16 files changed, 72 insertions, 23 deletions

diff --git a/src/cadet/gnunet-service-cadet_tunnels.c b/src/cadet/gnunet-service-cadet_tunnels.c
index 22e19ef70..fb91a4a6a 100644
--- a/src/cadet/gnunet-service-cadet_tunnels.c
+++ b/src/cadet/gnunet-service-cadet_tunnels.c
@@ -2856,7 +2856,9 @@ handle_plaintext_channel_destroy (void *cls,
  *
  * @param cls the `struct CadetTunnel` that got the message
  * @param msg the message
- * @return #GNUNET_OK (continue to process)
+ * @return #GNUNET_OK on success (always)
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 handle_decrypted (void *cls,
diff --git a/src/conversation/gnunet-helper-audio-playback-gst.c b/src/conversation/gnunet-helper-audio-playback-gst.c
index 264b14e76..002fed6c7 100644
--- a/src/conversation/gnunet-helper-audio-playback-gst.c
+++ b/src/conversation/gnunet-helper-audio-playback-gst.c
@@ -221,6 +221,11 @@ feed_buffer_to_gst (const char *audio, size_t b_len)
 
 /**
  * Message callback
+ *
+ * @param msg message we received.
+ * @return #GNUNET_OK on success,
+ *     #GNUNET_NO to stop further processing due to disconnect (no error)
+ *     #GNUNET_SYSERR to stop further processing due to error
  */
 static int
 stdin_receiver (void *cls,
diff --git a/src/conversation/gnunet-helper-audio-playback.c b/src/conversation/gnunet-helper-audio-playback.c
index 4344e1d41..18f63ad18 100644
--- a/src/conversation/gnunet-helper-audio-playback.c
+++ b/src/conversation/gnunet-helper-audio-playback.c
@@ -546,6 +546,11 @@ ogg_demux_and_decode ()
 
 /**
  * Message callback
+ *
+ * @param msg message we received.
+ * @return #GNUNET_OK on success,
+ *     #GNUNET_NO to stop further processing due to disconnect (no error)
+ *     #GNUNET_SYSERR to stop further processing due to error
  */
 static int
 stdin_receiver (void *cls,
diff --git a/src/conversation/gnunet_gst.c b/src/conversation/gnunet_gst.c
index 52cb2ccbc..828b35077 100644
--- a/src/conversation/gnunet_gst.c
+++ b/src/conversation/gnunet_gst.c
@@ -649,6 +649,11 @@ gnunet_read (GNUNET_gstData * d)
 
