android/net/ipmemorystore/NetworkAttributes.java - platform/prebuilts/fullsdk/sources/android-29 - Git at Google

 /*
  * Copyright (C) 2018 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.ipmemorystore;

 import android.annotation.NonNull;
 import android.annotation.Nullable;

 import com.android.internal.annotations.VisibleForTesting;

 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.StringJoiner;

 /**
  * A POD object to represent attributes of a single L2 network entry.
  * @hide
  */
 public class NetworkAttributes {
     private static final boolean DBG = true;

     // Weight cutoff for grouping. To group, a similarity score is computed with the following
     // algorithm : if both fields are non-null and equals() then add their assigned weight, else if
     // both are null then add a portion of their assigned weight (see NULL_MATCH_WEIGHT),
     // otherwise add nothing.
     // As a guideline, this should be something like 60~75% of the total weights in this class. The
     // design states "in essence a reader should imagine that if two important columns don't match,
     // or one important and several unimportant columns don't match then the two records are
     // considered a different group".
     private static final float TOTAL_WEIGHT_CUTOFF = 520.0f;
     // The portion of the weight that is earned when scoring group-sameness by having both columns
     // being null. This is because some networks rightfully don't have some attributes (e.g. a
     // V6-only network won't have an assigned V4 address) and both being null should count for
     // something, but attributes may also be null just because data is unavailable.
     private static final float NULL_MATCH_WEIGHT = 0.25f;

     // The v4 address that was assigned to this device the last time it joined this network.
     // This typically comes from DHCP but could be something else like static configuration.
     // This does not apply to IPv6.
     // TODO : add a list of v6 prefixes for the v6 case.
     @Nullable
     public final Inet4Address assignedV4Address;
     private static final float WEIGHT_ASSIGNEDV4ADDR = 300.0f;

     // The lease expiry timestamp of v4 address allocated from DHCP server, in milliseconds.
     @Nullable
     public final Long assignedV4AddressExpiry;
     // lease expiry doesn't imply any correlation between "the same lease expiry value" and "the
     // same L3 network".
     private static final float WEIGHT_ASSIGNEDV4ADDREXPIRY = 0.0f;

     // Optionally supplied by the client if it has an opinion on L3 network. For example, this
     // could be a hash of the SSID + security type on WiFi.
     @Nullable
     public final String groupHint;
     private static final float WEIGHT_GROUPHINT = 300.0f;

     // The list of DNS server addresses.
     @Nullable
     public final List<InetAddress> dnsAddresses;
     private static final float WEIGHT_DNSADDRESSES = 200.0f;

     // The mtu on this network.
     @Nullable
     public final Integer mtu;
     private static final float WEIGHT_MTU = 50.0f;

     // The sum of all weights in this class. Tests ensure that this stays equal to the total of
     // all weights.
     /** @hide */
     @VisibleForTesting
     public static final float TOTAL_WEIGHT = WEIGHT_ASSIGNEDV4ADDR
             + WEIGHT_ASSIGNEDV4ADDREXPIRY
             + WEIGHT_GROUPHINT
             + WEIGHT_DNSADDRESSES
             + WEIGHT_MTU;

     /** @hide */
     @VisibleForTesting
     public NetworkAttributes(
             @Nullable final Inet4Address assignedV4Address,
             @Nullable final Long assignedV4AddressExpiry,
             @Nullable final String groupHint,
             @Nullable final List<InetAddress> dnsAddresses,
             @Nullable final Integer mtu) {
         if (mtu != null && mtu < 0) throw new IllegalArgumentException("MTU can't be negative");
         if (assignedV4AddressExpiry != null && assignedV4AddressExpiry <= 0) {
             throw new IllegalArgumentException("lease expiry can't be negative or zero");
         }
         this.assignedV4Address = assignedV4Address;
         this.assignedV4AddressExpiry = assignedV4AddressExpiry;
         this.groupHint = groupHint;
         this.dnsAddresses = null == dnsAddresses ? null :
                 Collections.unmodifiableList(new ArrayList<>(dnsAddresses));
         this.mtu = mtu;
     }

