Avoid going over max service name length when renaming NSD services
As per RFC 1034/1035, the max size of the label is 63 bytes. It should
also be guaranteed when the serviceName is renamed due to the conflict.
Bug: 265865456
Test: atest FrameworksNetTests
Change-Id: I077d8abdb91071db62b9618d9918e3a12682aaf4
diff --git a/service-t/src/com/android/server/NsdService.java b/service-t/src/com/android/server/NsdService.java
index a62ee7f..1d99190 100644
--- a/service-t/src/com/android/server/NsdService.java
+++ b/service-t/src/com/android/server/NsdService.java
@@ -23,6 +23,7 @@
import static android.provider.DeviceConfig.NAMESPACE_TETHERING;
import static com.android.modules.utils.build.SdkLevel.isAtLeastU;
+import static com.android.server.connectivity.mdns.MdnsRecord.MAX_LABEL_LENGTH;
import android.annotation.NonNull;
import android.annotation.Nullable;
@@ -73,6 +74,7 @@
import com.android.server.connectivity.mdns.MdnsServiceInfo;
import com.android.server.connectivity.mdns.MdnsSocketClientBase;
import com.android.server.connectivity.mdns.MdnsSocketProvider;
+import com.android.server.connectivity.mdns.util.MdnsUtils;
import java.io.FileDescriptor;
import java.io.PrintWriter;
@@ -81,11 +83,6 @@
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
-import java.nio.ByteBuffer;
-import java.nio.CharBuffer;
-import java.nio.charset.Charset;
-import java.nio.charset.CharsetEncoder;
-import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
@@ -108,8 +105,6 @@
*/
private static final String MDNS_DISCOVERY_MANAGER_VERSION = "mdns_discovery_manager_version";
private static final String LOCAL_DOMAIN_NAME = "local";
- // Max label length as per RFC 1034/1035
- private static final int MAX_LABEL_LENGTH = 63;
/**
* Enable advertising using the Java MdnsAdvertiser, instead of the legacy mdnsresponder
@@ -570,18 +565,7 @@
*/
@NonNull
private String truncateServiceName(@NonNull String originalName) {
- // UTF-8 is at most 4 bytes per character; return early in the common case where
- // the name can't possibly be over the limit given its string length.
- if (originalName.length() <= MAX_LABEL_LENGTH / 4) return originalName;
-
- final Charset utf8 = StandardCharsets.UTF_8;
- final CharsetEncoder encoder = utf8.newEncoder();
- final ByteBuffer out = ByteBuffer.allocate(MAX_LABEL_LENGTH);
- // encode will write as many characters as possible to the out buffer, and just
- // return an overflow code if there were too many characters (no need to check the
- // return code here, this method truncates the name on purpose).
- encoder.encode(CharBuffer.wrap(originalName), out, true /* endOfInput */);
- return new String(out.array(), 0, out.position(), utf8);
+ return MdnsUtils.truncateServiceName(originalName, MAX_LABEL_LENGTH);
}
private void stopDiscoveryManagerRequest(ClientRequest request, int clientId, int id,
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java b/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java
index 33fef9d..a332da7 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsAdvertiser.java
@@ -16,6 +16,8 @@
package com.android.server.connectivity.mdns;
+import static com.android.server.connectivity.mdns.MdnsRecord.MAX_LABEL_LENGTH;
+
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.net.LinkAddress;
@@ -29,6 +31,7 @@
import com.android.internal.annotations.VisibleForTesting;
import com.android.net.module.util.SharedLog;
+import com.android.server.connectivity.mdns.util.MdnsUtils;
import java.io.PrintWriter;
import java.util.List;
@@ -359,7 +362,7 @@
// "Name (2)", then "Name (3)" etc.
// TODO: use a hidden method in NsdServiceInfo once MdnsAdvertiser is moved to service-t
final NsdServiceInfo newInfo = new NsdServiceInfo();
- newInfo.setServiceName(mOriginalName + " (" + (mConflictCount + renameCount + 1) + ")");
+ newInfo.setServiceName(getUpdatedServiceName(renameCount));
newInfo.setServiceType(mServiceInfo.getServiceType());
for (Map.Entry<String, byte[]> attr : mServiceInfo.getAttributes().entrySet()) {
newInfo.setAttribute(attr.getKey(),
@@ -372,6 +375,13 @@
return newInfo;
}
+ private String getUpdatedServiceName(int renameCount) {
+ final String suffix = " (" + (mConflictCount + renameCount + 1) + ")";
+ final String truncatedServiceName = MdnsUtils.truncateServiceName(mOriginalName,
+ MAX_LABEL_LENGTH - suffix.length());
+ return truncatedServiceName + suffix;
+ }
+
@NonNull
public NsdServiceInfo getServiceInfo() {
return mServiceInfo;
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsRecord.java b/service-t/src/com/android/server/connectivity/mdns/MdnsRecord.java
index bcee9d1..19630e3 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsRecord.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsRecord.java
@@ -46,6 +46,8 @@
public static final long RECEIPT_TIME_NOT_SENT = 0L;
public static final int CLASS_ANY = 0x00ff;
+ /** Max label length as per RFC 1034/1035 */
+ public static final int MAX_LABEL_LENGTH = 63;
/** Status indicating that the record is current. */
public static final int STATUS_OK = 0;
diff --git a/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java b/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java
index 4b9759d..5cc789f 100644
--- a/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java
+++ b/service-t/src/com/android/server/connectivity/mdns/util/MdnsUtils.java
@@ -21,6 +21,12 @@
import android.net.Network;
import android.os.Handler;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.StandardCharsets;
+
/**
* Mdns utility functions.
*/
@@ -73,4 +79,22 @@
@Nullable Network currentNetwork) {
return targetNetwork == null || targetNetwork.equals(currentNetwork);
}
-}
+
+ /**
+ * Truncate a service name to up to maxLength UTF-8 bytes.
+ */
+ public static String truncateServiceName(@NonNull String originalName, int maxLength) {
+ // UTF-8 is at most 4 bytes per character; return early in the common case where
+ // the name can't possibly be over the limit given its string length.
+ if (originalName.length() <= maxLength / 4) return originalName;
+
+ final Charset utf8 = StandardCharsets.UTF_8;
+ final CharsetEncoder encoder = utf8.newEncoder();
+ final ByteBuffer out = ByteBuffer.allocate(maxLength);
+ // encode will write as many characters as possible to the out buffer, and just
+ // return an overflow code if there were too many characters (no need to check the
+ // return code here, this method truncates the name on purpose).
+ encoder.encode(CharBuffer.wrap(originalName), out, true /* endOfInput */);
+ return new String(out.array(), 0, out.position(), utf8);
+ }
+}
\ No newline at end of file