Revert "[ST02] Add methods for synthesizing DNS packets"

Revert "[ST02.1] Add TYPE_CNAME constant to DnsResolver"

Revert submission 1387135-st02

Reason for revert: Usage of TYPE_CNAME in a library shared among
modules does not interact well with current module release process

Reverted Changes:
Ib5616c65c:[ST02.2] Use the getters of DnsHeader
I5e58f99b0:[ST02.1] Add TYPE_CNAME constant to DnsResolver
I0c1547cbc:[ST02] Add methods for synthesizing DNS packets

Change-Id: I9f8de47c9ba9fb4db7cf3695966f222f68a9a290
diff --git a/staticlibs/Android.bp b/staticlibs/Android.bp
index f4997a1..4dfc752 100644
--- a/staticlibs/Android.bp
+++ b/staticlibs/Android.bp
@@ -96,10 +96,7 @@
     visibility: [
         "//packages/services/Iwlan:__subpackages__",
     ],
-    libs: [
-        "framework-annotations-lib",
-        "framework-connectivity.stubs.module_lib",
-    ],
+    libs: ["framework-annotations-lib"],
 }
 
 filegroup {
diff --git a/staticlibs/framework/com/android/net/module/util/DnsPacket.java b/staticlibs/framework/com/android/net/module/util/DnsPacket.java
index 13a83ad..080781c 100644
--- a/staticlibs/framework/com/android/net/module/util/DnsPacket.java
+++ b/staticlibs/framework/com/android/net/module/util/DnsPacket.java
@@ -16,35 +16,15 @@
 
 package com.android.net.module.util;
 
-import static android.net.DnsResolver.TYPE_A;
-import static android.net.DnsResolver.TYPE_AAAA;
-import static android.net.DnsResolver.TYPE_CNAME;
-
-import static com.android.internal.annotations.VisibleForTesting.Visibility.PACKAGE;
-import static com.android.internal.annotations.VisibleForTesting.Visibility.PRIVATE;
-import static com.android.net.module.util.DnsPacketUtils.DnsRecordParser.domainNameToLabels;
-
-import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
-import android.text.TextUtils;
 
-import com.android.internal.annotations.VisibleForTesting;
 import com.android.net.module.util.DnsPacketUtils.DnsRecordParser;
 
-import java.io.ByteArrayOutputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.net.InetAddress;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
-import java.util.Objects;
 
 /**
  * Defines basic data for DNS protocol based on RFC 1035.
@@ -70,29 +50,13 @@
     }
 
     /**
-     * DNS header for DNS protocol based on RFC 1035 section 4.1.1.
-     *
-     *                                     1  1  1  1  1  1
-     *       0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                      ID                       |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |QR|   Opcode  |AA|TC|RD|RA|   Z    |   RCODE   |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                    QDCOUNT                    |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                    ANCOUNT                    |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                    NSCOUNT                    |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                    ARCOUNT                    |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+     * DNS header for DNS protocol based on RFC 1035.
      */
-    public static class DnsHeader {
+    public class DnsHeader {
         private static final String TAG = "DnsHeader";
-        private static final int SIZE_IN_BYTES = 12;
-        private final int mId;
-        private final int mFlags;
+        public final int id;
+        public final int flags;
+        public final int rcode;
         private final int[] mRecordCount;
 
         /* If this bit in the 'flags' field is set to 0, the DNS message corresponding to this
@@ -109,11 +73,10 @@
          * advanced to the end of the DNS header record.
          * This is meant to chain with other methods reading a DNS response in sequence.
          */
-        @VisibleForTesting
-        public DnsHeader(@NonNull ByteBuffer buf) throws BufferUnderflowException {
-            Objects.requireNonNull(buf);
-            mId = Short.toUnsignedInt(buf.getShort());
-            mFlags = Short.toUnsignedInt(buf.getShort());
+        DnsHeader(@NonNull ByteBuffer buf) throws BufferUnderflowException {
+            id = Short.toUnsignedInt(buf.getShort());
+            flags = Short.toUnsignedInt(buf.getShort());
+            rcode = flags & 0xF;
             mRecordCount = new int[NUM_SECTIONS];
             for (int i = 0; i < NUM_SECTIONS; ++i) {
                 mRecordCount[i] = Short.toUnsignedInt(buf.getShort());
@@ -125,23 +88,7 @@
          * RFC 1035 Section 4.1.1.
          */
         public boolean isResponse() {
-            return (mFlags & (1 << FLAGS_SECTION_QR_BIT)) != 0;
-        }
-
-        /**
-         * Create a new DnsHeader from specified parameters.
-         *
-         * This constructor only builds the question and answer sections. Authority
-         * and additional sections are not supported. Useful when synthesizing dns
-         * responses from query or reply packets.
-         */
-        @VisibleForTesting
-        public DnsHeader(int id, int flags, int qdcount, int ancount) {
-            this.mId = id;
-            this.mFlags = flags;
-            mRecordCount = new int[NUM_SECTIONS];
-            mRecordCount[QDSECTION] = qdcount;
-            mRecordCount[ANSECTION] = ancount;
+            return (flags & (1 << FLAGS_SECTION_QR_BIT)) != 0;
         }
 