     @VisibleForTesting
     public NetworkAttributes(@NonNull final NetworkAttributesParcelable parcelable) {
         // The call to the other constructor must be the first statement of this constructor,
         // so everything has to be inline
         this((Inet4Address) getByAddressOrNull(parcelable.assignedV4Address),
                 parcelable.assignedV4AddressExpiry > 0
                         ? parcelable.assignedV4AddressExpiry : null,
                 parcelable.groupHint,
                 blobArrayToInetAddressList(parcelable.dnsAddresses),
                 parcelable.mtu >= 0 ? parcelable.mtu : null);
     }

     @Nullable
     private static InetAddress getByAddressOrNull(@Nullable final byte[] address) {
         if (null == address) return null;
         try {
             return InetAddress.getByAddress(address);
         } catch (UnknownHostException e) {
             return null;
         }
     }

     @Nullable
     private static List<InetAddress> blobArrayToInetAddressList(@Nullable final Blob[] blobs) {
         if (null == blobs) return null;
         final ArrayList<InetAddress> list = new ArrayList<>(blobs.length);
         for (final Blob b : blobs) {
             final InetAddress addr = getByAddressOrNull(b.data);
             if (null != addr) list.add(addr);
         }
         return list;
     }

     @Nullable
     private static Blob[] inetAddressListToBlobArray(@Nullable final List<InetAddress> addresses) {
         if (null == addresses) return null;
         final ArrayList<Blob> blobs = new ArrayList<>();
         for (int i = 0; i < addresses.size(); ++i) {
             final InetAddress addr = addresses.get(i);
             if (null == addr) continue;
             final Blob b = new Blob();
             b.data = addr.getAddress();
             blobs.add(b);
         }
         return blobs.toArray(new Blob[0]);
     }

     /** Converts this NetworkAttributes to a parcelable object */
     @NonNull
     public NetworkAttributesParcelable toParcelable() {
         final NetworkAttributesParcelable parcelable = new NetworkAttributesParcelable();
         parcelable.assignedV4Address =
                 (null == assignedV4Address) ? null : assignedV4Address.getAddress();
         parcelable.assignedV4AddressExpiry =
                 (null == assignedV4AddressExpiry) ? 0 : assignedV4AddressExpiry;
         parcelable.groupHint = groupHint;
         parcelable.dnsAddresses = inetAddressListToBlobArray(dnsAddresses);
         parcelable.mtu = (null == mtu) ? -1 : mtu;
         return parcelable;
     }

     private float samenessContribution(final float weight,
             @Nullable final Object o1, @Nullable final Object o2) {
         if (null == o1) {
             return (null == o2) ? weight * NULL_MATCH_WEIGHT : 0f;
         }
         return Objects.equals(o1, o2) ? weight : 0f;
     }

     /** @hide */
     public float getNetworkGroupSamenessConfidence(@NonNull final NetworkAttributes o) {
         final float samenessScore =
                 samenessContribution(WEIGHT_ASSIGNEDV4ADDR, assignedV4Address, o.assignedV4Address)
                 + samenessContribution(WEIGHT_ASSIGNEDV4ADDREXPIRY, assignedV4AddressExpiry,
                       o.assignedV4AddressExpiry)
                 + samenessContribution(WEIGHT_GROUPHINT, groupHint, o.groupHint)
                 + samenessContribution(WEIGHT_DNSADDRESSES, dnsAddresses, o.dnsAddresses)
                 + samenessContribution(WEIGHT_MTU, mtu, o.mtu);
         // The minimum is 0, the max is TOTAL_WEIGHT and should be represented by 1.0, and
         // TOTAL_WEIGHT_CUTOFF should represent 0.5, but there is no requirement that
         // TOTAL_WEIGHT_CUTOFF would be half of TOTAL_WEIGHT (indeed, it should not be).
         // So scale scores under the cutoff between 0 and 0.5, and the scores over the cutoff
         // between 0.5 and 1.0.
         if (samenessScore < TOTAL_WEIGHT_CUTOFF) {
             return samenessScore / (TOTAL_WEIGHT_CUTOFF * 2);
         } else {
             return (samenessScore - TOTAL_WEIGHT_CUTOFF) / (TOTAL_WEIGHT - TOTAL_WEIGHT_CUTOFF) / 2
                     + 0.5f;
         }
     }

