/*

 * Copyright (c) 2004, 2015, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.net.util;

import java.io.IOException;

import java.io.UncheckedIOException;

import java.net.Inet6Address;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.net.NetworkInterface;

import java.net.SocketException;

import java.net.URL;

import java.security.AccessController;

import java.security.PrivilegedExceptionAction;

import java.security.PrivilegedActionException;

import java.util.Arrays;

import java.util.List;

import java.util.concurrent.ConcurrentHashMap;

import java.util.stream.Collectors;

public class IPAddressUtil {

    private static final int INADDR4SZ = 4;

    private static final int INADDR16SZ = 16;

    private static final int INT16SZ = 2;

    /*

     * Converts IPv4 address in its textual presentation form

     * into its numeric binary form.

     *

     * @param src a String representing an IPv4 address in standard format

     * @return a byte array representing the IPv4 numeric address

     */

    @SuppressWarnings("fallthrough")

    public static byte[] textToNumericFormatV4(String src)

    {

        byte[] res = new byte[INADDR4SZ];

        long tmpValue = 0;

        int currByte = 0;

        boolean newOctet = true;

        int len = src.length();

        if (len == 0 || len > 15) {

            return null;

        }

        /*

         * When only one part is given, the value is stored directly in

         * the network address without any byte rearrangement.

         *

         * When a two part address is supplied, the last part is

         * interpreted as a 24-bit quantity and placed in the right

         * most three bytes of the network address. This makes the

         * two part address format convenient for specifying Class A

         * network addresses as net.host.

         *

         * When a three part address is specified, the last part is

         * interpreted as a 16-bit quantity and placed in the right

         * most two bytes of the network address. This makes the

         * three part address format convenient for specifying

         * Class B net- work addresses as 128.net.host.

         *

         * When four parts are specified, each is interpreted as a

         * byte of data and assigned, from left to right, to the

         * four bytes of an IPv4 address.

         *

         * We determine and parse the leading parts, if any, as single

         * byte values in one pass directly into the resulting byte[],

         * then the remainder is treated as a 8-to-32-bit entity and

         * translated into the remaining bytes in the array.

         */

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

            char c = src.charAt(i);

            if (c == '.') {

                if (newOctet || tmpValue < 0 || tmpValue > 0xff || currByte == 3) {

                    return null;

                }

                res[currByte++] = (byte) (tmpValue & 0xff);

                tmpValue = 0;

                newOctet = true;

            } else {

                int digit = Character.digit(c, 10);

                if (digit < 0) {

                    return null;

                }

                tmpValue *= 10;

                tmpValue += digit;

                newOctet = false;

            }

        }

        if (newOctet || tmpValue < 0 || tmpValue >= (1L << ((4 - currByte) * 8))) {

            return null;

        }

        switch (currByte) {

            case 0:

                res[0] = (byte) ((tmpValue >> 24) & 0xff);

            case 1:

                res[1] = (byte) ((tmpValue >> 16) & 0xff);

            case 2:

                res[2] = (byte) ((tmpValue >>  8) & 0xff);

            case 3:

                res[3] = (byte) ((tmpValue >>  0) & 0xff);

        }

        return res;

    }

    /*

     * Convert IPv6 presentation level address to network order binary form.

     * credit:

     *  Converted from C code from Solaris 8 (inet_pton)

     *

     * Any component of the string following a per-cent % is ignored.