         /**
@@ -150,103 +97,15 @@
         public int getRecordCount(int type) {
             return mRecordCount[type];
         }
-
-        /**
-         * Get flags of this instance.
-         */
-        public int getFlags() {
-            return mFlags;
-        }
-
-        /**
-         * Get id of this instance.
-         */
-        public int getId() {
-            return mId;
-        }
-
-        @Override
-        public String toString() {
-            return "DnsHeader{" + "id=" + mId + ", flags=" + mFlags
-                    + ", recordCounts=" + Arrays.toString(mRecordCount) + '}';
-        }
-
-        @Override
-        public boolean equals(Object o) {
-            if (this == o) return true;
-            if (o.getClass() != getClass()) return false;
-            final DnsHeader other = (DnsHeader) o;
-            return mId == other.mId
-                    && mFlags == other.mFlags
-                    && Arrays.equals(mRecordCount, other.mRecordCount);
-        }
-
-        @Override
-        public int hashCode() {
-            return 31 * mId + 37 * mFlags + Arrays.hashCode(mRecordCount);
-        }
-
-        /**
-         * Get DnsHeader as byte array.
-         */
-        @NonNull
-        public byte[] getBytes() {
-            // TODO: if this is called often, optimize the ByteBuffer out and write to the
-            //  array directly.
-            final ByteBuffer buf = ByteBuffer.allocate(SIZE_IN_BYTES);
-            buf.putShort((short) mId);
-            buf.putShort((short) mFlags);
-            for (int i = 0; i < NUM_SECTIONS; ++i) {
-                buf.putShort((short) mRecordCount[i]);
-            }
-            return buf.array();
-        }
     }
 
     /**
      * Superclass for DNS questions and DNS resource records.
      *
-     * DNS questions (No TTL/RDLENGTH/RDATA) based on RFC 1035 section 4.1.2.
-     *                                     1  1  1  1  1  1
-     *       0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                                               |
-     *     /                     QNAME                     /
-     *     /                                               /
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                     QTYPE                     |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                     QCLASS                    |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *
-     * DNS resource records (With TTL/RDLENGTH/RDATA) based on RFC 1035 section 4.1.3.
-     *                                     1  1  1  1  1  1
-     *       0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                                               |
-     *     /                                               /
-     *     /                      NAME                     /
-     *     |                                               |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                      TYPE                     |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                     CLASS                     |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                      TTL                      |
-     *     |                                               |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-     *     |                   RDLENGTH                    |
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
-     *     /                     RDATA                     /
-     *     /                                               /
-     *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+     * DNS questions (No TTL/RDATA)
+     * DNS resource records (With TTL/RDATA)
      */
-    // TODO: Make DnsResourceRecord and DnsQuestion subclasses of DnsRecord, and construct
-    //  corresponding object from factory methods.
-    public static class DnsRecord {
-        // Refer to RFC 1035 section 2.3.4 for MAXNAMESIZE.
-        // NAME_NORMAL and NAME_COMPRESSION are used for checking name compression,
-        // refer to rfc 1035 section 4.1.4.
+    public class DnsRecord {
         private static final int MAXNAMESIZE = 255;
         public static final int NAME_NORMAL = 0;
         public static final int NAME_COMPRESSION = 0xC0;
@@ -258,31 +117,22 @@
         public final int nsClass;
         public final long ttl;
         private final byte[] mRdata;
-        /**
-         * Type of this DNS record.
-         */
-        @RecordType
-        public final int rType;
 
         /**
          * Create a new DnsRecord from a positioned ByteBuffer.
          *
          * Reads the passed ByteBuffer from its current position and decodes a DNS record.
          * When this constructor returns, the reading position of the ByteBuffer has been
-         * advanced to the end of the DNS resource record.
+         * advanced to the end of the DNS header record.
          * This is meant to chain with other methods reading a DNS response in sequence.
          *
-         * @param rType Type of the record.
          * @param buf ByteBuffer input of record, must be in network byte order
          *         (which is the default).
          */
-        @VisibleForTesting(visibility = PACKAGE)
-        public DnsRecord(@RecordType int rType, @NonNull ByteBuffer buf)
+        DnsRecord(int recordType, @NonNull ByteBuffer buf)
                 throws BufferUnderflowException, ParseException {
-            Objects.requireNonNull(buf);
-            this.rType = rType;
             dName = DnsRecordParser.parseName(buf, 0 /* Parse depth */,
-                    true /* isNameCompressionSupported */);
+                    /* isNameCompressionSupported= */ true);
             if (dName.length() > MAXNAMESIZE) {
                 throw new ParseException(
                         "Parse name fail, name size is too long: " + dName.length());
@@ -290,7 +140,7 @@
             nsType = Short.toUnsignedInt(buf.getShort());
             nsClass = Short.toUnsignedInt(buf.getShort());
 
-            if (rType != QDSECTION) {
+            if (recordType != QDSECTION) {
                 ttl = Integer.toUnsignedLong(buf.getInt());
                 final int length = Short.toUnsignedInt(buf.getShort());
                 mRdata = new byte[length];
@@ -302,95 +152,6 @@
         }
 
