/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.net;

import android.os.Parcel;
import android.util.Log;
import android.util.Pair;

import java.io.FileDescriptor;
import java.math.BigInteger;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Collection;
import java.util.Locale;
import java.util.TreeSet;

Native methods for managing network interfaces.
{@hide}
/**
 * Native methods for managing network interfaces.
 *
 * {@hide}
 */
public class NetworkUtils {

    private static final String TAG = "NetworkUtils";

    
Attaches a socket filter that accepts DHCP packets to the given socket.
/**
     * Attaches a socket filter that accepts DHCP packets to the given socket.
     */
    public native static void attachDhcpFilter(FileDescriptor fd) throws SocketException;

    
Attaches a socket filter that accepts ICMPv6 router advertisements to the given socket.
Params:
fd – the socket's FileDescriptor.
packetType – the hardware address type, one of ARPHRD_*./**
     * Attaches a socket filter that accepts ICMPv6 router advertisements to the given socket.
     * @param fd the socket's {@link FileDescriptor}.
     * @param packetType the hardware address type, one of ARPHRD_*.
     */
    public native static void attachRaFilter(FileDescriptor fd, int packetType) throws SocketException;

    
Attaches a socket filter that accepts L2-L4 signaling traffic required for IP connectivity.
This includes: all ARP, ICMPv6 RS/RA/NS/NA messages, and DHCPv4 exchanges.
Params:
fd – the socket's FileDescriptor.
packetType – the hardware address type, one of ARPHRD_*./**
     * Attaches a socket filter that accepts L2-L4 signaling traffic required for IP connectivity.
     *
     * This includes: all ARP, ICMPv6 RS/RA/NS/NA messages, and DHCPv4 exchanges.
     *
     * @param fd the socket's {@link FileDescriptor}.
     * @param packetType the hardware address type, one of ARPHRD_*.
     */
    public native static void attachControlPacketFilter(FileDescriptor fd, int packetType)
            throws SocketException;

    
Configures a socket for receiving ICMPv6 router solicitations and sending advertisements.
Params:
fd – the socket's FileDescriptor.
ifIndex – the interface index./**
     * Configures a socket for receiving ICMPv6 router solicitations and sending advertisements.
     * @param fd the socket's {@link FileDescriptor}.
     * @param ifIndex the interface index.
     */
    public native static void setupRaSocket(FileDescriptor fd, int ifIndex) throws SocketException;

    
Binds the current process to the network designated by netId. All sockets created in the future (and not explicitly bound via a bound SocketFactory (see Network.getSocketFactory) will be bound to this network. Note that if this Network ever disconnects all sockets created in this way will cease to work. This is by design so an application doesn't accidentally use sockets it thinks are still bound to a particular Network. Passing NETID_UNSET clears the binding. /**
     * Binds the current process to the network designated by {@code netId}.  All sockets created
     * in the future (and not explicitly bound via a bound {@link SocketFactory} (see
     * {@link Network#getSocketFactory}) will be bound to this network.  Note that if this
     * {@code Network} ever disconnects all sockets created in this way will cease to work.  This
     * is by design so an application doesn't accidentally use sockets it thinks are still bound to
     * a particular {@code Network}.  Passing NETID_UNSET clears the binding.
     */
    public native static boolean bindProcessToNetwork(int netId);

    
Return the netId last passed to bindProcessToNetwork, or NETID_UNSET if unbindProcessToNetwork has been called since bindProcessToNetwork. /**
     * Return the netId last passed to {@link #bindProcessToNetwork}, or NETID_UNSET if
     * {@link #unbindProcessToNetwork} has been called since {@link #bindProcessToNetwork}.
     */
    public native static int getBoundNetworkForProcess();

    
Binds host resolutions performed by this process to the network designated by netId. bindProcessToNetwork takes precedence over this setting. Passing NETID_UNSET clears the binding. 
Deprecated:
This is strictly for legacy usage to support startUsingNetworkFeature()./**
     * Binds host resolutions performed by this process to the network designated by {@code netId}.
     * {@link #bindProcessToNetwork} takes precedence over this setting.  Passing NETID_UNSET clears
     * the binding.
     *
     * @deprecated This is strictly for legacy usage to support startUsingNetworkFeature().
     */
    @Deprecated
    public native static boolean bindProcessToNetworkForHostResolution(int netId);