     *

     * @param src a String representing an IPv6 address in textual format

     * @return a byte array representing the IPv6 numeric address

     */

    public static byte[] textToNumericFormatV6(String src)

    {

        // Shortest valid string is "::", hence at least 2 chars

        if (src.length() < 2) {

            return null;

        }

        int colonp;

        char ch;

        boolean saw_xdigit;

        int val;

        char[] srcb = src.toCharArray();

        byte[] dst = new byte[INADDR16SZ];

        int srcb_length = srcb.length;

        int pc = src.indexOf ('%');

        if (pc == srcb_length -1) {

            return null;

        }

        if (pc != -1) {

            srcb_length = pc;

        }

        colonp = -1;

        int i = 0, j = 0;

        /* Leading :: requires some special handling. */

        if (srcb[i] == ':')

            if (srcb[++i] != ':')

                return null;

        int curtok = i;

        saw_xdigit = false;

        val = 0;

        while (i < srcb_length) {

            ch = srcb[i++];

            int chval = Character.digit(ch, 16);

            if (chval != -1) {

                val <<= 4;

                val |= chval;

                if (val > 0xffff)

                    return null;

                saw_xdigit = true;

                continue;

            }

            if (ch == ':') {

                curtok = i;

                if (!saw_xdigit) {

                    if (colonp != -1)

                        return null;

                    colonp = j;

                    continue;

                } else if (i == srcb_length) {

                    return null;

                }

                if (j + INT16SZ > INADDR16SZ)

                    return null;

                dst[j++] = (byte) ((val >> 8) & 0xff);

                dst[j++] = (byte) (val & 0xff);

                saw_xdigit = false;

                val = 0;

                continue;

            }

            if (ch == '.' && ((j + INADDR4SZ) <= INADDR16SZ)) {

                String ia4 = src.substring(curtok, srcb_length);

                /* check this IPv4 address has 3 dots, i.e. A.B.C.D */

                int dot_count = 0, index=0;

                while ((index = ia4.indexOf ('.', index)) != -1) {

                    dot_count ++;

                    index ++;

                }

                if (dot_count != 3) {

                    return null;

                }

                byte[] v4addr = textToNumericFormatV4(ia4);

                if (v4addr == null) {

                    return null;

                }

                for (int k = 0; k < INADDR4SZ; k++) {

                    dst[j++] = v4addr[k];

                }

                saw_xdigit = false;

                break;  /* '\0' was seen by inet_pton4(). */

            }

            return null;

        }

        if (saw_xdigit) {

            if (j + INT16SZ > INADDR16SZ)

                return null;

            dst[j++] = (byte) ((val >> 8) & 0xff);

            dst[j++] = (byte) (val & 0xff);

        }

        if (colonp != -1) {

            int n = j - colonp;

            if (j == INADDR16SZ)

                return null;

            for (i = 1; i <= n; i++) {

                dst[INADDR16SZ - i] = dst[colonp + n - i];

                dst[colonp + n - i] = 0;

            }

            j = INADDR16SZ;

        }

        if (j != INADDR16SZ)

            return null;

        byte[] newdst = convertFromIPv4MappedAddress(dst);

        if (newdst != null) {

            return newdst;

        } else {

            return dst;

        }

    }

    /**

     * @param src a String representing an IPv4 address in textual format

     * @return a boolean indicating whether src is an IPv4 literal address

     */

    public static boolean isIPv4LiteralAddress(String src) {

        return textToNumericFormatV4(src) != null;

    }

    /**

     * @param src a String representing an IPv6 address in textual format

     * @return a boolean indicating whether src is an IPv6 literal address

     */

    public static boolean isIPv6LiteralAddress(String src) {

        return textToNumericFormatV6(src) != null;

    }

    /*

     * Convert IPv4-Mapped address to IPv4 address. Both input and

     * returned value are in network order binary form.

     *

     * @param src a String representing an IPv4-Mapped address in textual format

     * @return a byte array representing the IPv4 numeric address

     */

    public static byte[] convertFromIPv4MappedAddress(byte[] addr) {

        if (isIPv4MappedAddress(addr)) {

            byte[] newAddr = new byte[INADDR4SZ];

            System.arraycopy(addr, 12, newAddr, 0, INADDR4SZ);

            return newAddr;

        }

        return null;

    }

    /**

     * Utility routine to check if the InetAddress is an

     * IPv4 mapped IPv6 address.

