Add support for custom TXT records in NSD
Change-Id: I8e6dc9852ad4d273c71ad6a63a7fbd28a206806d
diff --git a/core/java/android/net/nsd/NsdServiceInfo.java b/core/java/android/net/nsd/NsdServiceInfo.java
index 205a21d..6fdb0d0 100644
--- a/core/java/android/net/nsd/NsdServiceInfo.java
+++ b/core/java/android/net/nsd/NsdServiceInfo.java
@@ -18,8 +18,15 @@
import android.os.Parcelable;
import android.os.Parcel;
+import android.util.Log;
+import android.util.ArrayMap;
+import java.io.UnsupportedEncodingException;
import java.net.InetAddress;
+import java.nio.charset.StandardCharsets;
+import java.util.Collections;
+import java.util.Map;
+
/**
* A class representing service information for network service discovery
@@ -27,11 +34,13 @@
*/
public final class NsdServiceInfo implements Parcelable {
+ private static final String TAG = "NsdServiceInfo";
+
private String mServiceName;
private String mServiceType;
- private DnsSdTxtRecord mTxtRecord;
+ private final ArrayMap<String, byte[]> mTxtRecord = new ArrayMap<String, byte[]>();
private InetAddress mHost;
@@ -41,10 +50,9 @@
}
/** @hide */
- public NsdServiceInfo(String sn, String rt, DnsSdTxtRecord tr) {
+ public NsdServiceInfo(String sn, String rt) {
mServiceName = sn;
mServiceType = rt;
- mTxtRecord = tr;
}
/** Get the service name */
@@ -67,16 +75,6 @@
mServiceType = s;
}
- /** @hide */
- public DnsSdTxtRecord getTxtRecord() {
- return mTxtRecord;
- }
-
- /** @hide */
- public void setTxtRecord(DnsSdTxtRecord t) {
- mTxtRecord = new DnsSdTxtRecord(t);
- }
-
/** Get the host address. The host address is valid for a resolved service. */
public InetAddress getHost() {
return mHost;
@@ -97,14 +95,134 @@
mPort = p;
}
+ /** @hide */
+ public void setAttribute(String key, byte[] value) {
+ // Key must be printable US-ASCII, excluding =.
+ for (int i = 0; i < key.length(); ++i) {
+ char character = key.charAt(i);
+ if (character < 0x20 || character > 0x7E) {
+ throw new IllegalArgumentException("Key strings must be printable US-ASCII");
+ } else if (character == 0x3D) {
+ throw new IllegalArgumentException("Key strings must not include '='");
+ }
+ }
+
+ // Key length + value length must be < 255.
+ if (key.length() + (value == null ? 0 : value.length) >= 255) {
+ throw new IllegalArgumentException("Key length + value length must be < 255 bytes");
+ }
+
+ // Warn if key is > 9 characters, as recommended by RFC 6763 section 6.4.
+ if (key.length() > 9) {
+ Log.w(TAG, "Key lengths > 9 are discouraged: " + key);
+ }
+
+ // Check against total TXT record size limits.
+ // Arbitrary 400 / 1300 byte limits taken from RFC 6763 section 6.2.
+ int txtRecordSize = getTxtRecordSize();
+ int futureSize = txtRecordSize + key.length() + (value == null ? 0 : value.length) + 2;
+ if (futureSize > 1300) {
+ throw new IllegalArgumentException("Total length of attributes must be < 1300 bytes");
+ } else if (futureSize > 400) {
+ Log.w(TAG, "Total length of all attributes exceeds 400 bytes; truncation may occur");
+ }
+
+ mTxtRecord.put(key, value);
+ }
+
+ /**
+ * Add a service attribute as a key/value pair.
+ *
+ * <p> Service attributes are included as DNS-SD TXT record pairs.
+ *
+ * <p> The key must be US-ASCII printable characters, excluding the '=' character. Values may
+ * be UTF-8 strings or null. The total length of key + value must be less than 255 bytes.
+ *
+ * <p> Keys should be short, ideally no more than 9 characters, and unique per instance of
+ * {@link NsdServiceInfo}. Calling {@link #setAttribute} twice with the same key will overwrite
+ * first value.
+ */
+ public void setAttribute(String key, String value) {
+ try {
+ setAttribute(key, value == null ? (byte []) null : value.getBytes("UTF-8"));
+ } catch (UnsupportedEncodingException e) {
+ throw new IllegalArgumentException("Value must be UTF-8");
+ }
+ }
+
+ /** Remove an attribute by key */
+ public void removeAttribute(String key) {
+ mTxtRecord.remove(key);
+ }
+
+ /**
+ * Retrive attributes as a map of String keys to byte[] values.
