Move DhcpServer to NetworkStack app

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

Change-Id: I96c40e63e9ceb37b67705bdd4d120307e114715b

1 files changed, 370 insertions, 0 deletions

diff --git a/src/android/net/dhcp/DhcpServingParams.java b/src/android/net/dhcp/DhcpServingParams.java
new file mode 100644
index 0000000..f38888a
--- /dev/null
+++ b/src/android/net/dhcp/DhcpServingParams.java
@@ -0,0 +1,370 @@
+/*
+ * 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 com.android.server.util.NetworkStackConstants.INFINITE_LEASE;
+import static com.android.server.util.NetworkStackConstants.IPV4_MAX_MTU;
+import static com.android.server.util.NetworkStackConstants.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.
+     * @throws InvalidParameterException The parameters parcelable is null or invalid.
+     */
+    public static DhcpServingParams fromParcelableObject(@Nullable DhcpServingParamsParcel parcel)
+            throws InvalidParameterException {
+        if (parcel == null) {
+            throw new InvalidParameterException("Null serving parameters");
+        }
+        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());
+    }
+}