         /**
-         * Make an A or AAAA record based on the specified parameters.
-         *
-         * @param rType Type of the record, can be {@link #ANSECTION}, {@link #ARSECTION}
-         *              or {@link #NSSECTION}.
-         * @param dName Domain name of the record.
-         * @param nsClass Class of the record. See RFC 1035 section 3.2.4.
-         * @param ttl time interval (in seconds) that the resource record may be
-         *            cached before it should be discarded. Zero values are
-         *            interpreted to mean that the RR can only be used for the
-         *            transaction in progress, and should not be cached.
-         * @param address Instance of {@link InetAddress}
-         * @return A record if the {@code address} is an IPv4 address, or AAAA record if the
-         *         {@code address} is an IPv6 address.
-         */
-        public static DnsRecord makeAOrAAAARecord(int rType, @NonNull String dName,
-                int nsClass, long ttl, @NonNull InetAddress address) throws IOException {
-            final int nsType = (address.getAddress().length == 4) ? TYPE_A : TYPE_AAAA;
-            return new DnsRecord(rType, dName, nsType, nsClass, ttl, address, null /* rDataStr */);
-        }
-
-        /**
-         * Make an CNAME record based on the specified parameters.
-         *
-         * @param rType Type of the record, can be {@link #ANSECTION}, {@link #ARSECTION}
-         *              or {@link #NSSECTION}.
-         * @param dName Domain name of the record.
-         * @param nsClass Class of the record. See RFC 1035 section 3.2.4.
-         * @param ttl time interval (in seconds) that the resource record may be
-         *            cached before it should be discarded. Zero values are
-         *            interpreted to mean that the RR can only be used for the
-         *            transaction in progress, and should not be cached.
-         * @param domainName Canonical name of the {@code dName}.
-         * @return A record if the {@code address} is an IPv4 address, or AAAA record if the
-         *         {@code address} is an IPv6 address.
-         */
-        public static DnsRecord makeCNameRecord(int rType, @NonNull String dName, int nsClass,
-                long ttl, @NonNull String domainName) throws IOException {
-            return new DnsRecord(rType, dName, TYPE_CNAME, nsClass, ttl, null /* address */,
-                    domainName);
-        }
-
-        /**
-         * Make a DNS question based on the specified parameters.
-         */
-        public static DnsRecord makeQuestion(@NonNull String dName, int nsType, int nsClass) {
-            return new DnsRecord(dName, nsType, nsClass);
-        }
-
-        private static String requireHostName(@NonNull String name) {
-            if (!DnsRecordParser.isHostName(name)) {
-                throw new IllegalArgumentException("Expected domain name but got " + name);
-            }
-            return name;
-        }
-
-        /**
-         * Create a new query DnsRecord from specified parameters, useful when synthesizing
-         * dns response.
-         */
-        private DnsRecord(@NonNull String dName, int nsType, int nsClass) {
-            this.rType = QDSECTION;
-            this.dName = requireHostName(dName);
-            this.nsType = nsType;
-            this.nsClass = nsClass;
-            mRdata = null;
-            this.ttl = 0;
-        }
-
-        /**
-         * Create a new CNAME/A/AAAA DnsRecord from specified parameters.
-         *
-         * @param address The address only used when synthesizing A or AAAA record.
-         * @param rDataStr The alias of the domain, only used when synthesizing CNAME record.
-         */
-        private DnsRecord(@RecordType int rType, @NonNull String dName, int nsType, int nsClass,
-                long ttl, @Nullable InetAddress address, @Nullable String rDataStr)
-                throws IOException {
-            this.rType = rType;
-            this.dName = requireHostName(dName);
-            this.nsType = nsType;
-            this.nsClass = nsClass;
-            if (rType < 0 || rType >= NUM_SECTIONS || rType == QDSECTION) {
-                throw new IllegalArgumentException("Unexpected record type: " + rType);
-            }
-            mRdata = nsType == TYPE_CNAME ? domainNameToLabels(rDataStr) : address.getAddress();
-            this.ttl = ttl;
-        }
-
-        /**
          * Get a copy of rdata.
          */
         @Nullable
@@ -398,84 +159,13 @@
             return (mRdata == null) ? null : mRdata.clone();
         }
 
-        /**
-         * Get DnsRecord as byte array.
-         */
-        @NonNull
-        public byte[] getBytes() throws IOException {
-            final ByteArrayOutputStream baos = new ByteArrayOutputStream();
-            final DataOutputStream dos = new DataOutputStream(baos);
-            dos.write(domainNameToLabels(dName));
-            dos.writeShort(nsType);
-            dos.writeShort(nsClass);
-            if (rType != QDSECTION) {
-                dos.writeInt((int) ttl);
-                if (mRdata == null) {
-                    dos.writeShort(0);
-                } else {
-                    dos.writeShort(mRdata.length);
-                    dos.write(mRdata);
-                }
-            }
-            return baos.toByteArray();
-        }
-
-        @Override
-        public boolean equals(Object o) {
-            if (this == o) return true;
-            if (o.getClass() != getClass()) return false;
-            final DnsRecord other = (DnsRecord) o;
-            return rType == other.rType
-                    && nsType == other.nsType
-                    && nsClass == other.nsClass
-                    && ttl == other.ttl
-                    && TextUtils.equals(dName, other.dName)
-                    && Arrays.equals(mRdata, other.mRdata);
-        }
-
-        @Override
-        public int hashCode() {
-            return 31 * Objects.hash(dName)
-                    + 37 * ((int) (ttl & 0xFFFFFFFF))
-                    + 41 * ((int) (ttl >> 32))
-                    + 43 * nsType
-                    + 47 * nsClass
-                    + 53 * rType
-                    + Arrays.hashCode(mRdata);
-        }
-
-        @Override
-        public String toString() {
-            return "DnsRecord{"
-                    + "rType=" + rType
-                    + ", dName='" + dName + '\''
-                    + ", nsType=" + nsType
-                    + ", nsClass=" + nsClass
-                    + ", ttl=" + ttl
-                    + ", mRdata=" + Arrays.toString(mRdata)
-                    + '}';
-        }
     }
 