    
Explicitly binds socketfd to the network designated by netId. This overrides any binding via bindProcessToNetwork. 
Returns:
0 on success or negative errno on failure./**
     * Explicitly binds {@code socketfd} to the network designated by {@code netId}.  This
     * overrides any binding via {@link #bindProcessToNetwork}.
     * @return 0 on success or negative errno on failure.
     */
    public native static int bindSocketToNetwork(int socketfd, int netId);

    
Protect fd from VPN connections. After protecting, data sent through this socket will go directly to the underlying network, so its traffic will not be forwarded through the VPN. /**
     * Protect {@code fd} from VPN connections.  After protecting, data sent through
     * this socket will go directly to the underlying network, so its traffic will not be
     * forwarded through the VPN.
     */
    public static boolean protectFromVpn(FileDescriptor fd) {
        return protectFromVpn(fd.getInt$());
    }

    
Protect socketfd from VPN connections. After protecting, data sent through this socket will go directly to the underlying network, so its traffic will not be forwarded through the VPN. /**
     * Protect {@code socketfd} from VPN connections.  After protecting, data sent through
     * this socket will go directly to the underlying network, so its traffic will not be
     * forwarded through the VPN.
     */
    public native static boolean protectFromVpn(int socketfd);

    
Determine if uid can access network designated by netId. 
Returns:
true if uid can access network, false otherwise./**
     * Determine if {@code uid} can access network designated by {@code netId}.
     * @return {@code true} if {@code uid} can access network, {@code false} otherwise.
     */
    public native static boolean queryUserAccess(int uid, int netId);

    
Convert a IPv4 address from an integer to an InetAddress.
Params:
hostAddress – an int corresponding to the IPv4 address in network byte order/**
     * Convert a IPv4 address from an integer to an InetAddress.
     * @param hostAddress an int corresponding to the IPv4 address in network byte order
     */
    public static InetAddress intToInetAddress(int hostAddress) {
        byte[] addressBytes = { (byte)(0xff & hostAddress),
                                (byte)(0xff & (hostAddress >> 8)),
                                (byte)(0xff & (hostAddress >> 16)),
                                (byte)(0xff & (hostAddress >> 24)) };

        try {
           return InetAddress.getByAddress(addressBytes);
        } catch (UnknownHostException e) {
           throw new AssertionError();
        }
    }

    
Convert a IPv4 address from an InetAddress to an integer
Params:
inetAddr – is an InetAddress corresponding to the IPv4 address
Returns:
the IP address as an integer in network byte order/**
     * Convert a IPv4 address from an InetAddress to an integer
     * @param inetAddr is an InetAddress corresponding to the IPv4 address
     * @return the IP address as an integer in network byte order
     */
    public static int inetAddressToInt(Inet4Address inetAddr)
            throws IllegalArgumentException {
        byte [] addr = inetAddr.getAddress();
        return ((addr[3] & 0xff) << 24) | ((addr[2] & 0xff) << 16) |
                ((addr[1] & 0xff) << 8) | (addr[0] & 0xff);
    }

    
Convert a network prefix length to an IPv4 netmask integer
Params:
prefixLength – 
Returns:
the IPv4 netmask as an integer in network byte order/**
     * Convert a network prefix length to an IPv4 netmask integer
     * @param prefixLength
     * @return the IPv4 netmask as an integer in network byte order
     */
    public static int prefixLengthToNetmaskInt(int prefixLength)
            throws IllegalArgumentException {
        if (prefixLength < 0 || prefixLength > 32) {
            throw new IllegalArgumentException("Invalid prefix length (0 <= prefix <= 32)");
        }
        int value = 0xffffffff << (32 - prefixLength);
        return Integer.reverseBytes(value);
    }

    
Convert a IPv4 netmask integer to a prefix length
Params:
netmask – as an integer in network byte order
Returns:
the network prefix length/**
     * Convert a IPv4 netmask integer to a prefix length
     * @param netmask as an integer in network byte order
     * @return the network prefix length
     */
    public static int netmaskIntToPrefixLength(int netmask) {
        return Integer.bitCount(netmask);
    }