     /** @hide */
     public static class Builder {
         @Nullable
         private Inet4Address mAssignedAddress;
         @Nullable
         private Long mAssignedAddressExpiry;
         @Nullable
         private String mGroupHint;
         @Nullable
         private List<InetAddress> mDnsAddresses;
         @Nullable
         private Integer mMtu;

         /**
          * Set the assigned address.
          * @param assignedV4Address The assigned address.
          * @return This builder.
          */
         public Builder setAssignedV4Address(@Nullable final Inet4Address assignedV4Address) {
             mAssignedAddress = assignedV4Address;
             return this;
         }

         /**
          * Set the lease expiry timestamp of assigned v4 address. Long.MAX_VALUE is used
          * to represent "infinite lease".
          *
          * @param assignedV4AddressExpiry The lease expiry timestamp of assigned v4 address.
          * @return This builder.
          */
         public Builder setAssignedV4AddressExpiry(
                 @Nullable final Long assignedV4AddressExpiry) {
             if (null != assignedV4AddressExpiry && assignedV4AddressExpiry <= 0) {
                 throw new IllegalArgumentException("lease expiry can't be negative or zero");
             }
             mAssignedAddressExpiry = assignedV4AddressExpiry;
             return this;
         }

         /**
          * Set the group hint.
          * @param groupHint The group hint.
          * @return This builder.
          */
         public Builder setGroupHint(@Nullable final String groupHint) {
             mGroupHint = groupHint;
             return this;
         }

         /**
          * Set the DNS addresses.
          * @param dnsAddresses The DNS addresses.
          * @return This builder.
          */
         public Builder setDnsAddresses(@Nullable final List<InetAddress> dnsAddresses) {
             if (DBG && null != dnsAddresses) {
                 // Parceling code crashes if one of the addresses is null, therefore validate
                 // them when running in debug.
                 for (final InetAddress address : dnsAddresses) {
                     if (null == address) throw new IllegalArgumentException("Null DNS address");
                 }
             }
             this.mDnsAddresses = dnsAddresses;
             return this;
         }

         /**
          * Set the MTU.
          * @param mtu The MTU.
          * @return This builder.
          */
         public Builder setMtu(@Nullable final Integer mtu) {
             if (null != mtu && mtu < 0) throw new IllegalArgumentException("MTU can't be negative");
             mMtu = mtu;
             return this;
         }

         /**
          * Return the built NetworkAttributes object.
          * @return The built NetworkAttributes object.
          */
         public NetworkAttributes build() {
             return new NetworkAttributes(mAssignedAddress, mAssignedAddressExpiry,
                   mGroupHint, mDnsAddresses, mMtu);
         }
     }

     /** @hide */
     public boolean isEmpty() {
         return (null == assignedV4Address) && (null == assignedV4AddressExpiry)
                 && (null == groupHint) && (null == dnsAddresses) && (null == mtu);
     }

     @Override
     public boolean equals(@Nullable final Object o) {
         if (!(o instanceof NetworkAttributes)) return false;
         final NetworkAttributes other = (NetworkAttributes) o;
         return Objects.equals(assignedV4Address, other.assignedV4Address)
                 && Objects.equals(assignedV4AddressExpiry, other.assignedV4AddressExpiry)
                 && Objects.equals(groupHint, other.groupHint)
                 && Objects.equals(dnsAddresses, other.dnsAddresses)
                 && Objects.equals(mtu, other.mtu);
     }

