// Copyright 2004 Adam Megacz, see the COPYING file for licensing [GPL]
package org.xwt;

import java.net.*;
import java.io.*;
import java.util.*;
import org.xwt.js.*;
import org.xwt.util.*;
import org.bouncycastle.util.encoders.Base64;
import org.bouncycastle.crypto.digests.*;

/**
 *  This object encapsulates a *single* HTTP connection. Multiple requests may be pipelined over a connection (thread-safe),
 *  although any IOException encountered in a request will invalidate all later requests.
 */
public class HTTP {


    // Public Methods ////////////////////////////////////////////////////////////////////////////////////////

    public HTTP(String url) { this(url, false); }
    public HTTP(String url, boolean skipResolveCheck) { originalUrl = url; this.skipResolveCheck = skipResolveCheck; }

    /** Performs an HTTP GET request */
    public InputStream GET() throws IOException { return makeRequest(null, null); }

    /** Performs an HTTP POST request; content is additional headers, blank line, and body */
    public InputStream POST(String contentType, String content) throws IOException { return makeRequest(contentType, content); }

    public static class HTTPException extends IOException { public HTTPException(String s) { super(s); } }


    // Statics ///////////////////////////////////////////////////////////////////////////////////////////////

    static Hash resolvedHosts = new Hash();            ///< cache for resolveAndCheckIfFirewalled()
    private static Hash authCache = new Hash();        ///< cache of userInfo strings, keyed on originalUrl


    // Instance Data ///////////////////////////////////////////////////////////////////////////////////////////////

    final String originalUrl;              ///< the URL as passed to the original constructor; this is never changed
    URL url = null;                        ///< the URL to connect to; this is munged when the url is parsed */
    String host = null;                    ///< the host to connect to
    int port = -1;                         ///< the port to connect on
    boolean ssl = false;                   ///< true if SSL (HTTPS) should be used
    String path = null;                    ///< the path (URI) to retrieve on the server
    Socket sock = null;                    ///< the socket
    InputStream in = null;                 ///< the socket's inputstream
    String userInfo = null;                ///< the username and password portions of the URL
    boolean firstRequest = true;           ///< true iff this is the first request to be made on this socket
    boolean skipResolveCheck = false;      ///< allowed to skip the resolve check when downloading PAC script
    boolean proxied = false;               ///< true iff we're using a proxy

    /** this is null if the current request is the first request on
     *  this HTTP connection; otherwise it is a Semaphore which will be
     *  released once the request ahead of us has recieved its response
     */
    Semaphore okToRecieve = null;

    /**
     *  This method isn't synchronized; however, only one thread can be in the inner synchronized block at a time, and the rest of
     *  the method is protected by in-order one-at-a-time semaphore lock-steps
     */
    private InputStream makeRequest(String contentType, String content) throws IOException {

        // Step 1: send the request and establish a semaphore to stop any requests that pipeline after us
        Semaphore blockOn = null;
        Semaphore releaseMe = null;
        synchronized(this) {
            try {
                connect();
                sendRequest(contentType, content);
            } catch (IOException e) {
                reset();
                throw e;
            }
            blockOn = okToRecieve;
            releaseMe = okToRecieve = new Semaphore();
        }
        
        // Step 2: wait for requests ahead of us to complete, then read the reply off the stream
        boolean doRelease = true;
        try {
            if (blockOn != null) blockOn.block();
            
            // previous call wrecked the socket connection, but we already sent our request, so we can't just retry --
            // this could cause the server to receive the request twice, which could be bad (think of the case where the
            // server call causes Amazon.com to ship you an item with one-click purchasing).
            if (sock == null)
                throw new HTTPException("a previous pipelined call messed up the socket");
            
            Hashtable h = in == null ? null : parseHeaders(in);
            if (h == null) {
                if (firstRequest) throw new HTTPException("server closed the socket with no response");
                // sometimes the server chooses to close the stream between requests
                reset();
                releaseMe.release();
                return makeRequest(contentType, content);
            }

            String reply = h.get("STATUSLINE").toString();
            
            if (reply.startsWith("407") || reply.startsWith("401")) {
                
                if (reply.startsWith("407")) doProxyAuth(h, content == null ? "GET" : "POST");
                else doWebAuth(h, content == null ? "GET" : "POST");
                
                if (h.get("HTTP").equals("1.0") && h.get("content-length") == null) {
                    if (Log.on) Log.info(this, "proxy returned an HTTP/1.0 reply with no content-length...");
                    reset();
                } else {
                    int cl = h.get("content-length") == null ? -1 : Integer.parseInt(h.get("content-length").toString());
                    new HTTPInputStream(in, cl, releaseMe).close();
                }
                releaseMe.release();
                return makeRequest(contentType, content);
                
            } else if (reply.startsWith("2")) {
                if (h.get("HTTP").equals("1.0") && h.get("content-length") == null)
                    throw new HTTPException("XWT does not support HTTP/1.0 servers which fail to return the Content-Length header");
                int cl = h.get("content-length") == null ? -1 : Integer.parseInt(h.get("content-length").toString());
                InputStream ret = new HTTPInputStream(in, cl, releaseMe);
                if ("gzip".equals(h.get("content-encoding"))) ret = new java.util.zip.GZIPInputStream(ret);
                doRelease = false;
                return ret;
                
            } else {
                throw new HTTPException("HTTP Error: " + reply);
                
            }
            
        } catch (IOException e) { reset(); throw e;
        } finally { if (doRelease) releaseMe.release();
        }
    }


    // Safeguarded DNS Resolver ///////////////////////////////////////////////////////////////////////////

    /**
     *  resolves the hostname and returns it as a string in the form "x.y.z.w"
     *  @throws HTTPException if the host falls within a firewalled netblock
     */
    private void resolveAndCheckIfFirewalled(String host) throws HTTPException {

        // cached
        if (resolvedHosts.get(host) != null) return;

        // if all scripts are trustworthy (local FS), continue
        if (Main.originAddr == null) return;

        // resolve using DNS
        try {
            InetAddress addr = InetAddress.getByName(host);
            byte[] quadbyte = addr.getAddress();
            if ((quadbyte[0] == 10 ||
                 (quadbyte[0] == 192 && quadbyte[1] == 168) ||
                 (quadbyte[0] == 172 && (quadbyte[1] & 0xF0) == 16)) && !addr.equals(Main.originAddr))
                throw new HTTPException("security violation: " + host + " [" + addr.getHostAddress() +
                                        "] is in a firewalled netblock");
            return;
        } catch (UnknownHostException uhe) { }

        if (Platform.detectProxy() == null)
            throw new HTTPException("could not resolve hostname \"" + host + "\" and no proxy configured");
    }


    // Methods to attempt socket creation /////////////////////////////////////////////////////////////////

    private Socket getSocket(String host, int port, boolean ssl, boolean negotiate) throws IOException {
        Socket ret = ssl ? new SSL(host, port, negotiate) : new Socket(java.net.InetAddress.getByName(host), port);
        ret.setTcpNoDelay(true);
        return ret;
    }