    
Convert an IPv4 netmask to a prefix length, checking that the netmask is contiguous.
Params:
netmask – as a Inet4Address.
Throws:
IllegalArgumentException – the specified netmask was not contiguous.
Returns:
the network prefix length
@hide
/**
     * Convert an IPv4 netmask to a prefix length, checking that the netmask is contiguous.
     * @param netmask as a {@code Inet4Address}.
     * @return the network prefix length
     * @throws IllegalArgumentException the specified netmask was not contiguous.
     * @hide
     */
    public static int netmaskToPrefixLength(Inet4Address netmask) {
        // inetAddressToInt returns an int in *network* byte order.
        int i = Integer.reverseBytes(inetAddressToInt(netmask));
        int prefixLength = Integer.bitCount(i);
        int trailingZeros = Integer.numberOfTrailingZeros(i);
        if (trailingZeros != 32 - prefixLength) {
            throw new IllegalArgumentException("Non-contiguous netmask: " + Integer.toHexString(i));
        }
        return prefixLength;
    }


    
Create an InetAddress from a string where the string must be a standard
representation of a V4 or V6 address.  Avoids doing a DNS lookup on failure
but it will throw an IllegalArgumentException in that case.
Params:
addrString – 
Returns:
the InetAddress
@hide
/**
     * Create an InetAddress from a string where the string must be a standard
     * representation of a V4 or V6 address.  Avoids doing a DNS lookup on failure
     * but it will throw an IllegalArgumentException in that case.
     * @param addrString
     * @return the InetAddress
     * @hide
     */
    public static InetAddress numericToInetAddress(String addrString)
            throws IllegalArgumentException {
        return InetAddress.parseNumericAddress(addrString);
    }

    
Writes an InetAddress to a parcel. The address may be null. This is likely faster than
calling writeSerializable.
/**
     * Writes an InetAddress to a parcel. The address may be null. This is likely faster than
     * calling writeSerializable.
     */
    protected static void parcelInetAddress(Parcel parcel, InetAddress address, int flags) {
        byte[] addressArray = (address != null) ? address.getAddress() : null;
        parcel.writeByteArray(addressArray);
    }

    
Reads an InetAddress from a parcel. Returns null if the address that was written was null
or if the data is invalid.
/**
     * Reads an InetAddress from a parcel. Returns null if the address that was written was null
     * or if the data is invalid.
     */
    protected static InetAddress unparcelInetAddress(Parcel in) {
        byte[] addressArray = in.createByteArray();
        if (addressArray == null) {
            return null;
        }
        try {
            return InetAddress.getByAddress(addressArray);
        } catch (UnknownHostException e) {
            return null;
        }
    }


    
 Masks a raw IP address byte array with the specified prefix length.
/**
     *  Masks a raw IP address byte array with the specified prefix length.
     */
    public static void maskRawAddress(byte[] array, int prefixLength) {
        if (prefixLength < 0 || prefixLength > array.length * 8) {
            throw new RuntimeException("IP address with " + array.length +
                    " bytes has invalid prefix length " + prefixLength);
        }

        int offset = prefixLength / 8;
        int remainder = prefixLength % 8;
        byte mask = (byte)(0xFF << (8 - remainder));

        if (offset < array.length) array[offset] = (byte)(array[offset] & mask);

        offset++;

        for (; offset < array.length; offset++) {
            array[offset] = 0;
        }
    }

    
Get InetAddress masked with prefixLength.  Will never return null.
Params:
address – the IP address to mask with
prefixLength – the prefixLength used to mask the IP/**
     * Get InetAddress masked with prefixLength.  Will never return null.
     * @param address the IP address to mask with
     * @param prefixLength the prefixLength used to mask the IP
     */
    public static InetAddress getNetworkPart(InetAddress address, int prefixLength) {
        byte[] array = address.getAddress();
        maskRawAddress(array, prefixLength);

        InetAddress netPart = null;
        try {
            netPart = InetAddress.getByAddress(array);
        } catch (UnknownHostException e) {
            throw new RuntimeException("getNetworkPart error - " + e.toString());
        }
        return netPart;
    }

    
Returns the implicit netmask of an IPv4 address, as was the custom before 1993.
/**
     * Returns the implicit netmask of an IPv4 address, as was the custom before 1993.
     */
    public static int getImplicitNetmask(Inet4Address address) {
        int firstByte = address.getAddress()[0] & 0xff;  // Convert to an unsigned value.
        if (firstByte < 128) {
            return 8;
        } else if (firstByte < 192) {
            return 16;
        } else if (firstByte < 224) {
            return 24;
        } else {
            return 32;  // Will likely not end well for other reasons.
        }
    }

