One socket, multiple HTTP request, another host header, but the server returns the cached host header

Question

I use my own servlet engine for the vendor product. Our server has different proxies with different host names. Assuming host1.localhost.com and host2.localhost.com .

We have the following servlet

 public class MyServlet { public void doGet(...) { response.getOutputStream.write(request.getServerName().getBytes()) } } 

We encountered a problem that several times, if we make a request to host1.localhost.com/my/servlet , we see that we actually see host2.localhost.com/my/servlet in the response.

Decompiling the vendor product code showed that their servlet engine caches the host header while the socket is alive.

In an attempt to reproduce the problem, I wrote some low-level socket code to make HTTP requests:

 Socket s = new Socket(); s.connect(new InetSocketAddress("host2.localhost.com", 8080)); OutputStream os = s.getOutputStream(); /*this thread keeps printing stuff in the input stream*/ Thread t = new ResponsePrintThread(s.getInputStream()); t.start() os.write("GET /my/servlet/testservlet HTTP/1.1\r\n".getBytes()); os.write("Host: 12345\r\n".getBytes()); os.write("\r\n".getBytes()); os.flush(); os.write("GET /my/serlet/testservlet HTTP/1.1\r\n".getBytes()); os.write("Host: 7891011\r\n".getBytes()); os.write("\r\n".getBytes()); os.flush(); 

The above text will print

 12345 12345 

But I would expect

 12345 7891011 

My question is, does the servlet engine work properly by caching and returning the same host header for the same socket connection, or should it reanalyze the HTTP headers and update the header of the cached host? My thinking is that since HTTP was supposed to be stagnant, so any information in the HTTP request needs to be re-parsed and reloaded, even the host header.

Answer 1

HTTP is a bit vague about how connections are made between the client and server:

http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-22#section-6.2

This specification does not describe how connections are established through various transport or session protocol layers.

I see nothing wrong if the client uses the same persistent connection for two hostnames that resolve the same IP address. This should not cause any server side problems.