Add constructors to MDNS records

Add constructors to allow creating the records locally, which is useful
for advertising as opposed to only receiving such records in discovery.

Bug: 241738458
Test: atest
Change-Id: I61a1bb91cdc2d06e2e2e57e3951c63e2820203eb
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java
index 47ac20e..dd8a526 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java
@@ -43,7 +43,32 @@
      */
     public MdnsInetAddressRecord(String[] name, int type, MdnsPacketReader reader)
             throws IOException {
-        super(name, type, reader);
+        this(name, type, reader, false);
+    }
+
+    /**
+     * Constructs the {@link MdnsRecord}
+     *
+     * @param name       the service host name
+     * @param type       the type of record (either Type 'AAAA' or Type 'A')
+     * @param reader     the reader to read the record from.
+     * @param isQuestion whether the record is in the question section
+     */
+    public MdnsInetAddressRecord(String[] name, int type, MdnsPacketReader reader,
+            boolean isQuestion)
+            throws IOException {
+        super(name, type, reader, isQuestion);
+    }
+
+    public MdnsInetAddressRecord(String[] name, long receiptTimeMillis, boolean cacheFlush,
+                    long ttlMillis, InetAddress address) {
+        super(name, address instanceof Inet4Address ? TYPE_A : TYPE_AAAA,
+                MdnsConstants.QCLASS_INTERNET, receiptTimeMillis, cacheFlush, ttlMillis);
+        if (address instanceof Inet4Address) {
+            inet4Address = (Inet4Address) address;
+        } else {
+            inet6Address = (Inet6Address) address;
+        }
     }
 
     /** Returns the IPv6 address. */
@@ -127,4 +152,4 @@
                 && Objects.equals(inet4Address, ((MdnsInetAddressRecord) other).inet4Address)
                 && Objects.equals(inet6Address, ((MdnsInetAddressRecord) other).inet6Address);
     }
-}
\ No newline at end of file
+}
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java
index 9641a40..2c7b26b 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java
@@ -29,7 +29,19 @@
     private String[] pointer;
 
     public MdnsPointerRecord(String[] name, MdnsPacketReader reader) throws IOException {
-        super(name, TYPE_PTR, reader);
+        this(name, reader, false);
+    }
+
+    public MdnsPointerRecord(String[] name, MdnsPacketReader reader, boolean isQuestion)
+            throws IOException {
+        super(name, TYPE_PTR, reader, isQuestion);
+    }
+
+    public MdnsPointerRecord(String[] name, long receiptTimeMillis, boolean cacheFlush,
+                    long ttlMillis, String[] pointer) {
+        super(name, TYPE_PTR, MdnsConstants.QCLASS_INTERNET, receiptTimeMillis, cacheFlush,
+                ttlMillis);
+        this.pointer = pointer;
     }
 
     /** Returns the pointer as an array of labels. */
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java
index 35f6da1..7c802e6 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java
@@ -40,6 +40,10 @@
     public static final int TYPE_SRV = 0x0021;
     public static final int TYPE_TXT = 0x0010;
 
+    private static final int FLAG_CACHE_FLUSH = 0x8000;
+
+    public static final long RECEIPT_TIME_NOT_SENT = 0L;
+
     /** Status indicating that the record is current. */
     public static final int STATUS_OK = 0;
     /** Status indicating that the record has expired (TTL reached 0). */
@@ -58,23 +62,52 @@
      * Constructs a new record with the given name and type.
      *
      * @param reader The reader to read the record from.
+     * @param isQuestion Whether the record was included in the questions part of the message.
+     * @throws IOException If an error occurs while reading the packet.
+     */
+    protected MdnsRecord(String[] name, int type, MdnsPacketReader reader, boolean isQuestion)
+            throws IOException {
+        this.name = name;
+        this.type = type;
+        cls = reader.readUInt16();
+        receiptTimeMillis = SystemClock.elapsedRealtime();
+
+        if (isQuestion) {
+            // Questions do not have TTL or data
+            ttlMillis = 0L;
+        } else {
+            ttlMillis = SECONDS.toMillis(reader.readUInt32());
+            int dataLength = reader.readUInt16();
+
+            reader.setLimit(dataLength);
+            readData(reader);
+            reader.clearLimit();
+        }
+    }
+
+    /**
+     * Constructs a new record with the given name and type.
+     *
+     * @param reader The reader to read the record from.
      * @throws IOException If an error occurs while reading the packet.
      */
     // call to readData(com.android.server.connectivity.mdns.MdnsPacketReader) not allowed on given
     // receiver.
     @SuppressWarnings("nullness:method.invocation.invalid")
     protected MdnsRecord(String[] name, int type, MdnsPacketReader reader) throws IOException {
+        this(name, type, reader, false);
+    }
+
+    /**
+     * Constructs a new record with the given properties.
+     */
+    protected MdnsRecord(String[] name, int type, int cls, long receiptTimeMillis,
+            boolean cacheFlush, long ttlMillis) {
         this.name = name;
         this.type = type;
-        cls = reader.readUInt16();
-        ttlMillis = SECONDS.toMillis(reader.readUInt32());
-        int dataLength = reader.readUInt16();
-
-        receiptTimeMillis = SystemClock.elapsedRealtime();
-
-        reader.setLimit(dataLength);
-        readData(reader);
-        reader.clearLimit();
+        this.cls = cls | (cacheFlush ? FLAG_CACHE_FLUSH : 0);
+        this.receiptTimeMillis = receiptTimeMillis;
+        this.ttlMillis = ttlMillis;
     }
 
