6370908: Add support for HTTP_CONNECT proxy in Socket class

[Damjan Jovanovic]

On Mon, Feb 22, 2010 at 5:02 PM, Christopher Hegarty - Sun
Microsystems Ireland <Christopher.Hegarty at sun.com> wrote:
> Hi Damjan,
>
> Actually, I did some work on this back in 2006 (!), but never finished it. I
> brought the changes into a mercurial repository and created a webrev:
>
>  http://cr.openjdk.java.net/~chegar/6370908/webrev.00/webrev/
>
> Basically, this change provides the basic functionality, without any frills,
> authentication, etc. I think for tunneling sockets through a HTTP proxy it
> should be sufficient. Do you require authentication in your environment?
>
> To have authentication supported we would need to restructure the HTTP
> protocol handler in sun.net.www.protocol.http.HttpURLConnection, so that we
> can take advantage of the authentication schemes it already supports. Not a
> big deal, just needs to be done.

The major problem with authentication is that there is no guarantee
the HTTP connection will be persistent. Authentication generally
requires making additional requests to the proxy, so we may need to
connect to the proxy more than once. Each socket can only connect
once, and the HttpConnectSocketImpl is a single immutable socket, so
it cannot directly be used for authentication.

A workaround may be to connect with a different socket for the initial
request, and then connect through the HttpConnectSocketImpl's own
socket for the final request. But then the problem becomes that if the
proxy doesn't require authentication, the initial socket will succeed
in connecting to the target host, and it will be too late to stop it
and use HttpConnectSocketImpl's own socket...

So we have the following options:
1. Only support proxies for which the entire request chain can be made
over a single persistent connection.
2. Connect to each target host up to twice, once when we believe the
proxy needs authentication but doesn't, and then again later with the
real socket. This will probably kill protocols that use one shot
connections, like FTP.
3. Find some way to change socket identities, then use as many sockets
as it takes and somehow adopt the final socket into
HttpConnectSocketImpl's own.

Any suggestions?

> -Chris.

Damjan

> On 21/02/2010 13:09, Damjan Jovanovic wrote:
>>
>> Hi
>>
>>> From http://bugs.sun.com/view_bug.do?bug_id=6370908
>>
>> This RFE is basically about getting a TCP socket to tunnel through an
>> HTTP proxy using the HTTP CONNECT request.
>>
>> I've found a hack to get this feature to work, using sun.net.*
>> packages and lots of reflection. Would it be acceptable to use this
>> solution (with some way to change socket identity) in a patch that
>> adds a java.net.HttpSocketImpl class similar to the
>> java.net.SocksSocketImpl class that's already used to tunnel through
>> SOCKS proxies? If not, in what other way should such a patch be done?
>>
>> Thank you
>> Damjan Jovanovic
>>
>> import java.net.*;
>> import java.io.*;
>> import java.lang.reflect.*;
>>
>> public class TunnelProxy {
>>        private static Socket connectThroughHTTPProxy(String proxyHost, int
>> proxyPort, String destinationHost, int destinationPort) throws
>> Exception
>>        {
>>                URL destinationURL = new URL("http://" + destinationHost +
>> ":" +
>> destinationPort);
>>                sun.net.www.protocol.http.HttpURLConnection conn =
>>                        new sun.net.www.protocol.http.HttpURLConnection(
>>                                destinationURL, new
>> java.net.Proxy(java.net.Proxy.Type.HTTP, new
>> InetSocketAddress(proxyHost, proxyPort)));
>>                conn.setDoInput(true);
>>                conn.setDoOutput(true);
>>                conn.connect();
>>                conn.doTunneling();
>>                Field httpField = conn.getClass().getDeclaredField("http");
>>                httpField.setAccessible(true);
>>                sun.net.www.http.HttpClient httpClient =
>> (sun.net.www.http.HttpClient) httpField.get(conn);
>>                Field serverSocketField =
>> sun.net.NetworkClient.class.getDeclaredField("serverSocket");
>>                serverSocketField.setAccessible(true);
>>                Socket socket = (Socket) serverSocketField.get(httpClient);
>>                return socket;
>>        }
>>
>>        public static void main(String[] args) throws Exception {
>>                System.setProperty("java.net.useSystemProxies", "true");
>>                InputStream in = connectThroughHTTPProxy(args[0],
>> Integer.parseInt(args[1]), args[2],
>> Integer.parseInt(args[3])).getInputStream();
>>                byte[] bytes = new byte[1024];
>>                int bytesRead;
>>                while ((bytesRead = in.read(bytes)) != -1) {
>>                        System.out.print(new String(bytes));
>>                }
>>        }
>> }
>