    /** Attempts a direct connection */
    private Socket attemptDirect() {
        try {
            if (Log.verbose) Log.info(this, "attempting to create unproxied socket to " +
                                     host + ":" + port + (ssl ? " [ssl]" : ""));
            return getSocket(host, port, ssl, true);
        } catch (IOException e) {
            if (Log.on) Log.info(this, "exception in attemptDirect(): " + e);
            return null;
        }
    }

    /** Attempts to use an HTTP proxy, employing the CONNECT method if HTTPS is requested */
    private Socket attemptHttpProxy(String proxyHost, int proxyPort) {
        try {
            if (Log.verbose) Log.info(this, "attempting to create HTTP proxied socket using proxy " + proxyHost + ":" + proxyPort);
            Socket sock = getSocket(proxyHost, proxyPort, ssl, false);

            if (!ssl) {
                if (!path.startsWith("http://")) path = "http://" + host + ":" + port + path;
                return sock;
            }

            PrintWriter pw = new PrintWriter(new OutputStreamWriter(sock.getOutputStream()));
            BufferedReader br = new BufferedReader(new InputStreamReader(sock.getInputStream()));
            pw.print("CONNECT " + host + ":" + port + " HTTP/1.1\r\n\r\n");
            pw.flush();
            String s = br.readLine();
            if (s.charAt(9) != '2') throw new HTTPException("proxy refused CONNECT method: \"" + s + "\"");
            while (br.readLine().length() > 0) { };
            ((SSL)sock).negotiate();
            return sock;

        } catch (IOException e) {
            if (Log.on) Log.info(this, "exception in attemptHttpProxy(): " + e);
            return null;
        }
    }

    /**
     *  Implements SOCKSv4 with v4a DNS extension
     *  @see http://www.socks.nec.com/protocol/socks4.protocol
     *  @see http://www.socks.nec.com/protocol/socks4a.protocol
     */
    private Socket attemptSocksProxy(String proxyHost, int proxyPort) {

        // even if host is already a "x.y.z.w" string, we use this to parse it into bytes
        InetAddress addr = null;
        try { addr = InetAddress.getByName(host); } catch (Exception e) { }

        if (Log.verbose) Log.info(this, "attempting to create SOCKSv4" + (addr == null ? "" : "a") +
                                 " proxied socket using proxy " + proxyHost + ":" + proxyPort);

        try {
            Socket sock = getSocket(proxyHost, proxyPort, ssl, false);
            
            DataOutputStream dos = new DataOutputStream(sock.getOutputStream());
            dos.writeByte(0x04);                         // SOCKSv4(a)
            dos.writeByte(0x01);                         // CONNECT
            dos.writeShort(port & 0xffff);               // port
            if (addr == null) dos.writeInt(0x00000001);  // bogus IP
            else dos.write(addr.getAddress());           // actual IP
            dos.writeByte(0x00);                         // no userid
            if (addr == null) {
                PrintWriter pw = new PrintWriter(new OutputStreamWriter(dos));
                pw.print(host);
                pw.flush();
                dos.writeByte(0x00);                     // hostname null terminator
            }
            dos.flush();

            DataInputStream dis = new DataInputStream(sock.getInputStream());
            dis.readByte();                              // reply version
            byte success = dis.readByte();               // success/fail
            dis.skip(6);                                 // ip/port
            
            if ((int)(success & 0xff) == 90) {
                if (ssl) ((SSL)sock).negotiate();
                return sock;
            }
            if (Log.on) Log.info(this, "SOCKS server denied access, code " + (success & 0xff));
            return null;

        } catch (IOException e) {
            if (Log.on) Log.info(this, "exception in attemptSocksProxy(): " + e);
            return null;
        }
    }

    /** executes the PAC script and dispatches a call to one of the other attempt methods based on the result */
    private Socket attemptPAC(org.xwt.js.JS pacFunc) {
        if (Log.verbose) Log.info(this, "evaluating PAC script");
        String pac = null;
        try {
            org.xwt.js.JSArray args = new org.xwt.js.JSArray();
            Object obj = pacFunc.call(url.toString(), url.getHost(), null, null, 2);
            if (Log.verbose) Log.info(this, "  PAC script returned \"" + obj + "\"");
            pac = obj.toString();
        } catch (Throwable e) {
            if (Log.on) Log.info(this, "PAC script threw exception " + e);
            return null;
        }

        StringTokenizer st = new StringTokenizer(pac, ";", false);
        while (st.hasMoreTokens()) {
            String token = st.nextToken().trim();
            if (Log.verbose) Log.info(this, "  trying \"" + token + "\"...");
            try {
                Socket ret = null;
                if (token.startsWith("DIRECT"))
                    ret = attemptDirect();
                else if (token.startsWith("PROXY"))
                    ret = attemptHttpProxy(token.substring(token.indexOf(' ') + 1, token.indexOf(':')),
                                           Integer.parseInt(token.substring(token.indexOf(':') + 1)));
                else if (token.startsWith("SOCKS"))
                    ret = attemptSocksProxy(token.substring(token.indexOf(' ') + 1, token.indexOf(':')),
                                            Integer.parseInt(token.substring(token.indexOf(':') + 1)));
                if (ret != null) return ret;
            } catch (Throwable e) {
                if (Log.on) Log.info(this, "attempt at \"" + token + "\" failed due to " + e + "; trying next token");
            }
        }
        if (Log.on) Log.info(this, "all PAC results exhausted");
        return null;
    }


    // Everything Else ////////////////////////////////////////////////////////////////////////////

    private synchronized void connect() throws IOException {
        if (originalUrl.equals("stdio:")) { in = new BufferedInputStream(System.in); return; }
        if (sock != null) {
            if (in == null) in = new BufferedInputStream(sock.getInputStream());
            return;
        }
        // grab the userinfo; gcj doesn't have java.net.URL.getUserInfo()
        String url = originalUrl;
        userInfo = url.substring(url.indexOf("://") + 3);
        userInfo = userInfo.indexOf('/') == -1 ? userInfo : userInfo.substring(0, userInfo.indexOf('/'));
        if (userInfo.indexOf('@') != -1) {
            userInfo = userInfo.substring(0, userInfo.indexOf('@'));
            url = url.substring(0, url.indexOf("://") + 3) + url.substring(url.indexOf('@') + 1);
        } else {
            userInfo = null;
        }

        if (url.startsWith("https:")) {
            this.url = new URL("http" + url.substring(5));
            ssl = true;
        } else if (!url.startsWith("http:")) {
            throw new MalformedURLException("HTTP only supports http/https urls");
        } else {
            this.url = new URL(url);
        }
        if (!skipResolveCheck) resolveAndCheckIfFirewalled(this.url.getHost());
        port = this.url.getPort();
        path = this.url.getFile();
        if (port == -1) port = ssl ? 443 : 80;
        host = this.url.getHost();
        if (Log.verbose) Log.info(this, "creating HTTP object for connection to " + host + ":" + port);

