Add DnsSvcbRecord
This change is an initial implementation of DNS SVCB Record. It
can parse an SVCB Record in wire format.
The RDATA field of a SVCB Record is formatted as follows:
- SvcPriority: 2-byte field
- TargetName: a domain name that follows RFC1035 section 5.1
- SvcParams (optional): a list of SvcParam
This initial implementation focuses on the SvcParams related to DDR,
including alpn, port, ipv4hint, ipv6hint, and dohpath. For the other
SvcParams, such as mandatory and ech, this change doesn't check
whether their value is valid.
Bug: 240259333
Test: atest ConnectivityCoverageTests
Test: No test for DnsSvcbRecord for now. will add some tests in a
follow-up change
Change-Id: Icfe9b623eda8390c40b106123a718cdd2af3af99
diff --git a/staticlibs/Android.bp b/staticlibs/Android.bp
index 0bcb757..25a9291 100644
--- a/staticlibs/Android.bp
+++ b/staticlibs/Android.bp
@@ -96,12 +96,16 @@
srcs: [
"framework/**/DnsPacket.java",
"framework/**/DnsPacketUtils.java",
+ "framework/**/DnsSvcbRecord.java",
+ "framework/**/HexDump.java",
+ "framework/**/NetworkStackConstants.java",
],
sdk_version: "module_current",
visibility: [
"//packages/services/Iwlan:__subpackages__",
],
libs: [
+ "androidx.annotation_annotation",
"framework-annotations-lib",
"framework-connectivity.stubs.module_lib",
],
diff --git a/staticlibs/framework/com/android/net/module/util/DnsPacket.java b/staticlibs/framework/com/android/net/module/util/DnsPacket.java
index 0dcdf1e..63106a1 100644
--- a/staticlibs/framework/com/android/net/module/util/DnsPacket.java
+++ b/staticlibs/framework/com/android/net/module/util/DnsPacket.java
@@ -56,6 +56,7 @@
*/
// TODO: Define the constant as a public constant in DnsResolver since it can never change.
private static final int TYPE_CNAME = 5;
+ public static final int TYPE_SVCB = 64;
/**
* Thrown when parsing packet failed.
@@ -282,7 +283,7 @@
* @param buf ByteBuffer input of record, must be in network byte order
* (which is the default).
*/
- private DnsRecord(@RecordType int rType, @NonNull ByteBuffer buf)
+ protected DnsRecord(@RecordType int rType, @NonNull ByteBuffer buf)
throws BufferUnderflowException, ParseException {
Objects.requireNonNull(buf);
this.rType = rType;
@@ -326,6 +327,8 @@
// Return a DnsRecord instance by default for backward compatibility, this is useful
// when a partner supports new type of DnsRecord but does not inherit DnsRecord.
switch (nsType) {
+ case TYPE_SVCB:
+ return new DnsSvcbRecord(rType, buf);
default:
return new DnsRecord(rType, buf);
}
diff --git a/staticlibs/framework/com/android/net/module/util/DnsSvcbRecord.java b/staticlibs/framework/com/android/net/module/util/DnsSvcbRecord.java
new file mode 100644
index 0000000..669725c
--- /dev/null
+++ b/staticlibs/framework/com/android/net/module/util/DnsSvcbRecord.java
@@ -0,0 +1,516 @@
+/*
+ * Copyright (C) 2023 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 android.net.DnsResolver.CLASS_IN;
+
+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.DnsPacket.ParseException;
+
+import android.annotation.NonNull;
+import android.text.TextUtils;
+import android.util.SparseArray;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.nio.ShortBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.StringJoiner;
+
+/**
+ * A class for an SVCB record.
+ * https://www.iana.org/assignments/dns-svcb/dns-svcb.xhtml
+ * @hide
+ */
+@VisibleForTesting(visibility = PACKAGE)
+public final class DnsSvcbRecord extends DnsPacket.DnsRecord {
+ /**
+ * The following SvcParamKeys KEY_* are defined in
+ * https://www.iana.org/assignments/dns-svcb/dns-svcb.xhtml.
