Merge "Move Inet[4]AddressUtils to libs/net" into rvc-dev
diff --git a/common/src_frameworkcommon/com/android/net/module/util/DnsPacket.java b/common/src_frameworkcommon/com/android/net/module/util/DnsPacket.java
new file mode 100644
index 0000000..ac337e0
--- /dev/null
+++ b/common/src_frameworkcommon/com/android/net/module/util/DnsPacket.java
@@ -0,0 +1,252 @@
+/*
+ * Copyright (C) 2019 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 com.android.net.module.util;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.text.TextUtils;
+
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.text.DecimalFormat;
+import java.text.FieldPosition;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Defines basic data for DNS protocol based on RFC 1035.
+ * Subclasses create the specific format used in DNS packet.
+ *
+ * @hide
+ */
+public abstract class DnsPacket {
+    /**
+     * Thrown when parsing packet failed.
+     */
+    public static class ParseException extends RuntimeException {
+        public String reason;
+        public ParseException(@NonNull String reason) {
+            super(reason);
+            this.reason = reason;
+        }
+
+        public ParseException(@NonNull String reason, @NonNull Throwable cause) {
+            super(reason, cause);
+            this.reason = reason;
+        }
+    }
+
+    /**
+     * DNS header for DNS protocol based on RFC 1035.
+     */
+    public class DnsHeader {
+        private static final String TAG = "DnsHeader";
+        public final int id;
+        public final int flags;
+        public final int rcode;
+        private final int[] mRecordCount;
+
+        /**
+         * Create a new DnsHeader from a positioned ByteBuffer.
+         *
+         * The ByteBuffer must be in network byte order (which is the default).
+         * Reads the passed ByteBuffer from its current position and decodes a DNS header.
+         * When this constructor returns, the reading position of the ByteBuffer has been
+         * advanced to the end of the DNS header record.
+         * This is meant to chain with other methods reading a DNS response in sequence.
+         */
+        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());
+            }
+        }
+
+        /**
+         * Get record count by type.
+         */
+        public int getRecordCount(int type) {
+            return mRecordCount[type];
+        }
+    }
+
+    /**
+     * Superclass for DNS questions and DNS resource records.
+     *
+     * DNS questions (No TTL/RDATA)
+     * DNS resource records (With TTL/RDATA)
+     */
+    public class DnsRecord {
+        private static final int MAXNAMESIZE = 255;
+        private static final int MAXLABELSIZE = 63;
+        private static final int MAXLABELCOUNT = 128;
+        private static final int NAME_NORMAL = 0;
+        private static final int NAME_COMPRESSION = 0xC0;
+        private final DecimalFormat mByteFormat = new DecimalFormat();
+        private final FieldPosition mPos = new FieldPosition(0);
+
+        private static final String TAG = "DnsRecord";
+
+        public final String dName;
+        public final int nsType;
+        public final int nsClass;
+        public final long ttl;
+        private final byte[] mRdata;
+
+        /**
+         * 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 header record.
+         * This is meant to chain with other methods reading a DNS response in sequence.
+         *
+         * @param ByteBuffer input of record, must be in network byte order
+         *         (which is the default).
+         */
+        DnsRecord(int recordType, @NonNull ByteBuffer buf)
+                throws BufferUnderflowException, ParseException {
+            dName = parseName(buf, 0 /* Parse depth */);
+            if (dName.length() > MAXNAMESIZE) {
+                throw new ParseException(
+                        "Parse name fail, name size is too long: " + dName.length());
+            }
+            nsType = Short.toUnsignedInt(buf.getShort());
+            nsClass = Short.toUnsignedInt(buf.getShort());
+
+            if (recordType != QDSECTION) {
+                ttl = Integer.toUnsignedLong(buf.getInt());
+                final int length = Short.toUnsignedInt(buf.getShort());
+                mRdata = new byte[length];
+                buf.get(mRdata);
+            } else {
+                ttl = 0;
+                mRdata = null;
+            }
+        }
+
+        /**
+         * Get a copy of rdata.
+         */
+        @Nullable
+        public byte[] getRR() {
+            return (mRdata == null) ? null : mRdata.clone();
+        }
+
+        /**
+         * Convert label from {@code byte[]} to {@code String}
+         *
+         * Follows the same conversion rules of the native code (ns_name.c in libc)
+         */
+        private String labelToString(@NonNull byte[] label) {
+            final StringBuffer sb = new StringBuffer();
+            for (int i = 0; i < label.length; ++i) {
+                int b = Byte.toUnsignedInt(label[i]);
+                // Control characters and non-ASCII characters.
+                if (b <= 0x20 || b >= 0x7f) {
+                    // Append the byte as an escaped decimal number, e.g., "\19" for 0x13.
