shutdown vs. close in the socket

I was using the boost asio in windows XP to develop a simple proxy. The proxy will relay the traffic between the browser and the upstream server. Every time when some data is received from the server side, the  boost c++ asio async_write , will be used to send all the response to the client socket, and then it will try to read more from the server side socket. If the server side closes the connection, the client side should already flush out the http response received, so it would be safe to close the client side socket.

However, this did not work sometimes, for example, http://sourceforge.net/projects/tailforwin32/ works for firefox but does not work for IE8. Even if the log shows that all data has been written to client socket, the page just cannot be displayed.

The IE8 may detect the connection close before read all the data in the wire: when using step debug, the IE8 can handle it properly. The idea is to shutdown both read and write of the client socket instead of close it, so that the IE8 can read the data and detect the socket is closing. Here is a good article on socket close vs. shutdown. The close will close the socket id for the process, but other process may still use it, and it is still open for read and write. The shutdown will close the read/write pipe for all process. Any read/write will result in EOF.