Move DhcpServer to NetworkStack app

Test: atest FrameworksNetTests && atest NetworkStackTests
Bug: b/112869080

Change-Id: I96c40e63e9ceb37b67705bdd4d120307e114715b

12 files changed, 140 insertions, 1770 deletions

diff --git a/services/core/java/com/android/server/connectivity/Tethering.java b/services/core/java/com/android/server/connectivity/Tethering.java
index 9dfdddbea18a..eb5be77e4a33 100644
--- a/services/core/java/com/android/server/connectivity/Tethering.java
+++ b/services/core/java/com/android/server/connectivity/Tethering.java
@@ -1837,7 +1837,7 @@ public class Tethering extends BaseNetworkObserver {
         final TetherState tetherState = new TetherState(
                 new IpServer(iface, mLooper, interfaceType, mLog, mNMService, mStatsService,
                              makeControlCallback(), mConfig.enableLegacyDhcpServer,
-                             mDeps.getIpServerDependencies()));
+                             mDeps.getIpServerDependencies(mContext)));
         mTetherStates.put(iface, tetherState);
         tetherState.ipServer.start();
     }
diff --git a/services/core/java/com/android/server/connectivity/tethering/TetheringDependencies.java b/services/core/java/com/android/server/connectivity/tethering/TetheringDependencies.java
index 7daf71dda73b..a42efe960ff9 100644
--- a/services/core/java/com/android/server/connectivity/tethering/TetheringDependencies.java
+++ b/services/core/java/com/android/server/connectivity/tethering/TetheringDependencies.java
@@ -60,8 +60,8 @@ public class TetheringDependencies {
     /**
      * Get dependencies to be used by IpServer.
      */
-    public IpServer.Dependencies getIpServerDependencies() {
-        return new IpServer.Dependencies();
+    public IpServer.Dependencies getIpServerDependencies(Context context) {
+        return new IpServer.Dependencies(context);
     }
 