        Proxy pi = Platform.detectProxy();
        OUTER: do {
            if (pi != null) {
                for(int i=0; i<pi.excluded.length; i++) if (host.equals(pi.excluded[i])) break OUTER;
                if (sock == null && pi.proxyAutoConfigFunction != null) sock = attemptPAC(pi.proxyAutoConfigFunction);
                if (sock == null && ssl && pi.httpsProxyHost != null) sock = attemptHttpProxy(pi.httpsProxyHost,pi.httpsProxyPort);
                if (sock == null && pi.httpProxyHost != null) sock = attemptHttpProxy(pi.httpProxyHost, pi.httpProxyPort);
                if (sock == null && pi.socksProxyHost != null) sock = attemptSocksProxy(pi.socksProxyHost, pi.socksProxyPort);
            }
        } while (false);
        proxied = sock != null;
        if (sock == null) sock = attemptDirect();
        if (sock == null) throw new HTTPException("unable to contact host " + host);
        if (in == null) in = new BufferedInputStream(sock.getInputStream());
    }

    private void sendRequest(String contentType, String content) throws IOException {
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(originalUrl.equals("stdio:") ?
                                                                System.out : sock.getOutputStream()));
        if (content != null) {
            pw.print("POST " + path + " HTTP/1.1\r\n");
            int contentLength = content.substring(0, 2).equals("\r\n") ?
                content.length() - 2 :
                (content.length() - content.indexOf("\r\n\r\n") - 4);
            pw.print("Content-Length: " + contentLength + "\r\n");
            if (contentType != null) pw.print("Content-Type: " + contentType + "\r\n");
        } else {
            pw.print("GET " + path + " HTTP/1.1\r\n");
        }
        
        pw.print("User-Agent: XWT\r\n");
        pw.print("Accept-encoding: gzip\r\n");
        pw.print("Host: " + (host + (port == 80 ? "" : (":" + port))) + "\r\n");
        if (proxied) pw.print("X-RequestOrigin: " + Main.originHost + "\r\n");

        if (Proxy.Authorization.authorization != null) pw.print("Proxy-Authorization: "+Proxy.Authorization.authorization2+"\r\n");
        if (authCache.get(originalUrl) != null) pw.print("Authorization: " + authCache.get(originalUrl) + "\r\n");

        pw.print(content == null ? "\r\n" : content);
        pw.print("\r\n");
        pw.flush();
    }

    private void doWebAuth(Hashtable h0, String method) throws IOException {
        if (userInfo == null) throw new HTTPException("web server demanded username/password, but none were supplied");
        Hashtable h = parseAuthenticationChallenge(h0.get("www-authenticate").toString());
        
        if (h.get("AUTHTYPE").equals("Basic")) {
            if (authCache.get(originalUrl) != null) throw new HTTPException("username/password rejected");
            authCache.put(originalUrl, "Basic " + new String(Base64.encode(userInfo.getBytes("US-ASCII"))));
            
        } else if (h.get("AUTHTYPE").equals("Digest")) {
            if (authCache.get(originalUrl) != null && !"true".equals(h.get("stale")))
                throw new HTTPException("username/password rejected");
            String path2 = path;
            if (path2.startsWith("http://") || path2.startsWith("https://")) {
                path2 = path2.substring(path2.indexOf("://") + 3);
                path2 = path2.substring(path2.indexOf('/'));
            }
            String A1 = userInfo.substring(0, userInfo.indexOf(':')) + ":" + h.get("realm") + ":" +
                userInfo.substring(userInfo.indexOf(':') + 1);
            String A2 = method + ":" + path2;
            authCache.put(originalUrl,
                          "Digest " +
                          "username=\"" + userInfo.substring(0, userInfo.indexOf(':')) + "\", " +
                          "realm=\"" + h.get("realm") + "\", " +
                          "nonce=\"" + h.get("nonce") + "\", " +
                          "uri=\"" + path2 + "\", " +
                          (h.get("opaque") == null ? "" : ("opaque=\"" + h.get("opaque") + "\", ")) + 
                          "response=\"" + H(H(A1) + ":" + h.get("nonce") + ":" + H(A2)) + "\", " +
                          "algorithm=MD5"
                          );
            
        } else {
            throw new HTTPException("unknown authentication type: " + h.get("AUTHTYPE"));
        }
    }

    private void doProxyAuth(Hashtable h0, String method) throws IOException {
        if (Log.on) Log.info(this, "Proxy AuthChallenge: " + h0.get("proxy-authenticate"));
        Hashtable h = parseAuthenticationChallenge(h0.get("proxy-authenticate").toString());
        String style = h.get("AUTHTYPE").toString();
        String realm = (String)h.get("realm");

        if (style.equals("NTLM") && Proxy.Authorization.authorization2 == null) {
            Log.info(this, "Proxy identified itself as NTLM, sending Type 1 packet");
            Proxy.Authorization.authorization2 = "NTLM " + Base64.encode(Proxy.NTLM.type1);
            return;
        }

        if (!realm.equals("Digest") || Proxy.Authorization.authorization2 == null || !"true".equals(h.get("stale")))
            Proxy.Authorization.getPassword(realm, style, sock.getInetAddress().getHostAddress(),
                                            Proxy.Authorization.authorization);

        if (style.equals("Basic")) {
            Proxy.Authorization.authorization2 =
                "Basic " + new String(Base64.encode(Proxy.Authorization.authorization.getBytes("US-ASCII")));
            
        } else if (style.equals("Digest")) {
            String A1 = Proxy.Authorization.authorization.substring(0, userInfo.indexOf(':')) + ":" + h.get("realm") + ":" +
                Proxy.Authorization.authorization.substring(Proxy.Authorization.authorization.indexOf(':') + 1);
            String A2 = method + ":" + path;
            Proxy.Authorization.authorization2 = 
                "Digest " +
                "username=\"" + Proxy.Authorization.authorization.substring(0, Proxy.Authorization.authorization.indexOf(':')) +
                "\", " +
                "realm=\"" + h.get("realm") + "\", " +
                "nonce=\"" + h.get("nonce") + "\", " +
                "uri=\"" + path + "\", " +
                (h.get("opaque") == null ? "" : ("opaque=\"" + h.get("opaque") + "\", ")) + 
                "response=\"" + H(H(A1) + ":" + h.get("nonce") + ":" + H(A2)) + "\", " +
                "algorithm=MD5";