     *

     * @return a <code>boolean</code> indicating if the InetAddress is

     * an IPv4 mapped IPv6 address; or false if address is IPv4 address.

     */

    private static boolean isIPv4MappedAddress(byte[] addr) {

        if (addr.length < INADDR16SZ) {

            return false;

        }

        if ((addr[0] == 0x00) && (addr[1] == 0x00) &&

            (addr[2] == 0x00) && (addr[3] == 0x00) &&

            (addr[4] == 0x00) && (addr[5] == 0x00) &&

            (addr[6] == 0x00) && (addr[7] == 0x00) &&

            (addr[8] == 0x00) && (addr[9] == 0x00) &&

            (addr[10] == (byte)0xff) &&

            (addr[11] == (byte)0xff))  {

            return true;

        }

        return false;

    }

    /**

     * Mapping from unscoped local Inet(6)Address to the same address

     * including the correct scope-id, determined from NetworkInterface.

     */

    private final static ConcurrentHashMap<InetAddress,InetAddress>

        cache = new ConcurrentHashMap<>();

    /**

     * Returns a scoped version of the supplied local, link-local ipv6 address

     * if that scope-id can be determined from local NetworkInterfaces.

     * If the address already has a scope-id or if the address is not local, ipv6

     * or link local, then the original address is returned.

     *

     * @param addr

     * @exception SocketException if the given ipv6 link local address is found

     *            on more than one local interface

     * @return

     */

    public static InetAddress toScopedAddress(InetAddress address)

        throws SocketException {

        if (address instanceof Inet6Address && address.isLinkLocalAddress()

            && ((Inet6Address) address).getScopeId() == 0) {

            InetAddress cached = null;

            try {

                cached = cache.computeIfAbsent(address, k -> findScopedAddress(k));

            } catch (UncheckedIOException e) {

                throw (SocketException)e.getCause();

            }

            return cached != null ? cached : address;

        } else {

            return address;

        }

    }

    /**

     * Same as above for InetSocketAddress

     */

    public static InetSocketAddress toScopedAddress(InetSocketAddress address)

        throws SocketException {

        InetAddress addr;

        InetAddress orig = address.getAddress();

        if ((addr = toScopedAddress(orig)) == orig) {

            return address;

        } else {

            return new InetSocketAddress(addr, address.getPort());

        }

    }

    private static InetAddress findScopedAddress(InetAddress address) {

        PrivilegedExceptionAction<List<InetAddress>> pa = () -> NetworkInterface.networkInterfaces()

                .flatMap(NetworkInterface::inetAddresses)

                .filter(a -> (a instanceof Inet6Address)

                        && address.equals(a)

                        && ((Inet6Address) a).getScopeId() != 0)

                .collect(Collectors.toList());

        List<InetAddress> result;

        try {

            result = AccessController.doPrivileged(pa);

            var sz = result.size();

            if (sz == 0)

                return null;

            if (sz > 1)

                throw new UncheckedIOException(new SocketException(

                    "Duplicate link local addresses: must specify scope-id"));

            return result.get(0);

        } catch (PrivilegedActionException pae) {

            return null;

        }

    }

    // See java.net.URI for more details on how to generate these

    // masks.

    //

    // square brackets

    private static final long L_IPV6_DELIMS = 0x0L; // "[]"

    private static final long H_IPV6_DELIMS = 0x28000000L; // "[]"

    // RFC 3986 gen-delims

    private static final long L_GEN_DELIMS = 0x8400800800000000L; // ":/?#[]@"

    private static final long H_GEN_DELIMS = 0x28000001L; // ":/?#[]@"

    // These gen-delims can appear in authority

    private static final long L_AUTH_DELIMS = 0x400000000000000L; // "@[]:"

    private static final long H_AUTH_DELIMS = 0x28000001L; // "@[]:"

    // colon is allowed in userinfo

    private static final long L_COLON = 0x400000000000000L; // ":"

    private static final long H_COLON = 0x0L; // ":"