+                    sb.append('\\');
+                    mByteFormat.format(b, sb, mPos);
+                } else if (b == '"' || b == '.' || b == ';' || b == '\\'
+                        || b == '(' || b == ')' || b == '@' || b == '$') {
+                    // Append the byte as an escaped character, e.g., "\:" for 0x3a.
+                    sb.append('\\');
+                    sb.append((char) b);
+                } else {
+                    // Append the byte as a character, e.g., "a" for 0x61.
+                    sb.append((char) b);
+                }
+            }
+            return sb.toString();
+        }
+
+        private String parseName(@NonNull ByteBuffer buf, int depth) throws
+                BufferUnderflowException, ParseException {
+            if (depth > MAXLABELCOUNT) {
+                throw new ParseException("Failed to parse name, too many labels");
+            }
+            final int len = Byte.toUnsignedInt(buf.get());
+            final int mask = len & NAME_COMPRESSION;
+            if (0 == len) {
+                return "";
+            } else if (mask != NAME_NORMAL && mask != NAME_COMPRESSION) {
+                throw new ParseException("Parse name fail, bad label type");
+            } else if (mask == NAME_COMPRESSION) {
+                // Name compression based on RFC 1035 - 4.1.4 Message compression
+                final int offset = ((len & ~NAME_COMPRESSION) << 8) + Byte.toUnsignedInt(buf.get());
+                final int oldPos = buf.position();
+                if (offset >= oldPos - 2) {
+                    throw new ParseException("Parse compression name fail, invalid compression");
+                }
+                buf.position(offset);
+                final String pointed = parseName(buf, depth + 1);
+                buf.position(oldPos);
+                return pointed;
+            } else {
+                final byte[] label = new byte[len];
+                buf.get(label);
+                final String head = labelToString(label);
+                if (head.length() > MAXLABELSIZE) {
+                    throw new ParseException("Parse name fail, invalid label length");
+                }
+                final String tail = parseName(buf, depth + 1);
+                return TextUtils.isEmpty(tail) ? head : head + "." + tail;
+            }
+        }
+    }
+
+    public static final int QDSECTION = 0;
+    public static final int ANSECTION = 1;
+    public static final int NSSECTION = 2;
+    public static final int ARSECTION = 3;
+    private static final int NUM_SECTIONS = ARSECTION + 1;
+
+    private static final String TAG = DnsPacket.class.getSimpleName();
+
+    protected final DnsHeader mHeader;
+    protected final List<DnsRecord>[] mRecords;
+
+    protected DnsPacket(@NonNull byte[] data) throws ParseException {
+        if (null == data) throw new ParseException("Parse header failed, null input data");
+        final ByteBuffer buffer;
+        try {
+            buffer = ByteBuffer.wrap(data);
+            mHeader = new DnsHeader(buffer);
+        } catch (BufferUnderflowException e) {
+            throw new ParseException("Parse Header fail, bad input data", e);
+        }
+
+        mRecords = new ArrayList[NUM_SECTIONS];
+
+        for (int i = 0; i < NUM_SECTIONS; ++i) {
+            final int count = mHeader.getRecordCount(i);
+            if (count > 0) {
+                mRecords[i] = new ArrayList(count);
+            }
+            for (int j = 0; j < count; ++j) {
+                try {
+                    mRecords[i].add(new DnsRecord(i, buffer));
+                } catch (BufferUnderflowException e) {
+                    throw new ParseException("Parse record fail", e);
+                }
+            }
+        }
+    }
+}
diff --git a/common/tests/unit/src/com/android/module/util/DnsPacketTest.java b/common/tests/unit/src/com/android/module/util/DnsPacketTest.java
new file mode 100644
index 0000000..1bbba08
--- /dev/null
+++ b/common/tests/unit/src/com/android/module/util/DnsPacketTest.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2019 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 com.android.net.module.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.Arrays;
+import java.util.List;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class DnsPacketTest {
+    private void assertHeaderParses(DnsPacket.DnsHeader header, int id, int flag,
+            int qCount, int aCount, int nsCount, int arCount) {
+        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);
