(De-)serialize message to/from byte array instead of stream.

This lets us get rid of seperate `getBytes` function for signing,
and is needed for end to end encryption.

app/src/androidTest/scala/com.nutomic.ensichat.messages/CryptoTest.scala

@@ -1,8 +1,8 @@
 package com.nutomic.ensichat.messages
 
 import android.test.AndroidTestCase
-import junit.framework.Assert._
 import com.nutomic.ensichat.messages.MessageTest._
+import junit.framework.Assert._
 
 class CryptoTest extends AndroidTestCase {
 

app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageStoreTest.scala

@@ -8,8 +8,8 @@ import android.database.sqlite.SQLiteDatabase
 import android.test.AndroidTestCase
 import android.test.mock.MockContext
 import com.nutomic.ensichat.bluetooth.Device
-import junit.framework.Assert._
 import com.nutomic.ensichat.messages.MessageTest._
+import junit.framework.Assert._
 
 class MessageStoreTest extends AndroidTestCase {
 

app/src/androidTest/scala/com.nutomic.ensichat.messages/MessageTest.scala

@@ -29,8 +29,8 @@ class MessageTest extends AndroidTestCase {
   def testSerialize(): Unit = {
     val pis = new PipedInputStream()
     val pos = new PipedOutputStream(pis)
-    m1.write(pos, Array[Byte]())
-    val (msg, _) = Message.read(pis)
+    val bytes = m1.write(Array[Byte]())
+    val (msg, _) = Message.read(bytes)
     assertEquals(m1, msg)
   }
 

app/src/main/scala/com/nutomic/ensichat/bluetooth/TransferThread.scala

@@ -1,7 +1,6 @@
 package com.nutomic.ensichat.bluetooth
 
 import java.io._
-import java.util.Date
 
 import android.bluetooth.BluetoothSocket
 import android.util.Log
@@ -10,6 +9,8 @@ import com.nutomic.ensichat.messages.{Crypto, DeviceInfoMessage, Message, TextMe
 /**
  * Transfers data between connnected devices.
  *
+ * Messages must not be longer than [[TransferThread#MaxMessageLength]] bytes.
+ *
  * @param device The bluetooth device to interact with.
  * @param socket An open socket to the given device.
  * @param encrypt Object used to handle signing and encryption of messages.
@@ -18,7 +19,9 @@ import com.nutomic.ensichat.messages.{Crypto, DeviceInfoMessage, Message, TextMe
 class TransferThread(device: Device, socket: BluetoothSocket, localDevice: Device.ID,
                      encrypt: Crypto, onReceive: (Message) => Unit) extends Thread {
 
-  val Tag: String = "TransferThread"
+  private val Tag: String = "TransferThread"
+
+  private val MaxMessageLength = 4096
 
   val InStream: InputStream =
     try {
@@ -44,7 +47,9 @@ class TransferThread(device: Device, socket: BluetoothSocket, localDevice: Devic
     // Keep listening to the InputStream while connected
     while (true) {
       try {
-        val (msg, signature) = Message.read(InStream)
+        val bytes = new Array[Byte](MaxMessageLength)
+        InStream.read(bytes)
+        val (msg, signature) = Message.read(bytes)
         var messageValid = true
 
         if (msg.sender != device.id) {
@@ -57,14 +62,14 @@ class TransferThread(device: Device, socket: BluetoothSocket, localDevice: Devic
           messageValid = false
         }
 
-        // Add public key for new, local device.
+        // Add public key for new, directly connected device.
         // Explicitly check that message was not forwarded or spoofed.
         if (msg.isInstanceOf[DeviceInfoMessage] && !encrypt.havePublicKey(msg.sender) &&
             msg.sender == device.id) {
           val dim = msg.asInstanceOf[DeviceInfoMessage]
           // Permanently store public key for new local devices (also check signature).
-          if (msg.sender == device.id && encrypt.isValidSignature(msg, signature, dim.publicKey)) {
-            encrypt.addPublicKey(device.id, msg.asInstanceOf[DeviceInfoMessage].publicKey)
+          if (encrypt.isValidSignature(msg, signature, dim.publicKey)) {
+            encrypt.addPublicKey(device.id, dim.publicKey)
             Log.i(Tag, "Added public key for new device " + device.name)
           }
         }
@@ -91,7 +96,8 @@ class TransferThread(device: Device, socket: BluetoothSocket, localDevice: Devic
   def send(message: Message): Unit = {
     try {
       val sig = encrypt.calculateSignature(message)
-      message.write(OutStream, sig)
+      val bytes = message.write(sig)
+      OutStream.write(bytes)
     } catch {
       case e: IOException =>
         Log.e(Tag, "Failed to write message", e)

app/src/main/scala/com/nutomic/ensichat/messages/Crypto.scala

@@ -4,7 +4,6 @@ import java.io.{File, FileInputStream, FileOutputStream, IOException}
 import java.security._
 import java.security.spec.{PKCS8EncodedKeySpec, X509EncodedKeySpec}
 