        } else if (style.equals("NTLM")) {
            Log.info(this, "Proxy identified itself as NTLM, got Type 2 packet");
            byte[] type2 = Base64.decode(((String)h0.get("proxy-authenticate")).substring(5).trim());
            for(int i=0; i<type2.length; i += 4) {
                String log = "";
                if (i<type2.length) log += Integer.toString(type2[i] & 0xff, 16) + " ";
                if (i+1<type2.length) log += Integer.toString(type2[i+1] & 0xff, 16) + " ";
                if (i+2<type2.length) log += Integer.toString(type2[i+2] & 0xff, 16) + " ";
                if (i+3<type2.length) log += Integer.toString(type2[i+3] & 0xff, 16) + " ";
                Log.info(this, log);
            }
            // FEATURE: need to keep the connection open between type1 and type3
            // FEATURE: finish this
            //byte[] type3 = Proxy.NTLM.getResponse(
            //Proxy.Authorization.authorization2 = "NTLM " + Base64.encode(type3));
        }            
    }


    // HTTPInputStream ///////////////////////////////////////////////////////////////////////////////////

    /** An input stream that represents a subset of a longer input stream. Supports HTTP chunking as well */
    public class HTTPInputStream extends FilterInputStream implements KnownLength {

        private int length = 0;              ///< if chunking, numbytes left in this subset; else the remainder of the chunk
        private Semaphore releaseMe = null;  ///< this semaphore will be released when the stream is closed
        boolean chunkedDone = false;         ///< indicates that we have encountered the zero-length terminator chunk
        boolean firstChunk = true;           ///< if we're on the first chunk, we don't pre-read a CRLF
        private int contentLength = 0;       ///< the length of the entire content body; -1 if chunked

        HTTPInputStream(InputStream in, int length, Semaphore releaseMe) throws IOException {
            super(in);
            this.releaseMe = releaseMe;
            this.contentLength = length;
            this.length = length == -1 ? 0 : length;
        }

        public int getLength() { return contentLength; }
        public boolean markSupported() { return false; }
        public int read(byte[] b) throws IOException { return read(b, 0, b.length); }
        public long skip(long n) throws IOException { return read(null, -1, (int)n); }
        public int available() throws IOException {
            if (contentLength == -1) return java.lang.Math.min(super.available(), length);
            return super.available();
        }

        public int read() throws IOException {
            byte[] b = new byte[1];
            int ret = read(b, 0, 1);
            return ret == -1 ? -1 : b[0] & 0xff;
        }

        private void readChunk() throws IOException {
            if (chunkedDone) return;
            if (!firstChunk) super.skip(2); // CRLF
            firstChunk = false;
            String chunkLen = "";
            while(true) {
                int i = super.read();
                if (i == -1) throw new HTTPException("encountered end of stream while reading chunk length");

                // FEATURE: handle chunking extensions
                if (i == '\r') {
                    super.read();    // LF
                    break;
                } else {
                    chunkLen += (char)i;
                }
            }
            length = Integer.parseInt(chunkLen.trim(), 16);
            if (length == 0) chunkedDone = true;
        }

        public int read(byte[] b, int off, int len) throws IOException {
            boolean good = false;
            try {
                if (length == 0 && contentLength == -1) {
                    readChunk();
                    if (chunkedDone) { good = true; return -1; }
                } else {
                    if (length == 0) { good = true; return -1; }
                }
                if (len > length) len = length;
                int ret = b == null ? (int)super.skip(len) : super.read(b, off, len);
                if (ret >= 0) {
                    length -= ret;
                    good = true;
                }
                return ret;
            } finally {
                if (!good) reset();
            }
        }

        public void close() throws IOException {
            if (contentLength == -1) {
                while(!chunkedDone) {
                    if (length != 0) skip(length);
                    readChunk();
                }
                skip(2);
            } else {
                if (length != 0) skip(length);
            }
            if (releaseMe != null) releaseMe.release();
        }
    }

    void reset() {
        firstRequest = true;
        in = null;
        sock = null;
    }


    // Misc Helpers ///////////////////////////////////////////////////////////////////////////////////

    /** reads a set of HTTP headers off of the input stream, returning null if the stream is already at its end */
    private Hashtable parseHeaders(InputStream in) throws IOException {
        Hashtable ret = new Hashtable();

        // we can't use a BufferedReader directly on the input stream, since it will buffer past the end of the headers
        byte[] buf = new byte[4096];
        int buflen = 0;
        while(true) {
            int read = in.read();
            if (read == -1 && buflen == 0) return null;
            if (read == -1) throw new HTTPException("stream closed while reading headers");
            buf[buflen++] = (byte)read;
            if (buflen >= 4 && buf[buflen - 4] == '\r' && buf[buflen - 3] == '\n' &&
                buf[buflen - 2] == '\r' && buf[buflen - 1] == '\n')
                break;
            if (buflen == buf.length) {
                byte[] newbuf = new byte[buf.length * 2];
                System.arraycopy(buf, 0, newbuf, 0, buflen);
                buf = newbuf;
            }
        }

        BufferedReader br = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(buf, 0, buflen)));
        String s = br.readLine();
        if (!s.startsWith("HTTP/")) throw new HTTPException("Expected reply to start with \"HTTP/\", got: " + s);
        ret.put("STATUSLINE", s.substring(s.indexOf(' ') + 1));
        ret.put("HTTP", s.substring(5, s.indexOf(' ')));

        while((s = br.readLine()) != null && s.length() > 0) {
            String front = s.substring(0, s.indexOf(':')).toLowerCase();
            String back = s.substring(s.indexOf(':') + 1).trim();
            // ugly hack: we never replace a Digest-auth with a Basic-auth (proxy + www)
            if (front.endsWith("-authenticate") && ret.get(front) != null && !back.equals("Digest")) continue;
            ret.put(front, back);
        }
        return ret;
    }

    private Hashtable parseAuthenticationChallenge(String s) {
        Hashtable ret = new Hashtable();

        s = s.trim();
        ret.put("AUTHTYPE", s.substring(0, s.indexOf(' ')));
        s = s.substring(s.indexOf(' ')).trim();

        while (s.length() > 0) {
            String val = null;
            String key = s.substring(0, s.indexOf('='));
            s = s.substring(s.indexOf('=') + 1);
            if (s.charAt(0) == '\"') {
                s = s.substring(1);
                val = s.substring(0, s.indexOf('\"'));
                s = s.substring(s.indexOf('\"') + 1);
            } else {
                val = s.indexOf(',') == -1 ? s : s.substring(0, s.indexOf(','));
                s = s.indexOf(',') == -1 ? "" : s.substring(s.indexOf(',') + 1);
            }
            if (s.length() > 0 && s.charAt(0) == ',') s = s.substring(1);
            s = s.trim();
            ret.put(key, val);
        }
        return ret;
    }

    private String H(String s) throws IOException {
        byte[] b = s.getBytes("US-ASCII");
        MD5Digest md5 = new MD5Digest();
        md5.update(b, 0, b.length);
        byte[] out = new byte[md5.getDigestSize()];
        md5.doFinal(out, 0);
        String ret = "";
        for(int i=0; i<out.length; i++) {
            ret += "0123456789abcdef".charAt((out[i] & 0xf0) >> 4);
            ret += "0123456789abcdef".charAt(out[i] & 0x0f);
        }
        return ret;
    }


