properly handle key transport messages. use prekeyparsing only when that attribute is set

3 files changed, 38 insertions, 36 deletions

diff --git a/src/main/java/de/pixart/messenger/crypto/axolotl/AxolotlService.java b/src/main/java/de/pixart/messenger/crypto/axolotl/AxolotlService.java
index b77bb24fb..eb15fbabc 100644
--- a/src/main/java/de/pixart/messenger/crypto/axolotl/AxolotlService.java
+++ b/src/main/java/de/pixart/messenger/crypto/axolotl/AxolotlService.java
@@ -1311,16 +1311,15 @@ public class AxolotlService implements OnAdvancedStreamFeaturesLoaded {
         return session;
     }
 
-    public XmppAxolotlMessage.XmppAxolotlPlaintextMessage processReceivingPayloadMessage(XmppAxolotlMessage message) {
+    public XmppAxolotlMessage.XmppAxolotlPlaintextMessage processReceivingPayloadMessage(XmppAxolotlMessage message, boolean postponePreKeyMessageHandling) {
         XmppAxolotlMessage.XmppAxolotlPlaintextMessage plaintextMessage = null;
 
         XmppAxolotlSession session = getReceivingSession(message);
         try {
             plaintextMessage = message.decrypt(session, getOwnDeviceId());
-            Integer preKeyId = session.getPreKeyId();
+            Integer preKeyId = session.getPreKeyIdAndReset();
             if (preKeyId != null) {
-                publishBundlesIfNeeded(false, false);
-                session.resetPreKeyId();
+                postPreKeyMessageHandling(session, preKeyId, postponePreKeyMessageHandling);
             }
         } catch (CryptoFailedException e) {
             Log.w(Config.LOGTAG, getLogprefix(account) + "Failed to decrypt message from "+message.getFrom()+": " + e.getMessage());
@@ -1333,12 +1332,22 @@ public class AxolotlService implements OnAdvancedStreamFeaturesLoaded {
         return plaintextMessage;
     }
 
-    public XmppAxolotlMessage.XmppAxolotlKeyTransportMessage processReceivingKeyTransportMessage(XmppAxolotlMessage message) {
+    private void postPreKeyMessageHandling(final XmppAxolotlSession session, int preKeyId, final boolean postpone) {
+        Log.d(Config.LOGTAG, account.getJid().toBareJid() + ": postPreKeyMessageHandling() preKeyId=" + preKeyId + ", postpone=" + Boolean.toString(postpone));
+        //TODO: do not republish if we already removed this preKeyId
+        publishBundlesIfNeeded(false, false);
+    }
+
+    public XmppAxolotlMessage.XmppAxolotlKeyTransportMessage processReceivingKeyTransportMessage(XmppAxolotlMessage message, final boolean postponePreKeyMessageHandling) {
         XmppAxolotlMessage.XmppAxolotlKeyTransportMessage keyTransportMessage;
 
         XmppAxolotlSession session = getReceivingSession(message);
         try {
             keyTransportMessage = message.getParameters(session, getOwnDeviceId());
+            Integer preKeyId = session.getPreKeyIdAndReset();
+            if (preKeyId != null) {
+                postPreKeyMessageHandling(session, preKeyId, postponePreKeyMessageHandling);
+            }
         } catch (CryptoFailedException e) {
             Log.d(Config.LOGTAG,"could not decrypt keyTransport message "+e.getMessage());
             keyTransportMessage = null;
diff --git a/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlMessage.java b/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlMessage.java
index a55e741bb..ac16ccc47 100644
--- a/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlMessage.java
+++ b/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlMessage.java
@@ -2,15 +2,14 @@ package de.pixart.messenger.crypto.axolotl;
 
 import android.util.Base64;
 import android.util.Log;
+import android.util.SparseArray;
 
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.security.NoSuchProviderException;
 import java.security.SecureRandom;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 
 import javax.crypto.BadPaddingException;
 import javax.crypto.Cipher;
@@ -42,7 +41,7 @@ public class XmppAxolotlMessage {
     private byte[] ciphertext = null;
     private byte[] authtagPlusInnerKey = null;
     private byte[] iv = null;
-    private final Map<Integer, XmppAxolotlSession.AxolotlKey> keys;
+    private final SparseArray<XmppAxolotlSession.AxolotlKey> keys;
     private final Jid from;
     private final int sourceDeviceId;
 
@@ -98,7 +97,7 @@ public class XmppAxolotlMessage {
             throw new IllegalArgumentException("invalid source id");
         }
         List<Element> keyElements = header.getChildren();
-        this.keys = new HashMap<>(keyElements.size());
+        this.keys = new SparseArray<>();
         for (Element keyElement : keyElements) {
             switch (keyElement.getName()) {
                 case KEYTAG:
@@ -131,7 +130,7 @@ public class XmppAxolotlMessage {
     public XmppAxolotlMessage(Jid from, int sourceDeviceId) {
         this.from = from;
         this.sourceDeviceId = sourceDeviceId;
-        this.keys = new HashMap<>();
+        this.keys = new SparseArray<>();
         this.iv = generateIv();
         this.innerKey = generateKey();
     }
@@ -158,6 +157,10 @@ public class XmppAxolotlMessage {
         return iv;
     }
 