-    /**
-     * Header section types, refer to RFC 1035 section 4.1.1.
-     */
     public static final int QDSECTION = 0;
     public static final int ANSECTION = 1;
     public static final int NSSECTION = 2;
     public static final int ARSECTION = 3;
-    @VisibleForTesting(visibility = PRIVATE)
-    static final int NUM_SECTIONS = ARSECTION + 1;
-
-    @Retention(RetentionPolicy.SOURCE)
-    @IntDef(value = {
-            QDSECTION,
-            ANSECTION,
-            NSSECTION,
-            ARSECTION,
-    })
-    public @interface RecordType {}
-
+    private static final int NUM_SECTIONS = ARSECTION + 1;
 
     private static final String TAG = DnsPacket.class.getSimpleName();
 
@@ -499,7 +189,9 @@
 
         for (int i = 0; i < NUM_SECTIONS; ++i) {
             final int count = mHeader.getRecordCount(i);
-            mRecords[i] = new ArrayList(count);
+            if (count > 0) {
+                mRecords[i] = new ArrayList(count);
+            }
             for (int j = 0; j < count; ++j) {
                 try {
                     mRecords[i].add(new DnsRecord(i, buffer));
@@ -509,61 +201,4 @@
             }
         }
     }
-
-    /**
-     * Create a new {@link #DnsPacket} from specified parameters.
-     *
-     * Note that authority records section and additional records section is not supported.
-     */
-    protected DnsPacket(@NonNull DnsHeader header, @NonNull List<DnsRecord> qd,
-            @NonNull List<DnsRecord> an) {
-        mHeader = Objects.requireNonNull(header);
-        mRecords = new List[NUM_SECTIONS];
-        mRecords[QDSECTION] = Collections.unmodifiableList(new ArrayList<>(qd));
-        mRecords[ANSECTION] = Collections.unmodifiableList(new ArrayList<>(an));
-        mRecords[NSSECTION] = new ArrayList<>();
-        mRecords[ARSECTION] = new ArrayList<>();
-        for (int i = 0; i < NUM_SECTIONS; i++) {
-            if (mHeader.mRecordCount[i] != mRecords[i].size()) {
-                throw new IllegalArgumentException("Record count mismatch: expected "
-                        + mHeader.mRecordCount[i] + " but was " + mRecords[i]);
-            }
-        }
-    }
-
-    /**
-     * Get DnsPacket as byte array.
-     */
-    public @NonNull byte[] getBytes() throws IOException {
-        final ByteArrayOutputStream buf = new ByteArrayOutputStream();
-        buf.write(mHeader.getBytes());
-
-        for (int i = 0; i < NUM_SECTIONS; ++i) {
-            for (final DnsRecord record : mRecords[i]) {
-                buf.write(record.getBytes());
-            }
-        }
-        return buf.toByteArray();
-    }
-
-    @Override
-    public String toString() {
-        return "DnsPacket{" + "header=" + mHeader + ", records='" + Arrays.toString(mRecords) + '}';
-    }
-
-    @Override
-    public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o.getClass() != getClass()) return false;
-        final DnsPacket other = (DnsPacket) o;
-        return Objects.equals(mHeader, other.mHeader)
-                && Arrays.deepEquals(mRecords, other.mRecords);
-    }
-
-    @Override
-    public int hashCode() {
-        int result = Objects.hash(mHeader);
-        result = 31 * result + Arrays.hashCode(mRecords);
-        return result;
-    }
 }
diff --git a/staticlibs/framework/com/android/net/module/util/DnsPacketUtils.java b/staticlibs/framework/com/android/net/module/util/DnsPacketUtils.java
index c47bfa0..3448cad 100644
--- a/staticlibs/framework/com/android/net/module/util/DnsPacketUtils.java
+++ b/staticlibs/framework/com/android/net/module/util/DnsPacketUtils.java
@@ -20,19 +20,10 @@
 import static com.android.net.module.util.DnsPacket.DnsRecord.NAME_NORMAL;
 
 import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.net.InetAddresses;
-import android.net.ParseException;
 import android.text.TextUtils;
-import android.util.Patterns;
 
-import com.android.internal.annotations.VisibleForTesting;
-
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
-import java.nio.charset.StandardCharsets;
 import java.text.DecimalFormat;
 import java.text.FieldPosition;
 
@@ -47,7 +38,6 @@
      */
     public static class DnsRecordParser {
         private static final int MAXLABELSIZE = 63;
-        private static final int MAXNAMESIZE = 255;
         private static final int MAXLABELCOUNT = 128;
 
         private static final DecimalFormat sByteFormat = new DecimalFormat();
@@ -58,8 +48,7 @@
          *
          * <p>Follows the same conversion rules of the native code (ns_name.c in libc).
          */
-        @VisibleForTesting
-        static String labelToString(@NonNull byte[] label) {
+        private static String labelToString(@NonNull byte[] label) {
             final StringBuffer sb = new StringBuffer();
 
