diff --git a/src/sync_mixin.cc b/src/sync_mixin.cc
index 602c90b..e9ab9e0 100644
--- a/src/sync_mixin.cc
+++ b/src/sync_mixin.cc
@@ -10,7 +10,7 @@ namespace pEp {
         SyncMixIn::SyncMixIn()
         {
             PEP_STATUS status = register_sync_callbacks(session, (void *) this,
-                    _messageToSend, _showHandshake);
+                    _messageToSend, _showHandshake, NULL, NULL);
             assert(status == PEP_STATUS_OK);
         }
 
@@ -62,6 +62,29 @@ namespace pEp {
         }
 #endif
 
+
+        int SyncMixIn::inject_sync_msg(void *msg, void *management)
+        {
+            SyncMixIn *that = (SyncMixIn *) management;
+            val = 0;
+            that->_msg = msg;
+            setjmp(that->env);
+            if (!that->val)
+                do_sync_protocol(session, management);
+            return 0;
+        }
+
+        void *SyncMixIn::retrieve_next_sync_msg(void *management)
+        {
+            static int twice = 1;
+            twice = !twice;
+            SyncMixIn *that = (SyncMixIn *) management;
+            if (!twice)
+                return (void *) that->_msg;
+            longjmp(that->env, 1);
+            return (void *) 23;
+        }
+
         void SyncMixIn_callback::_messageToSend(Message msg)
         {
             call_method< void >(_self, "messageToSend", msg);
diff --git a/src/sync_mixin.hh b/src/sync_mixin.hh
index 8dff9f4..6ad0add 100644
--- a/src/sync_mixin.hh
+++ b/src/sync_mixin.hh
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "pEpmodule.hh"
+#include <setjmp.h> 
 
 namespace pEp {
     namespace PythonAdapter {
@@ -26,6 +27,12 @@ namespace pEp {
                 static PEP_STATUS _messageToSend(void *obj, message *msg);
                 static PEP_STATUS _showHandshake(void *obj,
                         pEp_identity *me, pEp_identity *partner);
+
+                static jmp_buf env;
+                static int val;
+                static void *_msg;
+                static int inject_sync_msg(void *msg, void *management);
+                static void *retrieve_next_sync_msg(void *management);
         };
 
         class SyncMixIn_callback : public SyncMixIn {