+ */
+
+ // The SvcParamKey "mandatory". The associated implementation of SvcParam is SvcParamMandatory.
+ private static final int KEY_MANDATORY = 0;
+
+ // The SvcParamKey "alpn". The associated implementation of SvcParam is SvcParamAlpn.
+ private static final int KEY_ALPN = 1;
+
+ // The SvcParamKey "no-default-alpn". The associated implementation of SvcParam is
+ // SvcParamNoDefaultAlpn.
+ private static final int KEY_NO_DEFAULT_ALPN = 2;
+
+ // The SvcParamKey "port". The associated implementation of SvcParam is SvcParamPort.
+ private static final int KEY_PORT = 3;
+
+ // The SvcParamKey "ipv4hint". The associated implementation of SvcParam is SvcParamIpv4Hint.
+ private static final int KEY_IPV4HINT = 4;
+
+ // The SvcParamKey "ech". The associated implementation of SvcParam is SvcParamEch.
+ private static final int KEY_ECH = 5;
+
+ // The SvcParamKey "ipv6hint". The associated implementation of SvcParam is SvcParamIpv6Hint.
+ private static final int KEY_IPV6HINT = 6;
+
+ // The SvcParamKey "dohpath". The associated implementation of SvcParam is SvcParamDohPath.
+ private static final int KEY_DOHPATH = 7;
+
+ // The minimal size of a SvcParam.
+ // https://www.ietf.org/archive/id/draft-ietf-dnsop-svcb-https-12.html#name-rdata-wire-format
+ private static final int MINSVCPARAMSIZE = 4;
+
+ private static final String TAG = DnsSvcbRecord.class.getSimpleName();
+
+ private final int mSvcPriority;
+
+ @NonNull
+ private final String mTargetName;
+
+ @NonNull
+ private final SparseArray<SvcParam> mAllSvcParams = new SparseArray<>();
+
+ @VisibleForTesting(visibility = PACKAGE)
+ public DnsSvcbRecord(@DnsPacket.RecordType int rType, @NonNull ByteBuffer buff)
+ throws IllegalStateException, ParseException {
+ super(rType, buff);
+ if (nsType != DnsPacket.TYPE_SVCB) {
+ throw new IllegalStateException("incorrect nsType: " + nsType);
+ }
+ if (nsClass != CLASS_IN) {
+ throw new ParseException("incorrect nsClass: " + nsClass);
+ }
+
+ // DNS Record in Question Section doesn't have Rdata.
+ if (rType == DnsPacket.QDSECTION) {
+ mSvcPriority = 0;
+ mTargetName = "";
+ return;
+ }
+
+ final byte[] rdata = getRR();
+ if (rdata == null) {
+ throw new ParseException("SVCB rdata is empty");
+ }
+
+ final ByteBuffer buf = ByteBuffer.wrap(rdata).asReadOnlyBuffer();
+ mSvcPriority = Short.toUnsignedInt(buf.getShort());
+ mTargetName = DnsPacketUtils.DnsRecordParser.parseName(buf, 0 /* Parse depth */,
+ false /* isNameCompressionSupported */);
+
+ if (mTargetName.length() > DnsPacket.DnsRecord.MAXNAMESIZE) {
+ throw new ParseException(
+ "Failed to parse SVCB target name, name size is too long: "
+ + mTargetName.length());
+ }
+ while (buf.remaining() >= MINSVCPARAMSIZE) {
+ final SvcParam svcParam = parseSvcParam(buf);
+ final int key = svcParam.getKey();
+ if (mAllSvcParams.get(key) != null) {
+ throw new ParseException("Invalid DnsSvcbRecord, key " + key + " is repeated");
+ }
+ mAllSvcParams.put(key, svcParam);
+ }
+ if (buf.hasRemaining()) {
+ throw new ParseException("Invalid DnsSvcbRecord. Got "
+ + buf.remaining() + " remaining bytes after parsing");
+ }
+ }
+
+ /**
+ * Returns the TargetName.