     @Override
     public int hashCode() {
         return Objects.hash(assignedV4Address, assignedV4AddressExpiry,
                 groupHint, dnsAddresses, mtu);
     }

     /** Pretty print */
     @Override
     public String toString() {
         final StringJoiner resultJoiner = new StringJoiner(" ", "{", "}");
         final ArrayList<String> nullFields = new ArrayList<>();

         if (null != assignedV4Address) {
             resultJoiner.add("assignedV4Addr :");
             resultJoiner.add(assignedV4Address.toString());
         } else {
             nullFields.add("assignedV4Addr");
         }

         if (null != assignedV4AddressExpiry) {
             resultJoiner.add("assignedV4AddressExpiry :");
             resultJoiner.add(assignedV4AddressExpiry.toString());
         } else {
             nullFields.add("assignedV4AddressExpiry");
         }

         if (null != groupHint) {
             resultJoiner.add("groupHint :");
             resultJoiner.add(groupHint);
         } else {
             nullFields.add("groupHint");
         }

         if (null != dnsAddresses) {
             resultJoiner.add("dnsAddr : [");
             for (final InetAddress addr : dnsAddresses) {
                 resultJoiner.add(addr.getHostAddress());
             }
             resultJoiner.add("]");
         } else {
             nullFields.add("dnsAddr");
         }

         if (null != mtu) {
             resultJoiner.add("mtu :");
             resultJoiner.add(mtu.toString());
         } else {
             nullFields.add("mtu");
         }

         if (!nullFields.isEmpty()) {
             resultJoiner.add("; Null fields : [");
             for (final String field : nullFields) {
                 resultJoiner.add(field);
             }
             resultJoiner.add("]");
         }

         return resultJoiner.toString();
     }
 }
	/*
	* Copyright (C) 2018 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.ipmemorystore;

	import android.annotation.NonNull;
	import android.annotation.Nullable;

	import com.android.internal.annotations.VisibleForTesting;

	import java.net.Inet4Address;
	import java.net.InetAddress;
	import java.net.UnknownHostException;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.List;
	import java.util.Objects;
	import java.util.StringJoiner;

	/**
	* A POD object to represent attributes of a single L2 network entry.
	* @hide
	*/
	public class NetworkAttributes {
	private static final boolean DBG = true;

	// Weight cutoff for grouping. To group, a similarity score is computed with the following
	// algorithm : if both fields are non-null and equals() then add their assigned weight, else if
	// both are null then add a portion of their assigned weight (see NULL_MATCH_WEIGHT),
	// otherwise add nothing.
	// As a guideline, this should be something like 60~75% of the total weights in this class. The
	// design states "in essence a reader should imagine that if two important columns don't match,
	// or one important and several unimportant columns don't match then the two records are
	// considered a different group".
	private static final float TOTAL_WEIGHT_CUTOFF = 520.0f;
	// The portion of the weight that is earned when scoring group-sameness by having both columns
	// being null. This is because some networks rightfully don't have some attributes (e.g. a
	// V6-only network won't have an assigned V4 address) and both being null should count for
	// something, but attributes may also be null just because data is unavailable.
	private static final float NULL_MATCH_WEIGHT = 0.25f;

	// The v4 address that was assigned to this device the last time it joined this network.
	// This typically comes from DHCP but could be something else like static configuration.
	// This does not apply to IPv6.
	// TODO : add a list of v6 prefixes for the v6 case.
	@Nullable
	public final Inet4Address assignedV4Address;
	private static final float WEIGHT_ASSIGNEDV4ADDR = 300.0f;