    
Utility method to parse strings such as "192.0.2.5/24" or "2001:db8::cafe:d00d/64".
@hide
/**
     * Utility method to parse strings such as "192.0.2.5/24" or "2001:db8::cafe:d00d/64".
     * @hide
     */
    public static Pair<InetAddress, Integer> parseIpAndMask(String ipAndMaskString) {
        InetAddress address = null;
        int prefixLength = -1;
        try {
            String[] pieces = ipAndMaskString.split("/", 2);
            prefixLength = Integer.parseInt(pieces[1]);
            address = InetAddress.parseNumericAddress(pieces[0]);
        } catch (NullPointerException e) {            // Null string.
        } catch (ArrayIndexOutOfBoundsException e) {  // No prefix length.
        } catch (NumberFormatException e) {           // Non-numeric prefix.
        } catch (IllegalArgumentException e) {        // Invalid IP address.
        }

        if (address == null || prefixLength == -1) {
            throw new IllegalArgumentException("Invalid IP address and mask " + ipAndMaskString);
        }

        return new Pair<InetAddress, Integer>(address, prefixLength);
    }

    
Check if IP address type is consistent between two InetAddress.
Returns:
true if both are the same type.  False otherwise./**
     * Check if IP address type is consistent between two InetAddress.
     * @return true if both are the same type.  False otherwise.
     */
    public static boolean addressTypeMatches(InetAddress left, InetAddress right) {
        return (((left instanceof Inet4Address) && (right instanceof Inet4Address)) ||
                ((left instanceof Inet6Address) && (right instanceof Inet6Address)));
    }

    
Convert a 32 char hex string into a Inet6Address.
throws a runtime exception if the string isn't 32 chars, isn't hex or can't be
made into an Inet6Address
Params:
addrHexString – a 32 character hex string representing an IPv6 addr
Returns:
addr an InetAddress representation for the string/**
     * Convert a 32 char hex string into a Inet6Address.
     * throws a runtime exception if the string isn't 32 chars, isn't hex or can't be
     * made into an Inet6Address
     * @param addrHexString a 32 character hex string representing an IPv6 addr
     * @return addr an InetAddress representation for the string
     */
    public static InetAddress hexToInet6Address(String addrHexString)
            throws IllegalArgumentException {
        try {
            return numericToInetAddress(String.format(Locale.US, "%s:%s:%s:%s:%s:%s:%s:%s",
                    addrHexString.substring(0,4),   addrHexString.substring(4,8),
                    addrHexString.substring(8,12),  addrHexString.substring(12,16),
                    addrHexString.substring(16,20), addrHexString.substring(20,24),
                    addrHexString.substring(24,28), addrHexString.substring(28,32)));
        } catch (Exception e) {
            Log.e("NetworkUtils", "error in hexToInet6Address(" + addrHexString + "): " + e);
            throw new IllegalArgumentException(e);
        }
    }

    
Create a string array of host addresses from a collection of InetAddresses
Params:
addrs – a Collection of InetAddresses
Returns:
an array of Strings containing their host addresses/**
     * Create a string array of host addresses from a collection of InetAddresses
     * @param addrs a Collection of InetAddresses
     * @return an array of Strings containing their host addresses
     */
    public static String[] makeStrings(Collection<InetAddress> addrs) {
        String[] result = new String[addrs.size()];
        int i = 0;
        for (InetAddress addr : addrs) {
            result[i++] = addr.getHostAddress();
        }
        return result;
    }