     /**
diff --git a/services/net/Android.bp b/services/net/Android.bp
index e0ae68f20483..ae697b7f093a 100644
--- a/services/net/Android.bp
+++ b/services/net/Android.bp
@@ -2,3 +2,19 @@ java_library_static {
     name: "services.net",
     srcs: ["java/**/*.java"],
 }
+
+// TODO: move to networking module with DhcpClient and remove lib
+java_library {
+    name: "dhcp-packet-lib",
+    srcs: [
+        "java/android/net/dhcp/*Packet.java",
+    ]
+}
+
+// TODO: move to networking module with IpNeighborMonitor/ConnectivityPacketTracker and remove lib
+java_library {
+    name: "frameworks-net-shared-utils",
+    srcs: [
+        "java/android/net/util/FdEventsReader.java",
+    ]
+}
\ No newline at end of file
diff --git a/services/net/java/android/net/dhcp/DhcpLease.java b/services/net/java/android/net/dhcp/DhcpLease.java
deleted file mode 100644
index 6849cfadc22a..000000000000
--- a/services/net/java/android/net/dhcp/DhcpLease.java
+++ /dev/null
@@ -1,153 +0,0 @@
-/*
- * 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.dhcp;
-
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.net.MacAddress;
-import android.os.SystemClock;
-import android.text.TextUtils;
-
-import com.android.internal.util.HexDump;
-
-import java.net.Inet4Address;
-import java.util.Arrays;
-import java.util.Objects;
-
-/**
- * An IPv4 address assignment done through DHCPv4.
- * @hide
- */
-public class DhcpLease {
-    public static final long EXPIRATION_NEVER = Long.MAX_VALUE;
-    public static final String HOSTNAME_NONE = null;
-
-    @Nullable
-    private final byte[] mClientId;
-    @NonNull
-    private final MacAddress mHwAddr;
-    @NonNull
-    private final Inet4Address mNetAddr;
-    /**
-     * Expiration time for the lease, to compare with {@link SystemClock#elapsedRealtime()}.
-     */
-    private final long mExpTime;
-    @Nullable
-    private final String mHostname;
-
-    public DhcpLease(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,
-            @NonNull Inet4Address netAddr, long expTime, @Nullable String hostname) {
-        mClientId = (clientId == null ? null : Arrays.copyOf(clientId, clientId.length));
-        mHwAddr = hwAddr;
-        mNetAddr = netAddr;
-        mExpTime = expTime;
-        mHostname = hostname;
-    }
-
-    /**
-     * Get the clientId associated with this lease, if any.
-     *
-     * <p>If the lease is not associated to a clientId, this returns null.
-     */
-    @Nullable
-    public byte[] getClientId() {
-        if (mClientId == null) {
-            return null;
-        }
-        return Arrays.copyOf(mClientId, mClientId.length);
-    }
-
-    @NonNull
-    public MacAddress getHwAddr() {
-        return mHwAddr;
-    }
-
-    @Nullable
-    public String getHostname() {
-        return mHostname;
-    }
-
-    @NonNull
-    public Inet4Address getNetAddr() {
-        return mNetAddr;
-    }
-
-    public long getExpTime() {
-        return mExpTime;
-    }
-
-    /**
-     * Push back the expiration time of this lease. If the provided time is sooner than the original
-     * expiration time, the lease time will not be updated.
-     *
-     * <p>The lease hostname is updated with the provided one if set.
-     * @return A {@link DhcpLease} with expiration time set to max(expTime, currentExpTime)
-     */
-    public DhcpLease renewedLease(long expTime, @Nullable String hostname) {
-        return new DhcpLease(mClientId, mHwAddr, mNetAddr, Math.max(expTime, mExpTime),
-                (hostname == null ? mHostname : hostname));
-    }
-
-    /**
-     * Determine whether this lease matches a client with the specified parameters.
-     * @param clientId clientId of the client if any, or null otherwise.
-     * @param hwAddr Hardware address of the client.
-     */
-    public boolean matchesClient(@Nullable byte[] clientId, @NonNull MacAddress hwAddr) {
-        if (mClientId != null) {
-            return Arrays.equals(mClientId, clientId);
-        } else {
-            return clientId == null && mHwAddr.equals(hwAddr);
-        }
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        if (!(obj instanceof DhcpLease)) {
-            return false;
-        }
-        final DhcpLease other = (DhcpLease) obj;
-        return Arrays.equals(mClientId, other.mClientId)
-                && mHwAddr.equals(other.mHwAddr)
-                && mNetAddr.equals(other.mNetAddr)
-                && mExpTime == other.mExpTime
-                && TextUtils.equals(mHostname, other.mHostname);
-    }
-
-    @Override
-    public int hashCode() {
-        return Objects.hash(mClientId, mHwAddr, mNetAddr, mHostname, mExpTime);
-    }
-
-    static String clientIdToString(byte[] bytes) {
-        if (bytes == null) {
-            return "null";
-        }
-        return HexDump.toHexString(bytes);
-    }
-
-    static String inet4AddrToString(@Nullable Inet4Address addr) {
-        return (addr == null) ? "null" : addr.getHostAddress();
-    }
-
-    @Override
-    public String toString() {
-        return String.format("clientId: %s, hwAddr: %s, netAddr: %s, expTime: %d, hostname: %s",
-                clientIdToString(mClientId), mHwAddr.toString(), inet4AddrToString(mNetAddr),
-                mExpTime, mHostname);
-    }
-}
diff --git a/services/net/java/android/net/dhcp/DhcpLeaseRepository.java b/services/net/java/android/net/dhcp/DhcpLeaseRepository.java
deleted file mode 100644
index b3d0512ba447..000000000000
--- a/services/net/java/android/net/dhcp/DhcpLeaseRepository.java
+++ /dev/null
@@ -1,544 +0,0 @@
-/*
- * 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.dhcp;
-
-import static android.net.NetworkUtils.inet4AddressToIntHTH;
-import static android.net.NetworkUtils.intToInet4AddressHTH;
-import static android.net.NetworkUtils.prefixLengthToV4NetmaskIntHTH;
-import static android.net.dhcp.DhcpLease.EXPIRATION_NEVER;
-import static android.net.dhcp.DhcpLease.inet4AddrToString;
-import static android.net.util.NetworkConstants.IPV4_ADDR_BITS;
-
-import static java.lang.Math.min;
-
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.net.IpPrefix;
-import android.net.MacAddress;
-import android.net.dhcp.DhcpServer.Clock;
-import android.net.util.SharedLog;
-import android.util.ArrayMap;
-
-import java.net.Inet4Address;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.Set;
-import java.util.function.Function;
-
-/**
- * A repository managing IPv4 address assignments through DHCPv4.
- *
- * <p>This class is not thread-safe. All public methods should be called on a common thread or
- * use some synchronization mechanism.
- *
- * <p>Methods are optimized for a small number of allocated leases, assuming that most of the time
- * only 2~10 addresses will be allocated, which is the common case. Managing a large number of
- * addresses is supported but will be slower: some operations have complexity in O(num_leases).
- * @hide
- */
-class DhcpLeaseRepository {
-    public static final byte[] CLIENTID_UNSPEC = null;
-    public static final Inet4Address INETADDR_UNSPEC = null;
-
-    @NonNull
-    private final SharedLog mLog;
-    @NonNull
-    private final Clock mClock;
-
-    @NonNull
-    private IpPrefix mPrefix;
-    @NonNull
-    private Set<Inet4Address> mReservedAddrs;
-    private int mSubnetAddr;
-    private int mSubnetMask;
-    private int mNumAddresses;
-    private long mLeaseTimeMs;
-
-    /**
-     * Next timestamp when committed or declined leases should be checked for expired ones. This
-     * will always be lower than or equal to the time for the first lease to expire: it's OK not to
-     * update this when removing entries, but it must always be updated when adding/updating.
-     */
-    private long mNextExpirationCheck = EXPIRATION_NEVER;
-
-    static class DhcpLeaseException extends Exception {
-        DhcpLeaseException(String message) {
-            super(message);
-        }
-    }
-
-    static class OutOfAddressesException extends DhcpLeaseException {
-        OutOfAddressesException(String message) {
-            super(message);
-        }
-    }
-
-    static class InvalidAddressException extends DhcpLeaseException {
-        InvalidAddressException(String message) {
-            super(message);
-        }
-    }
-
-    static class InvalidSubnetException extends DhcpLeaseException {
-        InvalidSubnetException(String message) {
-            super(message);
-        }
-    }
-
-    /**
-     * Leases by IP address
-     */
-    private final ArrayMap<Inet4Address, DhcpLease> mCommittedLeases = new ArrayMap<>();
-
-    /**
-     * Map address -> expiration timestamp in ms. Addresses are guaranteed to be valid as defined
-     * by {@link #isValidAddress(Inet4Address)}, but are not necessarily otherwise available for
-     * assignment.
-     */
-    private final LinkedHashMap<Inet4Address, Long> mDeclinedAddrs = new LinkedHashMap<>();
-
-    DhcpLeaseRepository(@NonNull IpPrefix prefix, @NonNull Set<Inet4Address> reservedAddrs,
-            long leaseTimeMs, @NonNull SharedLog log, @NonNull Clock clock) {
-        updateParams(prefix, reservedAddrs, leaseTimeMs);
-        mLog = log;
-        mClock = clock;
-    }
-
-    public void updateParams(@NonNull IpPrefix prefix, @NonNull Set<Inet4Address> reservedAddrs,
-            long leaseTimeMs) {
-        mPrefix = prefix;
-        mReservedAddrs = Collections.unmodifiableSet(new HashSet<>(reservedAddrs));
-        mSubnetMask = prefixLengthToV4NetmaskIntHTH(prefix.getPrefixLength());
-        mSubnetAddr = inet4AddressToIntHTH((Inet4Address) prefix.getAddress()) & mSubnetMask;
-        mNumAddresses = 1 << (IPV4_ADDR_BITS - prefix.getPrefixLength());
-        mLeaseTimeMs = leaseTimeMs;
-
-        cleanMap(mCommittedLeases);
-        cleanMap(mDeclinedAddrs);
-    }
-
-    /**
-     * From a map keyed by {@link Inet4Address}, remove entries where the key is invalid (as
-     * specified by {@link #isValidAddress(Inet4Address)}), or is a reserved address.
-     */
-    private <T> void cleanMap(Map<Inet4Address, T> map) {
-        final Iterator<Entry<Inet4Address, T>> it = map.entrySet().iterator();
-        while (it.hasNext()) {
-            final Inet4Address addr = it.next().getKey();
-            if (!isValidAddress(addr) || mReservedAddrs.contains(addr)) {
-                it.remove();
-            }
-        }
-    }
-
-    /**
-     * Get a DHCP offer, to reply to a DHCPDISCOVER. Follows RFC2131 #4.3.1.
-     *
-     * @param clientId Client identifier option if specified, or {@link #CLIENTID_UNSPEC}
-     * @param relayAddr Internet address of the relay (giaddr), can be {@link Inet4Address#ANY}
-     * @param reqAddr Requested address by the client (option 50), or {@link #INETADDR_UNSPEC}
-     * @param hostname Client-provided hostname, or {@link DhcpLease#HOSTNAME_NONE}
-     * @throws OutOfAddressesException The server does not have any available address
-     * @throws InvalidSubnetException The lease was requested from an unsupported subnet
-     */
-    @NonNull
-    public DhcpLease getOffer(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,
-            @NonNull Inet4Address relayAddr, @Nullable Inet4Address reqAddr,
-            @Nullable String hostname) throws OutOfAddressesException, InvalidSubnetException {
-        final long currentTime = mClock.elapsedRealtime();
-        final long expTime = currentTime + mLeaseTimeMs;
-
-        removeExpiredLeases(currentTime);
-        checkValidRelayAddr(relayAddr);
-
-        final DhcpLease currentLease = findByClient(clientId, hwAddr);
-        final DhcpLease newLease;
-        if (currentLease != null) {
-            newLease = currentLease.renewedLease(expTime, hostname);
-            mLog.log("Offering extended lease " + newLease);
-            // Do not update lease time in the map: the offer is not committed yet.
-        } else if (reqAddr != null && isValidAddress(reqAddr) && isAvailable(reqAddr)) {
-            newLease = new DhcpLease(clientId, hwAddr, reqAddr, expTime, hostname);
-            mLog.log("Offering requested lease " + newLease);
-        } else {
-            newLease = makeNewOffer(clientId, hwAddr, expTime, hostname);
-            mLog.log("Offering new generated lease " + newLease);
-        }
-        return newLease;
-    }
-
-    private void checkValidRelayAddr(@Nullable Inet4Address relayAddr)
-            throws InvalidSubnetException {
-        // As per #4.3.1, addresses are assigned based on the relay address if present. This
-        // implementation only assigns addresses if the relayAddr is inside our configured subnet.
-        // This also applies when the client requested a specific address for consistency between
-        // requests, and with older behavior.
-        if (isIpAddrOutsidePrefix(mPrefix, relayAddr)) {
-            throw new InvalidSubnetException("Lease requested by relay from outside of subnet");
-        }
-    }
-
-    private static boolean isIpAddrOutsidePrefix(@NonNull IpPrefix prefix,
-            @Nullable Inet4Address addr) {
-        return addr != null && !addr.equals(Inet4Address.ANY) && !prefix.contains(addr);
-    }
-
-    @Nullable
-    private DhcpLease findByClient(@Nullable byte[] clientId, @NonNull MacAddress hwAddr) {
-        for (DhcpLease lease : mCommittedLeases.values()) {
-            if (lease.matchesClient(clientId, hwAddr)) {
-                return lease;
-            }
-        }
-
-        // Note this differs from dnsmasq behavior, which would match by hwAddr if clientId was
-        // given but no lease keyed on clientId matched. This would prevent one interface from
-        // obtaining multiple leases with different clientId.
-        return null;
-    }
-
-    /**
-     * Make a lease conformant to a client DHCPREQUEST or renew the client's existing lease,
-     * commit it to the repository and return it.
-     *
-     * <p>This method always succeeds and commits the lease if it does not throw, and has no side
-     * effects if it throws.
-     *
-     * @param clientId Client identifier option if specified, or {@link #CLIENTID_UNSPEC}
-     * @param reqAddr Requested address by the client (option 50), or {@link #INETADDR_UNSPEC}
-     * @param sidSet Whether the server identifier was set in the request
-     * @return The newly created or renewed lease
-     * @throws InvalidAddressException The client provided an address that conflicts with its
-     *                                 current configuration, or other committed/reserved leases.
-     */
