/*

 * Copyright 2009 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.net.spi;

import sun.net.NetHooks;

import java.net.InetAddress;

import java.net.Inet4Address;

import java.net.UnknownHostException;

import java.util.*;

import java.io.File;

import java.io.FileDescriptor;

import java.io.IOException;

import java.io.PrintStream;

import sun.misc.SharedSecrets;

import sun.misc.JavaIOFileDescriptorAccess;

/**

 * A NetHooks provider that converts sockets from the TCP to SDP protocol prior

 * to binding or connecting.

 */

public class SdpProvider extends NetHooks.Provider {

    private static final JavaIOFileDescriptorAccess fdAccess =

        SharedSecrets.getJavaIOFileDescriptorAccess();

    // maximum port

    private static final int MAX_PORT = 65535;

    // indicates if SDP is enabled and the rules for when the protocol is used

    private final boolean enabled;

    private final List<Rule> rules;

    // logging for debug purposes

    private PrintStream log;

    public SdpProvider() {

        // if this property is not defined then there is nothing to do.

        String file = System.getProperty("com.sun.sdp.conf");

        if (file == null) {

            this.enabled = false;

            this.rules = null;

            return;

        }

        // load configuration file

        List<Rule> list = null;

        if (file != null) {

            try {

                list = loadRulesFromFile(file);

            } catch (IOException e) {

                fail("Error reading %s: %s", file, e.getMessage());

            }

        }

        // check if debugging is enabled

        PrintStream out = null;

        String logfile = System.getProperty("com.sun.sdp.debug");

        if (logfile != null) {

            out = System.out;

            if (logfile.length() > 0) {

                try {

                    out = new PrintStream(logfile);

                } catch (IOException ignore) { }

            }

        }

        this.enabled = !list.isEmpty();

        this.rules = list;

        this.log = out;

    }

    // supported actions

    private static enum Action {

        BIND,

        CONNECT;

    }

    // a rule for matching a bind or connect request

    private static interface Rule {

        boolean match(Action action, InetAddress address, int port);

    }

    // rule to match port[-end]

    private static class PortRangeRule implements Rule {

        private final Action action;

        private final int portStart;

        private final int portEnd;

        PortRangeRule(Action action, int portStart, int portEnd) {

            this.action = action;

            this.portStart = portStart;

            this.portEnd = portEnd;

        }

        Action action() {

            return action;

        }

        @Override

        public boolean match(Action action, InetAddress address, int port) {

            return (action == this.action &&

                    port >= this.portStart &&

                    port <= this.portEnd);

        }

    }

    // rule to match address[/prefix] port[-end]

    private static class AddressPortRangeRule extends PortRangeRule {

        private final byte[] addressAsBytes;

        private final int prefixByteCount;

        private final byte mask;

        AddressPortRangeRule(Action action, InetAddress address,

                             int prefix, int port, int end)

        {

            super(action, port, end);

            this.addressAsBytes = address.getAddress();

            this.prefixByteCount = prefix >> 3;

            this.mask = (byte)(0xff << (8 - (prefix % 8)));

        }

        @Override

        public boolean match(Action action, InetAddress address, int port) {

            if (action != action())

                return false;

            byte[] candidate = address.getAddress();

            // same address type?

            if (candidate.length != addressAsBytes.length)

                return false;

            // check bytes

            for (int i=0; i<prefixByteCount; i++) {

                if (candidate[i] != addressAsBytes[i])

                    return false;

            }

            // check remaining bits

            if ((prefixByteCount < addressAsBytes.length) &&

                ((candidate[prefixByteCount] & mask) !=

                 (addressAsBytes[prefixByteCount] & mask)))

                    return false;

            return super.match(action, address, port);

        }

    }

    // parses port:[-end]

    private static int[] parsePortRange(String s) {

        int pos = s.indexOf('-');

        try {

            int[] result = new int[2];

            if (pos < 0) {

                boolean all = s.equals("*");

                result[0] = all ? 0 : Integer.parseInt(s);

                result[1] = all ? MAX_PORT : result[0];

            } else {

                String low = s.substring(0, pos);

                if (low.length() == 0) low = "*";

                String high = s.substring(pos+1);

                if (high.length() == 0) high = "*";

                result[0] = low.equals("*") ? 0 : Integer.parseInt(low);

                result[1] = high.equals("*") ? MAX_PORT : Integer.parseInt(high);

            }

            return result;

        } catch (NumberFormatException e) {

            return new int[0];