 /**
  * Message callback
+ *
+ * @param msg message we received.
+ * @return #GNUNET_OK on success,
+ *     #GNUNET_NO to stop further processing due to disconnect (no error)
+ *     #GNUNET_SYSERR to stop further processing due to error
  */
 static int
 stdin_receiver (void *cls,
diff --git a/src/conversation/microphone.c b/src/conversation/microphone.c
index 7871433a3..11468fc59 100644
--- a/src/conversation/microphone.c
+++ b/src/conversation/microphone.c
@@ -65,7 +65,9 @@ struct Microphone
  *
  * @param cls clsoure with our `struct Microphone`
  * @param msg the message from the helper
- * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 process_record_messages (void *cls,
diff --git a/src/core/gnunet-service-core.c b/src/core/gnunet-service-core.c
index 625bf9655..214f72904 100644
--- a/src/core/gnunet-service-core.c
+++ b/src/core/gnunet-service-core.c
@@ -426,6 +426,9 @@ struct TokenizerContext
  *
  * @param cls reservation request (`struct TokenizerContext`)
  * @param message the actual message
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 tokenized_cb (void *cls,
diff --git a/src/core/gnunet-service-core_kx.c b/src/core/gnunet-service-core_kx.c
index 8a7cada5c..ae0ae508f 100644
--- a/src/core/gnunet-service-core_kx.c
+++ b/src/core/gnunet-service-core_kx.c
@@ -708,6 +708,9 @@ setup_fresh_ping (struct GSC_KeyExchangeInfo *kx)
  *
  * @param cls the `struct GSC_KeyExchangeInfo`
  * @param m the message
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 deliver_message (void *cls,
diff --git a/src/fs/fs_dirmetascan.c b/src/fs/fs_dirmetascan.c
index 7b9f178fd..8a3e37b49 100644
--- a/src/fs/fs_dirmetascan.c
+++ b/src/fs/fs_dirmetascan.c
@@ -246,6 +246,9 @@ finish_scan (void *cls)
  *
  * @param cls the closure (directory scanner object)
  * @param msg message from the helper process
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 process_helper_msgs (void *cls,
diff --git a/src/include/gnunet_mst_lib.h b/src/include/gnunet_mst_lib.h
index 7a1ca7a55..fe6524eb3 100644
--- a/src/include/gnunet_mst_lib.h
+++ b/src/include/gnunet_mst_lib.h
@@ -61,7 +61,9 @@ struct GNUNET_MessageStreamTokenizer;
  *
  * @param cls closure
  * @param message the actual message
- * @return #GNUNET_OK on success, #GNUNET_SYSERR to stop further processing
+ * @return #GNUNET_OK on success,
+ *     #GNUNET_NO to stop further processing due to disconnect (no error)
+ *     #GNUNET_SYSERR to stop further processing due to error
  */
 typedef int
 (*GNUNET_MessageTokenizerCallback) (void *cls,
diff --git a/src/statistics/gnunet-service-statistics.c b/src/statistics/gnunet-service-statistics.c
index 0cb136b99..87e966a01 100644
--- a/src/statistics/gnunet-service-statistics.c
+++ b/src/statistics/gnunet-service-statistics.c
@@ -998,7 +998,9 @@ client_disconnect_cb (void *cls,
  *
  * @param cls NULL
  * @param message the message found on disk
- * @return #GNUNET_OK on success, #GNUNET_SYSERR to stop further processing
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 inject_message (void *cls,
diff --git a/src/testbed/gnunet-helper-testbed.c b/src/testbed/gnunet-helper-testbed.c
index 392f257dd..9601e7567 100644
--- a/src/testbed/gnunet-helper-testbed.c
+++ b/src/testbed/gnunet-helper-testbed.c
@@ -292,8 +292,9 @@ child_death_task (void *cls)
  *
  * @param cls identification of the client
  * @param message the actual message
- *
- * @return #GNUNET_OK on success, #GNUNET_SYSERR to stop further processing
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 tokenizer_cb (void *cls,
@@ -359,7 +360,7 @@ tokenizer_cb (void *cls,
   cfg = GNUNET_CONFIGURATION_create ();
   if (GNUNET_OK !=
       GNUNET_CONFIGURATION_deserialize (cfg,
-                                        config, 
+                                        config,
                                         ul_config_size,
                                         NULL))
   {
diff --git a/src/transport/gnunet-helper-transport-wlan-dummy.c b/src/transport/gnunet-helper-transport-wlan-dummy.c
index 63ed9c4b7..f02d8bdd7 100644
--- a/src/transport/gnunet-helper-transport-wlan-dummy.c
+++ b/src/transport/gnunet-helper-transport-wlan-dummy.c
@@ -121,6 +121,9 @@ send_mac_to_plugin (char *buffer, struct GNUNET_TRANSPORT_WLAN_MacAddress *mac)
  *
  * @param cls the 'struct SendBuffer' to copy the converted message to
  * @param hdr inbound message from the FIFO
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 stdin_send (void *cls,
@@ -167,6 +170,9 @@ stdin_send (void *cls,
  *
  * @param cls the 'struct SendBuffer' to copy to
  * @param hdr the message we received to copy to the buffer
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 file_in_send (void *cls,
diff --git a/src/transport/plugin_transport_http_server.c b/src/transport/plugin_transport_http_server.c
index d9fade44f..6a9c1b0ba 100644
--- a/src/transport/plugin_transport_http_server.c
+++ b/src/transport/plugin_transport_http_server.c
@@ -1651,7 +1651,7 @@ server_send_callback (void *cls,
  *
  * @param cls current session as closure
  * @param message the message to be forwarded to transport service
- * @return #GNUNET_OK
+ * @return #GNUNET_OK (all OK)
  */
 static int
 server_receive_mst_cb (void *cls,
diff --git a/src/util/client.c b/src/util/client.c
index 90bc837d7..138b1cfdd 100644
--- a/src/util/client.c
+++ b/src/util/client.c
@@ -306,7 +306,9 @@ transmit_ready (void *cls)
  *
  * @param cls the `struct ClientState`
  * @param msg message we received.
- * @return #GNUNET_OK on success, #GNUNET_SYSERR to stop further processing
+ * @return #GNUNET_OK on success,
+ *     #GNUNET_NO to stop further processing due to disconnect (no error)
+ *     #GNUNET_SYSERR to stop further processing due to error
  */
 static int
 recv_message (void *cls,
@@ -315,7 +317,7 @@ recv_message (void *cls,
   struct ClientState *cstate = cls;
 
