read specific size of data from boost asio udp socket

I want to read specific number of bytes from udp socket. In tcp socket I can use socket.read where I can specify the amount of data to receive. I don't find similar function for UDP socke开发者_运维问答t. I am using receive_from() where I can specify the amount of data to read, but if there is more data then no data is read and I get following error.

"A message sent on a datagram socket was larger than the internal message buffer or some other network limit, or the buffer used to receive a datagram into was smaller than the datagram itself"   std::basic_string<char,std::char_traits<char>,std::allocator<char> >

I am not able to find what value do I need to give for message_flags (3rd arg to receive_from) so that it will read the number of bytes specified. Currenly I am using the following code to read data but it either reads all data or no data.

        size_t size=socket.receive_from(boost::asio::buffer((const void*)&discRsp,sizeof(DataStructure)),remote_endpoint,0,errors);

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Try this:

socket.set_option(boost::asio::socket_base::receive_buffer_size(65536));