    // Proxy ///////////////////////////////////////////////////////////

    /** encapsulates most of the proxy logic; some is shared in HTTP.java */
    public static class Proxy {
        
        public Proxy() { }
        
        public String httpProxyHost = null;                  ///< the HTTP Proxy host to use
        public int httpProxyPort = -1;                       ///< the HTTP Proxy port to use
        public String httpsProxyHost = null;                 ///< seperate proxy for HTTPS
        public int httpsProxyPort = -1;
        public String socksProxyHost = null;                 ///< the SOCKS Proxy Host to use
        public int socksProxyPort = -1;                      ///< the SOCKS Proxy Port to use
        public String[] excluded = null;                     ///< hosts to be excluded from proxy use; wildcards permitted
        public JS proxyAutoConfigFunction = null;  ///< the PAC script
    
        public static Proxy detectProxyViaManual() {
            Proxy ret = new Proxy();
        
            ret.httpProxyHost = Platform.getEnv("http_proxy");
            if (ret.httpProxyHost != null) {
                if (ret.httpProxyHost.startsWith("http://")) ret.httpProxyHost = ret.httpProxyHost.substring(7);
                if (ret.httpProxyHost.endsWith("/"))
                    ret.httpProxyHost = ret.httpProxyHost.substring(0, ret.httpProxyHost.length() - 1);
                if (ret.httpProxyHost.indexOf(':') != -1) {
                    ret.httpProxyPort = Integer.parseInt(ret.httpProxyHost.substring(ret.httpProxyHost.indexOf(':') + 1));
                    ret.httpProxyHost = ret.httpProxyHost.substring(0, ret.httpProxyHost.indexOf(':'));
                } else {
                    ret.httpProxyPort = 80;
                }
            }
        
            ret.httpsProxyHost = Platform.getEnv("https_proxy");
            if (ret.httpsProxyHost != null) {
                if (ret.httpsProxyHost.startsWith("https://")) ret.httpsProxyHost = ret.httpsProxyHost.substring(7);
                if (ret.httpsProxyHost.endsWith("/"))
                    ret.httpsProxyHost = ret.httpsProxyHost.substring(0, ret.httpsProxyHost.length() - 1);
                if (ret.httpsProxyHost.indexOf(':') != -1) {
                    ret.httpsProxyPort = Integer.parseInt(ret.httpsProxyHost.substring(ret.httpsProxyHost.indexOf(':') + 1));
                    ret.httpsProxyHost = ret.httpsProxyHost.substring(0, ret.httpsProxyHost.indexOf(':'));
                } else {
                    ret.httpsProxyPort = 80;
                }
            }
        
            ret.socksProxyHost = Platform.getEnv("socks_proxy");
            if (ret.socksProxyHost != null) {
                if (ret.socksProxyHost.startsWith("socks://")) ret.socksProxyHost = ret.socksProxyHost.substring(7);
                if (ret.socksProxyHost.endsWith("/"))
                    ret.socksProxyHost = ret.socksProxyHost.substring(0, ret.socksProxyHost.length() - 1);
                if (ret.socksProxyHost.indexOf(':') != -1) {
                    ret.socksProxyPort = Integer.parseInt(ret.socksProxyHost.substring(ret.socksProxyHost.indexOf(':') + 1));
                    ret.socksProxyHost = ret.socksProxyHost.substring(0, ret.socksProxyHost.indexOf(':'));
                } else {
                    ret.socksProxyPort = 80;
                }
            }
        
            String noproxy = Platform.getEnv("no_proxy");
            if (noproxy != null) {
                StringTokenizer st = new StringTokenizer(noproxy, ",");
                ret.excluded = new String[st.countTokens()];
                for(int i=0; st.hasMoreTokens(); i++) ret.excluded[i] = st.nextToken();
            }
        
            if (ret.httpProxyHost == null && ret.socksProxyHost == null) return null;
            return ret;
        }
    
        public static JSScope proxyAutoConfigRootScope = new ProxyAutoConfigRootScope();
        public static JS getProxyAutoConfigFunction(String url) {
            try { 
                BufferedReader br = new BufferedReader(new InputStreamReader(new HTTP(url, true).GET()));
                String s = null;
                String script = "";
                while((s = br.readLine()) != null) script += s + "\n";
                if (Log.on) Log.info(Proxy.class, "successfully retrieved WPAD PAC:");
                if (Log.on) Log.info(Proxy.class, script);
            
                // MS CARP hack
                Vector carpHosts = new Vector();
                for(int i=0; i<script.length(); i++)
                    if (script.regionMatches(i, "new Node(", 0, 9)) {
                        String host = script.substring(i + 10, script.indexOf('\"', i + 11));
                        if (Log.on) Log.info(Proxy.class, "Detected MS Proxy Server CARP Script, Host=" + host);
                        carpHosts.addElement(host);
                    }
                if (carpHosts.size() > 0) {
                    script = "function FindProxyForURL(url, host) {\nreturn \"";
                    for(int i=0; i<carpHosts.size(); i++)
                        script += "PROXY " + carpHosts.elementAt(i) + "; ";
                    script += "\";\n}";
                    if (Log.on) Log.info(Proxy.class, "DeCARPed PAC script:");
                    if (Log.on) Log.info(Proxy.class, script);
                }

                JS scr = JS.fromReader("PAC script at " + url, 0, new StringReader(script));
                JS.cloneWithNewParentScope(scr, proxyAutoConfigRootScope).call(null, null, null, null, 0);
                return (JS)proxyAutoConfigRootScope.get("FindProxyForURL");
            } catch (Exception e) {
                if (Log.on) {
                    Log.info(Platform.class, "WPAD detection failed due to:");
                    if (e instanceof JSExn) {
                        try {
                            org.xwt.js.JSArray arr = new org.xwt.js.JSArray();
                            arr.addElement(((JSExn)e).getObject());
                        } catch (Exception e2) {
                            Log.info(Platform.class, e);
                        }
                    }
                    else Log.info(Platform.class, e);
                }
                return null;
            }
        }


        // Authorization ///////////////////////////////////////////////////////////////////////////////////

        public static class Authorization {

            static public String authorization = null;
            static public String authorization2 = null;
            static public Semaphore waitingForUser = new Semaphore();

            public static synchronized void getPassword(final String realm, final String style,
                                                        final String proxyIP, String oldAuth) {

                // this handles cases where multiple threads hit the proxy auth at the same time -- all but one will block on the
                // synchronized keyword. If 'authorization' changed while the thread was blocked, it means that the user entered
                // a password, so we should reattempt authorization.