+ */
+ @VisibleForTesting(visibility = PACKAGE)
+ @NonNull
+ public String getTargetName() {
+ return mTargetName;
+ }
+
+ /**
+ * Returns an unmodifiable list of alpns from SvcParam alpn.
+ */
+ @VisibleForTesting(visibility = PACKAGE)
+ @NonNull
+ public List<String> getAlpns() {
+ final SvcParamAlpn sp = (SvcParamAlpn) mAllSvcParams.get(KEY_ALPN);
+ final List<String> list = (sp != null) ? sp.getValue() : Collections.EMPTY_LIST;
+ return Collections.unmodifiableList(list);
+ }
+
+ /**
+ * Returns the port number from SvcParam port.
+ */
+ @VisibleForTesting(visibility = PACKAGE)
+ public int getPort() {
+ final SvcParamPort sp = (SvcParamPort) mAllSvcParams.get(KEY_PORT);
+ return (sp != null) ? sp.getValue() : -1;
+ }
+
+ /**
+ * Returns a list of the IP addresses from both of SvcParam ipv4hint and ipv6hint.
+ */
+ @VisibleForTesting(visibility = PACKAGE)
+ @NonNull
+ public List<InetAddress> getAddresses() {
+ final List<InetAddress> out = new ArrayList<>();
+ final SvcParamIpHint sp4 = (SvcParamIpHint) mAllSvcParams.get(KEY_IPV4HINT);
+ if (sp4 != null) {
+ out.addAll(sp4.getValue());
+ }
+ final SvcParamIpHint sp6 = (SvcParamIpHint) mAllSvcParams.get(KEY_IPV6HINT);
+ if (sp6 != null) {
+ out.addAll(sp6.getValue());
+ }
+ return out;
+ }
+
+ /**
+ * Returns the doh path from SvcParam dohPath.
+ */
+ @VisibleForTesting(visibility = PACKAGE)
+ @NonNull
+ public String getDohPath() {
+ final SvcParamDohPath sp = (SvcParamDohPath) mAllSvcParams.get(KEY_DOHPATH);
+ return (sp != null) ? sp.getValue() : "";
+ }
+
+ @Override
+ public String toString() {
+ if (rType == DnsPacket.QDSECTION) {
+ return dName + " IN SVCB";
+ }
+
+ final StringJoiner sj = new StringJoiner(" ");
+ for (int i = 0; i < mAllSvcParams.size(); i++) {
+ sj.add(mAllSvcParams.valueAt(i).toString());
+ }
+ return dName + " " + ttl + " IN SVCB " + mSvcPriority + " " + mTargetName + " "
+ + sj.toString();
+ }
+
+ private static SvcParam parseSvcParam(@NonNull ByteBuffer buf) throws ParseException {
+ try {
+ final int key = Short.toUnsignedInt(buf.getShort());
+ switch (key) {
+ case KEY_MANDATORY: return new SvcParamMandatory(buf);
+ case KEY_ALPN: return new SvcParamAlpn(buf);
+ case KEY_NO_DEFAULT_ALPN: return new SvcParamNoDefaultAlpn(buf);
+ case KEY_PORT: return new SvcParamPort(buf);
+ case KEY_IPV4HINT: return new SvcParamIpv4Hint(buf);
+ case KEY_ECH: return new SvcParamEch(buf);
+ case KEY_IPV6HINT: return new SvcParamIpv6Hint(buf);
+ case KEY_DOHPATH: return new SvcParamDohPath(buf);
+ default: return new SvcParamGeneric(key, buf);
+ }
+ } catch (BufferUnderflowException e) {
+ throw new ParseException("Malformed packet", e);
+ }
+ }
+
+ /**
+ * The base class for all SvcParam.