             for (int i = 0; i < label.length; ++i) {
@@ -83,52 +72,6 @@
         }
 
         /**
-         * Converts domain name to labels according to RFC 1035.
-         *
-         * @param name Domain name as String that needs to be converted to labels.
-         * @return An encoded byte array that is constructed out of labels,
-         *         and ends with zero-length label.
-         * @throws ParseException if failed to parse the given domain name or
-         *         IOException if failed to output labels.
-         */
-        public static @NonNull byte[] domainNameToLabels(@NonNull String name) throws
-                IOException, ParseException {
-            if (name.length() > MAXNAMESIZE) {
-                throw new ParseException("Domain name exceeds max length: " + name.length());
-            }
-            if (!isHostName(name)) {
-                throw new ParseException("Failed to parse domain name: " + name);
-            }
-            final ByteArrayOutputStream buf = new ByteArrayOutputStream();
-            final String[] labels = name.split("\\.");
-            for (final String label : labels) {
-                if (label.length() > MAXLABELSIZE) {
-                    throw new ParseException("label is too long: " + label);
-                }
-                buf.write(label.length());
-                // Encode as UTF-8 as suggested in RFC 6055 section 3.
-                buf.write(label.getBytes(StandardCharsets.UTF_8));
-            }
-            buf.write(0x00); // end with zero-length label
-            return buf.toByteArray();
-        }
-
-        /**
-         * Check whether the input is a valid hostname based on rfc 1035 section 3.3.
-         *
-         * @param hostName the target host name.
-         * @return true if the input is a valid hostname.
-         */
-        public static boolean isHostName(@Nullable String hostName) {
-            // TODO: Use {@code Patterns.HOST_NAME} if available.
-            // Patterns.DOMAIN_NAME accepts host names or IP addresses, so reject
-            // IP addresses.
-            return hostName != null
-                    && Patterns.DOMAIN_NAME.matcher(hostName).matches()
-                    && !InetAddresses.isNumericAddress(hostName);
-        }
-
-        /**
          * Parses the domain / target name of a DNS record.
          *
          * As described in RFC 1035 Section 4.1.3, the NAME field of a DNS Resource Record always
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketTest.java
index 409c1eb..1bbba08 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketTest.java
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketTest.java
@@ -16,45 +16,26 @@
 
 package com.android.net.module.util;
 
-import static android.net.DnsResolver.CLASS_IN;
-import static android.net.DnsResolver.TYPE_A;
-import static android.net.DnsResolver.TYPE_AAAA;
-
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotEquals;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-
 import androidx.test.filters.SmallTest;
 import androidx.test.runner.AndroidJUnit4;
 
-import libcore.net.InetAddressUtils;
-
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import java.io.IOException;
-import java.nio.BufferUnderflowException;
-import java.nio.ByteBuffer;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
 public class DnsPacketTest {
-    private static final int TEST_DNS_PACKET_ID = 0x7722;
-    private static final int TEST_DNS_PACKET_FLAGS = 0x8180;
-
     private void assertHeaderParses(DnsPacket.DnsHeader header, int id, int flag,
             int qCount, int aCount, int nsCount, int arCount) {
-        assertEquals(header.getId(), id);
-        assertEquals(header.getFlags(), flag);
+        assertEquals(header.id, id);
+        assertEquals(header.flags, flag);
         assertEquals(header.getRecordCount(DnsPacket.QDSECTION), qCount);
         assertEquals(header.getRecordCount(DnsPacket.ANSECTION), aCount);
         assertEquals(header.getRecordCount(DnsPacket.NSSECTION), nsCount);
@@ -70,16 +51,11 @@
         assertTrue(Arrays.equals(record.getRR(), rr));
     }
 
-    static class TestDnsPacket extends DnsPacket {
+    class TestDnsPacket extends DnsPacket {
         TestDnsPacket(byte[] data) throws DnsPacket.ParseException {
             super(data);
         }
 