                if (authorization != oldAuth) return;
                if (Log.on) Log.info(Authorization.class, "displaying proxy authorization dialog");
                Scheduler.add(new Scheduler.Task() {
                        public void perform() throws Exception {
                            Box b = new Box();
                            Template t = new Template(Stream.getInputStream((JS)Main.builtin.get("org/xwt/builtin/proxy_authorization.xwt")), new XWT(null));
                            t.apply(b);
                            b.put("realm", realm);
                            b.put("proxyIP", proxyIP);
                        }
                    });

                waitingForUser.block();
                if (Log.on) Log.info(Authorization.class, "got proxy authorization info; re-attempting connection");
            }
        }


        // ProxyAutoConfigRootJSScope ////////////////////////////////////////////////////////////////////

        public static class ProxyAutoConfigRootScope extends JSScope.Global {

            public ProxyAutoConfigRootScope() { super(); }
        
            public Object get(Object name) throws JSExn {
                //#switch(name)
                case "isPlainHostName": return METHOD;
                case "dnsDomainIs": return METHOD;
                case "localHostOrDomainIs": return METHOD;
                case "isResolvable": return METHOD;
                case "isInNet": return METHOD;
                case "dnsResolve": return METHOD;
                case "myIpAddress": return METHOD;
                case "dnsDomainLevels": return METHOD;
                case "shExpMatch": return METHOD;
                case "weekdayRange": return METHOD;
                case "dateRange": return METHOD;
                case "timeRange": return METHOD;
                case "ProxyConfig": return ProxyConfig;
                //#end
                return super.get(name);
            }
        
            private static final JS proxyConfigBindings = new JS();
            private static final JS ProxyConfig = new JS() {
                    public Object get(Object name) {
                        if (name.equals("bindings")) return proxyConfigBindings;
                        return null;
                    }
                };

            public Object callMethod(Object method, Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
                //#switch(method)
                case "isPlainHostName": return (a0.toString().indexOf('.') == -1) ? Boolean.TRUE : Boolean.FALSE;
                case "dnsDomainIs": return (a0.toString().endsWith(a1.toString())) ? Boolean.TRUE : Boolean.FALSE;
                case "localHostOrDomainIs":
                    return (a0.equals(a1) || (a0.toString().indexOf('.') == -1 && a1.toString().startsWith(a0.toString()))) ? T:F;
                case "isResolvable": try {
                    return (InetAddress.getByName(a0.toString()) != null) ? Boolean.TRUE : Boolean.FALSE;
                } catch (UnknownHostException e) { return F; }
                case "isInNet":
                    if (nargs != 3) return Boolean.FALSE;
                    try {
                        byte[] host = InetAddress.getByName(a0.toString()).getAddress();
                        byte[] net = InetAddress.getByName(a1.toString()).getAddress();
                        byte[] mask = InetAddress.getByName(a2.toString()).getAddress();
                        return ((host[0] & mask[0]) == net[0] &&
                                (host[1] & mask[1]) == net[1] &&
                                (host[2] & mask[2]) == net[2] &&
                                (host[3] & mask[3]) == net[3]) ?
                            Boolean.TRUE : Boolean.FALSE;
                    } catch (Exception e) {
                        throw new JSExn("exception in isInNet(): " + e);
                    }
                case "dnsResolve":
                    try {
                        return InetAddress.getByName(a0.toString()).getHostAddress();
                    } catch (UnknownHostException e) {
                        return null;
                    }
                case "myIpAddress":
                    try {
                        return InetAddress.getLocalHost().getHostAddress();
                    } catch (UnknownHostException e) {
                        if (Log.on) Log.info(this, "strange... host does not know its own address");
                        return null;
                    }
                case "dnsDomainLevels":
                    String s = a0.toString();
                    int i = 0;
                    while((i = s.indexOf('.', i)) != -1) i++;
                    return new Integer(i);
                case "shExpMatch":
                    StringTokenizer st = new StringTokenizer(a1.toString(), "*", false);
                    String[] arr = new String[st.countTokens()];
                    String s = a0.toString();
                    for (int i=0; st.hasMoreTokens(); i++) arr[i] = st.nextToken();
                    return match(arr, s, 0) ? Boolean.TRUE : Boolean.FALSE;
                case "weekdayRange":
                    TimeZone tz = (nargs < 3 || a2 == null || !a2.equals("GMT")) ?
                        TimeZone.getTimeZone("UTC") : TimeZone.getDefault();
                    Calendar c = new GregorianCalendar();
                    c.setTimeZone(tz);
                    c.setTime(new java.util.Date());
                    java.util.Date d = c.getTime();
                    int day = d.getDay();
                    String d1s = a0.toString().toUpperCase();
                    int d1 = 0, d2 = 0;
                    for(int i=0; i<days.length; i++) if (days[i].equals(d1s)) d1 = i;
                    
                    if (nargs == 1)
                        return d1 == day ? Boolean.TRUE : Boolean.FALSE;
                    
                    String d2s = a1.toString().toUpperCase();
                    for(int i=0; i<days.length; i++) if (days[i].equals(d2s)) d2 = i;
                    
                    return ((d1 <= d2 && day >= d1 && day <= d2) || (d1 > d2 && (day >= d1 || day <= d2))) ? T : F;
                    
                case "dateRange": throw new JSExn("XWT does not support dateRange() in PAC scripts");
                case "timeRange": throw new JSExn("XWT does not support timeRange() in PAC scripts");
                //#end
                return super.callMethod(method, a0, a1, a2, rest, nargs);
            }       
            private static boolean match(String[] arr, String s, int index) {
                if (index >= arr.length) return true;
                for(int i=0; i<s.length(); i++) {
                    String s2 = s.substring(i);
                    if (s2.startsWith(arr[index]) && match(arr, s2.substring(arr[index].length()), index + 1)) return true;
                }
                return false;
            }
            public static String[] days = { "SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT" };
        }


        /**
         *  An implementation of Microsoft's proprietary NTLM authentication protocol.  This code was derived from Eric
         *  Glass's work, and is copyright as follows:
         *
         *  Copyright (c) 2003 Eric Glass     (eglass1 at comcast.net). 
         *
         *  Permission to use, copy, modify, and distribute this document for any purpose and without any fee is hereby
         *  granted, provided that the above copyright notice and this list of conditions appear in all copies.
         *  The most current version of this document may be obtained from http://davenport.sourceforge.net/ntlm.html .
         */ 
        public static class NTLM {
            
            public static final byte[] type1 = new byte[] { 0x4e, 0x54, 0x4c, 0x4d, 0x53, 0x53, 0x50, 0x00, 0x01,
                                                            0x00, 0x00, 0x00, 0x00, 0x02, 0x02, 0x00 };
            
            /**
             * Calculates the NTLM Response for the given challenge, using the
             * specified password.
             *
             * @param password The user's password.
             * @param challenge The Type 2 challenge from the server.
             *
             * @return The NTLM Response.
             */
            public static byte[] getNTLMResponse(String password, byte[] challenge)
                throws Exception {
                byte[] ntlmHash = ntlmHash(password);
                return lmResponse(ntlmHash, challenge);
            }