+ */
+ private abstract static class SvcParam {
+ private final int mKey;
+
+ SvcParam(int key) {
+ mKey = key;
+ }
+
+ int getKey() {
+ return mKey;
+ }
+ }
+
+ private static class SvcParamMandatory extends SvcParam {
+ private final short[] mValue;
+
+ private SvcParamMandatory(@NonNull ByteBuffer buf) throws BufferUnderflowException,
+ ParseException {
+ super(KEY_MANDATORY);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = Short.toUnsignedInt(buf.getShort());
+ final ByteBuffer svcParamValue = sliceAndAdvance(buf, len);
+ mValue = SvcParamValueUtil.toShortArray(svcParamValue);
+ if (mValue.length == 0) {
+ throw new ParseException("mandatory value must be non-empty");
+ }
+ }
+
+ @Override
+ public String toString() {
+ final StringJoiner valueJoiner = new StringJoiner(",");
+ for (short key : mValue) {
+ valueJoiner.add(toKeyName(key));
+ }
+ return toKeyName(getKey()) + "=" + valueJoiner.toString();
+ }
+ }
+
+ private static class SvcParamAlpn extends SvcParam {
+ private final List<String> mValue;
+
+ SvcParamAlpn(@NonNull ByteBuffer buf) throws BufferUnderflowException, ParseException {
+ super(KEY_ALPN);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = Short.toUnsignedInt(buf.getShort());
+ final ByteBuffer svcParamValue = sliceAndAdvance(buf, len);
+ mValue = SvcParamValueUtil.toStringList(svcParamValue);
+ if (mValue.isEmpty()) {
+ throw new ParseException("alpn value must be non-empty");
+ }
+ }
+
+ List<String> getValue() {
+ return Collections.unmodifiableList(mValue);
+ }
+
+ @Override
+ public String toString() {
+ return toKeyName(getKey()) + "=" + TextUtils.join(",", mValue);
+ }
+ }
+
+ private static class SvcParamNoDefaultAlpn extends SvcParam {
+ SvcParamNoDefaultAlpn(@NonNull ByteBuffer buf) throws BufferUnderflowException,
+ ParseException {
+ super(KEY_NO_DEFAULT_ALPN);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = buf.getShort();
+ if (len != 0) {
+ throw new ParseException("no-default-alpn value must be empty");
+ }
+ }
+
+ @Override
+ public String toString() {
+ return toKeyName(getKey());
+ }
+ }
+
+ private static class SvcParamPort extends SvcParam {
+ private final int mValue;
+
+ SvcParamPort(@NonNull ByteBuffer buf) throws BufferUnderflowException, ParseException {
+ super(KEY_PORT);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = buf.getShort();
+ if (len != Short.BYTES) {
+ throw new ParseException("key port len is not 2 but " + len);
+ }
+ mValue = Short.toUnsignedInt(buf.getShort());
+ }
+
+ int getValue() {
+ return mValue;
+ }
+
+ @Override
+ public String toString() {
+ return toKeyName(getKey()) + "=" + mValue;
+ }
+ }
+
+ private static class SvcParamIpHint extends SvcParam {
+ private final List<InetAddress> mValue;
+
+ private SvcParamIpHint(int key, @NonNull ByteBuffer buf, int addrLen) throws
+ BufferUnderflowException, ParseException {
+ super(key);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = Short.toUnsignedInt(buf.getShort());
+ final ByteBuffer svcParamValue = sliceAndAdvance(buf, len);
+ mValue = SvcParamValueUtil.toInetAddressList(svcParamValue, addrLen);
+ if (mValue.isEmpty()) {
+ throw new ParseException(toKeyName(getKey()) + " value must be non-empty");
+ }
+ }
+
+ List<InetAddress> getValue() {
+ return Collections.unmodifiableList(mValue);
+ }
+
+ @Override
+ public String toString() {