	// The lease expiry timestamp of v4 address allocated from DHCP server, in milliseconds.
	@Nullable
	public final Long assignedV4AddressExpiry;
	// lease expiry doesn't imply any correlation between "the same lease expiry value" and "the
	// same L3 network".
	private static final float WEIGHT_ASSIGNEDV4ADDREXPIRY = 0.0f;

	// Optionally supplied by the client if it has an opinion on L3 network. For example, this
	// could be a hash of the SSID + security type on WiFi.
	@Nullable
	public final String groupHint;
	private static final float WEIGHT_GROUPHINT = 300.0f;

	// The list of DNS server addresses.
	@Nullable
	public final List<InetAddress> dnsAddresses;
	private static final float WEIGHT_DNSADDRESSES = 200.0f;

	// The mtu on this network.
	@Nullable
	public final Integer mtu;
	private static final float WEIGHT_MTU = 50.0f;

	// The sum of all weights in this class. Tests ensure that this stays equal to the total of
	// all weights.
	/** @hide */
	@VisibleForTesting
	public static final float TOTAL_WEIGHT = WEIGHT_ASSIGNEDV4ADDR
	+ WEIGHT_ASSIGNEDV4ADDREXPIRY
	+ WEIGHT_GROUPHINT
	+ WEIGHT_DNSADDRESSES
	+ WEIGHT_MTU;

	/** @hide */
	@VisibleForTesting
	public NetworkAttributes(
	@Nullable final Inet4Address assignedV4Address,
	@Nullable final Long assignedV4AddressExpiry,
	@Nullable final String groupHint,
	@Nullable final List<InetAddress> dnsAddresses,
	@Nullable final Integer mtu) {
	if (mtu != null && mtu < 0) throw new IllegalArgumentException("MTU can't be negative");
	if (assignedV4AddressExpiry != null && assignedV4AddressExpiry <= 0) {
	throw new IllegalArgumentException("lease expiry can't be negative or zero");
	}
	this.assignedV4Address = assignedV4Address;
	this.assignedV4AddressExpiry = assignedV4AddressExpiry;
	this.groupHint = groupHint;
	this.dnsAddresses = null == dnsAddresses ? null :
	Collections.unmodifiableList(new ArrayList<>(dnsAddresses));
	this.mtu = mtu;
	}

	@VisibleForTesting
	public NetworkAttributes(@NonNull final NetworkAttributesParcelable parcelable) {
	// The call to the other constructor must be the first statement of this constructor,
	// so everything has to be inline
	this((Inet4Address) getByAddressOrNull(parcelable.assignedV4Address),
	parcelable.assignedV4AddressExpiry > 0
	? parcelable.assignedV4AddressExpiry : null,
	parcelable.groupHint,
	blobArrayToInetAddressList(parcelable.dnsAddresses),
	parcelable.mtu >= 0 ? parcelable.mtu : null);
	}

	@Nullable
	private static InetAddress getByAddressOrNull(@Nullable final byte[] address) {
	if (null == address) return null;
	try {
	return InetAddress.getByAddress(address);
	} catch (UnknownHostException e) {
	return null;
	}
	}

	@Nullable
	private static List<InetAddress> blobArrayToInetAddressList(@Nullable final Blob[] blobs) {
	if (null == blobs) return null;
	final ArrayList<InetAddress> list = new ArrayList<>(blobs.length);
	for (final Blob b : blobs) {
	final InetAddress addr = getByAddressOrNull(b.data);
	if (null != addr) list.add(addr);
	}
	return list;
	}

	@Nullable
	private static Blob[] inetAddressListToBlobArray(@Nullable final List<InetAddress> addresses) {
	if (null == addresses) return null;
	final ArrayList<Blob> blobs = new ArrayList<>();
	for (int i = 0; i < addresses.size(); ++i) {
	final InetAddress addr = addresses.get(i);
	if (null == addr) continue;
	final Blob b = new Blob();
	b.data = addr.getAddress();
	blobs.add(b);
	}
	return blobs.toArray(new Blob[0]);
	}