-    @NonNull
-    public DhcpLease requestLease(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,
-            @NonNull Inet4Address clientAddr, @NonNull Inet4Address relayAddr,
-            @Nullable Inet4Address reqAddr, boolean sidSet, @Nullable String hostname)
-            throws InvalidAddressException, InvalidSubnetException {
-        final long currentTime = mClock.elapsedRealtime();
-        removeExpiredLeases(currentTime);
-        checkValidRelayAddr(relayAddr);
-        final DhcpLease assignedLease = findByClient(clientId, hwAddr);
-
-        final Inet4Address leaseAddr = reqAddr != null ? reqAddr : clientAddr;
-        if (assignedLease != null) {
-            if (sidSet && reqAddr != null) {
-                // Client in SELECTING state; remove any current lease before creating a new one.
-                mCommittedLeases.remove(assignedLease.getNetAddr());
-            } else if (!assignedLease.getNetAddr().equals(leaseAddr)) {
-                // reqAddr null (RENEWING/REBINDING): client renewing its own lease for clientAddr.
-                // reqAddr set with sid not set (INIT-REBOOT): client verifying configuration.
-                // In both cases, throw if clientAddr or reqAddr does not match the known lease.
-                throw new InvalidAddressException("Incorrect address for client in "
-                        + (reqAddr != null ? "INIT-REBOOT" : "RENEWING/REBINDING"));
-            }
-        }
-
-        // In the init-reboot case, RFC2131 #4.3.2 says that the server must not reply if
-        // assignedLease == null, but dnsmasq will let the client use the requested address if
-        // available, when configured with --dhcp-authoritative. This is preferable to avoid issues
-        // if the server lost the lease DB: the client would not get a reply because the server
-        // does not know their lease.
-        // Similarly in RENEWING/REBINDING state, create a lease when possible if the
-        // client-provided lease is unknown.
-        final DhcpLease lease =
-                checkClientAndMakeLease(clientId, hwAddr, leaseAddr, hostname, currentTime);
-        mLog.logf("DHCPREQUEST assignedLease %s, reqAddr=%s, sidSet=%s: created/renewed lease %s",
-                assignedLease, inet4AddrToString(reqAddr), sidSet, lease);
-        return lease;
-    }
-
-    /**
-     * Check that the client can request the specified address, make or renew the lease if yes, and
-     * commit it.
-     *
-     * <p>This method always succeeds and returns the lease if it does not throw, and has no
-     * side-effect if it throws.
-     *
-     * @return The newly created or renewed, committed lease
-     * @throws InvalidAddressException The client provided an address that conflicts with its
-     *                                 current configuration, or other committed/reserved leases.
-     */
-    private DhcpLease checkClientAndMakeLease(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,
-            @NonNull Inet4Address addr, @Nullable String hostname, long currentTime)
-            throws InvalidAddressException {
-        final long expTime = currentTime + mLeaseTimeMs;
-        final DhcpLease currentLease = mCommittedLeases.getOrDefault(addr, null);
-        if (currentLease != null && !currentLease.matchesClient(clientId, hwAddr)) {
-            throw new InvalidAddressException("Address in use");
-        }
-
-        final DhcpLease lease;
-        if (currentLease == null) {
-            if (isValidAddress(addr) && !mReservedAddrs.contains(addr)) {
-                lease = new DhcpLease(clientId, hwAddr, addr, expTime, hostname);
-            } else {
-                throw new InvalidAddressException("Lease not found and address unavailable");
-            }
-        } else {
-            lease = currentLease.renewedLease(expTime, hostname);
-        }
-        commitLease(lease);
-        return lease;
-    }
-
-    private void commitLease(@NonNull DhcpLease lease) {
-        mCommittedLeases.put(lease.getNetAddr(), lease);
-        maybeUpdateEarliestExpiration(lease.getExpTime());
-    }
-
-    /**
-     * Delete a committed lease from the repository.
-     *
-     * @return true if a lease matching parameters was found.
-     */
-    public boolean releaseLease(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,
-            @NonNull Inet4Address addr) {
-        final DhcpLease currentLease = mCommittedLeases.getOrDefault(addr, null);
-        if (currentLease == null) {
-            mLog.w("Could not release unknown lease for " + inet4AddrToString(addr));
-            return false;
-        }
-        if (currentLease.matchesClient(clientId, hwAddr)) {
-            mCommittedLeases.remove(addr);
-            mLog.log("Released lease " + currentLease);
-            return true;
-        }
-        mLog.w(String.format("Not releasing lease %s: does not match client (cid %s, hwAddr %s)",
-                currentLease, DhcpLease.clientIdToString(clientId), hwAddr));
-        return false;
-    }
-
-    public void markLeaseDeclined(@NonNull Inet4Address addr) {
-        if (mDeclinedAddrs.containsKey(addr) || !isValidAddress(addr)) {
-            mLog.logf("Not marking %s as declined: already declined or not assignable",
-                    inet4AddrToString(addr));
-            return;
-        }
-        final long expTime = mClock.elapsedRealtime() + mLeaseTimeMs;
-        mDeclinedAddrs.put(addr, expTime);
-        mLog.logf("Marked %s as declined expiring %d", inet4AddrToString(addr), expTime);
-        maybeUpdateEarliestExpiration(expTime);
-    }
-
-    /**
-     * Get the list of currently valid committed leases in the repository.
-     */
-    @NonNull
-    public List<DhcpLease> getCommittedLeases() {
-        removeExpiredLeases(mClock.elapsedRealtime());
-        return new ArrayList<>(mCommittedLeases.values());
-    }
-
-    /**
-     * Get the set of addresses that have been marked as declined in the repository.
-     */
-    @NonNull
-    public Set<Inet4Address> getDeclinedAddresses() {
-        removeExpiredLeases(mClock.elapsedRealtime());
-        return new HashSet<>(mDeclinedAddrs.keySet());
-    }
-
-    /**
-     * Given the expiration time of a new committed lease or declined address, update
-     * {@link #mNextExpirationCheck} so it stays lower than or equal to the time for the first lease
-     * to expire.
-     */
-    private void maybeUpdateEarliestExpiration(long expTime) {
-        if (expTime < mNextExpirationCheck) {
-            mNextExpirationCheck = expTime;
-        }
-    }
-
-    /**
-     * Remove expired entries from a map keyed by {@link Inet4Address}.
-     *
-     * @param tag Type of lease in the map, for logging
-     * @param getExpTime Functor returning the expiration time for an object in the map.
-     *                   Must not return null.
-     * @return The lowest expiration time among entries remaining in the map
-     */
-    private <T> long removeExpired(long currentTime, @NonNull Map<Inet4Address, T> map,
-            @NonNull String tag, @NonNull Function<T, Long> getExpTime) {
-        final Iterator<Entry<Inet4Address, T>> it = map.entrySet().iterator();
-        long firstExpiration = EXPIRATION_NEVER;
-        while (it.hasNext()) {
-            final Entry<Inet4Address, T> lease = it.next();
-            final long expTime = getExpTime.apply(lease.getValue());
-            if (expTime <= currentTime) {
-                mLog.logf("Removing expired %s lease for %s (expTime=%s, currentTime=%s)",
-                        tag, lease.getKey(), expTime, currentTime);
-                it.remove();
-            } else {
-                firstExpiration = min(firstExpiration, expTime);
-            }
-        }
-        return firstExpiration;
-    }
-
-    /**
-     * Go through committed and declined leases and remove the expired ones.
-     */
-    private void removeExpiredLeases(long currentTime) {
-        if (currentTime < mNextExpirationCheck) {
-            return;
-        }
-
-        final long commExp = removeExpired(
-                currentTime, mCommittedLeases, "committed", DhcpLease::getExpTime);
-        final long declExp = removeExpired(
-                currentTime, mDeclinedAddrs, "declined", Function.identity());
-
-        mNextExpirationCheck = min(commExp, declExp);
-    }
-
-    private boolean isAvailable(@NonNull Inet4Address addr) {
-        return !mReservedAddrs.contains(addr) && !mCommittedLeases.containsKey(addr);
-    }
-
-    /**
-     * Get the 0-based index of an address in the subnet.
-     *
-     * <p>Given ordering of addresses 5.6.7.8 < 5.6.7.9 < 5.6.8.0, the index on a subnet is defined
-     * so that the first address is 0, the second 1, etc. For example on a /16, 192.168.0.0 -> 0,
-     * 192.168.0.1 -> 1, 192.168.1.0 -> 256
-     *
-     */
-    private int getAddrIndex(int addr) {
-        return addr & ~mSubnetMask;
-    }
-
-    private int getAddrByIndex(int index) {
-        return mSubnetAddr | index;
-    }
-
-    /**
-     * Get a valid address starting from the supplied one.
-     *
-     * <p>This only checks that the address is numerically valid for assignment, not whether it is
-     * already in use. The return value is always inside the configured prefix, even if the supplied
-     * address is not.
-     *
-     * <p>If the provided address is valid, it is returned as-is. Otherwise, the next valid
-     * address (with the ordering in {@link #getAddrIndex(int)}) is returned.
-     */
-    private int getValidAddress(int addr) {
-        final int lastByteMask = 0xff;
-        int addrIndex = getAddrIndex(addr); // 0-based index of the address in the subnet
-
-        // Some OSes do not handle addresses in .255 or .0 correctly: avoid those.
-        final int lastByte = getAddrByIndex(addrIndex) & lastByteMask;
-        if (lastByte == lastByteMask) {
-            // Avoid .255 address, and .0 address that follows
-            addrIndex = (addrIndex + 2) % mNumAddresses;
-        } else if (lastByte == 0) {
-            // Avoid .0 address
-            addrIndex = (addrIndex + 1) % mNumAddresses;
-        }
-
-        // Do not use first or last address of range
-        if (addrIndex == 0 || addrIndex == mNumAddresses - 1) {
-            // Always valid and not end of range since prefixLength is at most 30 in serving params
-            addrIndex = 1;
-        }
-        return getAddrByIndex(addrIndex);
-    }
-
-    /**
-     * Returns whether the address is in the configured subnet and part of the assignable range.
-     */
-    private boolean isValidAddress(Inet4Address addr) {
-        final int intAddr = inet4AddressToIntHTH(addr);
-        return getValidAddress(intAddr) == intAddr;
-    }
-
-    private int getNextAddress(int addr) {
-        final int addrIndex = getAddrIndex(addr);
-        final int nextAddress = getAddrByIndex((addrIndex + 1) % mNumAddresses);
-        return getValidAddress(nextAddress);
-    }
-
-    /**
-     * Calculate a first candidate address for a client by hashing the hardware address.
-     *
-     * <p>This will be a valid address as checked by {@link #getValidAddress(int)}, but may be
-     * in use.
-     *
-     * @return An IPv4 address encoded as 32-bit int
-     */
-    private int getFirstClientAddress(MacAddress hwAddr) {
-        // This follows dnsmasq behavior. Advantages are: clients will often get the same
-        // offers for different DISCOVER even if the lease was not yet accepted or has expired,
-        // and address generation will generally not need to loop through many allocated addresses
-        // until it finds a free one.
-        int hash = 0;
-        for (byte b : hwAddr.toByteArray()) {
-            hash += b + (b << 8) + (b << 16);
-        }
-        // This implementation will not always result in the same IPs as dnsmasq would give out in
-        // Android <= P, because it includes invalid and reserved addresses in mNumAddresses while
-        // the configured ranges for dnsmasq did not.
-        final int addrIndex = hash % mNumAddresses;
-        return getValidAddress(getAddrByIndex(addrIndex));
-    }
-
-    /**
-     * Create a lease that can be offered to respond to a client DISCOVER.
-     *
-     * <p>This method always succeeds and returns the lease if it does not throw. If no non-declined
-     * address is available, it will try to offer the oldest declined address if valid.
-     *
-     * @throws OutOfAddressesException The server has no address left to offer
-     */
-    private DhcpLease makeNewOffer(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,
-            long expTime, @Nullable String hostname) throws OutOfAddressesException {
-        int intAddr = getFirstClientAddress(hwAddr);
-        // Loop until a free address is found, or there are no more addresses.
-        // There is slightly less than this many usable addresses, but some extra looping is OK
-        for (int i = 0; i < mNumAddresses; i++) {
-            final Inet4Address addr = intToInet4AddressHTH(intAddr);
-            if (isAvailable(addr) && !mDeclinedAddrs.containsKey(addr)) {
-                return new DhcpLease(clientId, hwAddr, addr, expTime, hostname);
-            }
-            intAddr = getNextAddress(intAddr);
-        }
-
-        // Try freeing DECLINEd addresses if out of addresses.
-        final Iterator<Inet4Address> it = mDeclinedAddrs.keySet().iterator();
-        while (it.hasNext()) {
-            final Inet4Address addr = it.next();
-            it.remove();
-            mLog.logf("Out of addresses in address pool: dropped declined addr %s",
-                    inet4AddrToString(addr));
-            // isValidAddress() is always verified for entries in mDeclinedAddrs.
-            // However declined addresses may have been requested (typically by the machine that was
-            // already using the address) after being declined.
-            if (isAvailable(addr)) {
-                return new DhcpLease(clientId, hwAddr, addr, expTime, hostname);
-            }
-        }
-
-        throw new OutOfAddressesException("No address available for offer");
-    }
-}
diff --git a/services/net/java/android/net/dhcp/DhcpPacket.java b/services/net/java/android/net/dhcp/DhcpPacket.java
index 6ba7d94117b1..ce8b7e78d0f8 100644
--- a/services/net/java/android/net/dhcp/DhcpPacket.java
+++ b/services/net/java/android/net/dhcp/DhcpPacket.java
@@ -1,8 +1,5 @@
 package android.net.dhcp;
 
