Basic proxy authentication for HTTPS URLs returns HTTP/1.0 407 Proxy Authentication Required

Question

I want to use a proxy with basic authentication (username, password) for a connection (and only this connection) in Java. The following code works for HTTP URLs (e.g. "http://www.google.com"):

URL url = new URL("http://www.google.com");
HttpURLConnection httpURLConnection = null;
InetSocketAddress proxyLocation = new InetSocketAddress(proxyHost, proxyPort);
Proxy proxy = new Proxy(Proxy.Type.HTTP, proxyLocation);
httpURLConnection = (HttpURLConnection) url.openConnection(proxy);
// Works for HTTP only! Doesn't work for HTTPS!
String encoded = new sun.misc.BASE64Encoder().encodeBuffer((proxyUserName + ":" + proxyPassword).getBytes()).replace("\r\n", "");
httpURLConnection.setRequestProperty("Proxy-Authorization", "Basic " + encoded);
InputStream is = httpURLConnection.getInputStream();
InputStreamReader isr = new InputStreamReader(is); 
int data = isr.read();
while(data != -1){
  char c = (char) data;
  data = isr.read();
  System.out.print(c);
}
isr.close();

The code doesn't work for HTTPS URLs (e.g. "https://www.google.com"), though! I get java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.0 407 Proxy Authentication Required" when I try to access an HTTPS URL.

This code works for HTTP and HTTPS:

URL url = new URL("https://www.google.com");
HttpURLConnection httpURLConnection = null;
InetSocketAddress proxyLocation = new InetSocketAddress(proxyHost, proxyPort);
Proxy proxy = new Proxy(Proxy.Type.HTTP, proxyLocation);
httpURLConnection = (HttpURLConnection) url.openConnection(proxy);
// Works for HTTP and HTTPS, but sets a global default!
Authenticator.setDefault(new Authenticator() {
  protected PasswordAuthentication getPasswordAuthentication() {
    return new PasswordAuthentication(proxyUserName, proxyPassword.toCharArray());
  }
});
InputStream is = httpURLConnection.getInputStream();
InputStreamReader isr = new InputStreamReader(is); 
int data = isr.read();
while(data != -1){
  char c = (char) data;
  data = isr.read();
  System.out.print(c);
}
isr.close();

The problem with the 2nd code is that it sets a new default Authenticator and I don't want to do that, because this proxy is only used by a part of the application and a different part of the application could be using a different proxy. I don't want to set a global default for the whole application. Is there a way to get the 1st code to work with HTTPS or a way to use an Authenticator without setting it as default?

I have to use java.net.HttpURLConnection, because I'm overriding a method of a class which has to return an HttpURLConnection, so I can't use Apache HttpClient.

Answer 1

You can extend ProxiedHttpsConnection and handle all the low level related stuff by yourself.

The following steps need to be done to make a connection over a HTTP proxy to a https website:

Note: the communication with the proxy and http server should be in ASCII7.

1. Send CONNECT stackoverflow.com:443 HTTP/1.0\r\n to the proxy
2. Send your authentication: Proxy-Authorization: Basic c2F5WW91SGF2ZVNlZW5UaGlzSW5UaGVDb21tZW50cw==\r\n.
3. End the first request: \r\n
4. Read the response from the proxy until you see the combination "\r\n\r\n".
5. Parse the first line of the response you got from the proxy and check if it starts with HTTP/1.0 200.
6. Start a SSL session in place over the existing connection.
7. Send the start of a http request: GET /questions/3304006/persistent-httpurlconnection-in-java HTTP/1.0\r\n
8. Set the proper Host header: Host: stackoverflow.com\r\n
9. End the request to the http server: \r\n
10. Read till \r\n and parse first line as status message
11. Read till end of stream for request body

When we want to implement the HttpUrlConnection class, there are a few things we also need to consider:

• At the time the class is constructed, the class should store data for future connections, but NOT make it directly
• Any methods can be called in any order
• The closure of the OutputStream means the data transfer is done, not that the connection must finish
• Every api uses the methods in a different order
• HTTP headers are case insensitive, java maps are case sensitive.

Quickly said, there are just many pitfalls

In the class I designed, it uses boolean flags to remember if the connect method and the afterPostClosure methods are called, it also has support if getInputStream() is called before the OutputStream is closed.