    // slash should be encoded in authority

    private static final long L_SLASH = 0x800000000000L; // "/"

    private static final long H_SLASH = 0x0L; // "/"

    // backslash should always be encoded

    private static final long L_BACKSLASH = 0x0L; // "\"

    private static final long H_BACKSLASH = 0x10000000L; // "\"

    // ASCII chars 0-31 + 127 - various controls + CRLF + TAB

    private static final long L_NON_PRINTABLE = 0xffffffffL;

    private static final long H_NON_PRINTABLE = 0x8000000000000000L;

    // All of the above

    private static final long L_EXCLUDE = 0x84008008ffffffffL;

    private static final long H_EXCLUDE = 0x8000000038000001L;

    private static final char[] OTHERS = {

            8263,8264,8265,8448,8449,8453,8454,10868,

            65109,65110,65119,65131,65283,65295,65306,65311,65312

    };

    // Tell whether the given character is found by the given mask pair

    public static boolean match(char c, long lowMask, long highMask) {

        if (c < 64)

            return ((1L << c) & lowMask) != 0;

        if (c < 128)

            return ((1L << (c - 64)) & highMask) != 0;

        return false; // other non ASCII characters are not filtered

    }

    // returns -1 if the string doesn't contain any characters

    // from the mask, the index of the first such character found

    // otherwise.

    public static int scan(String s, long lowMask, long highMask) {

        int i = -1, len;

        if (s == null || (len = s.length()) == 0) return -1;

        boolean match = false;

        while (++i < len && !(match = match(s.charAt(i), lowMask, highMask)));

        if (match) return i;

        return -1;

    }

    public static int scan(String s, long lowMask, long highMask, char[] others) {

        int i = -1, len;

        if (s == null || (len = s.length()) == 0) return -1;

        boolean match = false;

        char c, c0 = others[0];

        while (++i < len && !(match = match((c=s.charAt(i)), lowMask, highMask))) {

            if (c >= c0 && (Arrays.binarySearch(others, c) > -1)) {

                match = true; break;

            }

        }

        if (match) return i;

        return -1;

    }

    private static String describeChar(char c) {

        if (c < 32 || c == 127) {

            if (c == '\n') return "LF";

            if (c == '\r') return "CR";

            return "control char (code=" + (int)c + ")";

        }

        if (c == '\\') return "'\\'";

        return "'" + c + "'";

    }

    private static String checkUserInfo(String str) {

        // colon is permitted in user info

        int index = scan(str, L_EXCLUDE & ~L_COLON,

                H_EXCLUDE & ~H_COLON);

        if (index >= 0) {

            return "Illegal character found in user-info: "

                    + describeChar(str.charAt(index));

        }

        return null;

    }

    private static String checkHost(String str) {

        int index;

        if (str.startsWith("[") && str.endsWith("]")) {

            str = str.substring(1, str.length() - 1);

            if (isIPv6LiteralAddress(str)) {

                index = str.indexOf('%');

                if (index >= 0) {

                    index = scan(str = str.substring(index),

                            L_NON_PRINTABLE | L_IPV6_DELIMS,

                            H_NON_PRINTABLE | H_IPV6_DELIMS);

                    if (index >= 0) {

                        return "Illegal character found in IPv6 scoped address: "

                                + describeChar(str.charAt(index));

                    }

                }

                return null;

            }

            return "Unrecognized IPv6 address format";

        } else {

            index = scan(str, L_EXCLUDE, H_EXCLUDE);

            if (index >= 0) {

                return "Illegal character found in host: "

                        + describeChar(str.charAt(index));

            }

        }

        return null;

    }

    private static String checkAuth(String str) {

        int index = scan(str,

                L_EXCLUDE & ~L_AUTH_DELIMS,

                H_EXCLUDE & ~H_AUTH_DELIMS);

        if (index >= 0) {

            return "Illegal character found in authority: "

                    + describeChar(str.charAt(index));

        }

        return null;

    }