+ final StringJoiner valueJoiner = new StringJoiner(",");
+ for (InetAddress ip : mValue) {
+ valueJoiner.add(ip.getHostAddress());
+ }
+ return toKeyName(getKey()) + "=" + valueJoiner.toString();
+ }
+ }
+
+ private static class SvcParamIpv4Hint extends SvcParamIpHint {
+ SvcParamIpv4Hint(@NonNull ByteBuffer buf) throws BufferUnderflowException, ParseException {
+ super(KEY_IPV4HINT, buf, NetworkStackConstants.IPV4_ADDR_LEN);
+ }
+ }
+
+ private static class SvcParamIpv6Hint extends SvcParamIpHint {
+ SvcParamIpv6Hint(@NonNull ByteBuffer buf) throws BufferUnderflowException, ParseException {
+ super(KEY_IPV6HINT, buf, NetworkStackConstants.IPV6_ADDR_LEN);
+ }
+ }
+
+ private static class SvcParamEch extends SvcParamGeneric {
+ SvcParamEch(@NonNull ByteBuffer buf) throws BufferUnderflowException, ParseException {
+ super(KEY_ECH, buf);
+ }
+ }
+
+ private static class SvcParamDohPath extends SvcParam {
+ private final String mValue;
+
+ SvcParamDohPath(@NonNull ByteBuffer buf) throws BufferUnderflowException, ParseException {
+ super(KEY_DOHPATH);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = Short.toUnsignedInt(buf.getShort());
+ final byte[] value = new byte[len];
+ buf.get(value);
+ mValue = new String(value, StandardCharsets.UTF_8);
+ }
+
+ String getValue() {
+ return mValue;
+ }
+
+ @Override
+ public String toString() {
+ return toKeyName(getKey()) + "=" + mValue;
+ }
+ }
+
+ // For other unrecognized and unimplemented SvcParams, they are stored as SvcParamGeneric.
+ private static class SvcParamGeneric extends SvcParam {
+ private final byte[] mValue;
+
+ SvcParamGeneric(int key, @NonNull ByteBuffer buf) throws BufferUnderflowException,
+ ParseException {
+ super(key);
+ // The caller already read 2 bytes for SvcParamKey.
+ final int len = Short.toUnsignedInt(buf.getShort());
+ mValue = new byte[len];
+ buf.get(mValue);
+ }
+
+ @Override
+ public String toString() {
+ final StringBuilder out = new StringBuilder();
+ out.append(toKeyName(getKey()));
+ if (mValue != null && mValue.length > 0) {
+ out.append("=");
+ out.append(HexDump.toHexString(mValue));
+ }
+ return out.toString();
+ }
+ }
+
+ private static String toKeyName(int key) {
+ switch (key) {
+ case KEY_MANDATORY: return "mandatory";
+ case KEY_ALPN: return "alpn";
+ case KEY_NO_DEFAULT_ALPN: return "no-default-alpn";
+ case KEY_PORT: return "port";
+ case KEY_IPV4HINT: return "ipv4hint";
+ case KEY_ECH: return "ech";
+ case KEY_IPV6HINT: return "ipv6hint";
+ case KEY_DOHPATH: return "dohpath";
+ default: return "key" + key;
+ }
+ }
+
+ /**
+ * Returns a read-only ByteBuffer (with position = 0, limit = `length`, and capacity = `length`)
+ * sliced from `buf`'s current position, and moves the position of `buf` by `length`.
+ */
+ @VisibleForTesting(visibility = PRIVATE)
+ public static ByteBuffer sliceAndAdvance(@NonNull ByteBuffer buf, int length)
+ throws BufferUnderflowException {
+ if (buf.remaining() < length) {
+ throw new BufferUnderflowException();
+ }
+ final int pos = buf.position();
+
+ // `out` equals to `buf.slice(pos, length)` that is supported in API level 34.
+ final ByteBuffer out = ((ByteBuffer) buf.slice().limit(length)).slice();
+
+ buf.position(pos + length);
+ return out.asReadOnlyBuffer();
+ }
+
+ // A utility to convert the byte array of SvcParamValue to other types.