    
Trim leading zeros from IPv4 address strings
Our base libraries will interpret that as octel..
Must leave non v4 addresses and host names alone.
For example, 192.168.000.010 -> 192.168.0.10
TODO - fix base libraries and remove this function
Params:
addr – a string representing an ip addr
Returns:
a string propertly trimmed/**
     * Trim leading zeros from IPv4 address strings
     * Our base libraries will interpret that as octel..
     * Must leave non v4 addresses and host names alone.
     * For example, 192.168.000.010 -> 192.168.0.10
     * TODO - fix base libraries and remove this function
     * @param addr a string representing an ip addr
     * @return a string propertly trimmed
     */
    public static String trimV4AddrZeros(String addr) {
        if (addr == null) return null;
        String[] octets = addr.split("\\.");
        if (octets.length != 4) return addr;
        StringBuilder builder = new StringBuilder(16);
        String result = null;
        for (int i = 0; i < 4; i++) {
            try {
                if (octets[i].length() > 3) return addr;
                builder.append(Integer.parseInt(octets[i]));
            } catch (NumberFormatException e) {
                return addr;
            }
            if (i < 3) builder.append('.');
        }
        result = builder.toString();
        return result;
    }

    
Returns a prefix set without overlaps.
This expects the src set to be sorted from shorter to longer. Results are undefined
failing this condition. The returned prefix set is sorted in the same order as the
passed set, with the same comparator.
/**
     * Returns a prefix set without overlaps.
     *
     * This expects the src set to be sorted from shorter to longer. Results are undefined
     * failing this condition. The returned prefix set is sorted in the same order as the
     * passed set, with the same comparator.
     */
    private static TreeSet<IpPrefix> deduplicatePrefixSet(final TreeSet<IpPrefix> src) {
        final TreeSet<IpPrefix> dst = new TreeSet<>(src.comparator());
        // Prefixes match addresses that share their upper part up to their length, therefore
        // the only kind of possible overlap in two prefixes is strict inclusion of the longer
        // (more restrictive) in the shorter (including equivalence if they have the same
        // length).
        // Because prefixes in the src set are sorted from shorter to longer, deduplicating
        // is done by simply iterating in order, and not adding any longer prefix that is
        // already covered by a shorter one.
        newPrefixes:
        for (IpPrefix newPrefix : src) {
            for (IpPrefix existingPrefix : dst) {
                if (existingPrefix.containsPrefix(newPrefix)) {
                    continue newPrefixes;
                }
            }
            dst.add(newPrefix);
        }
        return dst;
    }

    
Returns how many IPv4 addresses match any of the prefixes in the passed ordered set.
Obviously this returns an integral value between 0 and 2**32.
The behavior is undefined if any of the prefixes is not an IPv4 prefix or if the
set is not ordered smallest prefix to longer prefix.
Params:
prefixes – the set of prefixes, ordered by length/**
     * Returns how many IPv4 addresses match any of the prefixes in the passed ordered set.
     *
     * Obviously this returns an integral value between 0 and 2**32.
     * The behavior is undefined if any of the prefixes is not an IPv4 prefix or if the
     * set is not ordered smallest prefix to longer prefix.
     *
     * @param prefixes the set of prefixes, ordered by length
     */
    public static long routedIPv4AddressCount(final TreeSet<IpPrefix> prefixes) {
        long routedIPCount = 0;
        for (final IpPrefix prefix : deduplicatePrefixSet(prefixes)) {
            if (!prefix.isIPv4()) {
                Log.wtf(TAG, "Non-IPv4 prefix in routedIPv4AddressCount");
            }
            int rank = 32 - prefix.getPrefixLength();
            routedIPCount += 1L << rank;
        }
        return routedIPCount;
    }

    
Returns how many IPv6 addresses match any of the prefixes in the passed ordered set.
This returns a BigInteger between 0 and 2**128.
The behavior is undefined if any of the prefixes is not an IPv6 prefix or if the
set is not ordered smallest prefix to longer prefix.
/**
     * Returns how many IPv6 addresses match any of the prefixes in the passed ordered set.
     *
     * This returns a BigInteger between 0 and 2**128.
     * The behavior is undefined if any of the prefixes is not an IPv6 prefix or if the
     * set is not ordered smallest prefix to longer prefix.
     */
    public static BigInteger routedIPv6AddressCount(final TreeSet<IpPrefix> prefixes) {
        BigInteger routedIPCount = BigInteger.ZERO;
        for (final IpPrefix prefix : deduplicatePrefixSet(prefixes)) {
            if (!prefix.isIPv6()) {
                Log.wtf(TAG, "Non-IPv6 prefix in routedIPv6AddressCount");
            }
            int rank = 128 - prefix.getPrefixLength();
            routedIPCount = routedIPCount.add(BigInteger.ONE.shiftLeft(rank));
        }
        return routedIPCount;
    }
}