-import static android.net.util.NetworkConstants.IPV4_MAX_MTU;
-import static android.net.util.NetworkConstants.IPV4_MIN_MTU;
-
 import android.annotation.Nullable;
 import android.net.DhcpResults;
 import android.net.LinkAddress;
@@ -37,6 +34,9 @@ import java.util.List;
 public abstract class DhcpPacket {
     protected static final String TAG = "DhcpPacket";
 
+    // TODO: use NetworkStackConstants.IPV4_MIN_MTU once this class is moved to the network stack.
+    private static final int IPV4_MIN_MTU = 68;
+
     // dhcpcd has a minimum lease of 20 seconds, but DhcpStateMachine would refuse to wake up the
     // CPU for anything shorter than 5 minutes. For sanity's sake, this must be higher than the
     // DHCP client timeout.
diff --git a/services/net/java/android/net/dhcp/DhcpPacketListener.java b/services/net/java/android/net/dhcp/DhcpPacketListener.java
deleted file mode 100644
index dce8b619494e..000000000000
--- a/services/net/java/android/net/dhcp/DhcpPacketListener.java
+++ /dev/null
@@ -1,88 +0,0 @@
-/*
- * 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.dhcp;
-
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.net.util.FdEventsReader;
-import android.os.Handler;
-import android.system.Os;
-
-import java.io.FileDescriptor;
-import java.net.Inet4Address;
-import java.net.InetSocketAddress;
-
-/**
- * A {@link FdEventsReader} to receive and parse {@link DhcpPacket}.
- * @hide
- */
-abstract class DhcpPacketListener extends FdEventsReader<DhcpPacketListener.Payload> {
-    static final class Payload {
-        protected final byte[] mBytes = new byte[DhcpPacket.MAX_LENGTH];
-        protected Inet4Address mSrcAddr;
-        protected int mSrcPort;
-    }
-
-    DhcpPacketListener(@NonNull Handler handler) {
-        super(handler, new Payload());
-    }
-
-    @Override
-    protected int recvBufSize(@NonNull Payload buffer) {
-        return buffer.mBytes.length;
-    }
-
-    @Override
-    protected final void handlePacket(@NonNull Payload recvbuf, int length) {
-        if (recvbuf.mSrcAddr == null) {
-            return;
-        }
-
-        try {
-            final DhcpPacket packet = DhcpPacket.decodeFullPacket(recvbuf.mBytes, length,
-                    DhcpPacket.ENCAP_BOOTP);
-            onReceive(packet, recvbuf.mSrcAddr, recvbuf.mSrcPort);
-        } catch (DhcpPacket.ParseException e) {
-            logParseError(recvbuf.mBytes, length, e);
-        }
-    }
-
-    @Override
-    protected int readPacket(@NonNull FileDescriptor fd, @NonNull Payload packetBuffer)
-            throws Exception {
-        final InetSocketAddress addr = new InetSocketAddress();
-        final int read = Os.recvfrom(
-                fd, packetBuffer.mBytes, 0, packetBuffer.mBytes.length, 0 /* flags */, addr);
-
-        // Buffers with null srcAddr will be dropped in handlePacket()
-        packetBuffer.mSrcAddr = inet4AddrOrNull(addr);
-        packetBuffer.mSrcPort = addr.getPort();
-        return read;
-    }
-
-    @Nullable
-    private static Inet4Address inet4AddrOrNull(@NonNull InetSocketAddress addr) {
-        return addr.getAddress() instanceof Inet4Address
-                ? (Inet4Address) addr.getAddress()
-                : null;
-    }
-
-    protected abstract void onReceive(@NonNull DhcpPacket packet, @NonNull Inet4Address srcAddr,
-            int srcPort);
-    protected abstract void logParseError(@NonNull byte[] packet, int length,
-            @NonNull DhcpPacket.ParseException e);
-}
diff --git a/services/net/java/android/net/dhcp/DhcpServer.java b/services/net/java/android/net/dhcp/DhcpServer.java
deleted file mode 100644
index 641bba2ed306..000000000000
--- a/services/net/java/android/net/dhcp/DhcpServer.java
+++ /dev/null
@@ -1,582 +0,0 @@
-/*
- * 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.dhcp;
-
-import static android.net.NetworkUtils.getBroadcastAddress;
-import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
-import static android.net.TrafficStats.TAG_SYSTEM_DHCP_SERVER;
-import static android.net.dhcp.DhcpPacket.DHCP_CLIENT;
-import static android.net.dhcp.DhcpPacket.DHCP_HOST_NAME;
-import static android.net.dhcp.DhcpPacket.DHCP_SERVER;
-import static android.net.dhcp.DhcpPacket.ENCAP_BOOTP;
-import static android.net.dhcp.DhcpPacket.INFINITE_LEASE;
-import static android.system.OsConstants.AF_INET;
-import static android.system.OsConstants.IPPROTO_UDP;
-import static android.system.OsConstants.SOCK_DGRAM;
-import static android.system.OsConstants.SOL_SOCKET;
-import static android.system.OsConstants.SO_BINDTODEVICE;
-import static android.system.OsConstants.SO_BROADCAST;
-import static android.system.OsConstants.SO_REUSEADDR;
-
-import static java.lang.Integer.toUnsignedLong;
-
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.net.MacAddress;
-import android.net.NetworkUtils;
-import android.net.TrafficStats;
-import android.net.util.SharedLog;
-import android.os.Handler;
-import android.os.Looper;
-import android.os.Message;
-import android.os.SystemClock;
-import android.system.ErrnoException;
-import android.system.Os;
-import android.text.TextUtils;
-
-import com.android.internal.annotations.VisibleForTesting;
-import com.android.internal.util.HexDump;
-
-import java.io.FileDescriptor;
-import java.io.IOException;
-import java.net.Inet4Address;
-import java.net.InetAddress;
-import java.nio.ByteBuffer;
-import java.util.ArrayList;
-
-/**
- * A DHCPv4 server.
- *
- * <p>This server listens for and responds to packets on a single interface. It considers itself
- * authoritative for all leases on the subnet, which means that DHCP requests for unknown leases of
- * unknown hosts receive a reply instead of being ignored.
- *
- * <p>The server is single-threaded (including send/receive operations): all internal operations are
- * done on the provided {@link Looper}. Public methods are thread-safe and will schedule operations
- * on the looper asynchronously.
- * @hide
- */
-public class DhcpServer {
-    private static final String REPO_TAG = "Repository";
-
-    // Lease time to transmit to client instead of a negative time in case a lease expired before
-    // the server could send it (if the server process is suspended for example).
-    private static final int EXPIRED_FALLBACK_LEASE_TIME_SECS = 120;
-
-    private static final int CMD_START_DHCP_SERVER = 1;
-    private static final int CMD_STOP_DHCP_SERVER = 2;
-    private static final int CMD_UPDATE_PARAMS = 3;
-
-    @NonNull
-    private final ServerHandler mHandler;
-    @NonNull
-    private final String mIfName;
-    @NonNull
-    private final DhcpLeaseRepository mLeaseRepo;
-    @NonNull
-    private final SharedLog mLog;
-    @NonNull
-    private final Dependencies mDeps;
-    @NonNull
-    private final Clock mClock;
-    @NonNull
-    private final DhcpPacketListener mPacketListener;
-
-    @Nullable
-    private FileDescriptor mSocket;
-    @NonNull
-    private DhcpServingParams mServingParams;
-
-    /**
-     * Clock to be used by DhcpServer to track time for lease expiration.
-     *
-     * <p>The clock should track time as may be measured by clients obtaining a lease. It does not
-     * need to be monotonous across restarts of the server as long as leases are cleared when the
-     * server is stopped.
-     */
-    public static class Clock {
-        /**
-         * @see SystemClock#elapsedRealtime()
-         */
-        public long elapsedRealtime() {
-            return SystemClock.elapsedRealtime();
-        }
-    }
-
-    /**
-     * Dependencies for the DhcpServer. Useful to be mocked in tests.
-     */
-    public interface Dependencies {
-        /**
-         * Send a packet to the specified datagram socket.
-         *
-         * @param fd File descriptor of the socket.
-         * @param buffer Data to be sent.
-         * @param dst Destination address of the packet.
-         */
-        void sendPacket(@NonNull FileDescriptor fd, @NonNull ByteBuffer buffer,
-                @NonNull InetAddress dst) throws ErrnoException, IOException;
-
-        /**
-         * Create a DhcpLeaseRepository for the server.
-         * @param servingParams Parameters used to serve DHCP requests.
-         * @param log Log to be used by the repository.
-         * @param clock Clock that the repository must use to track time.
-         */
-        DhcpLeaseRepository makeLeaseRepository(@NonNull DhcpServingParams servingParams,
-                @NonNull SharedLog log, @NonNull Clock clock);
-
-        /**
-         * Create a packet listener that will send packets to be processed.
-         */
-        DhcpPacketListener makePacketListener();
-
-        /**
-         * Create a clock that the server will use to track time.
-         */
-        Clock makeClock();
-
-        /**
-         * Add an entry to the ARP cache table.
-         * @param fd Datagram socket file descriptor that must use the new entry.
-         */
-        void addArpEntry(@NonNull Inet4Address ipv4Addr, @NonNull MacAddress ethAddr,
-                @NonNull String ifname, @NonNull FileDescriptor fd) throws IOException;
-    }
-
-    private class DependenciesImpl implements Dependencies {
-        @Override
-        public void sendPacket(@NonNull FileDescriptor fd, @NonNull ByteBuffer buffer,
-                @NonNull InetAddress dst) throws ErrnoException, IOException {
-            Os.sendto(fd, buffer, 0, dst, DhcpPacket.DHCP_CLIENT);
-        }
-
-        @Override
-        public DhcpLeaseRepository makeLeaseRepository(@NonNull DhcpServingParams servingParams,
-                @NonNull SharedLog log, @NonNull Clock clock) {
-            return new DhcpLeaseRepository(
-                    DhcpServingParams.makeIpPrefix(servingParams.serverAddr),
-                    servingParams.excludedAddrs,
-                    servingParams.dhcpLeaseTimeSecs * 1000, log.forSubComponent(REPO_TAG), clock);
-        }
-
-        @Override
-        public DhcpPacketListener makePacketListener() {
-            return new PacketListener();
-        }
-
-        @Override
-        public Clock makeClock() {
-            return new Clock();
-        }
-
-        @Override
-        public void addArpEntry(@NonNull Inet4Address ipv4Addr, @NonNull MacAddress ethAddr,
-                @NonNull String ifname, @NonNull FileDescriptor fd) throws IOException {
-            NetworkUtils.addArpEntry(ipv4Addr, ethAddr, ifname, fd);
-        }
-    }
-
-    private static class MalformedPacketException extends Exception {
-        MalformedPacketException(String message, Throwable t) {
-            super(message, t);
-        }
-    }
-
-    public DhcpServer(@NonNull Looper looper, @NonNull String ifName,
-            @NonNull DhcpServingParams params, @NonNull SharedLog log) {
-        this(looper, ifName, params, log, null);
-    }
-
-    @VisibleForTesting
-    DhcpServer(@NonNull Looper looper, @NonNull String ifName,
-            @NonNull DhcpServingParams params, @NonNull SharedLog log,
-            @Nullable Dependencies deps) {
-        if (deps == null) {
-            deps = new DependenciesImpl();
-        }
-        mHandler = new ServerHandler(looper);
-        mIfName = ifName;
-        mServingParams = params;
-        mLog = log;
-        mDeps = deps;
-        mClock = deps.makeClock();
-        mPacketListener = deps.makePacketListener();
-        mLeaseRepo = deps.makeLeaseRepository(mServingParams, mLog, mClock);
-    }
-
-    /**
-     * Start listening for and responding to packets.
-     */
-    public void start() {
-        mHandler.sendEmptyMessage(CMD_START_DHCP_SERVER);
-    }
-
-    /**
-     * Update serving parameters. All subsequently received requests will be handled with the new
-     * parameters, and current leases that are incompatible with the new parameters are dropped.
-     */
-    public void updateParams(@NonNull DhcpServingParams params) {
-        sendMessage(CMD_UPDATE_PARAMS, params);
-    }
-
-    /**
-     * Stop listening for packets.
-     *
-     * <p>As the server is stopped asynchronously, some packets may still be processed shortly after
-     * calling this method.
-     */
-    public void stop() {
-        mHandler.sendEmptyMessage(CMD_STOP_DHCP_SERVER);
-    }
-
-    private void sendMessage(int what, @Nullable Object obj) {
-        mHandler.sendMessage(mHandler.obtainMessage(what, obj));
-    }
-
-    private class ServerHandler extends Handler {
-        ServerHandler(@NonNull Looper looper) {
-            super(looper);
-        }
-
-        @Override
-        public void handleMessage(@NonNull Message msg) {
-            switch (msg.what) {
-                case CMD_UPDATE_PARAMS:
-                    final DhcpServingParams params = (DhcpServingParams) msg.obj;
-                    mServingParams = params;
-                    mLeaseRepo.updateParams(
-                            DhcpServingParams.makeIpPrefix(mServingParams.serverAddr),
-                            params.excludedAddrs,
-                            params.dhcpLeaseTimeSecs);
-                    break;
-                case CMD_START_DHCP_SERVER:
-                    // This is a no-op if the listener is already started
-                    mPacketListener.start();
-                    break;
-                case CMD_STOP_DHCP_SERVER:
-                    // This is a no-op if the listener was not started
-                    mPacketListener.stop();
-                    break;
-            }
-        }
-    }
-
-    @VisibleForTesting
-    void processPacket(@NonNull DhcpPacket packet, int srcPort) {
-        final String packetType = packet.getClass().getSimpleName();
-        if (srcPort != DHCP_CLIENT) {
-            mLog.logf("Ignored packet of type %s sent from client port %d", packetType, srcPort);
-            return;
-        }
-
-        mLog.log("Received packet of type " + packetType);
-        final Inet4Address sid = packet.mServerIdentifier;