This class also uses as little wrapping as possible over the streams returned by the socket, to prevent being really complex.

public class ProxiedHttpsConnection extends HttpURLConnection {

    private final String proxyHost;
    private final int proxyPort;
    private static final byte[] NEWLINE = "\r\n".getBytes();//should be "ASCII7"

    private Socket socket;
    private final Map<String, List<String>> headers = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
    private final Map<String, List<String>> sendheaders = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
    private final Map<String, List<String>> proxyheaders = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
    private final Map<String, List<String>> proxyreturnheaders = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
    private int statusCode;
    private String statusLine;
    private boolean isDoneWriting;

    public ProxiedHttpsConnection(URL url,
            String proxyHost, int proxyPort, String username, String password)
            throws IOException {
        super(url);
        socket = new Socket();
        this.proxyHost = proxyHost;
        this.proxyPort = proxyPort;
        String encoded = Base64.encode((username + ":" + password).getBytes())
                .replace("\r\n", "");
        proxyheaders.put("Proxy-Authorization", new ArrayList<>(Arrays.asList("Basic " + encoded)));
    }

    @Override
    public OutputStream getOutputStream() throws IOException {
        connect();
        afterWrite();
        return new FilterOutputStream(socket.getOutputStream()) {
            @Override
            public void write(byte[] b, int off, int len) throws IOException {
                out.write(String.valueOf(len).getBytes());
                out.write(NEWLINE);
                out.write(b, off, len);
                out.write(NEWLINE);
            }

            @Override
            public void write(byte[] b) throws IOException {
                out.write(String.valueOf(b.length).getBytes());
                out.write(NEWLINE);
                out.write(b);
                out.write(NEWLINE);
            }

            @Override
            public void write(int b) throws IOException {
                out.write(String.valueOf(1).getBytes());
                out.write(NEWLINE);
                out.write(b);
                out.write(NEWLINE);
            }

            @Override
            public void close() throws IOException {
                afterWrite();
            }

        };
    }

    private boolean afterwritten = false;

    @Override
    public InputStream getInputStream() throws IOException {
        connect();
        return socket.getInputStream();

    }

    @Override
    public void setRequestMethod(String method) throws ProtocolException {
        this.method = method;
    }

    @Override
    public void setRequestProperty(String key, String value) {
        sendheaders.put(key, new ArrayList<>(Arrays.asList(value)));
    }

    @Override
    public void addRequestProperty(String key, String value) {
        sendheaders.computeIfAbsent(key, l -> new ArrayList<>()).add(value);
    }

    @Override
    public Map<String, List<String>> getHeaderFields() {
        return headers;
    }

    @Override
    public void connect() throws IOException {
        if (connected) {
            return;
        }
        connected = true;
        socket.setSoTimeout(getReadTimeout());
        socket.connect(new InetSocketAddress(proxyHost, proxyPort), getConnectTimeout());
        StringBuilder msg = new StringBuilder();
        msg.append("CONNECT ");
        msg.append(url.getHost());
        msg.append(':');
        msg.append(url.getPort() == -1 ? 443 : url.getPort());
        msg.append(" HTTP/1.0\r\n");
        for (Map.Entry<String, List<String>> header : proxyheaders.entrySet()) {
            for (String l : header.getValue()) {
                msg.append(header.getKey()).append(": ").append(l);
                msg.append("\r\n");
            }
        }

        msg.append("Connection: close\r\n");
        msg.append("\r\n");
        byte[] bytes;
        try {
            bytes = msg.toString().getBytes("ASCII7");
        } catch (UnsupportedEncodingException ignored) {
            bytes = msg.toString().getBytes();
        }
        socket.getOutputStream().write(bytes);
        socket.getOutputStream().flush();
        byte reply[] = new byte[200];
        byte header[] = new byte[200];
        int replyLen = 0;
        int headerLen = 0;
        int newlinesSeen = 0;
        boolean headerDone = false;
        /* Done on first newline */
        InputStream in = socket.getInputStream();
        while (newlinesSeen < 2) {
            int i = in.read();
            if (i < 0) {
                throw new IOException("Unexpected EOF from remote server");
            }
            if (i == '\n') {
                if (newlinesSeen != 0) {
                    String h = new String(header, 0, headerLen);
                    String[] split = h.split(": ");
                    if (split.length != 1) {
                        proxyreturnheaders.computeIfAbsent(split[0], l -> new ArrayList<>()).add(split[1]);
                    }
                }
                headerDone = true;
                ++newlinesSeen;
                headerLen = 0;
            } else if (i != '\r') {
                newlinesSeen = 0;
                if (!headerDone && replyLen < reply.length) {
                    reply[replyLen++] = (byte) i;
                } else if (headerLen < reply.length) {
                    header[headerLen++] = (byte) i;
                }
            }
        }

        String replyStr;
        try {
            replyStr = new String(reply, 0, replyLen, "ASCII7");
        } catch (UnsupportedEncodingException ignored) {
            replyStr = new String(reply, 0, replyLen);
        }

