Improved callback support added Task support and passing SessionRecord

    This modifies the existing callback support to work with Task based callbacks.  It also passes the SessionRecord (when available) to the callback (as not yet committed for prekey), needed for protocol version check code that already exists).

Author: mitchcapper

libsignal-protocol-dotnet/DecryptionCallback.cs

@@ -1,24 +1,25 @@
-/** 
- * Copyright (C) 2016 smndtrl, langboost
- * 
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- * 
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
+using libsignal.state;
+using System.Threading.Tasks;
+/** 
+* Copyright (C) 2016 smndtrl, langboost
+* 
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+* 
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
 namespace libsignal
 {
     public interface DecryptionCallback
     {
-        void handlePlaintext(byte[] plaintext);
+        Task handlePlaintext(byte[] plaintext, SessionRecord sessionRecord);
     }
 }

libsignal-protocol-dotnet/SessionCipher.cs

@@ -24,6 +24,7 @@
 using Strilanc.Value;
 using System;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 
 namespace libsignal
 {
@@ -141,7 +142,9 @@ public CiphertextMessage encrypt(byte[] paddedMessage)
          */
         public byte[] decrypt(PreKeySignalMessage ciphertext)
         {
-            return decrypt(ciphertext, new NullDecryptionCallback());
+            var tsk = (decrypt(ciphertext, new NullDecryptionCallback()));
+            tsk.Wait();
+            return tsk.Result;
         }
 
         /**
@@ -165,7 +168,7 @@ public byte[] decrypt(PreKeySignalMessage ciphertext)
          * @throws InvalidKeyException when the message is formatted incorrectly.
          * @throws UntrustedIdentityException when the {@link IdentityKey} of the sender is untrusted.
          */
-        public byte[] decrypt(PreKeySignalMessage ciphertext, DecryptionCallback callback)
+        public Task<byte[]> decrypt(PreKeySignalMessage ciphertext, DecryptionCallback callback)
         {
             lock (SESSION_LOCK)
             {
@@ -175,7 +178,7 @@ public byte[] decrypt(PreKeySignalMessage ciphertext, DecryptionCallback callbac
 
                 identityKeyStore.SaveIdentity(remoteAddress, sessionRecord.getSessionState().getRemoteIdentityKey());
 
-                callback.handlePlaintext(plaintext);
+                callback.handlePlaintext(plaintext, sessionRecord).Wait();
 
                 sessionStore.StoreSession(remoteAddress, sessionRecord);
 
@@ -184,7 +187,7 @@ public byte[] decrypt(PreKeySignalMessage ciphertext, DecryptionCallback callbac
                     preKeyStore.RemovePreKey(unsignedPreKeyId.ForceGetValue());
                 }
 
-                return plaintext;
+                return Task.FromResult(plaintext);
             }
         }
 
@@ -202,7 +205,9 @@ public byte[] decrypt(PreKeySignalMessage ciphertext, DecryptionCallback callbac
          */
         public byte[] decrypt(SignalMessage ciphertext)
         {
-            return decrypt(ciphertext, new NullDecryptionCallback());
+            var tsk = decrypt(ciphertext, new NullDecryptionCallback());
+            tsk.Wait();
+            return tsk.Result;
         }
 
         /**
@@ -223,7 +228,7 @@ public byte[] decrypt(SignalMessage ciphertext)
          *                                is no longer supported.
          * @throws NoSessionException if there is no established session for this contact.
          */
-        public byte[] decrypt(SignalMessage ciphertext, DecryptionCallback callback)
+        public Task<byte[]> decrypt(SignalMessage ciphertext, DecryptionCallback callback)
         {
             lock (SESSION_LOCK)
             {
@@ -241,11 +246,11 @@ public byte[] decrypt(SignalMessage ciphertext, DecryptionCallback callback)
                     throw new UntrustedIdentityException(remoteAddress.Name, sessionRecord.getSessionState().getRemoteIdentityKey());
                 }
 
-                callback.handlePlaintext(plaintext);
+                callback.handlePlaintext(plaintext, sessionRecord).Wait();//no async in a lock
 
                 sessionStore.StoreSession(remoteAddress, sessionRecord);
 
-                return plaintext;
+                return Task.FromResult(plaintext);
             }
         }
 
@@ -425,7 +430,7 @@ private byte[] getPlaintext(MessageKeys messageKeys, byte[] cipherText)
         private class NullDecryptionCallback : DecryptionCallback
         {
 
-            public void handlePlaintext(byte[] plaintext) { }
+            public Task handlePlaintext(byte[] plaintext, SessionRecord sessionRecord) => Task.CompletedTask;
         }
     }
 }

libsignal-protocol-dotnet/groups/GroupCipher.cs

@@ -18,8 +18,10 @@
 using libsignal.groups.ratchet;
 using libsignal.groups.state;
 using libsignal.protocol;
+using libsignal.state;
 using libsignal.util;
 using System;
+using System.Threading.Tasks;
 
 namespace libsignal.groups
 {
@@ -134,7 +136,7 @@ public byte[] decrypt(byte[] senderKeyMessageBytes, DecryptionCallback callback)
 
                     byte[] plaintext = getPlainText(senderKey.getIv(), senderKey.getCipherKey(), senderKeyMessage.getCipherText());
 
-                    callback.handlePlaintext(plaintext);
+                    callback.handlePlaintext(plaintext, null).Wait();
 
                     senderKeyStore.storeSenderKey(senderKeyId, record);
 
@@ -217,8 +219,9 @@ private byte[] getCipherText(byte[] iv, byte[] key, byte[] plaintext)
 
         private  class NullDecryptionCallback : DecryptionCallback
         {
-            public void handlePlaintext(byte[] plaintext) { }
-        }
+			public Task handlePlaintext(byte[] plaintext, SessionRecord sessionRecord) => Task.CompletedTask;
+
+		}
 
     }
 }