-import android.content.Context
 import android.util.Log
 import com.nutomic.ensichat.bluetooth.Device
 import com.nutomic.ensichat.messages.Crypto._
@@ -80,6 +79,8 @@ class Crypto(filesDir: File) {
   /**
    * Checks if the message was properly signed.
    *
+   * This is done by signing the output of [[Message.write()]] called with an empty signature.
+   *
    * @param message The message to verify.
    * @param signature The signature that was sent
    * @return True if the signature is valid.
@@ -89,19 +90,21 @@ class Crypto(filesDir: File) {
       if (key != null) key
       else loadKey(message.sender.toString, classOf[PublicKey])
     val sig = Signature.getInstance(SignAlgorithm)
-    sig.initVerify(key)
-    sig.update(message.getBytes)
+    sig.initVerify(publicKey)
+    sig.update(message.write(Array[Byte]()))
     sig.verify(signature)
   }
 
   /**
    * Returns a cryptographic signature for the given message (using local private key).
+   *
+   * This is done by signing the output of [[Message.write()]] called with an empty signature.
    */
   def calculateSignature(message: Message): Array[Byte] = {
     val sig = Signature.getInstance(SignAlgorithm)
     val key = loadKey(PrivateKeyAlias, classOf[PrivateKey])
     sig.initSign(key)
-    sig.update(message.getBytes)
+    sig.update(message.write(Array[Byte]()))
     sig.sign
   }
 

app/src/main/scala/com/nutomic/ensichat/messages/DeviceInfoMessage.scala

@@ -40,6 +40,4 @@ class DeviceInfoMessage(override val sender: Device.ID, override val receiver: D
   override def toString = "DeviceInfoMessage(" + sender.toString + ", " + receiver.toString +
     ", " + date.toString + ", " + publicKey.toString + ")"
 
-  override def getBytes = super.getBytes ++ publicKey.getEncoded
-
 }

app/src/main/scala/com/nutomic/ensichat/messages/Message.scala

@@ -1,7 +1,5 @@
 package com.nutomic.ensichat.messages
 
-import java.io.{InputStream, OutputStream}
-import java.nio.ByteBuffer
 import java.util.Date
 
 import com.nutomic.ensichat.bluetooth.Device
@@ -28,12 +26,14 @@ object Message {
   }
 
   /**
-   * Deserializes a stream that was written by [[Message.write]] into the correct subclass.
+   * Reads a byte array that was written by [[Message.write]] into the correct
+   * message implementation..
    *
    * @return Deserialized message and sits signature.
    */
-  def read(in: InputStream): (Message, Array[Byte]) = {
-    val up = new ScalaMessagePack().createUnpacker(in)
+  def read(bytes: Array[Byte]): (Message, Array[Byte]) = {
+    val up = new ScalaMessagePack().createBufferUnpacker(bytes)
+
     val messageType = up.readInt()
     val sender      = new Device.ID(up.readString())
     val receiver    = new Device.ID(up.readString())
@@ -70,16 +70,19 @@ abstract class Message(messageType: Int) {
   val date: Date
 
   /**
-   * Serializes this message and the given signature into stream.
+   * Writes this message and the given signature into byte array.
+   *
+   * Signature may not be null, but can be an empty array.
    */
-  def write(os: OutputStream, signature: Array[Byte]): Unit = {
-    val packer = new ScalaMessagePack().createPacker(os)
-      .write(messageType)
+  def write(signature: Array[Byte]): Array[Byte] = {
+    val packer = new ScalaMessagePack().createBufferPacker()
+    packer.write(messageType)
       .write(sender.toString)
       .write(receiver.toString)
       .write(date.getTime)
       .write(signature)
     doWrite(packer)
+    packer.toByteArray
   }
 
   /**
@@ -109,17 +112,4 @@ abstract class Message(messageType: Int) {
 
   override def toString: String
 
-  /**
-   * Returns this object's data encoded as Array[Byte].
-   *
-   * Implementations must provide their own implementation to check the result of this
-   * function and their own data.
-   */
-  def getBytes: Array[Byte] = intToBytes(messageType) ++ sender.toString.getBytes ++
-    receiver.toString.getBytes ++ longToBytes(date.getTime)
-
-  private def intToBytes(i: Int) = ByteBuffer.allocate(java.lang.Integer.SIZE / 8).putInt(i).array()
-
-  private def longToBytes(l: Long) = ByteBuffer.allocate(java.lang.Long.SIZE / 8).putLong(l).array()
-
 }

app/src/main/scala/com/nutomic/ensichat/messages/TextMessage.scala

@@ -29,6 +29,4 @@ class TextMessage(override val sender: Device.ID, override val receiver: Device.
   override def toString = "TextMessage(" + sender.toString + ", " + receiver.toString +
     ", " + date.toString + ", " + text + ")"
 
-  override def getBytes = super.getBytes ++ text.getBytes
-
 }