-        TestDnsPacket(@NonNull DnsHeader header, @Nullable ArrayList<DnsRecord> qd,
-                @Nullable ArrayList<DnsRecord> an) {
-            super(header, qd, an);
-        }
-
         public DnsHeader getHeader() {
             return mHeader;
         }
@@ -180,247 +156,4 @@
                 new byte[]{ 0x24, 0x04, 0x68, 0x00, 0x40, 0x05, 0x08, 0x0d,
                     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x04 });
     }
-
-    /** Verifies that the synthesized {@link DnsPacket.DnsHeader} can be parsed correctly. */
-    @Test
-    public void testDnsHeaderSynthesize() {
-        final DnsPacket.DnsHeader testHeader = new DnsPacket.DnsHeader(TEST_DNS_PACKET_ID,
-                TEST_DNS_PACKET_FLAGS, 3 /* qcount */, 5 /* ancount */);
-        final DnsPacket.DnsHeader actualHeader = new DnsPacket.DnsHeader(
-                ByteBuffer.wrap(testHeader.getBytes()));
-        assertEquals(testHeader, actualHeader);
-    }
-
-    /** Verifies that the synthesized {@link DnsPacket.DnsRecord} can be parsed correctly. */
-    @Test
-    public void testDnsRecordSynthesize() throws IOException {
-        assertDnsRecordRoundTrip(
-                DnsPacket.DnsRecord.makeAOrAAAARecord(DnsPacket.ANSECTION,
-                        "test.com", CLASS_IN, 5 /* ttl */,
-                        InetAddressUtils.parseNumericAddress("abcd::fedc")));
-        assertDnsRecordRoundTrip(DnsPacket.DnsRecord.makeQuestion("test.com", TYPE_AAAA, CLASS_IN));
-        assertDnsRecordRoundTrip(DnsPacket.DnsRecord.makeCNameRecord(DnsPacket.ANSECTION,
-                "test.com", CLASS_IN, 0 /* ttl */, "example.com"));
-    }
-
-    /**
-     * Verifies ttl/rData error handling when parsing
-     * {@link DnsPacket.DnsRecord} from bytes.
-     */
-    @Test
-    public void testDnsRecordTTLRDataErrorHandling() throws IOException {
-        // Verify the constructor ignore ttl/rData of questions even if they are supplied.
-        final byte[] qdWithTTLRData = new byte[]{
-                0x03, 0x77, 0x77, 0x77, 0x06, 0x67, 0x6F, 0x6F, 0x67, 0x6c, 0x65,
-                0x03, 0x63, 0x6f, 0x6d, 0x00, /* Name */
-                0x00, 0x00, /* Type */
-                0x00, 0x01, /* Class */
-                0x00, 0x00, 0x01, 0x2b, /* TTL */
-                0x00, 0x04, /* Data length */
-                (byte) 0xac, (byte) 0xd9, (byte) 0xa1, (byte) 0x84 /* Address */};
-        final DnsPacket.DnsRecord questionsFromBytes =
-                new DnsPacket.DnsRecord(DnsPacket.QDSECTION, ByteBuffer.wrap(qdWithTTLRData));
-        assertEquals(0, questionsFromBytes.ttl);
-        assertNull(questionsFromBytes.getRR());
-
-        // Verify ANSECTION must have rData when constructing.
-        final byte[] anWithoutTTLRData = new byte[]{
-                0x03, 0x77, 0x77, 0x77, 0x06, 0x67, 0x6F, 0x6F, 0x67, 0x6c, 0x65,
-                0x03, 0x63, 0x6f, 0x6d, 0x00, /* Name */
-                0x00, 0x01, /* Type */
-                0x00, 0x01, /* Class */};
-        assertThrows(BufferUnderflowException.class, () ->
-                new DnsPacket.DnsRecord(DnsPacket.ANSECTION, ByteBuffer.wrap(anWithoutTTLRData)));
-    }
-
-    private void assertDnsRecordRoundTrip(DnsPacket.DnsRecord before)
-            throws IOException {
-        final DnsPacket.DnsRecord after = new DnsPacket.DnsRecord(before.rType,
-                ByteBuffer.wrap(before.getBytes()));
-        assertEquals(after, before);
-    }
-
-    /** Verifies that the synthesized {@link DnsPacket} can be parsed correctly. */
-    @Test
-    public void testDnsPacketSynthesize() throws IOException {
-        // Ipv4 dns response packet generated by scapy:
-        //   dns_r = scapy.DNS(
-        //      id=0xbeef,
-        //      qr=1,
-        //      qd=scapy.DNSQR(qname="hello.example.com"),
-        //      an=scapy.DNSRR(rrname="hello.example.com", type="CNAME", rdata='test.com') /
-        //      scapy.DNSRR(rrname="hello.example.com", rdata='1.2.3.4'))
-        //   scapy.hexdump(dns_r)
-        //   dns_r.show2()
-        // Note that since the synthesizing does not support name compression yet, the domain
-        // name of the sample need to be uncompressed when generating.
-        final byte[] v4BlobUncompressed = new byte[]{
-                /* Header */
-                (byte) 0xbe, (byte) 0xef, /* Transaction ID */
-                (byte) 0x81, 0x00, /* Flags */
-                0x00, 0x01, /* Questions */
-                0x00, 0x02, /* Answer RRs */
-                0x00, 0x00, /* Authority RRs */
-                0x00, 0x00, /* Additional RRs */
-                /* Queries */
-                0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x07, 0x65, 0x78, 0x61,
-                0x6D, 0x70, 0x6C, 0x65, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Name: hello.example.com */
-                0x00, 0x01, /* Type */
-                0x00, 0x01, /* Class */
-                /* Answers */
-                0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x07, 0x65, 0x78, 0x61,
-                0x6D, 0x70, 0x6C, 0x65, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Name: hello.example.com */
-                0x00, 0x05, /* Type */
-                0x00, 0x01, /* Class */
-                0x00, 0x00, 0x00, 0x00, /* TTL */
-                0x00, 0x0A, /* Data length */
-                0x04, 0x74, 0x65, 0x73, 0x74, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Alias: test.com */
-                0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x07, 0x65, 0x78, 0x61,
-                0x6D, 0x70, 0x6C, 0x65, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Name: hello.example.com */
-                0x00, 0x01, /* Type */
-                0x00, 0x01, /* Class */
-                0x00, 0x00, 0x00, 0x00, /* TTL */
-                0x00, 0x04, /* Data length */
-                0x01, 0x02, 0x03, 0x04, /* Address: 1.2.3.4 */
-        };
-
-        // Forge one via constructors.
-        final DnsPacket.DnsHeader testHeader = new DnsPacket.DnsHeader(0xbeef,
-                0x8100, 1 /* qcount */, 2 /* ancount */);
-        final ArrayList<DnsPacket.DnsRecord> qlist = new ArrayList<>();
-        final ArrayList<DnsPacket.DnsRecord> alist = new ArrayList<>();
-        qlist.add(DnsPacket.DnsRecord.makeQuestion(
-                "hello.example.com", TYPE_A, CLASS_IN));
-        alist.add(DnsPacket.DnsRecord.makeCNameRecord(
-                DnsPacket.ANSECTION, "hello.example.com", CLASS_IN, 0 /* ttl */, "test.com"));
-        alist.add(DnsPacket.DnsRecord.makeAOrAAAARecord(
-                DnsPacket.ANSECTION, "hello.example.com", CLASS_IN, 0 /* ttl */,
-                InetAddressUtils.parseNumericAddress("1.2.3.4")));
-        final TestDnsPacket testPacket = new TestDnsPacket(testHeader, qlist, alist);
-
-        // Assert content equals in both ways.
-        assertTrue(Arrays.equals(v4BlobUncompressed, testPacket.getBytes()));
-        assertEquals(new TestDnsPacket(v4BlobUncompressed), testPacket);
-    }
-
-    @Test
-    public void testDnsPacketSynthesize_recordCountMismatch() throws IOException {