+ private static class SvcParamValueUtil {
+ // Refer to draft-ietf-dnsop-svcb-https-10#section-7.1 for the wire format of alpn.
+ @NonNull
+ private static List<String> toStringList(@NonNull ByteBuffer buf)
+ throws BufferUnderflowException, ParseException {
+ final List<String> out = new ArrayList<>();
+ while (buf.hasRemaining()) {
+ final int alpnLen = Byte.toUnsignedInt(buf.get());
+ if (alpnLen == 0) {
+ throw new ParseException("alpn should not be an empty string");
+ }
+ final byte[] alpn = new byte[alpnLen];
+ buf.get(alpn);
+ out.add(new String(alpn, StandardCharsets.UTF_8));
+ }
+ return out;
+ }
+
+ // Refer to draft-ietf-dnsop-svcb-https-10#section-7.5 for the wire format of SvcParamKey
+ // "mandatory".
+ @NonNull
+ private static short[] toShortArray(@NonNull ByteBuffer buf)
+ throws BufferUnderflowException, ParseException {
+ if (buf.remaining() % Short.BYTES != 0) {
+ throw new ParseException("Can't parse whole byte array");
+ }
+ final ShortBuffer sb = buf.asShortBuffer();
+ final short[] out = new short[sb.remaining()];
+ sb.get(out);
+ return out;
+ }
+
+ // Refer to draft-ietf-dnsop-svcb-https-10#section-7.4 for the wire format of ipv4hint and
+ // ipv6hint.
+ @NonNull
+ private static List<InetAddress> toInetAddressList(@NonNull ByteBuffer buf, int addrLen)
+ throws BufferUnderflowException, ParseException {
+ if (buf.remaining() % addrLen != 0) {
+ throw new ParseException("Can't parse whole byte array");
+ }
+
+ final List<InetAddress> out = new ArrayList<>();
+ final byte[] addr = new byte[addrLen];
+ while (buf.remaining() >= addrLen) {
+ buf.get(addr);
+ try {
+ out.add(InetAddress.getByAddress(addr));
+ } catch (UnknownHostException e) {
+ throw new ParseException("Can't parse byte array as an IP address");
+ }
+ }
+ return out;
+ }
+ }
+}
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 28e183a..88d9e1e 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
@@ -203,6 +203,30 @@
"test.com", CLASS_IN, 0 /* ttl */, "example.com"));
}
+ /** Verifies that the type of implementation returned from DnsRecord#parse is correct */
+ @Test
+ public void testDnsRecordParse() throws IOException {
+ final byte[] svcbQuestionRecord = new byte[] {
+ 0x07, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 0x03, 'c', 'o', 'm', 0x00, /* Name */
+ 0x00, 0x40, /* Type */
+ 0x00, 0x01, /* Class */
+ };
+ assertTrue(DnsPacket.DnsRecord.parse(DnsPacket.QDSECTION,
+ ByteBuffer.wrap(svcbQuestionRecord)) instanceof DnsSvcbRecord);
+
+ final byte[] svcbAnswerRecord = new byte[] {
+ 0x07, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 0x03, 'c', 'o', 'm', 0x00, /* Name */
+ 0x00, 0x40, /* Type */
+ 0x00, 0x01, /* Class */
+ 0x00, 0x00, 0x01, 0x2b, /* TTL */
+ 0x00, 0x0b, /* Data length */
+ 0x00, 0x01, /* SvcPriority */
+ 0x03, 'd', 'o', 't', 0x03, 'c', 'o', 'm', 0x00, /* TargetName */
+ };
+ assertTrue(DnsPacket.DnsRecord.parse(DnsPacket.ANSECTION,
+ ByteBuffer.wrap(svcbAnswerRecord)) instanceof DnsSvcbRecord);
+ }
+
/**
* Verifies ttl/rData error handling when parsing
* {@link DnsPacket.DnsRecord} from bytes.