            /**
             * Calculates the LM Response for the given challenge, using the specified
             * password.
             *
             * @param password The user's password.
             * @param challenge The Type 2 challenge from the server.
             *
             * @return The LM Response.
             */
            public static byte[] getLMResponse(String password, byte[] challenge)
                throws Exception {
                byte[] lmHash = lmHash(password);
                return lmResponse(lmHash, challenge);
            }

            /**
             * Calculates the NTLMv2 Response for the given challenge, using the
             * specified authentication target, username, password, target information
             * block, and client challenge.
             *
             * @param target The authentication target (i.e., domain).
             * @param user The username. 
             * @param password The user's password.
             * @param targetInformation The target information block from the Type 2
             * message.
             * @param challenge The Type 2 challenge from the server.
             * @param clientChallenge The random 8-byte client challenge. 
             *
             * @return The NTLMv2 Response.
             */
            public static byte[] getNTLMv2Response(String target, String user,
                                                   String password, byte[] targetInformation, byte[] challenge,
                                                   byte[] clientChallenge) throws Exception {
                byte[] ntlmv2Hash = ntlmv2Hash(target, user, password);
                byte[] blob = createBlob(targetInformation, clientChallenge);
                return lmv2Response(ntlmv2Hash, blob, challenge);
            }

            /**
             * Calculates the LMv2 Response for the given challenge, using the
             * specified authentication target, username, password, and client
             * challenge.
             *
             * @param target The authentication target (i.e., domain).
             * @param user The username.
             * @param password The user's password.
             * @param challenge The Type 2 challenge from the server.
             * @param clientChallenge The random 8-byte client challenge.
             *
             * @return The LMv2 Response. 
             */
            public static byte[] getLMv2Response(String target, String user,
                                                 String password, byte[] challenge, byte[] clientChallenge)
                throws Exception {
                byte[] ntlmv2Hash = ntlmv2Hash(target, user, password);
                return lmv2Response(ntlmv2Hash, clientChallenge, challenge);
            }

            /**
             * Calculates the NTLM2 Session Response for the given challenge, using the
             * specified password and client challenge.
             *
             * @param password The user's password.
             * @param challenge The Type 2 challenge from the server.
             * @param clientChallenge The random 8-byte client challenge.
             *
             * @return The NTLM2 Session Response.  This is placed in the NTLM
             * response field of the Type 3 message; the LM response field contains
             * the client challenge, null-padded to 24 bytes.
             */
            public static byte[] getNTLM2SessionResponse(String password,
                                                         byte[] challenge, byte[] clientChallenge) throws Exception {
                byte[] ntlmHash = ntlmHash(password);
                MD5Digest md5 = new MD5Digest();
                md5.update(challenge, 0, challenge.length);
                md5.update(clientChallenge, 0, clientChallenge.length);
                byte[] sessionHash = new byte[8];
                byte[] md5_out = new byte[md5.getDigestSize()];
                md5.doFinal(md5_out, 0);
                System.arraycopy(md5_out, 0, sessionHash, 0, 8);
                return lmResponse(ntlmHash, sessionHash);
            }

            /**
             * Creates the LM Hash of the user's password.
             *
             * @param password The password.
             *
             * @return The LM Hash of the given password, used in the calculation
             * of the LM Response.
             */
            private static byte[] lmHash(String password) throws Exception {
                /*
                byte[] oemPassword = password.toUpperCase().getBytes("US-ASCII");
                int length = java.lang.Math.min(oemPassword.length, 14);
                byte[] keyBytes = new byte[14];
                System.arraycopy(oemPassword, 0, keyBytes, 0, length);
                Key lowKey = createDESKey(keyBytes, 0);
                Key highKey = createDESKey(keyBytes, 7);
                byte[] magicConstant = "KGS!@#$%".getBytes("US-ASCII");
                Cipher des = Cipher.getInstance("DES/ECB/NoPadding");
                des.init(Cipher.ENCRYPT_MODE, lowKey);
                byte[] lowHash = des.doFinal(magicConstant);
                des.init(Cipher.ENCRYPT_MODE, highKey);
                byte[] highHash = des.doFinal(magicConstant);
                byte[] lmHash = new byte[16];
                System.arraycopy(lowHash, 0, lmHash, 0, 8);
                System.arraycopy(highHash, 0, lmHash, 8, 8);
                return lmHash;
                */
                return null;
            }

            /**
             * Creates the NTLM Hash of the user's password.
             *
             * @param password The password.
             *
             * @return The NTLM Hash of the given password, used in the calculation
             * of the NTLM Response and the NTLMv2 and LMv2 Hashes.
             */
            private static byte[] ntlmHash(String password) throws Exception {
                byte[] unicodePassword = password.getBytes("UnicodeLittleUnmarked");
                MD4Digest md4 = new MD4Digest();
                md4.update(unicodePassword, 0, unicodePassword.length);
                byte[] ret = new byte[md4.getDigestSize()];
                return ret;
            }

            /**
             * Creates the NTLMv2 Hash of the user's password.
             *
             * @param target The authentication target (i.e., domain).
             * @param user The username.
             * @param password The password.
             *
             * @return The NTLMv2 Hash, used in the calculation of the NTLMv2
             * and LMv2 Responses. 
             */
            private static byte[] ntlmv2Hash(String target, String user,
                                             String password) throws Exception {
                byte[] ntlmHash = ntlmHash(password);
                String identity = user.toUpperCase() + target.toUpperCase();
                return hmacMD5(identity.getBytes("UnicodeLittleUnmarked"), ntlmHash);
            }

            /**
             * Creates the LM Response from the given hash and Type 2 challenge.
             *
             * @param hash The LM or NTLM Hash.
             * @param challenge The server challenge from the Type 2 message.
             *
             * @return The response (either LM or NTLM, depending on the provided
             * hash).
             */
            private static byte[] lmResponse(byte[] hash, byte[] challenge)
                throws Exception {
                /*
                byte[] keyBytes = new byte[21];
                System.arraycopy(hash, 0, keyBytes, 0, 16);
                Key lowKey = createDESKey(keyBytes, 0);
                Key middleKey = createDESKey(keyBytes, 7);
                Key highKey = createDESKey(keyBytes, 14);
                Cipher des = Cipher.getInstance("DES/ECB/NoPadding");
                des.init(Cipher.ENCRYPT_MODE, lowKey);
                byte[] lowResponse = des.doFinal(challenge);
                des.init(Cipher.ENCRYPT_MODE, middleKey);
                byte[] middleResponse = des.doFinal(challenge);
                des.init(Cipher.ENCRYPT_MODE, highKey);
                byte[] highResponse = des.doFinal(challenge);
                byte[] lmResponse = new byte[24];
                System.arraycopy(lowResponse, 0, lmResponse, 0, 8);
                System.arraycopy(middleResponse, 0, lmResponse, 8, 8);
                System.arraycopy(highResponse, 0, lmResponse, 16, 8);
                return lmResponse;
                */
                return null;
            }