     /**
@@ -126,13 +159,29 @@
         return type;
     }
 
+    /** Return the record's class. */
+    public final int getRecordClass() {
+        return cls & ~FLAG_CACHE_FLUSH;
+    }
+
+    /** Return whether the cache flush flag is set. */
+    public final boolean getCacheFlush() {
+        return (cls & FLAG_CACHE_FLUSH) != 0;
+    }
+
     /**
      * Returns the record's remaining TTL.
      *
+     * If the record was not sent yet (receipt time {@link #RECEIPT_TIME_NOT_SENT}), this is the
+     * original TTL of the record.
      * @param now The current system time.
      * @return The remaning TTL, in milliseconds.
      */
     public long getRemainingTTL(final long now) {
+        if (receiptTimeMillis == RECEIPT_TIME_NOT_SENT) {
+            return ttlMillis;
+        }
+
         long age = now - receiptTimeMillis;
         if (age > ttlMillis) {
             return 0;
@@ -187,6 +236,9 @@
 
     /** Gets the status of the record. */
     public int getStatus(final long now) {
+        if (receiptTimeMillis == RECEIPT_TIME_NOT_SENT) {
+            return STATUS_OK;
+        }
         final long age = now - receiptTimeMillis;
         if (age > ttlMillis) {
             return STATUS_EXPIRED;
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java
index c52d25e..ebd8b77 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java
@@ -39,7 +39,23 @@
     private String[] serviceHost;
 
     public MdnsServiceRecord(String[] name, MdnsPacketReader reader) throws IOException {
-        super(name, TYPE_SRV, reader);
+        this(name, reader, false);
+    }
+
+    public MdnsServiceRecord(String[] name, MdnsPacketReader reader, boolean isQuestion)
+            throws IOException {
+        super(name, TYPE_SRV, reader, isQuestion);
+    }
+
+    public MdnsServiceRecord(String[] name, long receiptTimeMillis, boolean cacheFlush,
+                    long ttlMillis, int servicePriority, int serviceWeight, int servicePort,
+                    String[] serviceHost) {
+        super(name, TYPE_SRV, MdnsConstants.QCLASS_INTERNET, receiptTimeMillis, cacheFlush,
+                ttlMillis);
+        this.servicePriority = servicePriority;
+        this.serviceWeight = serviceWeight;
+        this.servicePort = servicePort;
+        this.serviceHost = serviceHost;
     }
 
     /** Returns the service's port number. */
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java
index 1e66589..4149dbe 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java
@@ -33,7 +33,19 @@
     private List<TextEntry> entries;
 
     public MdnsTextRecord(String[] name, MdnsPacketReader reader) throws IOException {
-        super(name, TYPE_TXT, reader);
+        this(name, reader, false);
+    }
+
+    public MdnsTextRecord(String[] name, MdnsPacketReader reader, boolean isQuestion)
+            throws IOException {
+        super(name, TYPE_TXT, reader, isQuestion);
+    }
+
+    public MdnsTextRecord(String[] name, long receiptTimeMillis, boolean cacheFlush, long ttlMillis,
+            List<TextEntry> entries) {
+        super(name, TYPE_TXT, MdnsConstants.QCLASS_INTERNET, receiptTimeMillis, cacheFlush,
+                ttlMillis);
+        this.entries = entries;
     }
 
     /** Returns the list of strings. */