HTTP代理检测HTTP客户端断开连接

Question

I'm new to HTTP, and developing an applicative proxy. I want to avoid defining timeouts for operations, and instead rely on the the client to close the connection. I'm wondering if this is possible?

here's a very dumbed down pseudo code

void handle_request(Request http_request, Response http_response)
{
   string modified_request = parse(http_request);
   response_from_server = remote_server->send_request(modified_request);
   while(true) {
     if(response_from_server ->wait_for_data(1000 /* milliseconds */)) {
       http_response->write_data(response_from_server->read_data());
       continue;
     }

     if(!http_response.check_if_the_client_connection_to_me_is_still_active()) // how to do this?
         return;
     }
   }
}

another way to ask this is:

1. in an HTTP proxy, can I use the timeouts from the remote cilent and the remote server without adding yet another timeout?
2. how do I detect that either the remote server or remote client have timed-out?

incidentally, I'm developing in C++ using Poco.

Answer 1

You cannot write a serious TCP application without using timeouts. They are in some cases the only way you can detect a dropped connection while reading. TCP provides the following ways to detect a dropped connection:

1. The various EOS conditions on read.
2. 'Connection reset' on write or occasionally read.
3. Read timeout.

That's it. There aren't any more.

You should also enable TCP keepalive from your end, but that only kicks in after two hours.