        // Some proxies return http/1.1, some http/1.0 even we asked for 1.0
        if (!replyStr.startsWith("HTTP/1.0 200") && !replyStr.startsWith("HTTP/1.1 200")) {
            throw new IOException("Unable to tunnel. Proxy returns \"" + replyStr + "\"");
        }
        SSLSocket s = (SSLSocket) ((SSLSocketFactory) SSLSocketFactory.getDefault())
                .createSocket(socket, url.getHost(), url.getPort(), true);
        s.startHandshake();
        socket = s;
        msg.setLength(0);
        msg.append(method);
        msg.append(" ");
        msg.append(url.toExternalForm().split(String.valueOf(url.getPort()), -2)[1]);
        msg.append(" HTTP/1.0\r\n");
        for (Map.Entry<String, List<String>> h : sendheaders.entrySet()) {
            for (String l : h.getValue()) {
                msg.append(h.getKey()).append(": ").append(l);
                msg.append("\r\n");
            }
        }
        if (method.equals("POST") || method.equals("PUT")) {
            msg.append("Transfer-Encoding: Chunked\r\n");
        }
        msg.append("Host: ").append(url.getHost()).append("\r\n");
        msg.append("Connection: close\r\n");
        msg.append("\r\n");
        try {
            bytes = msg.toString().getBytes("ASCII7");
        } catch (UnsupportedEncodingException ignored) {
            bytes = msg.toString().getBytes();
        }
        socket.getOutputStream().write(bytes);
        socket.getOutputStream().flush();
    }

    private void afterWrite() throws IOException {
        if (afterwritten) {
            return;
        }
        afterwritten = true;
        socket.getOutputStream().write(String.valueOf(0).getBytes());
        socket.getOutputStream().write(NEWLINE);
        socket.getOutputStream().write(NEWLINE);
        byte reply[] = new byte[200];
        byte header[] = new byte[200];
        int replyLen = 0;
        int headerLen = 0;
        int newlinesSeen = 0;
        boolean headerDone = false;
        /* Done on first newline */
        InputStream in = socket.getInputStream();
        while (newlinesSeen < 2) {
            int i = in.read();
            if (i < 0) {
                throw new IOException("Unexpected EOF from remote server");
            }
            if (i == '\n') {
                if (headerDone) {
                    String h = new String(header, 0, headerLen);
                    String[] split = h.split(": ");
                    if (split.length != 1) {
                        headers.computeIfAbsent(split[0], l -> new ArrayList<>()).add(split[1]);
                    }
                }
                headerDone = true;
                ++newlinesSeen;
                headerLen = 0;
            } else if (i != '\r') {
                newlinesSeen = 0;
                if (!headerDone && replyLen < reply.length) {
                    reply[replyLen++] = (byte) i;
                } else if (headerLen < header.length) {
                    header[headerLen++] = (byte) i;
                }
            }
        }

        String replyStr;
        try {
            replyStr = new String(reply, 0, replyLen, "ASCII7");
        } catch (UnsupportedEncodingException ignored) {
            replyStr = new String(reply, 0, replyLen);
        }

        /* We asked for HTTP/1.0, so we should get that back */
        if ((!replyStr.startsWith("HTTP/1.0 200")) && !replyStr.startsWith("HTTP/1.1 200")) {
            throw new IOException("Server returns \"" + replyStr + "\"");
        }
    }

    @Override
    public void disconnect() {
        try {
            socket.close();
        } catch (IOException ex) {
            Logger.getLogger(ProxiedHttpsConnection.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    @Override
    public boolean usingProxy() {
        return true;
    }
}

Current bugs with the above code:

• Streams are not closed on errors during post
• Streams are not closed during errors with the initial contact with the proxy
• It doesn't support http redirects
• It doesn't support the http 1.1 things like chunked and gzip encoding, but this is no problem as we announce ourselves as a http1.0 client.

The above code can be used like:

    ProxiedHttpsConnection n = new ProxiedHttpsConnection(
            new URL("https://stackoverflow.com:443/questions/3304006/persistent-httpurlconnection-in-java"), 
            "proxy.example.com", 8080, "root", "flg83yvem#");
    n.setRequestMethod("GET");
    n.addRequestProperty("User-Agent", "Java test https://stackoverflow.com/users/1542723/ferrybig");
    //try (OutputStream out = n.getOutputStream()) {
    //  out.write("Hello?".getBytes());
    //}
    try (InputStream in = n.getInputStream()) {
        byte[] buff = new byte[1024];
        int length;
        while ((length = in.read(buff)) >= 0) {
            System.out.write(buff, 0, length);
        }
    }

If you are going to use this with a kind of proxy selector, you should check the protocol of the url to see if its http or https, if its http, don't use this class, and instead attach the header manually like:

httpURLConnection.setRequestProperty("Proxy-Authorization", "Basic " + encoded);

Why not using httpsUrlConnection.setSSLSocketFactory

While java has this method, attempts to use it will show you why it won't work, java just keeps calling the createSocket(Socket s, String host, int port, boolean autoClose) with an already open connection, making it impossible to do the proxy stuff manually.