   if (GNUNET_YES == cstate->in_destroy)
-    return GNUNET_SYSERR;
+    return GNUNET_NO;
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        "Received message of type %u and size %u from %s\n",
        ntohs (msg->type),
@@ -324,7 +326,7 @@ recv_message (void *cls,
   GNUNET_MQ_inject_message (cstate->mq,
                             msg);
   if (GNUNET_YES == cstate->in_destroy)
-    return GNUNET_SYSERR;
+    return GNUNET_NO;
   return GNUNET_OK;
 }
 
diff --git a/src/util/mst.c b/src/util/mst.c
index 4c2a74212..5e472965f 100644
--- a/src/util/mst.c
+++ b/src/util/mst.c
@@ -126,6 +126,7 @@ GNUNET_MST_from_buffer (struct GNUNET_MessageStreamTokenizer *mst,
   int need_align;
   unsigned long offset;
   int ret;
+  int cbret;
 
   GNUNET_assert (mst->off <= mst->pos);
   GNUNET_assert (mst->pos <= mst->curr_buf);
@@ -229,13 +230,15 @@ do_align:
     if (one_shot == GNUNET_YES)
       one_shot = GNUNET_SYSERR;
     mst->off += want;
-    if (GNUNET_SYSERR == mst->cb (mst->cb_cls,
-                                  hdr))
+    if (GNUNET_OK !=
+        (cbret = mst->cb (mst->cb_cls,
+                           hdr)))
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  "Failure processing message of type %u and size %u\n",
-                  ntohs (hdr->type),
-                  ntohs (hdr->size));
+      if (GNUNET_SYSERR == cbret)
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Failure processing message of type %u and size %u\n",
+                    ntohs (hdr->type),
+                    ntohs (hdr->size));
       return GNUNET_SYSERR;
     }
     if (mst->off == mst->pos)
@@ -277,13 +280,15 @@ do_align:
       }
       if (one_shot == GNUNET_YES)
         one_shot = GNUNET_SYSERR;
-      if (GNUNET_SYSERR == mst->cb (mst->cb_cls,
-                                    hdr))
+      if (GNUNET_OK !=
+          (cbret = mst->cb (mst->cb_cls,
+                            hdr)))
       {
-        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                    "Failure processing message of type %u and size %u\n",
-                    ntohs (hdr->type),
-                    ntohs (hdr->size));
+        if (GNUNET_SYSERR == cbret)
+          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                      "Failure processing message of type %u and size %u\n",
+                      ntohs (hdr->type),
+                      ntohs (hdr->size));
         return GNUNET_SYSERR;
       }
       buf += want;
diff --git a/src/vpn/gnunet-service-vpn.c b/src/vpn/gnunet-service-vpn.c
index d9daaa7e2..bdc638176 100644
--- a/src/vpn/gnunet-service-vpn.c
+++ b/src/vpn/gnunet-service-vpn.c
@@ -2218,6 +2218,9 @@ route_packet (struct DestinationEntry *destination,
  *
  * @param cls closure, NULL
  * @param message message we got from the client (VPN channel interface)
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
  */
 static int
 message_token (void *cls,