        }

    }

    private static void fail(String msg, Object... args) {

        Formatter f = new Formatter();

        f.format(msg, args);

        throw new RuntimeException(f.out().toString());

    }

    // loads rules from the given file

    // Each non-blank/non-comment line must have the format:

    // ("bind" | "connect") 1*LWSP-char (hostname | ipaddress["/" prefix])

    //     1*LWSP-char ("*" | port) [ "-" ("*" | port) ]

    private static List<Rule> loadRulesFromFile(String file)

        throws IOException

    {

        Scanner scanner = new Scanner(new File(file));

        try {

            List<Rule> result = new ArrayList<Rule>();

            while (scanner.hasNextLine()) {

                String line = scanner.nextLine().trim();

                // skip blank lines and comments

                if (line.length() == 0 || line.charAt(0) == '#')

                    continue;

                // must have 3 fields

                String[] s = line.split("\\s+");

                if (s.length != 3) {

                    fail("Malformed line '%s'", line);

                    continue;

                }

                // first field is the action ("bind" or "connect")

                Action action = null;

                for (Action a: Action.values()) {

                    if (s[0].equalsIgnoreCase(a.name())) {

                        action = a;

                        break;

                    }

                }

                if (action == null) {

                    fail("Action '%s' not recognized", s[0]);

                    continue;

                }

                // * port[-end]

                int[] ports = parsePortRange(s[2]);

                if (ports.length == 0) {

                    fail("Malformed port range '%s'", s[2]);

                    continue;

                }

                // match all addresses

                if (s[1].equals("*")) {

                    result.add(new PortRangeRule(action, ports[0], ports[1]));

                    continue;

                }

                // hostname | ipaddress[/prefix]

                int pos = s[1].indexOf('/');

                try {

                    if (pos < 0) {

                        // hostname or ipaddress (no prefix)

                        InetAddress[] addresses = InetAddress.getAllByName(s[1]);

                        for (InetAddress address: addresses) {

                            int prefix =

                                (address instanceof Inet4Address) ? 32 : 128;

                            result.add(new AddressPortRangeRule(action, address,

                                prefix, ports[0], ports[1]));

                        }

                    } else {

                        // ipaddress/prefix

                        InetAddress address = InetAddress

                            .getByName(s[1].substring(0, pos));

                        int prefix = -1;

                        try {

                            prefix = Integer.parseInt(s[1].substring(pos+1));

                            if (address instanceof Inet4Address) {

                                // must be 1-31

                                if (prefix < 0 || prefix > 32) prefix = -1;

                            } else {

                                // must be 1-128

                                if (prefix < 0 || prefix > 128) prefix = -1;

                            }

                        } catch (NumberFormatException e) {

                        }

                        if (prefix > 0) {

                            result.add(new AddressPortRangeRule(action,

                                        address, prefix, ports[0], ports[1]));

                        } else {

                            fail("Malformed prefix '%s'", s[1]);

                            continue;

                        }

                    }

                } catch (UnknownHostException uhe) {

                    fail("Unknown host or malformed IP address '%s'", s[1]);

                    continue;

                }

            }

            return result;

        } finally {

            scanner.close();

        }

    }

    // converts unbound TCP socket to a SDP socket if it matches the rules

    private void convertTcpToSdpIfMatch(FileDescriptor fdObj,

                                               Action action,

                                               InetAddress address,

                                               int port)

        throws IOException

    {

        boolean matched = false;

        for (Rule rule: rules) {

            if (rule.match(action, address, port)) {

                int fd = fdAccess.get(fdObj);

                convert(fd);

                matched = true;

                break;

            }

        }

        if (log != null) {

            String addr = (address instanceof Inet4Address) ?

                address.getHostAddress() : "[" + address.getHostAddress() + "]";

            if (matched) {

                log.format("%s to %s:%d (socket converted to SDP protocol)\n", action, addr, port);

            } else {

                log.format("%s to %s:%d (no match)\n", action, addr, port);

            }

        }

    }

    @Override

    public void implBeforeTcpBind(FileDescriptor fdObj,

                              InetAddress address,

                              int port)

        throws IOException

    {

        if (enabled)

            convertTcpToSdpIfMatch(fdObj, Action.BIND, address, port);

    }

    @Override

    public void implBeforeTcpConnect(FileDescriptor fdObj,

                                InetAddress address,

                                int port)

        throws IOException

    {

        if (enabled)

            convertTcpToSdpIfMatch(fdObj, Action.CONNECT, address, port);

    }

    // -- native methods --

    private static native void convert(int fd) throws IOException;

}