+    public boolean hasPayload() {
+        return ciphertext != null;
+    }
+
     public void encrypt(String plaintext) throws CryptoFailedException {
         try {
             SecretKey secretKey = new SecretKeySpec(innerKey, KEYTYPE);
@@ -204,10 +207,6 @@ public class XmppAxolotlMessage {
         return sourceDeviceId;
     }
 
-    public byte[] getCiphertext() {
-        return ciphertext;
-    }
-
     public void addDevice(XmppAxolotlSession session) {
         XmppAxolotlSession.AxolotlKey key;
         if (authtagPlusInnerKey != null) {
@@ -232,13 +231,13 @@ public class XmppAxolotlMessage {
         Element encryptionElement = new Element(CONTAINERTAG, AxolotlService.PEP_PREFIX);
         Element headerElement = encryptionElement.addChild(HEADER);
         headerElement.setAttribute(SOURCEID, sourceDeviceId);
-        for (Map.Entry<Integer, XmppAxolotlSession.AxolotlKey> keyEntry : keys.entrySet()) {
+        for(int i = 0; i < keys.size(); ++i) {
             Element keyElement = new Element(KEYTAG);
-            keyElement.setAttribute(REMOTEID, keyEntry.getKey());
-            if (keyEntry.getValue().prekey) {
+            keyElement.setAttribute(REMOTEID, keys.keyAt(i));
+            if (keys.valueAt(i).prekey) {
                 keyElement.setAttribute("prekey", "true");
             }
-            keyElement.setContent(Base64.encodeToString(keyEntry.getValue().key, Base64.NO_WRAP));
+            keyElement.setContent(Base64.encodeToString(keys.valueAt(i).key, Base64.NO_WRAP));
             headerElement.addChild(keyElement);
         }
         headerElement.addChild(IVTAG).setContent(Base64.encodeToString(iv, Base64.NO_WRAP));
diff --git a/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlSession.java b/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlSession.java
index 4327c6116..771ff9f19 100644
--- a/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlSession.java
+++ b/src/main/java/de/pixart/messenger/crypto/axolotl/XmppAxolotlSession.java
@@ -43,15 +43,12 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
         this.account = account;
     }
 
-    public Integer getPreKeyId() {
+    public Integer getPreKeyIdAndReset() {
+        final Integer preKeyId = this.preKeyId;
+        this.preKeyId = null;
         return preKeyId;
     }
 
-    public void resetPreKeyId() {
-
-        preKeyId = null;
-    }
-
     public String getFingerprint() {
         return identityKey == null ? null : CryptoHelper.bytesToHex(identityKey.getPublicKey().serialize());
     }
@@ -87,11 +84,10 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
         FingerprintStatus status = getTrust();
         if (!status.isCompromised()) {
             try {
-                CiphertextMessage ciphertextMessage;
-                try {
-                    ciphertextMessage = new PreKeySignalMessage(encryptedKey.key);
-                    Optional<Integer> optionalPreKeyId = ((PreKeySignalMessage) ciphertextMessage).getPreKeyId();
-                    IdentityKey identityKey = ((PreKeySignalMessage) ciphertextMessage).getIdentityKey();
+                if (encryptedKey.prekey) {
+                    PreKeySignalMessage preKeySignalMessage = new PreKeySignalMessage(encryptedKey.key);
+                    Optional<Integer> optionalPreKeyId = preKeySignalMessage.getPreKeyId();
+                    IdentityKey identityKey = preKeySignalMessage.getIdentityKey();
                     if (!optionalPreKeyId.isPresent()) {
                         throw new CryptoFailedException("PreKeyWhisperMessage did not contain a PreKeyId");
                     }
@@ -100,15 +96,13 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
                         throw new CryptoFailedException("Received PreKeyWhisperMessage but preexisting identity key changed.");
                     }
                     this.identityKey = identityKey;
-                } catch (InvalidVersionException | InvalidMessageException e) {
-                    ciphertextMessage = new SignalMessage(encryptedKey.key);
-                }
-                if (ciphertextMessage instanceof PreKeySignalMessage) {
-                    plaintext = cipher.decrypt((PreKeySignalMessage) ciphertextMessage);
+                    plaintext = cipher.decrypt(preKeySignalMessage);
                 } else {
-                    plaintext = cipher.decrypt((SignalMessage) ciphertextMessage);
+                    SignalMessage signalMessage = new SignalMessage(encryptedKey.key);
+                    plaintext = cipher.decrypt(signalMessage);
+                    preKeyId = null; //better safe than sorry because we use that to do special after prekey handling
                 }
-            } catch (InvalidKeyException | LegacyMessageException | InvalidMessageException | DuplicateMessageException | NoSessionException | InvalidKeyIdException | UntrustedIdentityException e) {
+            } catch (InvalidVersionException | InvalidKeyException | LegacyMessageException | InvalidMessageException | DuplicateMessageException | NoSessionException | InvalidKeyIdException | UntrustedIdentityException e) {
                 if (!(e instanceof DuplicateMessageException)) {
                     e.printStackTrace();
                 }