	/** Converts this NetworkAttributes to a parcelable object */
	@NonNull
	public NetworkAttributesParcelable toParcelable() {
	final NetworkAttributesParcelable parcelable = new NetworkAttributesParcelable();
	parcelable.assignedV4Address =
	(null == assignedV4Address) ? null : assignedV4Address.getAddress();
	parcelable.assignedV4AddressExpiry =
	(null == assignedV4AddressExpiry) ? 0 : assignedV4AddressExpiry;
	parcelable.groupHint = groupHint;
	parcelable.dnsAddresses = inetAddressListToBlobArray(dnsAddresses);
	parcelable.mtu = (null == mtu) ? -1 : mtu;
	return parcelable;
	}

	private float samenessContribution(final float weight,
	@Nullable final Object o1, @Nullable final Object o2) {
	if (null == o1) {
	return (null == o2) ? weight * NULL_MATCH_WEIGHT : 0f;
	}
	return Objects.equals(o1, o2) ? weight : 0f;
	}

	/** @hide */
	public float getNetworkGroupSamenessConfidence(@NonNull final NetworkAttributes o) {
	final float samenessScore =
	samenessContribution(WEIGHT_ASSIGNEDV4ADDR, assignedV4Address, o.assignedV4Address)
	+ samenessContribution(WEIGHT_ASSIGNEDV4ADDREXPIRY, assignedV4AddressExpiry,
	o.assignedV4AddressExpiry)
	+ samenessContribution(WEIGHT_GROUPHINT, groupHint, o.groupHint)
	+ samenessContribution(WEIGHT_DNSADDRESSES, dnsAddresses, o.dnsAddresses)
	+ samenessContribution(WEIGHT_MTU, mtu, o.mtu);
	// The minimum is 0, the max is TOTAL_WEIGHT and should be represented by 1.0, and
	// TOTAL_WEIGHT_CUTOFF should represent 0.5, but there is no requirement that
	// TOTAL_WEIGHT_CUTOFF would be half of TOTAL_WEIGHT (indeed, it should not be).
	// So scale scores under the cutoff between 0 and 0.5, and the scores over the cutoff
	// between 0.5 and 1.0.
	if (samenessScore < TOTAL_WEIGHT_CUTOFF) {
	return samenessScore / (TOTAL_WEIGHT_CUTOFF * 2);
	} else {
	return (samenessScore - TOTAL_WEIGHT_CUTOFF) / (TOTAL_WEIGHT - TOTAL_WEIGHT_CUTOFF) / 2
	+ 0.5f;
	}
	}

	/** @hide */
	public static class Builder {
	@Nullable
	private Inet4Address mAssignedAddress;
	@Nullable
	private Long mAssignedAddressExpiry;
	@Nullable
	private String mGroupHint;
	@Nullable
	private List<InetAddress> mDnsAddresses;
	@Nullable
	private Integer mMtu;

	/**
	* Set the assigned address.
	* @param assignedV4Address The assigned address.
	* @return This builder.
	*/
	public Builder setAssignedV4Address(@Nullable final Inet4Address assignedV4Address) {
	mAssignedAddress = assignedV4Address;
	return this;
	}

	/**
	* Set the lease expiry timestamp of assigned v4 address. Long.MAX_VALUE is used
	* to represent "infinite lease".
	*
	* @param assignedV4AddressExpiry The lease expiry timestamp of assigned v4 address.
	* @return This builder.
	*/
	public Builder setAssignedV4AddressExpiry(
	@Nullable final Long assignedV4AddressExpiry) {
	if (null != assignedV4AddressExpiry && assignedV4AddressExpiry <= 0) {
	throw new IllegalArgumentException("lease expiry can't be negative or zero");
	}
	mAssignedAddressExpiry = assignedV4AddressExpiry;
	return this;
	}