+ *
+ * <p> The returned map is unmodifiable; changes must be made through {@link #setAttribute} and
+ * {@link #removeAttribute}.
+ */
+ public Map<String, byte[]> getAttributes() {
+ return Collections.unmodifiableMap(mTxtRecord);
+ }
+
+ private int getTxtRecordSize() {
+ int txtRecordSize = 0;
+ for (Map.Entry<String, byte[]> entry : mTxtRecord.entrySet()) {
+ txtRecordSize += 2; // One for the length byte, one for the = between key and value.
+ txtRecordSize += entry.getKey().length();
+ byte[] value = entry.getValue();
+ txtRecordSize += value == null ? 0 : value.length;
+ }
+ return txtRecordSize;
+ }
+
+ /** @hide */
+ public byte[] getTxtRecord() {
+ int txtRecordSize = getTxtRecordSize();
+ if (txtRecordSize == 0) {
+ return null;
+ }
+
+ byte[] txtRecord = new byte[txtRecordSize];
+ int ptr = 0;
+ for (Map.Entry<String, byte[]> entry : mTxtRecord.entrySet()) {
+ String key = entry.getKey();
+ byte[] value = entry.getValue();
+
+ // One byte to record the length of this key/value pair.
+ txtRecord[ptr++] = (byte) (key.length() + (value == null ? 0 : value.length) + 1);
+
+ // The key, in US-ASCII.
+ // Note: use the StandardCharsets const here because it doesn't raise exceptions and we
+ // already know the key is ASCII at this point.
+ System.arraycopy(key.getBytes(StandardCharsets.US_ASCII), 0, txtRecord, ptr,
+ key.length());
+ ptr += key.length();
+
+ // US-ASCII '=' character.
+ txtRecord[ptr++] = (byte)'=';
+
+ // The value, as any raw bytes.
+ if (value != null) {
+ System.arraycopy(value, 0, txtRecord, ptr, value.length);
+ ptr += value.length;
+ }
+ }
+ return txtRecord;
+ }
+
public String toString() {
StringBuffer sb = new StringBuffer();
- sb.append("name: ").append(mServiceName).
- append("type: ").append(mServiceType).
- append("host: ").append(mHost).
- append("port: ").append(mPort).
- append("txtRecord: ").append(mTxtRecord);
+ sb.append("name: ").append(mServiceName)
+ .append(", type: ").append(mServiceType)
+ .append(", host: ").append(mHost)
+ .append(", port: ").append(mPort);
+
+ byte[] txtRecord = getTxtRecord();
+ if (txtRecord != null) {
+ sb.append(", txtRecord: ").append(new String(txtRecord, StandardCharsets.UTF_8));
+ }
return sb.toString();
}
@@ -117,14 +235,27 @@
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(mServiceName);
dest.writeString(mServiceType);
- dest.writeParcelable(mTxtRecord, flags);
if (mHost != null) {
- dest.writeByte((byte)1);
+ dest.writeInt(1);
dest.writeByteArray(mHost.getAddress());
} else {
- dest.writeByte((byte)0);
+ dest.writeInt(0);
}
dest.writeInt(mPort);
+
+ // TXT record key/value pairs.
+ dest.writeInt(mTxtRecord.size());
+ for (String key : mTxtRecord.keySet()) {
+ byte[] value = mTxtRecord.get(key);
+ if (value != null) {
+ dest.writeInt(1);
+ dest.writeInt(value.length);
+ dest.writeByteArray(value);
+ } else {
+ dest.writeInt(0);
+ }
+ dest.writeString(key);
+ }
}
/** Implement the Parcelable interface */
@@ -134,15 +265,26 @@
NsdServiceInfo info = new NsdServiceInfo();
info.mServiceName = in.readString();
info.mServiceType = in.readString();
- info.mTxtRecord = in.readParcelable(null);
- if (in.readByte() == 1) {
+ if (in.readInt() == 1) {
try {
info.mHost = InetAddress.getByAddress(in.createByteArray());
} catch (java.net.UnknownHostException e) {}
}
info.mPort = in.readInt();
+
+ // TXT record key/value pairs.
+ int recordCount = in.readInt();
+ for (int i = 0; i < recordCount; ++i) {
+ byte[] valueArray = null;
+ if (in.readInt() == 1) {
+ int valueLength = in.readInt();
+ valueArray = new byte[valueLength];
+ in.readByteArray(valueArray);
+ }
+ info.mTxtRecord.put(in.readString(), valueArray);
+ }
return info;
}