            /**
             * Creates the LMv2 Response from the given hash, client data, and
             * Type 2 challenge.
             *
             * @param hash The NTLMv2 Hash.
             * @param clientData The client data (blob or client challenge).
             * @param challenge The server challenge from the Type 2 message.
             *
             * @return The response (either NTLMv2 or LMv2, depending on the
             * client data).
             */
            private static byte[] lmv2Response(byte[] hash, byte[] clientData,
                                               byte[] challenge) throws Exception {
                byte[] data = new byte[challenge.length + clientData.length];
                System.arraycopy(challenge, 0, data, 0, challenge.length);
                System.arraycopy(clientData, 0, data, challenge.length,
                                 clientData.length);
                byte[] mac = hmacMD5(data, hash);
                byte[] lmv2Response = new byte[mac.length + clientData.length];
                System.arraycopy(mac, 0, lmv2Response, 0, mac.length);
                System.arraycopy(clientData, 0, lmv2Response, mac.length,
                                 clientData.length);
                return lmv2Response;
            }

            /**
             * Creates the NTLMv2 blob from the given target information block and
             * client challenge.
             *
             * @param targetInformation The target information block from the Type 2
             * message.
             * @param clientChallenge The random 8-byte client challenge.
             *
             * @return The blob, used in the calculation of the NTLMv2 Response.
             */
            private static byte[] createBlob(byte[] targetInformation,
                                             byte[] clientChallenge) {
                byte[] blobSignature = new byte[] {
                    (byte) 0x01, (byte) 0x01, (byte) 0x00, (byte) 0x00
                };
                byte[] reserved = new byte[] {
                    (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00
                };
                byte[] unknown1 = new byte[] {
                    (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00
                };
                byte[] unknown2 = new byte[] {
                    (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00
                };
                long time = System.currentTimeMillis();
                time += 11644473600000l; // milliseconds from January 1, 1601 -> epoch.
                time *= 10000; // tenths of a microsecond.
                // convert to little-endian byte array.
                byte[] timestamp = new byte[8];
                for (int i = 0; i < 8; i++) {
                    timestamp[i] = (byte) time;
                    time >>>= 8;
                }
                byte[] blob = new byte[blobSignature.length + reserved.length +
                                       timestamp.length + clientChallenge.length +
                                       unknown1.length + targetInformation.length +
                                       unknown2.length];
                int offset = 0;
                System.arraycopy(blobSignature, 0, blob, offset, blobSignature.length);
                offset += blobSignature.length;
                System.arraycopy(reserved, 0, blob, offset, reserved.length);
                offset += reserved.length;
                System.arraycopy(timestamp, 0, blob, offset, timestamp.length);
                offset += timestamp.length;
                System.arraycopy(clientChallenge, 0, blob, offset,
                                 clientChallenge.length);
                offset += clientChallenge.length;
                System.arraycopy(unknown1, 0, blob, offset, unknown1.length);
                offset += unknown1.length;
                System.arraycopy(targetInformation, 0, blob, offset,
                                 targetInformation.length);
                offset += targetInformation.length;
                System.arraycopy(unknown2, 0, blob, offset, unknown2.length);
                return blob;
            }

            /**
             * Calculates the HMAC-MD5 hash of the given data using the specified
             * hashing key.
             *
             * @param data The data for which the hash will be calculated. 
             * @param key The hashing key.
             *
             * @return The HMAC-MD5 hash of the given data.
             */
            private static byte[] hmacMD5(byte[] data, byte[] key) throws Exception {
                byte[] ipad = new byte[64];
                byte[] opad = new byte[64];
                for (int i = 0; i < 64; i++) {
                    ipad[i] = (byte) 0x36;
                    opad[i] = (byte) 0x5c;
                }
                for (int i = key.length - 1; i >= 0; i--) {
                    ipad[i] ^= key[i];
                    opad[i] ^= key[i];
                }
                byte[] content = new byte[data.length + 64];
                System.arraycopy(ipad, 0, content, 0, 64);
                System.arraycopy(data, 0, content, 64, data.length);
                MD5Digest md5 = new MD5Digest();
                md5.update(content, 0, content.length);
                data = new byte[md5.getDigestSize()];
                md5.doFinal(data, 0);
                content = new byte[data.length + 64];
                System.arraycopy(opad, 0, content, 0, 64);
                System.arraycopy(data, 0, content, 64, data.length);
                md5 = new MD5Digest();
                md5.update(content, 0, content.length);
                byte[] ret = new byte[md5.getDigestSize()];
                md5.doFinal(ret, 0);
                return ret;
            }

            /**
             * Creates a DES encryption key from the given key material.
             *
             * @param bytes A byte array containing the DES key material.
             * @param offset The offset in the given byte array at which
             * the 7-byte key material starts.
             *
             * @return A DES encryption key created from the key material
             * starting at the specified offset in the given byte array.
             */
                /*
            private static Key createDESKey(byte[] bytes, int offset) {
                byte[] keyBytes = new byte[7];
                System.arraycopy(bytes, offset, keyBytes, 0, 7);
                byte[] material = new byte[8];
                material[0] = keyBytes[0];
                material[1] = (byte) (keyBytes[0] << 7 | (keyBytes[1] & 0xff) >>> 1);
                material[2] = (byte) (keyBytes[1] << 6 | (keyBytes[2] & 0xff) >>> 2);
                material[3] = (byte) (keyBytes[2] << 5 | (keyBytes[3] & 0xff) >>> 3);
                material[4] = (byte) (keyBytes[3] << 4 | (keyBytes[4] & 0xff) >>> 4);
                material[5] = (byte) (keyBytes[4] << 3 | (keyBytes[5] & 0xff) >>> 5);
                material[6] = (byte) (keyBytes[5] << 2 | (keyBytes[6] & 0xff) >>> 6);
                material[7] = (byte) (keyBytes[6] << 1);
                oddParity(material);
                return new SecretKeySpec(material, "DES");
            }
                */

            /**
             * Applies odd parity to the given byte array.
             *
             * @param bytes The data whose parity bits are to be adjusted for
             * odd parity.
             */
            private static void oddParity(byte[] bytes) {
                for (int i = 0; i < bytes.length; i++) {
                    byte b = bytes[i];
                    boolean needsParity = (((b >>> 7) ^ (b >>> 6) ^ (b >>> 5) ^
                                            (b >>> 4) ^ (b >>> 3) ^ (b >>> 2) ^
                                            (b >>> 1)) & 0x01) == 0;
                    if (needsParity) {
                        bytes[i] |= (byte) 0x01;
                    } else {
                        bytes[i] &= (byte) 0xfe;
                    }
                }
            }

        }
    }
}