From 72619de889a80f2d3b17f8ddbc30c2f60e6068e0 Mon Sep 17 00:00:00 2001
From: Andreas Straub <andy@strb.org>
Date: Fri, 3 Jul 2015 13:34:34 +0200
Subject: [PATCH] Refresh PEP on session establish

We now track preKeys used to establish incoming sessions with us. On
each new established session, we remove the used prekey from PEP. We
have to do this because libaxolotl-java internally clears the used
preKey from its storage, so we will not be able to establish any future
sessions using that key.
---
 .../crypto/axolotl/AxolotlService.java         | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/main/java/eu/siacs/conversations/crypto/axolotl/AxolotlService.java b/src/main/java/eu/siacs/conversations/crypto/axolotl/AxolotlService.java
index d79fa1bf8..420c75b5b 100644
--- a/src/main/java/eu/siacs/conversations/crypto/axolotl/AxolotlService.java
+++ b/src/main/java/eu/siacs/conversations/crypto/axolotl/AxolotlService.java
@@ -444,6 +444,7 @@ public class AxolotlService {
 	public static class XmppAxolotlSession {
 		private SessionCipher cipher;
 		private boolean isTrusted = false;
+		private Integer preKeyId = null;
 		private SQLiteAxolotlStore sqLiteAxolotlStore;
 		private AxolotlAddress remoteAddress;
 
@@ -463,6 +464,14 @@ public class AxolotlService {
 			return this.isTrusted;
 		}
 
+		public Integer getPreKeyId() {
+			return preKeyId;
+		}
+
+		public void resetPreKeyId() {
+			preKeyId = null;
+		}
+
 		public byte[] processReceiving(XmppAxolotlMessage.XmppAxolotlMessageHeader incomingHeader) {
 			byte[] plaintext = null;
 			try {
@@ -470,6 +479,9 @@ public class AxolotlService {
 					PreKeyWhisperMessage message = new PreKeyWhisperMessage(incomingHeader.getContents());
 					Log.d(Config.LOGTAG, "PreKeyWhisperMessage ID:" + message.getSignedPreKeyId() + "/" + message.getPreKeyId());
 					plaintext = cipher.decrypt(message);
+					if (message.getPreKeyId().isPresent()) {
+						preKeyId = message.getPreKeyId().get();
+					}
 				} catch (InvalidMessageException | InvalidVersionException e) {
 					WhisperMessage message = new WhisperMessage(incomingHeader.getContents());
 					plaintext = cipher.decrypt(message);
@@ -946,6 +958,12 @@ public class AxolotlService {
 					Log.d(Config.LOGTAG, "Got payload key from axolotl header. Decrypting message...");
 					plaintextMessage = message.decrypt(session, payloadKey);
 				}
+				Integer preKeyId = session.getPreKeyId();
+				if (preKeyId != null) {
+					publishBundlesIfNeeded();
+					session.resetPreKeyId();
+				}
+				break;
 			}
 		}