chan: Remove dead var cell handler from channel_t

The variable lenght cells are handled directly by
channel_tls_handle_var_cell() from an OR connection reading its inbuf. The
channel var cell handler (agnostic) was never used.

Closes #32892

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/ticket32892

@@ -0,0 +1,3 @@
+  o Code simplification and refactoring (channel):
+    - Channel layer had a variable length cell handler that was not used and
+      thus removed. Closes ticket 32892.

src/core/or/channel.c

@@ -1066,23 +1066,6 @@ channel_get_cell_handler(channel_t *chan)
   return NULL;
 }
 
-/**
- * Return the variable-length cell handler for a channel.
- *
- * This function gets the handler for incoming variable-length cells
- * installed on a channel.
- */
-channel_var_cell_handler_fn_ptr
-channel_get_var_cell_handler(channel_t *chan)
-{
-  tor_assert(chan);
-
-  if (CHANNEL_CAN_HANDLE_CELLS(chan))
-    return chan->var_cell_handler;
-
-  return NULL;
-}
-
 /**
  * Set both cell handlers for a channel.
  *
@@ -1091,9 +1074,7 @@ channel_get_var_cell_handler(channel_t *chan)
  */
 void
 channel_set_cell_handlers(channel_t *chan,
-                          channel_cell_handler_fn_ptr cell_handler,
+                          channel_cell_handler_fn_ptr cell_handler)
-                          channel_var_cell_handler_fn_ptr
-                            var_cell_handler)
 {
   tor_assert(chan);
   tor_assert(CHANNEL_CAN_HANDLE_CELLS(chan));
@@ -1101,13 +1082,9 @@ channel_set_cell_handlers(channel_t *chan,
   log_debug(LD_CHANNEL,
            "Setting cell_handler callback for channel %p to %p",
            chan, cell_handler);
-  log_debug(LD_CHANNEL,
-           "Setting var_cell_handler callback for channel %p to %p",
-           chan, var_cell_handler);
 
   /* Change them */
   chan->cell_handler = cell_handler;
-  chan->var_cell_handler = var_cell_handler;
 }
 
 /*

src/core/or/channel.h

@@ -22,7 +22,6 @@ struct tor_timer_t;
 /* Channel handler function pointer typedefs */
 typedef void (*channel_listener_fn_ptr)(channel_listener_t *, channel_t *);
 typedef void (*channel_cell_handler_fn_ptr)(channel_t *, cell_t *);
-typedef void (*channel_var_cell_handler_fn_ptr)(channel_t *, var_cell_t *);
 
 /**
  * This enum is used by channelpadding to decide when to pad channels.
@@ -320,7 +319,6 @@ struct channel_t {
 
   /** Registered handlers for incoming cells */
   channel_cell_handler_fn_ptr cell_handler;
-  channel_var_cell_handler_fn_ptr var_cell_handler;
 
   /* Methods implemented by the lower layer */
 
@@ -542,13 +540,8 @@ void channel_listener_set_listener_fn(channel_listener_t *chan,
 /* Incoming cell callbacks */
 channel_cell_handler_fn_ptr channel_get_cell_handler(channel_t *chan);
 
-channel_var_cell_handler_fn_ptr
-channel_get_var_cell_handler(channel_t *chan);
-
 void channel_set_cell_handlers(channel_t *chan,
-                               channel_cell_handler_fn_ptr cell_handler,
+                               channel_cell_handler_fn_ptr cell_handler);
-                               channel_var_cell_handler_fn_ptr
-                                 var_cell_handler);
 
 /* Clean up closed channels and channel listeners periodically; these are
  * called from run_scheduled_events() in main.c.

src/core/or/command.c

@@ -217,23 +217,6 @@ command_process_cell(channel_t *chan, cell_t *cell)
   }
 }
 
-/** Process an incoming var_cell from a channel; in the current protocol all
- * the var_cells are handshake-related and handled below the channel layer,
- * so this just logs a warning and drops the cell.
- */
-
-void
-command_process_var_cell(channel_t *chan, var_cell_t *var_cell)
-{
-  tor_assert(chan);
-  tor_assert(var_cell);
-
-  log_info(LD_PROTOCOL,
-           "Received unexpected var_cell above the channel layer of type %d"
-           "; dropping it.",
-           var_cell->command);
-}
-
 /** Process a 'create' <b>cell</b> that just arrived from <b>chan</b>. Make a
  * new circuit with the p_circ_id specified in cell. Put the circuit in state
  * onionskin_pending, and pass the onionskin to the cpuworker. Circ will get
@@ -685,8 +668,7 @@ command_setup_channel(channel_t *chan)
   tor_assert(chan);
 
   channel_set_cell_handlers(chan,
-                            command_process_cell,
+                            command_process_cell);
-                            command_process_var_cell);
 }
 
 /** Given a listener, install the right handler to process incoming

src/core/or/command.h

@@ -15,7 +15,6 @@
 #include "core/or/channel.h"
 
 void command_process_cell(channel_t *chan, cell_t *cell);
-void command_process_var_cell(channel_t *chan, var_cell_t *cell);
 void command_setup_channel(channel_t *chan);
 void command_setup_listener(channel_listener_t *chan_l);
 

src/test/test_channel.c

@@ -34,8 +34,6 @@
 static int test_chan_accept_cells = 0;
 static int test_chan_fixed_cells_recved = 0;
 static cell_t * test_chan_last_seen_fixed_cell_ptr = NULL;
-static int test_chan_var_cells_recved = 0;
-static var_cell_t * test_chan_last_seen_var_cell_ptr = NULL;
 static int test_cells_written = 0;
 static int test_doesnt_want_writes_count = 0;
 static int test_dumpstats_calls = 0;
@@ -113,24 +111,6 @@ chan_test_dumpstats(channel_t *ch, int severity)
   return;
 }
 
-/*
- * Handle an incoming variable-size cell for unit tests
- */
-
-static void
-chan_test_var_cell_handler(channel_t *ch,
-                           var_cell_t *var_cell)
-{
-  tt_assert(ch);
-  tt_assert(var_cell);
-
-  test_chan_last_seen_var_cell_ptr = var_cell;
-  ++test_chan_var_cells_recved;
-
- done:
-  return;
-}
-
 static void
 chan_test_close(channel_t *ch)
 {
@@ -492,11 +472,8 @@ test_channel_dumpstats(void *arg)
 
   /* Receive path */
   channel_set_cell_handlers(ch,
-                            chan_test_cell_handler,
+                            chan_test_cell_handler);
-                            chan_test_var_cell_handler);
   tt_ptr_op(channel_get_cell_handler(ch), OP_EQ, chan_test_cell_handler);
-  tt_ptr_op(channel_get_var_cell_handler(ch), OP_EQ,
-            chan_test_var_cell_handler);
   cell = tor_malloc_zero(sizeof(*cell));
   old_count = test_chan_fixed_cells_recved;
   channel_process_cell(ch, cell);
@@ -722,7 +699,7 @@ test_channel_inbound_cell(void *arg)
 
   /* Setup incoming cell handlers. We don't care about var cell, the channel
    * layers is not handling those. */
-  channel_set_cell_handlers(chan, chan_test_cell_handler, NULL);
+  channel_set_cell_handlers(chan, chan_test_cell_handler);
   tt_ptr_op(chan->cell_handler, OP_EQ, chan_test_cell_handler);
   /* Now process the cell, we should see it. */
   old_count = test_chan_fixed_cells_recved;