Refactor header serialization

TICESoftware · Apr 3, 2020 · 07b7031 · 07b7031
1 parent 323cae3
commit 07b7031
Showing 1 changed file with 10 additions and 8 deletions.
diff --git a/androiddoubleratchet/src/main/java/com/ticeapp/androiddoubleratchet/Message.kt b/androiddoubleratchet/src/main/java/com/ticeapp/androiddoubleratchet/Message.kt
@@ -7,19 +7,21 @@ class Message(val header: Header, val cipher: ByteArray)
 class Header(val publicKey: Key, val numberOfMessagesInPreviousSendingChain: Int, val messageNumber: Int) {
     fun bytes(): ByteArray {
         var bytes = publicKey.asBytes.clone()
+        bytes += byteArray(numberOfMessagesInPreviousSendingChain, 8)
+        bytes += byteArray(messageNumber, 8)
 
-        if (numberOfMessagesInPreviousSendingChain < Int.MAX_VALUE) {
-            bytes += ByteArray(4) // Padding to be compatible with 64-bit
-        }
+        return bytes
+    }
 
-        bytes += BigInteger.valueOf(numberOfMessagesInPreviousSendingChain.toLong()).toByteArray()
+    private fun byteArray(value: Int, byteCount: Int): ByteArray {
+        val valueBytes = BigInteger.valueOf(value.toLong()).toByteArray()
 
-        if (messageNumber < Int.MAX_VALUE) {
-            bytes += ByteArray(4) // Padding to be compatible with 64-bit
+        if (valueBytes.size > byteCount) {
+            throw IllegalArgumentException("Binary representation of given value needs more bytes then specified by byteCount.")
         }
 
-        bytes += BigInteger.valueOf(messageNumber.toLong()).toByteArray()
+        val paddingBytes = ByteArray(byteCount - valueBytes.size)
 
-        return bytes
+        return paddingBytes + valueBytes
     }
 }