-        final DnsPacket.DnsHeader testHeader = new DnsPacket.DnsHeader(0xbeef,
-                0x8100, 1 /* qcount */, 1 /* ancount */);
-        final ArrayList<DnsPacket.DnsRecord> qlist = new ArrayList<>();
-        final ArrayList<DnsPacket.DnsRecord> alist = new ArrayList<>();
-        qlist.add(DnsPacket.DnsRecord.makeQuestion(
-                "hello.example.com", TYPE_A, CLASS_IN));
-
-        // Assert throws if the supplied answer records fewer than the declared count.
-        assertThrows(IllegalArgumentException.class, () ->
-                new TestDnsPacket(testHeader, qlist, alist));
-
-        // Assert throws if the supplied answer records more than the declared count.
-        alist.add(DnsPacket.DnsRecord.makeCNameRecord(
-                DnsPacket.ANSECTION, "hello.example.com", CLASS_IN, 0 /* ttl */, "test.com"));
-        alist.add(DnsPacket.DnsRecord.makeAOrAAAARecord(
-                DnsPacket.ANSECTION, "hello.example.com", CLASS_IN, 0 /* ttl */,
-                InetAddressUtils.parseNumericAddress("1.2.3.4")));
-        assertThrows(IllegalArgumentException.class, () ->
-                new TestDnsPacket(testHeader, qlist, alist));
-
-        // Assert counts matched if the byte buffer still has data when parsing ended.
-        final byte[] blobTooMuchData = new byte[]{
-                /* Header */
-                (byte) 0xbe, (byte) 0xef, /* Transaction ID */
-                (byte) 0x81, 0x00, /* Flags */
-                0x00, 0x00, /* Questions */
-                0x00, 0x00, /* Answer RRs */
-                0x00, 0x00, /* Authority RRs */
-                0x00, 0x00, /* Additional RRs */
-                /* Queries */
-                0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x07, 0x65, 0x78, 0x61,
-                0x6D, 0x70, 0x6C, 0x65, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Name */
-                0x00, 0x01, /* Type */
-                0x00, 0x01, /* Class */
-        };
-        final TestDnsPacket packetFromTooMuchData = new TestDnsPacket(blobTooMuchData);
-        for (int i = 0; i < DnsPacket.NUM_SECTIONS; i++) {
-            assertEquals(0, packetFromTooMuchData.getRecordList(i).size());
-            assertEquals(0, packetFromTooMuchData.getHeader().getRecordCount(i));
-        }
-
-        // Assert throws if the byte buffer ended when expecting more records.
-        final byte[] blobNotEnoughData = new byte[]{
-                /* Header */
-                (byte) 0xbe, (byte) 0xef, /* Transaction ID */
-                (byte) 0x81, 0x00, /* Flags */
-                0x00, 0x01, /* Questions */
-                0x00, 0x02, /* Answer RRs */
-                0x00, 0x00, /* Authority RRs */
-                0x00, 0x00, /* Additional RRs */
-                /* Queries */
-                0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x07, 0x65, 0x78, 0x61,
-                0x6D, 0x70, 0x6C, 0x65, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Name */
-                0x00, 0x01, /* Type */
-                0x00, 0x01, /* Class */
-                /* Answers */
-                0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x07, 0x65, 0x78, 0x61,
-                0x6D, 0x70, 0x6C, 0x65, 0x03, 0x63, 0x6F, 0x6D, 0x00, /* Name */
-                0x00, 0x01, /* Type */
-                0x00, 0x01, /* Class */
-                0x00, 0x00, 0x00, 0x00, /* TTL */
-                0x00, 0x04, /* Data length */
-                0x01, 0x02, 0x03, 0x04, /* Address */
-        };
-        assertThrows(DnsPacket.ParseException.class, () -> new TestDnsPacket(blobNotEnoughData));
-    }
-
-    @Test
-    public void testEqualsAndHashCode() throws IOException {
-        // Verify DnsHeader equals and hashCode.
-        final DnsPacket.DnsHeader testHeader = new DnsPacket.DnsHeader(TEST_DNS_PACKET_ID,
-                TEST_DNS_PACKET_FLAGS, 1 /* qcount */, 1 /* ancount */);
-        final DnsPacket.DnsHeader emptyHeader = new DnsPacket.DnsHeader(TEST_DNS_PACKET_ID + 1,
-                TEST_DNS_PACKET_FLAGS + 0x08, 0 /* qcount */, 0 /* ancount */);
-        final DnsPacket.DnsHeader headerFromBytes =
-                new DnsPacket.DnsHeader(ByteBuffer.wrap(testHeader.getBytes()));
-        assertEquals(testHeader, headerFromBytes);
-        assertEquals(testHeader.hashCode(), headerFromBytes.hashCode());
-        assertNotEquals(testHeader, emptyHeader);
-        assertNotEquals(testHeader.hashCode(), emptyHeader.hashCode());
-        assertNotEquals(headerFromBytes, emptyHeader);
-        assertNotEquals(headerFromBytes.hashCode(), emptyHeader.hashCode());
-
-        // Verify DnsRecord equals and hashCode.
-        final DnsPacket.DnsRecord testQuestion = DnsPacket.DnsRecord.makeQuestion(
-                "test.com", TYPE_AAAA, CLASS_IN);
-        final DnsPacket.DnsRecord testAnswer = DnsPacket.DnsRecord.makeCNameRecord(
-                DnsPacket.ANSECTION, "test.com", CLASS_IN, 9, "www.test.com");
-        final DnsPacket.DnsRecord questionFromBytes = new DnsPacket.DnsRecord(DnsPacket.QDSECTION,
-                ByteBuffer.wrap(testQuestion.getBytes()));
-        assertEquals(testQuestion, questionFromBytes);
-        assertEquals(testQuestion.hashCode(), questionFromBytes.hashCode());
-        assertNotEquals(testQuestion, testAnswer);
-        assertNotEquals(testQuestion.hashCode(), testAnswer.hashCode());
-        assertNotEquals(questionFromBytes, testAnswer);
-        assertNotEquals(questionFromBytes.hashCode(), testAnswer.hashCode());
-
-        // Verify DnsPacket equals and hashCode.
-        final ArrayList<DnsPacket.DnsRecord> qlist = new ArrayList<>();
-        final ArrayList<DnsPacket.DnsRecord> alist = new ArrayList<>();
-        qlist.add(testQuestion);
-        alist.add(testAnswer);
-        final TestDnsPacket testPacket = new TestDnsPacket(testHeader, qlist, alist);
-        final TestDnsPacket emptyPacket = new TestDnsPacket(
-                emptyHeader, new ArrayList<>(), new ArrayList<>());
-        final TestDnsPacket packetFromBytes = new TestDnsPacket(testPacket.getBytes());
-        assertEquals(testPacket, packetFromBytes);
-        assertEquals(testPacket.hashCode(), packetFromBytes.hashCode());
-        assertNotEquals(testPacket, emptyPacket);
-        assertNotEquals(testPacket.hashCode(), emptyPacket.hashCode());
-        assertNotEquals(packetFromBytes, emptyPacket);
-        assertNotEquals(packetFromBytes.hashCode(), emptyPacket.hashCode());
-
-        // Verify DnsPacket with empty list.
-        final TestDnsPacket emptyPacketFromBytes = new TestDnsPacket(emptyPacket.getBytes());
-        assertEquals(emptyPacket, emptyPacketFromBytes);
-        assertEquals(emptyPacket.hashCode(), emptyPacketFromBytes.hashCode());
-    }
 }
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketUtilsTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketUtilsTest.java
index 9e1ab82..48777ac 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketUtilsTest.java
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/DnsPacketUtilsTest.java
@@ -18,20 +18,12 @@
 