-        if (sid != null && !sid.equals(mServingParams.serverAddr.getAddress())) {
-            mLog.log("Packet ignored due to wrong server identifier: " + sid);
-            return;
-        }
-
-        try {
-            if (packet instanceof DhcpDiscoverPacket) {
-                processDiscover((DhcpDiscoverPacket) packet);
-            } else if (packet instanceof DhcpRequestPacket) {
-                processRequest((DhcpRequestPacket) packet);
-            } else if (packet instanceof DhcpReleasePacket) {
-                processRelease((DhcpReleasePacket) packet);
-            } else {
-                mLog.e("Unknown packet type: " + packet.getClass().getSimpleName());
-            }
-        } catch (MalformedPacketException e) {
-            // Not an internal error: only logging exception message, not stacktrace
-            mLog.e("Ignored malformed packet: " + e.getMessage());
-        }
-    }
-
-    private void logIgnoredPacketInvalidSubnet(DhcpLeaseRepository.InvalidSubnetException e) {
-        // Not an internal error: only logging exception message, not stacktrace
-        mLog.e("Ignored packet from invalid subnet: " + e.getMessage());
-    }
-
-    private void processDiscover(@NonNull DhcpDiscoverPacket packet)
-            throws MalformedPacketException {
-        final DhcpLease lease;
-        final MacAddress clientMac = getMacAddr(packet);
-        try {
-            lease = mLeaseRepo.getOffer(packet.getExplicitClientIdOrNull(), clientMac,
-                    packet.mRelayIp, packet.mRequestedIp, packet.mHostName);
-        } catch (DhcpLeaseRepository.OutOfAddressesException e) {
-            transmitNak(packet, "Out of addresses to offer");
-            return;
-        } catch (DhcpLeaseRepository.InvalidSubnetException e) {
-            logIgnoredPacketInvalidSubnet(e);
-            return;
-        }
-
-        transmitOffer(packet, lease, clientMac);
-    }
-
-    private void processRequest(@NonNull DhcpRequestPacket packet) throws MalformedPacketException {
-        // If set, packet SID matches with this server's ID as checked in processPacket().
-        final boolean sidSet = packet.mServerIdentifier != null;
-        final DhcpLease lease;
-        final MacAddress clientMac = getMacAddr(packet);
-        try {
-            lease = mLeaseRepo.requestLease(packet.getExplicitClientIdOrNull(), clientMac,
-                    packet.mClientIp, packet.mRelayIp, packet.mRequestedIp, sidSet,
-                    packet.mHostName);
-        } catch (DhcpLeaseRepository.InvalidAddressException e) {
-            transmitNak(packet, "Invalid requested address");
-            return;
-        } catch (DhcpLeaseRepository.InvalidSubnetException e) {
-            logIgnoredPacketInvalidSubnet(e);
-            return;
-        }
-
-        transmitAck(packet, lease, clientMac);
-    }
-
-    private void processRelease(@NonNull DhcpReleasePacket packet)
-            throws MalformedPacketException {
-        final byte[] clientId = packet.getExplicitClientIdOrNull();
-        final MacAddress macAddr = getMacAddr(packet);
-        // Don't care about success (there is no ACK/NAK); logging is already done in the repository
-        mLeaseRepo.releaseLease(clientId, macAddr, packet.mClientIp);
-    }
-
-    private Inet4Address getAckOrOfferDst(@NonNull DhcpPacket request, @NonNull DhcpLease lease,
-            boolean broadcastFlag) {
-        // Unless relayed or broadcast, send to client IP if already configured on the client, or to
-        // the lease address if the client has no configured address
-        if (!isEmpty(request.mRelayIp)) {
-            return request.mRelayIp;
-        } else if (broadcastFlag) {
-            return (Inet4Address) Inet4Address.ALL;
-        } else if (!isEmpty(request.mClientIp)) {
-            return request.mClientIp;
-        } else {
-            return lease.getNetAddr();
-        }
-    }
-
-    /**
-     * Determine whether the broadcast flag should be set in the BOOTP packet flags. This does not
-     * apply to NAK responses, which should always have it set.
-     */
-    private static boolean getBroadcastFlag(@NonNull DhcpPacket request, @NonNull DhcpLease lease) {
-        // No broadcast flag if the client already has a configured IP to unicast to. RFC2131 #4.1
-        // has some contradictions regarding broadcast behavior if a client already has an IP
-        // configured and sends a request with both ciaddr (renew/rebind) and the broadcast flag
-        // set. Sending a unicast response to ciaddr matches previous behavior and is more
-        // efficient.
-        // If the client has no configured IP, broadcast if requested by the client or if the lease
-        // address cannot be used to send a unicast reply either.
-        return isEmpty(request.mClientIp) && (request.mBroadcast || isEmpty(lease.getNetAddr()));
-    }
-
-    /**
-     * Get the hostname from a lease if non-empty and requested in the incoming request.
-     * @param request The incoming request.
-     * @return The hostname, or null if not requested or empty.
-     */
-    @Nullable
-    private static String getHostnameIfRequested(@NonNull DhcpPacket request,
-            @NonNull DhcpLease lease) {
-        return request.hasRequestedParam(DHCP_HOST_NAME) && !TextUtils.isEmpty(lease.getHostname())
-                ? lease.getHostname()
-                : null;
-    }
-
-    private boolean transmitOffer(@NonNull DhcpPacket request, @NonNull DhcpLease lease,
-            @NonNull MacAddress clientMac) {
-        final boolean broadcastFlag = getBroadcastFlag(request, lease);
-        final int timeout = getLeaseTimeout(lease);
-        final Inet4Address prefixMask =
-                getPrefixMaskAsInet4Address(mServingParams.serverAddr.getPrefixLength());
-        final Inet4Address broadcastAddr = getBroadcastAddress(
-                mServingParams.getServerInet4Addr(), mServingParams.serverAddr.getPrefixLength());
-        final String hostname = getHostnameIfRequested(request, lease);
-        final ByteBuffer offerPacket = DhcpPacket.buildOfferPacket(
-                ENCAP_BOOTP, request.mTransId, broadcastFlag, mServingParams.getServerInet4Addr(),
-                request.mRelayIp, lease.getNetAddr(), request.mClientMac, timeout, prefixMask,
-                broadcastAddr, new ArrayList<>(mServingParams.defaultRouters),
-                new ArrayList<>(mServingParams.dnsServers),
-                mServingParams.getServerInet4Addr(), null /* domainName */, hostname,
-                mServingParams.metered, (short) mServingParams.linkMtu);
-
-        return transmitOfferOrAckPacket(offerPacket, request, lease, clientMac, broadcastFlag);
-    }
-
-    private boolean transmitAck(@NonNull DhcpPacket request, @NonNull DhcpLease lease,
-            @NonNull MacAddress clientMac) {
-        // TODO: replace DhcpPacket's build methods with real builders and use common code with
-        // transmitOffer above
-        final boolean broadcastFlag = getBroadcastFlag(request, lease);
-        final int timeout = getLeaseTimeout(lease);
-        final String hostname = getHostnameIfRequested(request, lease);
-        final ByteBuffer ackPacket = DhcpPacket.buildAckPacket(ENCAP_BOOTP, request.mTransId,
-                broadcastFlag, mServingParams.getServerInet4Addr(), request.mRelayIp,
-                lease.getNetAddr(), request.mClientIp, request.mClientMac, timeout,
-                mServingParams.getPrefixMaskAsAddress(), mServingParams.getBroadcastAddress(),
-                new ArrayList<>(mServingParams.defaultRouters),
-                new ArrayList<>(mServingParams.dnsServers),
-                mServingParams.getServerInet4Addr(), null /* domainName */, hostname,
-                mServingParams.metered, (short) mServingParams.linkMtu);
-
-        return transmitOfferOrAckPacket(ackPacket, request, lease, clientMac, broadcastFlag);
-    }
-
-    private boolean transmitNak(DhcpPacket request, String message) {
-        mLog.w("Transmitting NAK: " + message);
-        // Always set broadcast flag for NAK: client may not have a correct IP
-        final ByteBuffer nakPacket = DhcpPacket.buildNakPacket(
-                ENCAP_BOOTP, request.mTransId, mServingParams.getServerInet4Addr(),
-                request.mRelayIp, request.mClientMac, true /* broadcast */, message);
-
-        final Inet4Address dst = isEmpty(request.mRelayIp)
-                ? (Inet4Address) Inet4Address.ALL
-                : request.mRelayIp;
-        return transmitPacket(nakPacket, DhcpNakPacket.class.getSimpleName(), dst);
-    }
-
-    private boolean transmitOfferOrAckPacket(@NonNull ByteBuffer buf, @NonNull DhcpPacket request,
-            @NonNull DhcpLease lease, @NonNull MacAddress clientMac, boolean broadcastFlag) {
-        mLog.logf("Transmitting %s with lease %s", request.getClass().getSimpleName(), lease);
-        // Client may not yet respond to ARP for the lease address, which may be the destination
-        // address. Add an entry to the ARP cache to save future ARP probes and make sure the
-        // packet reaches its destination.
-        if (!addArpEntry(clientMac, lease.getNetAddr())) {
-            // Logging for error already done
-            return false;
-        }
-        final Inet4Address dst = getAckOrOfferDst(request, lease, broadcastFlag);
-        return transmitPacket(buf, request.getClass().getSimpleName(), dst);
-    }
-
-    private boolean transmitPacket(@NonNull ByteBuffer buf, @NonNull String packetTypeTag,
-            @NonNull Inet4Address dst) {
-        try {
-            mDeps.sendPacket(mSocket, buf, dst);
-        } catch (ErrnoException | IOException e) {
-            mLog.e("Can't send packet " + packetTypeTag, e);
-            return false;
-        }
-        return true;
-    }
-
-    private boolean addArpEntry(@NonNull MacAddress macAddr, @NonNull Inet4Address inetAddr) {
-        try {
-            mDeps.addArpEntry(inetAddr, macAddr, mIfName, mSocket);
-            return true;
-        } catch (IOException e) {
-            mLog.e("Error adding client to ARP table", e);
-            return false;
-        }
-    }
-
-    /**
-     * Get the remaining lease time in seconds, starting from {@link Clock#elapsedRealtime()}.
-     *
-     * <p>This is an unsigned 32-bit integer, so it cannot be read as a standard (signed) Java int.
-     * The return value is only intended to be used to populate the lease time field in a DHCP
-     * response, considering that lease time is an unsigned 32-bit integer field in DHCP packets.
-     *
-     * <p>Lease expiration times are tracked internally with millisecond precision: this method
-     * returns a rounded down value.
-     */
-    private int getLeaseTimeout(@NonNull DhcpLease lease) {
-        final long remainingTimeSecs = (lease.getExpTime() - mClock.elapsedRealtime()) / 1000;
-        if (remainingTimeSecs < 0) {
-            mLog.e("Processing expired lease " + lease);
-            return EXPIRED_FALLBACK_LEASE_TIME_SECS;
-        }
-
-        if (remainingTimeSecs >= toUnsignedLong(INFINITE_LEASE)) {
-            return INFINITE_LEASE;
-        }
-
-        return (int) remainingTimeSecs;
-    }
-
-    /**
-     * Get the client MAC address from a packet.
-     *
-     * @throws MalformedPacketException The address in the packet uses an unsupported format.
-     */
-    @NonNull
-    private MacAddress getMacAddr(@NonNull DhcpPacket packet) throws MalformedPacketException {
-        try {
-            return MacAddress.fromBytes(packet.getClientMac());
-        } catch (IllegalArgumentException e) {
-            final String message = "Invalid MAC address in packet: "
-                    + HexDump.dumpHexString(packet.getClientMac());
-            throw new MalformedPacketException(message, e);
-        }
-    }
-
-    private static boolean isEmpty(@Nullable Inet4Address address) {
-        return address == null || Inet4Address.ANY.equals(address);
-    }
-
-    private class PacketListener extends DhcpPacketListener {
-        PacketListener() {
-            super(mHandler);
-        }
-
-        @Override
-        protected void onReceive(@NonNull DhcpPacket packet, @NonNull Inet4Address srcAddr,
-                int srcPort) {
-            processPacket(packet, srcPort);
-        }
-
-        @Override
-        protected void logError(@NonNull String msg, Exception e) {
-            mLog.e("Error receiving packet: " + msg, e);
-        }
-
-        @Override
-        protected void logParseError(@NonNull byte[] packet, int length,
-                @NonNull DhcpPacket.ParseException e) {
-            mLog.e("Error parsing packet", e);
-        }
-
-        @Override
-        protected FileDescriptor createFd() {
-            // TODO: have and use an API to set a socket tag without going through the thread tag
-            final int oldTag = TrafficStats.getAndSetThreadStatsTag(TAG_SYSTEM_DHCP_SERVER);
-            try {
-                mSocket = Os.socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-                Os.setsockoptInt(mSocket, SOL_SOCKET, SO_REUSEADDR, 1);
-                // SO_BINDTODEVICE actually takes a string. This works because the first member
-                // of struct ifreq is a NULL-terminated interface name.
-                // TODO: add a setsockoptString()
-                Os.setsockoptIfreq(mSocket, SOL_SOCKET, SO_BINDTODEVICE, mIfName);
-                Os.setsockoptInt(mSocket, SOL_SOCKET, SO_BROADCAST, 1);
-                Os.bind(mSocket, Inet4Address.ANY, DHCP_SERVER);
-                NetworkUtils.protectFromVpn(mSocket);
-
-                return mSocket;
-            } catch (IOException | ErrnoException e) {
-                mLog.e("Error creating UDP socket", e);
-                DhcpServer.this.stop();
-                return null;
-            } finally {
-                TrafficStats.setThreadStatsTag(oldTag);
