_endpoint ? peer_endpoint->capacity() : 0)
   {
   }
 
@@ -50,34 +51,38 @@
     reactive_socket_accept_op_base* o(
         static_cast<reactive_socket_accept_op_base*>(base));
 
-    std::size_t addrlen = o->peer_endpoint_ ? o->peer_endpoint_->capacity() : 0;
     socket_type new_socket = invalid_socket;
     status result = socket_ops::non_blocking_accept(o->socket_,
         o->state_, o->peer_endpoint_ ? o->peer_endpoint_->data() : 0,
-        o->peer_endpoint_ ? &addrlen : 0, o->ec_, new_socket) ? done : not_done;
+        o->peer_endpoint_ ? &o->addrlen_ : 0, o->ec_, new_socket)
+    ? done : not_done;
+    o->new_socket_.reset(new_socket);
 
     ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_accept", o->ec_));
 
-    // On success, assign new connection to peer socket object.
-    if (new_socket != invalid_socket)
-    {
-      socket_holder new_socket_holder(new_socket);
-      if (o->peer_endpoint_)
-        o->peer_endpoint_->resize(addrlen);
-      o->peer_.assign(o->protocol_, new_socket, o->ec_);
-      if (!o->ec_)
-        new_socket_holder.release();
-    }
-
     return result;
   }
 
+  void do_assign()
+  {
+    if (new_socket_.get() != invalid_socket)
+    {
+      if (peer_endpoint_)
+        peer_endpoint_->resize(addrlen_);
+      peer_.assign(protocol_, new_socket_.get(), ec_);
+      if (!ec_)
+        new_socket_.release();
+    }
+  }
+
 private:
   socket_type socket_;
   socket_ops::state_type state_;
+  socket_holder new_socket_;
   Socket& peer_;
   Protocol protocol_;
   typename Protocol::endpoint* peer_endpoint_;
+  std::size_t addrlen_;
 };
 
 template <typename Socket, typename Protocol, typename Handler>
@@ -106,6 +111,10 @@
     ptr p = { asio::detail::addressof(o->handler_), o, o };
     handler_work<Handler> w(o->handler_);
 
+    // On success, assign new connection to peer socket object.
+    if (owner)
+      o->do_assign();
+
     ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
@@ -165,6 +174,10 @@
     ptr p = { asio::detail::addressof(o->handler_), o, o };
     handler_work<Handler> w(o->handler_);
 
+    // On success, assign new connection to peer socket object.
+    if (owner)
+      o->do_assign();
+
     ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before

asio/src/examples/cpp11/http/server/server.cpp

diff --git a/asio/src/examples/cpp11/http/server/server.cpp b/asio/src/examples/cpp11/http/server/server.cpp
index 123866c..fa76a4d 100644
--- a/asio/src/examples/cpp11/http/server/server.cpp
+++ b/asio/src/examples/cpp11/http/server/server.cpp
@@ -17,7 +17,7 @@
 
 server::server(const std::string& address, const std::string& port,
     const std::string& doc_root)
-  : io_context_(),
+  : io_context_(1),
     signals_(io_context_),
     acceptor_(io_context_),
     connection_manager_(),