 import static com.android.net.module.util.DnsPacketUtils.DnsRecordParser;
 
-import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThrows;
 
-import android.net.ParseException;
-import android.os.Build;
-
 import androidx.test.filters.SmallTest;
 import androidx.test.runner.AndroidJUnit4;
 
-import com.android.testutils.DevSdkIgnoreRule;
-
-import org.junit.Assert;
-import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -40,8 +32,6 @@
 @RunWith(AndroidJUnit4.class)
 @SmallTest
 public class DnsPacketUtilsTest {
-    @Rule
-    public final DevSdkIgnoreRule mIgnoreRule = new DevSdkIgnoreRule();
 
     /**
      * Verifies that the compressed NAME field in the answer section of the DNS message is parsed
@@ -126,31 +116,4 @@
                 notNameCompressedBuf, /* depth= */ 0, /* isNameCompressionSupported= */ false);
         assertEquals(domainName, "www.google.com");
     }
-
-    // Skip test on R- devices since ParseException only available on S+ devices.
-    @DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.R)
-    @Test
-    public void testDomainNameToLabels() throws Exception {
-        assertArrayEquals(
-                new byte[]{3, 'w', 'w', 'w', 6, 'g', 'o', 'o', 'g', 'l', 'e', 3, 'c', 'o', 'm', 0},
-                DnsRecordParser.domainNameToLabels("www.google.com"));
-        assertThrows(ParseException.class, () ->
-                DnsRecordParser.domainNameToLabels("aaa."));
-        assertThrows(ParseException.class, () ->
-                DnsRecordParser.domainNameToLabels("aaa"));
-        assertThrows(ParseException.class, () ->
-                DnsRecordParser.domainNameToLabels("."));
-        assertThrows(ParseException.class, () ->
-                DnsRecordParser.domainNameToLabels(""));
-    }
-
-    @Test
-    public void testIsHostName() {
-        Assert.assertTrue(DnsRecordParser.isHostName("www.google.com"));
-        Assert.assertFalse(DnsRecordParser.isHostName("com"));
-        Assert.assertFalse(DnsRecordParser.isHostName("1.2.3.4"));
-        Assert.assertFalse(DnsRecordParser.isHostName("1234::5678"));
-        Assert.assertFalse(DnsRecordParser.isHostName(null));
-        Assert.assertFalse(DnsRecordParser.isHostName(""));
-    }
 }