-            }
-        }
-    }
-}
diff --git a/services/net/java/android/net/dhcp/DhcpServingParams.java b/services/net/java/android/net/dhcp/DhcpServingParams.java
deleted file mode 100644
index 2780814a2f33..000000000000
--- a/services/net/java/android/net/dhcp/DhcpServingParams.java
+++ /dev/null
@@ -1,365 +0,0 @@
-/*
- * 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.dhcp;
-
-import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
-import static android.net.NetworkUtils.intToInet4AddressHTH;
-import static android.net.dhcp.DhcpPacket.INFINITE_LEASE;
-import static android.net.util.NetworkConstants.IPV4_MAX_MTU;
-import static android.net.util.NetworkConstants.IPV4_MIN_MTU;
-
-import static java.lang.Integer.toUnsignedLong;
-
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.net.IpPrefix;
-import android.net.LinkAddress;
-import android.net.NetworkUtils;
-
-import com.google.android.collect.Sets;
-
-import java.net.Inet4Address;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Set;
-
-/**
- * Parameters used by the DhcpServer to serve requests.
- *
- * <p>Instances are immutable. Use {@link DhcpServingParams.Builder} to instantiate.
- * @hide
- */
-public class DhcpServingParams {
-    public static final int MTU_UNSET = 0;
-    public static final int MIN_PREFIX_LENGTH = 16;
-    public static final int MAX_PREFIX_LENGTH = 30;
-
-    /** Server inet address and prefix to serve */
-    @NonNull
-    public final LinkAddress serverAddr;
-
-    /**
-     * Default routers to be advertised to DHCP clients. May be empty.
-     * This set is provided by {@link DhcpServingParams.Builder} and is immutable.
-     */
-    @NonNull
-    public final Set<Inet4Address> defaultRouters;
-
-    /**
-     * DNS servers to be advertised to DHCP clients. May be empty.
-     * This set is provided by {@link DhcpServingParams.Builder} and is immutable.
-     */
-    @NonNull
-    public final Set<Inet4Address> dnsServers;
-
-    /**
-     * Excluded addresses that the DHCP server is not allowed to assign to clients.
-     * This set is provided by {@link DhcpServingParams.Builder} and is immutable.
-     */
-    @NonNull
-    public final Set<Inet4Address> excludedAddrs;
-
-    // DHCP uses uint32. Use long for clearer code, and check range when building.
-    public final long dhcpLeaseTimeSecs;
-    public final int linkMtu;
-
-    /**
-     * Indicates whether the DHCP server should send the ANDROID_METERED vendor-specific option.
-     */
-    public final boolean metered;
-
-    /**
-     * Checked exception thrown when some parameters used to build {@link DhcpServingParams} are
-     * missing or invalid.
-     */
-    public static class InvalidParameterException extends Exception {
-        public InvalidParameterException(String message) {
-            super(message);
-        }
-    }
-
-    private DhcpServingParams(@NonNull LinkAddress serverAddr,
-            @NonNull Set<Inet4Address> defaultRouters,
-            @NonNull Set<Inet4Address> dnsServers, @NonNull Set<Inet4Address> excludedAddrs,
-            long dhcpLeaseTimeSecs, int linkMtu, boolean metered) {
-        this.serverAddr = serverAddr;
-        this.defaultRouters = defaultRouters;
-        this.dnsServers = dnsServers;
-        this.excludedAddrs = excludedAddrs;
-        this.dhcpLeaseTimeSecs = dhcpLeaseTimeSecs;
-        this.linkMtu = linkMtu;
-        this.metered = metered;
-    }
-
-    /**
-     * Create parameters from a stable AIDL-compatible parcel.
-     */
-    public static DhcpServingParams fromParcelableObject(@NonNull DhcpServingParamsParcel parcel)
-            throws InvalidParameterException {
-        final LinkAddress serverAddr = new LinkAddress(
-                intToInet4AddressHTH(parcel.serverAddr),
-                parcel.serverAddrPrefixLength);
-        return new Builder()
-                .setServerAddr(serverAddr)
-                .setDefaultRouters(toInet4AddressSet(parcel.defaultRouters))
-                .setDnsServers(toInet4AddressSet(parcel.dnsServers))
-                .setExcludedAddrs(toInet4AddressSet(parcel.excludedAddrs))
-                .setDhcpLeaseTimeSecs(parcel.dhcpLeaseTimeSecs)
-                .setLinkMtu(parcel.linkMtu)
-                .setMetered(parcel.metered)
-                .build();
-    }
-
-    private static Set<Inet4Address> toInet4AddressSet(@Nullable int[] addrs) {
-        if (addrs == null) {
-            return new HashSet<>(0);
-        }
-
-        final HashSet<Inet4Address> res = new HashSet<>();
-        for (int addr : addrs) {
-            res.add(intToInet4AddressHTH(addr));
-        }
-        return res;
-    }
-
-    @NonNull
-    public Inet4Address getServerInet4Addr() {
-        return (Inet4Address) serverAddr.getAddress();
-    }
-
-    /**
-     * Get the served prefix mask as an IPv4 address.
-     *
-     * <p>For example, if the served prefix is 192.168.42.0/24, this will return 255.255.255.0.
-     */
-    @NonNull
-    public Inet4Address getPrefixMaskAsAddress() {
-        return getPrefixMaskAsInet4Address(serverAddr.getPrefixLength());
-    }
-
-    /**
-     * Get the server broadcast address.
-     *
-     * <p>For example, if the server {@link LinkAddress} is 192.168.42.1/24, this will return
-     * 192.168.42.255.
-     */
-    @NonNull
-    public Inet4Address getBroadcastAddress() {
-        return NetworkUtils.getBroadcastAddress(getServerInet4Addr(), serverAddr.getPrefixLength());
-    }
-
-    /**
-     * Utility class to create new instances of {@link DhcpServingParams} while checking validity
-     * of the parameters.
-     */
-    public static class Builder {
-        private LinkAddress mServerAddr;
-        private Set<Inet4Address> mDefaultRouters;
-        private Set<Inet4Address> mDnsServers;
-        private Set<Inet4Address> mExcludedAddrs;
-        private long mDhcpLeaseTimeSecs;
-        private int mLinkMtu = MTU_UNSET;
-        private boolean mMetered;
-
-        /**
-         * Set the server address and served prefix for the DHCP server.
-         *
-         * <p>This parameter is required.
-         */
-        public Builder setServerAddr(@NonNull LinkAddress serverAddr) {
-            this.mServerAddr = serverAddr;
-            return this;
-        }
-
-        /**
-         * Set the default routers to be advertised to DHCP clients.
-         *
-         * <p>Each router must be inside the served prefix. This may be an empty set, but it must
-         * always be set explicitly before building the {@link DhcpServingParams}.
-         */
-        public Builder setDefaultRouters(@NonNull Set<Inet4Address> defaultRouters) {
-            this.mDefaultRouters = defaultRouters;
-            return this;
-        }
-
-        /**
-         * Set the default routers to be advertised to DHCP clients.
-         *
-         * <p>Each router must be inside the served prefix. This may be an empty list of routers,
-         * but it must always be set explicitly before building the {@link DhcpServingParams}.
-         */
-        public Builder setDefaultRouters(@NonNull Inet4Address... defaultRouters) {
-            return setDefaultRouters(Sets.newArraySet(defaultRouters));
-        }
-
-        /**
-         * Convenience method to build the parameters with no default router.
-         *
-         * <p>Equivalent to calling {@link #setDefaultRouters(Inet4Address...)} with no address.
-         */
-        public Builder withNoDefaultRouter() {
-            return setDefaultRouters();
-        }
-
-        /**
-         * Set the DNS servers to be advertised to DHCP clients.
-         *
-         * <p>This may be an empty set, but it must always be set explicitly before building the
-         * {@link DhcpServingParams}.
-         */
-        public Builder setDnsServers(@NonNull Set<Inet4Address> dnsServers) {
-            this.mDnsServers = dnsServers;
-            return this;
-        }
-
-        /**
-         * Set the DNS servers to be advertised to DHCP clients.
-         *
-         * <p>This may be an empty list of servers, but it must always be set explicitly before
-         * building the {@link DhcpServingParams}.
-         */
-        public Builder setDnsServers(@NonNull Inet4Address... dnsServers) {
-            return setDnsServers(Sets.newArraySet(dnsServers));
-        }
-
-        /**
-         * Convenience method to build the parameters with no DNS server.
-         *
-         * <p>Equivalent to calling {@link #setDnsServers(Inet4Address...)} with no address.
-         */
-        public Builder withNoDnsServer() {
-            return setDnsServers();
-        }
-
-        /**
-         * Set excluded addresses that the DHCP server is not allowed to assign to clients.
-         *
-         * <p>This parameter is optional. DNS servers and default routers are always excluded
-         * and do not need to be set here.
-         */
-        public Builder setExcludedAddrs(@NonNull Set<Inet4Address> excludedAddrs) {
-            this.mExcludedAddrs = excludedAddrs;
-            return this;
-        }
-
-        /**
-         * Set excluded addresses that the DHCP server is not allowed to assign to clients.
-         *
-         * <p>This parameter is optional. DNS servers and default routers are always excluded
-         * and do not need to be set here.
-         */
-        public Builder setExcludedAddrs(@NonNull Inet4Address... excludedAddrs) {
-            return setExcludedAddrs(Sets.newArraySet(excludedAddrs));
-        }
-
-        /**
-         * Set the lease time for leases assigned by the DHCP server.
-         *
-         * <p>This parameter is required.
-         */
-        public Builder setDhcpLeaseTimeSecs(long dhcpLeaseTimeSecs) {
-            this.mDhcpLeaseTimeSecs = dhcpLeaseTimeSecs;
-            return this;
-        }
-
-        /**
-         * Set the link MTU to be advertised to DHCP clients.
-         *
-         * <p>If set to {@link #MTU_UNSET}, no MTU will be advertised to clients. This parameter
-         * is optional and defaults to {@link #MTU_UNSET}.
-         */
-        public Builder setLinkMtu(int linkMtu) {
-            this.mLinkMtu = linkMtu;
-            return this;
-        }
-
-        /**
-         * Set whether the DHCP server should send the ANDROID_METERED vendor-specific option.
-         *
-         * <p>If not set, the default value is false.
-         */
-        public Builder setMetered(boolean metered) {
-            this.mMetered = metered;
-            return this;
-        }
-
-        /**
-         * Create a new {@link DhcpServingParams} instance based on parameters set in the builder.
-         *
-         * <p>This method has no side-effects. If it does not throw, a valid
-         * {@link DhcpServingParams} is returned.
-         * @return The constructed parameters.
-         * @throws InvalidParameterException At least one parameter is missing or invalid.
-         */
-        @NonNull
-        public DhcpServingParams build() throws InvalidParameterException {
-            if (mServerAddr == null) {
-                throw new InvalidParameterException("Missing serverAddr");
-            }
-            if (mDefaultRouters == null) {
-                throw new InvalidParameterException("Missing defaultRouters");
-            }
-            if (mDnsServers == null) {
-                // Empty set is OK, but enforce explicitly setting it
-                throw new InvalidParameterException("Missing dnsServers");
-            }
-            if (mDhcpLeaseTimeSecs <= 0 || mDhcpLeaseTimeSecs > toUnsignedLong(INFINITE_LEASE)) {
-                throw new InvalidParameterException("Invalid lease time: " + mDhcpLeaseTimeSecs);
-            }
-            if (mLinkMtu != MTU_UNSET && (mLinkMtu < IPV4_MIN_MTU || mLinkMtu > IPV4_MAX_MTU)) {
-                throw new InvalidParameterException("Invalid link MTU: " + mLinkMtu);
-            }
-            if (!mServerAddr.isIPv4()) {
-                throw new InvalidParameterException("serverAddr must be IPv4");
-            }
-            if (mServerAddr.getPrefixLength() < MIN_PREFIX_LENGTH
-                    || mServerAddr.getPrefixLength() > MAX_PREFIX_LENGTH) {
-                throw new InvalidParameterException("Prefix length is not in supported range");
-            }
-
-            final IpPrefix prefix = makeIpPrefix(mServerAddr);
-            for (Inet4Address addr : mDefaultRouters) {
-                if (!prefix.contains(addr)) {
-                    throw new InvalidParameterException(String.format(
-                            "Default router %s is not in server prefix %s", addr, mServerAddr));
-                }
-            }
-
-            final Set<Inet4Address> excl = new HashSet<>();
-            if (mExcludedAddrs != null) {
-                excl.addAll(mExcludedAddrs);
-            }
-            excl.add((Inet4Address) mServerAddr.getAddress());
-            excl.addAll(mDefaultRouters);
-            excl.addAll(mDnsServers);
-
-            return new DhcpServingParams(mServerAddr,
-                    Collections.unmodifiableSet(new HashSet<>(mDefaultRouters)),
-                    Collections.unmodifiableSet(new HashSet<>(mDnsServers)),
-                    Collections.unmodifiableSet(excl),
-                    mDhcpLeaseTimeSecs, mLinkMtu, mMetered);
-        }
-    }
-
-    /**
-     * Utility method to create an IpPrefix with the address and prefix length of a LinkAddress.
-     */
-    @NonNull
-    static IpPrefix makeIpPrefix(@NonNull LinkAddress addr) {
-        return new IpPrefix(addr.getAddress(), addr.getPrefixLength());
-    }
-}
diff --git a/services/net/java/android/net/ip/IpServer.java b/services/net/java/android/net/ip/IpServer.java
index 493350d776f3..8b22f68286af 100644
--- a/services/net/java/android/net/ip/IpServer.java
+++ b/services/net/java/android/net/ip/IpServer.java
@@ -17,20 +17,26 @@
 package android.net.ip;
 