+        assertEquals(header.getRecordCount(DnsPacket.ARSECTION), arCount);
+    }
+
+    private void assertRecordParses(DnsPacket.DnsRecord record, String dname,
+            int dtype, int dclass, int ttl, byte[] rr) {
+        assertEquals(record.dName, dname);
+        assertEquals(record.nsType, dtype);
+        assertEquals(record.nsClass, dclass);
+        assertEquals(record.ttl, ttl);
+        assertTrue(Arrays.equals(record.getRR(), rr));
+    }
+
+    class TestDnsPacket extends DnsPacket {
+        TestDnsPacket(byte[] data) throws DnsPacket.ParseException {
+            super(data);
+        }
+
+        public DnsHeader getHeader() {
+            return mHeader;
+        }
+        public List<DnsRecord> getRecordList(int secType) {
+            return mRecords[secType];
+        }
+    }
+
+    @Test
+    public void testNullDisallowed() {
+        try {
+            new TestDnsPacket(null);
+            fail("Exception not thrown for null byte array");
+        } catch (DnsPacket.ParseException e) {
+        }
+    }
+
+    @Test
+    public void testV4Answer() throws Exception {
+        final byte[] v4blob = new byte[] {
+            /* Header */
+            0x55, 0x66, /* Transaction ID */
+            (byte) 0x81, (byte) 0x80, /* Flags */
+            0x00, 0x01, /* Questions */
+            0x00, 0x01, /* Answer RRs */
+            0x00, 0x00, /* Authority RRs */
+            0x00, 0x00, /* Additional RRs */
+            /* Queries */
+            0x03, 0x77, 0x77, 0x77, 0x06, 0x67, 0x6F, 0x6F, 0x67, 0x6c, 0x65,
+            0x03, 0x63, 0x6f, 0x6d, 0x00, /* Name */
+            0x00, 0x01, /* Type */
+            0x00, 0x01, /* Class */
+            /* Answers */
+            (byte) 0xc0, 0x0c, /* Name */
+            0x00, 0x01, /* Type */
+            0x00, 0x01, /* Class */
+            0x00, 0x00, 0x01, 0x2b, /* TTL */
+            0x00, 0x04, /* Data length */
+            (byte) 0xac, (byte) 0xd9, (byte) 0xa1, (byte) 0x84 /* Address */
+        };
+        TestDnsPacket packet = new TestDnsPacket(v4blob);
+
+        // Header part
+        assertHeaderParses(packet.getHeader(), 0x5566, 0x8180, 1, 1, 0, 0);
+
+        // Record part
+        List<DnsPacket.DnsRecord> qdRecordList =
+                packet.getRecordList(DnsPacket.QDSECTION);
+        assertEquals(qdRecordList.size(), 1);
+        assertRecordParses(qdRecordList.get(0), "www.google.com", 1, 1, 0, null);
+
+        List<DnsPacket.DnsRecord> anRecordList =
+                packet.getRecordList(DnsPacket.ANSECTION);
+        assertEquals(anRecordList.size(), 1);
+        assertRecordParses(anRecordList.get(0), "www.google.com", 1, 1, 0x12b,
+                new byte[]{ (byte) 0xac, (byte) 0xd9, (byte) 0xa1, (byte) 0x84 });
+    }
+
+    @Test
+    public void testV6Answer() throws Exception {
+        final byte[] v6blob = new byte[] {
+            /* Header */
+            0x77, 0x22, /* Transaction ID */
+            (byte) 0x81, (byte) 0x80, /* Flags */
+            0x00, 0x01, /* Questions */
+            0x00, 0x01, /* Answer RRs */
+            0x00, 0x00, /* Authority RRs */
+            0x00, 0x00, /* Additional RRs */
+            /* Queries */
+            0x03, 0x77, 0x77, 0x77, 0x06, 0x67, 0x6F, 0x6F, 0x67, 0x6c, 0x65,
+            0x03, 0x63, 0x6f, 0x6d, 0x00, /* Name */
+            0x00, 0x1c, /* Type */
+            0x00, 0x01, /* Class */
+            /* Answers */
+            (byte) 0xc0, 0x0c, /* Name */
+            0x00, 0x1c, /* Type */
+            0x00, 0x01, /* Class */
+            0x00, 0x00, 0x00, 0x37, /* TTL */
+            0x00, 0x10, /* Data length */
+            0x24, 0x04, 0x68, 0x00, 0x40, 0x05, 0x08, 0x0d,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x04 /* Address */
+        };
+        TestDnsPacket packet = new TestDnsPacket(v6blob);
+
+        // Header part
+        assertHeaderParses(packet.getHeader(), 0x7722, 0x8180, 1, 1, 0, 0);
+
+        // Record part
+        List<DnsPacket.DnsRecord> qdRecordList =
+                packet.getRecordList(DnsPacket.QDSECTION);
+        assertEquals(qdRecordList.size(), 1);
+        assertRecordParses(qdRecordList.get(0), "www.google.com", 28, 1, 0, null);
+
+        List<DnsPacket.DnsRecord> anRecordList =
+                packet.getRecordList(DnsPacket.ANSECTION);
+        assertEquals(anRecordList.size(), 1);
+        assertRecordParses(anRecordList.get(0), "www.google.com", 28, 1, 0x37,
+                new byte[]{ 0x24, 0x04, 0x68, 0x00, 0x40, 0x05, 0x08, 0x0d,
+                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x04 });
+    }
+}