Add generic record reader and writer.

bramble-api/src/main/java/org/briarproject/bramble/api/record/Record.java

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.api.record;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class Record {
+
+	public static final int RECORD_HEADER_BYTES = 4;
+	public static final int MAX_RECORD_PAYLOAD_BYTES = 48 * 1024; // 48 KiB
+
+	private final byte protocolVersion, recordType;
+	private final byte[] payload;
+
+	public Record(byte protocolVersion, byte recordType, byte[] payload) {
+		if (payload.length > MAX_RECORD_PAYLOAD_BYTES)
+			throw new IllegalArgumentException();
+		this.protocolVersion = protocolVersion;
+		this.recordType = recordType;
+		this.payload = payload;
+	}
+
+	public byte getProtocolVersion() {
+		return protocolVersion;
+	}
+
+	public byte getRecordType() {
+		return recordType;
+	}
+
+	public byte[] getPayload() {
+		return payload;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReader.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.record;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.EOFException;
+import java.io.IOException;
+
+@NotNullByDefault
+public interface RecordReader {
+
+	/**
+	 * Reads and returns the next record.
+	 *
+	 * @throws EOFException if the end of the stream is reached without reading
+	 * a complete record
+	 */
+	Record readRecord() throws IOException;
+
+	void close() throws IOException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReaderFactory.java

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.api.record;
+
+import java.io.InputStream;
+
+public interface RecordReaderFactory {
+
+	RecordReader createRecordReader(InputStream in);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriter.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.record;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.IOException;
+
+@NotNullByDefault
+public interface RecordWriter {
+
+	void writeRecord(Record r) throws IOException;
+
+	void flush() throws IOException;
+
+	void close() throws IOException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriterFactory.java

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.api.record;
+
+import java.io.OutputStream;
+
+public interface RecordWriterFactory {
+
+	RecordWriter createRecordWriter(OutputStream out);
+}