 import static android.net.NetworkUtils.numericToInetAddress;
-import static android.net.util.NetworkConstants.asByte;
+import static android.net.dhcp.IDhcpServer.STATUS_SUCCESS;
 import static android.net.util.NetworkConstants.FF;
 import static android.net.util.NetworkConstants.RFC7421_PREFIX_LENGTH;
+import static android.net.util.NetworkConstants.asByte;
 
+import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.INetd;
+import android.net.INetworkStackStatusCallback;
 import android.net.INetworkStatsService;
 import android.net.InterfaceConfiguration;
 import android.net.IpPrefix;
 import android.net.LinkAddress;
 import android.net.LinkProperties;
+import android.net.NetworkStack;
 import android.net.RouteInfo;
-import android.net.dhcp.DhcpServer;
-import android.net.dhcp.DhcpServingParams;
+import android.net.dhcp.DhcpServerCallbacks;
+import android.net.dhcp.DhcpServingParamsParcel;
+import android.net.dhcp.DhcpServingParamsParcelExt;
+import android.net.dhcp.IDhcpServer;
 import android.net.ip.RouterAdvertisementDaemon.RaParams;
 import android.net.util.InterfaceParams;
 import android.net.util.InterfaceSet;
@@ -126,6 +132,10 @@ public class IpServer extends StateMachine {
     }
 