	/**
	* Set the group hint.
	* @param groupHint The group hint.
	* @return This builder.
	*/
	public Builder setGroupHint(@Nullable final String groupHint) {
	mGroupHint = groupHint;
	return this;
	}

	/**
	* Set the DNS addresses.
	* @param dnsAddresses The DNS addresses.
	* @return This builder.
	*/
	public Builder setDnsAddresses(@Nullable final List<InetAddress> dnsAddresses) {
	if (DBG && null != dnsAddresses) {
	// Parceling code crashes if one of the addresses is null, therefore validate
	// them when running in debug.
	for (final InetAddress address : dnsAddresses) {
	if (null == address) throw new IllegalArgumentException("Null DNS address");
	}
	}
	this.mDnsAddresses = dnsAddresses;
	return this;
	}

	/**
	* Set the MTU.
	* @param mtu The MTU.
	* @return This builder.
	*/
	public Builder setMtu(@Nullable final Integer mtu) {
	if (null != mtu && mtu < 0) throw new IllegalArgumentException("MTU can't be negative");
	mMtu = mtu;
	return this;
	}

	/**
	* Return the built NetworkAttributes object.
	* @return The built NetworkAttributes object.
	*/
	public NetworkAttributes build() {
	return new NetworkAttributes(mAssignedAddress, mAssignedAddressExpiry,
	mGroupHint, mDnsAddresses, mMtu);
	}
	}

	/** @hide */
	public boolean isEmpty() {
	return (null == assignedV4Address) && (null == assignedV4AddressExpiry)
	&& (null == groupHint) && (null == dnsAddresses) && (null == mtu);
	}

	@Override
	public boolean equals(@Nullable final Object o) {
	if (!(o instanceof NetworkAttributes)) return false;
	final NetworkAttributes other = (NetworkAttributes) o;
	return Objects.equals(assignedV4Address, other.assignedV4Address)
	&& Objects.equals(assignedV4AddressExpiry, other.assignedV4AddressExpiry)
	&& Objects.equals(groupHint, other.groupHint)
	&& Objects.equals(dnsAddresses, other.dnsAddresses)
	&& Objects.equals(mtu, other.mtu);
	}

	@Override
	public int hashCode() {
	return Objects.hash(assignedV4Address, assignedV4AddressExpiry,
	groupHint, dnsAddresses, mtu);
	}

	/** Pretty print */
	@Override
	public String toString() {
	final StringJoiner resultJoiner = new StringJoiner(" ", "{", "}");
	final ArrayList<String> nullFields = new ArrayList<>();

	if (null != assignedV4Address) {
	resultJoiner.add("assignedV4Addr :");
	resultJoiner.add(assignedV4Address.toString());
	} else {
	nullFields.add("assignedV4Addr");
	}

	if (null != assignedV4AddressExpiry) {
	resultJoiner.add("assignedV4AddressExpiry :");
	resultJoiner.add(assignedV4AddressExpiry.toString());
	} else {
	nullFields.add("assignedV4AddressExpiry");
	}

	if (null != groupHint) {
	resultJoiner.add("groupHint :");
	resultJoiner.add(groupHint);
	} else {
	nullFields.add("groupHint");
	}

	if (null != dnsAddresses) {
	resultJoiner.add("dnsAddr : [");
	for (final InetAddress addr : dnsAddresses) {
	resultJoiner.add(addr.getHostAddress());
	}
	resultJoiner.add("]");
	} else {
	nullFields.add("dnsAddr");
	}

	if (null != mtu) {
	resultJoiner.add("mtu :");
	resultJoiner.add(mtu.toString());
	} else {
	nullFields.add("mtu");
	}

	if (!nullFields.isEmpty()) {
	resultJoiner.add("; Null fields : [");
	for (final String field : nullFields) {
	resultJoiner.add(field);
	}
	resultJoiner.add("]");
	}

	return resultJoiner.toString();
	}
	}