     public static class Dependencies {
+        private final Context mContext;
+        public Dependencies(Context context) {
+            mContext = context;
+        }
         public RouterAdvertisementDaemon getRouterAdvertisementDaemon(InterfaceParams ifParams) {
             return new RouterAdvertisementDaemon(ifParams);
         }
@@ -138,9 +148,12 @@ public class IpServer extends StateMachine {
             return NetdService.getInstance();
         }
 
-        public DhcpServer makeDhcpServer(Looper looper, String ifName,
-                DhcpServingParams params, SharedLog log) {
-            return new DhcpServer(looper, ifName, params, log);
+        /**
+         * Create a DhcpServer instance to be used by IpServer.
+         */
+        public void makeDhcpServer(String ifName, DhcpServingParamsParcel params,
+                DhcpServerCallbacks cb) {
+            mContext.getSystemService(NetworkStack.class).makeDhcpServer(ifName, params, cb);
         }
     }
 
@@ -197,7 +210,10 @@ public class IpServer extends StateMachine {
     // Advertisements (otherwise, we do not add them to mLinkProperties at all).
     private LinkProperties mLastIPv6LinkProperties;
     private RouterAdvertisementDaemon mRaDaemon;
-    private DhcpServer mDhcpServer;
+
+    // To be accessed only on the handler thread
+    private int mDhcpServerStartIndex = 0;
+    private IDhcpServer mDhcpServer;
     private RaParams mLastRaParams;
 
     public IpServer(
@@ -252,35 +268,109 @@ public class IpServer extends StateMachine {
 
     private boolean startIPv4() { return configureIPv4(true); }
 
+    /**
+     * Convenience wrapper around INetworkStackStatusCallback to run callbacks on the IpServer
+     * handler.
+     *
+     * <p>Different instances of this class can be created for each call to IDhcpServer methods,
+     * with different implementations of the callback, to differentiate handling of success/error in
+     * each call.
+     */
+    private abstract class OnHandlerStatusCallback extends INetworkStackStatusCallback.Stub {
+        @Override
+        public void onStatusAvailable(int statusCode) {
+            getHandler().post(() -> callback(statusCode));
+        }
+
+        public abstract void callback(int statusCode);
+    }
+
+    private class DhcpServerCallbacksImpl extends DhcpServerCallbacks {
+        private final int mStartIndex;
+
+        private DhcpServerCallbacksImpl(int startIndex) {
+            mStartIndex = startIndex;
+        }
+
+        @Override
+        public void onDhcpServerCreated(int statusCode, IDhcpServer server) throws RemoteException {
+            getHandler().post(() -> {
+                // We are on the handler thread: mDhcpServerStartIndex can be read safely.
+                if (mStartIndex != mDhcpServerStartIndex) {
+                    // This start request is obsolete. When the |server| binder token goes out of
+                    // scope, the garbage collector will finalize it, which causes the network stack
+                    // process garbage collector to collect the server itself.
+                    return;
+                }
+
+                if (statusCode != STATUS_SUCCESS) {
+                    mLog.e("Error obtaining DHCP server: " + statusCode);
+                    handleError();
+                    return;
+                }
+
+                mDhcpServer = server;
+                try {
+                    mDhcpServer.start(new OnHandlerStatusCallback() {
+                        @Override
+                        public void callback(int startStatusCode) {
+                            if (startStatusCode != STATUS_SUCCESS) {
+                                mLog.e("Error starting DHCP server: " + startStatusCode);
+                                handleError();
+                            }
+                        }
+                    });
+                } catch (RemoteException e) {
+                    e.rethrowFromSystemServer();
+                }
+            });
+        }
+
+        private void handleError() {
+            mLastError = ConnectivityManager.TETHER_ERROR_DHCPSERVER_ERROR;
+            transitionTo(mInitialState);
+        }
+    }
+
     private boolean startDhcp(Inet4Address addr, int prefixLen) {
         if (mUsingLegacyDhcp) {
             return true;
         }
-        final DhcpServingParams params;
-        try {
-            params = new DhcpServingParams.Builder()
-                    .setDefaultRouters(addr)
-                    .setDhcpLeaseTimeSecs(DHCP_LEASE_TIME_SECS)
-                    .setDnsServers(addr)
-                    .setServerAddr(new LinkAddress(addr, prefixLen))
-                    .setMetered(true)
-                    .build();
-            // TODO: also advertise link MTU
-        } catch (DhcpServingParams.InvalidParameterException e) {
-            Log.e(TAG, "Invalid DHCP parameters", e);
-            return false;
-        }
-
-        mDhcpServer = mDeps.makeDhcpServer(getHandler().getLooper(), mIfaceName, params,
-                mLog.forSubComponent("DHCP"));
-        mDhcpServer.start();
+        final DhcpServingParamsParcel params;
+        params = new DhcpServingParamsParcelExt()
+                .setDefaultRouters(addr)
+                .setDhcpLeaseTimeSecs(DHCP_LEASE_TIME_SECS)
+                .setDnsServers(addr)
+                .setServerAddr(new LinkAddress(addr, prefixLen))
+                .setMetered(true);
+        // TODO: also advertise link MTU
+
+        mDhcpServerStartIndex++;
+        mDeps.makeDhcpServer(
+                mIfaceName, params, new DhcpServerCallbacksImpl(mDhcpServerStartIndex));
         return true;
     }
 
     private void stopDhcp() {
+        // Make all previous start requests obsolete so servers are not started later
+        mDhcpServerStartIndex++;
+
         if (mDhcpServer != null) {
-            mDhcpServer.stop();
-            mDhcpServer = null;
+            try {
+                mDhcpServer.stop(new OnHandlerStatusCallback() {
+                    @Override
+                    public void callback(int statusCode) {
+                        if (statusCode != STATUS_SUCCESS) {
+                            mLog.e("Error stopping DHCP server: " + statusCode);
+                            mLastError = ConnectivityManager.TETHER_ERROR_DHCPSERVER_ERROR;
+                            // Not much more we can do here
+                        }
+                    }
+                });
+                mDhcpServer = null;
+            } catch (RemoteException e) {
+                e.rethrowFromSystemServer();
+            }
         }
     }
 
diff --git a/services/net/java/android/net/util/NetworkConstants.java b/services/net/java/android/net/util/NetworkConstants.java
index 3defe56939f5..c183b81362dc 100644
--- a/services/net/java/android/net/util/NetworkConstants.java
+++ b/services/net/java/android/net/util/NetworkConstants.java
@@ -16,9 +16,6 @@
 
 package android.net.util;
 
-import java.nio.ByteBuffer;
-
-
 /**
  * Networking protocol constants.
  *
@@ -81,8 +78,6 @@ public final class NetworkConstants {
      *     - https://tools.ietf.org/html/rfc791
      */
     public static final int IPV4_HEADER_MIN_LEN = 20;
-    public static final int IPV4_MIN_MTU = 68;
-    public static final int IPV4_MAX_MTU = 65_535;
     public static final int IPV4_IHL_MASK = 0xf;
     public static final int IPV4_FLAGS_OFFSET = 6;
     public static final int IPV4_FRAGMENT_MASK = 0x1fff;
diff --git a/services/net/java/android/net/util/SharedLog.java b/services/net/java/android/net/util/SharedLog.java
index 74bc1470293f..8b7b59d20978 100644
--- a/services/net/java/android/net/util/SharedLog.java
+++ b/services/net/java/android/net/util/SharedLog.java
@@ -32,6 +32,7 @@ import java.util.StringJoiner;
  *
  * All access to class methods other than dump() must be on the same thread.
  *
+ * TODO: this is a copy of SharedLog in the NetworkStack. Remove after Tethering is migrated.
  * @hide
  */
 public class SharedLog {