Don't check create cells too much when we're relaying them

We want to sanity-check our own create cells carefully, and other
people's loosely.

src/or/circuitbuild.c

@@ -55,7 +55,8 @@ static channel_t * channel_connect_for_circuit(const tor_addr_t *addr,
                                                uint16_t port,
                                                const char *id_digest);
 static int circuit_deliver_create_cell(circuit_t *circ,
-                                       const create_cell_t *create_cell);
+                                       const create_cell_t *create_cell,
+                                       int relayed);
 static int onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit);
 static crypt_path_t *onion_next_hop_in_cpath(crypt_path_t *cpath);
 static int onion_extend_cpath(origin_circuit_t *circ);
@@ -474,7 +475,7 @@ circuit_n_chan_done(channel_t *chan, int status)
       } else {
         /* pull the create cell out of circ->n_chan_create_cell, and send it */
         tor_assert(circ->n_chan_create_cell);
-        if (circuit_deliver_create_cell(circ, circ->n_chan_create_cell)<0) {
+        if (circuit_deliver_create_cell(circ, circ->n_chan_create_cell, 1)<0) {
           circuit_mark_for_close(circ, END_CIRC_REASON_RESOURCELIMIT);
           continue;
         }
@@ -491,14 +492,16 @@ circuit_n_chan_done(channel_t *chan, int status)
  * for the outgoing
  * circuit <b>circ</b>, and deliver a cell of type <b>cell_type</b>
  * (either CELL_CREATE or CELL_CREATE_FAST) with payload <b>payload</b>
- * to this circuit. DOCDOC payload_len
+ * to this circuit. DOCDOC new arguments
  * Return -1 if we failed to find a suitable circid, else return 0.
  */
 static int
-circuit_deliver_create_cell(circuit_t *circ, const create_cell_t *create_cell)
+circuit_deliver_create_cell(circuit_t *circ, const create_cell_t *create_cell,
+                            int relayed)
 {
   cell_t cell;
   circid_t id;
+  int r;
 
   tor_assert(circ);
   tor_assert(circ->n_chan);
@@ -516,7 +519,9 @@ circuit_deliver_create_cell(circuit_t *circ, const create_cell_t *create_cell)
   circuit_set_n_circid_chan(circ, id, circ->n_chan);
 
   memset(&cell, 0, sizeof(cell_t));
-  if (create_cell_format(&cell, create_cell) < 0) {
+  r = relayed ? create_cell_format_relayed(&cell, create_cell)
+              : create_cell_format(&cell, create_cell);
+  if (r < 0) {
     log_warn(LD_CIRC,"Couldn't format create cell");
     return -1;
   }
@@ -657,7 +662,7 @@ circuit_send_next_onion_skin(origin_circuit_t *circ)
     }
     cc.handshake_len = len;
 
-    if (circuit_deliver_create_cell(TO_CIRCUIT(circ), &cc) < 0)
+    if (circuit_deliver_create_cell(TO_CIRCUIT(circ), &cc, 0) < 0)
       return - END_CIRC_REASON_RESOURCELIMIT;
 
     circ->cpath->state = CPATH_STATE_AWAITING_KEYS;
@@ -901,8 +906,6 @@ circuit_extend(cell_t *cell, circuit_t *circ)
                                   &ec.orport_ipv4.addr,
                                   ec.orport_ipv4.port);
 
-    /* XXXX Make sure we can eventually deliver create cell with weird
-     * content */
     circ->n_chan_create_cell = tor_memdup(&ec.create_cell,
                                           sizeof(ec.create_cell));
 
@@ -933,7 +936,7 @@ circuit_extend(cell_t *cell, circuit_t *circ)
             "n_chan is %s",
             channel_get_canonical_remote_descr(n_chan));
 
-  if (circuit_deliver_create_cell(circ, &ec.create_cell) < 0)
+  if (circuit_deliver_create_cell(circ, &ec.create_cell, 1) < 0)
     return -1;
   return 0;
 }

src/or/onion.c

@@ -808,13 +808,14 @@ extended_cell_parse(extended_cell_t *cell_out,
 
 /** Fill <b>cell_out</b> with a correctly formatted version of the
  * CREATE{,_FAST,2} cell in <b>cell_in</b>. Return 0 on success, -1 on
- * failure. */
-int
-create_cell_format(cell_t *cell_out, const create_cell_t *cell_in)
+ * failure.  This is a cell we didn't originate if <b>relayed</b> is true. */
+static int
+create_cell_format_impl(cell_t *cell_out, const create_cell_t *cell_in,
+                        int relayed)
 {
   uint8_t *p;
   size_t space;
-  if (check_create_cell(cell_in, 0) < 0)
+  if (check_create_cell(cell_in, relayed) < 0)
     return -1;
 
   memset(cell_out->payload, 0, sizeof(cell_out->payload));
@@ -848,6 +849,18 @@ create_cell_format(cell_t *cell_out, const create_cell_t *cell_in)
   return 0;
 }
 
+int
+create_cell_format(cell_t *cell_out, const create_cell_t *cell_in)
+{
+  return create_cell_format_impl(cell_out, cell_in, 0);
+}
+
+int
+create_cell_format_relayed(cell_t *cell_out, const create_cell_t *cell_in)
+{
+  return create_cell_format_impl(cell_out, cell_in, 1);
+}
+
 /** Fill <b>cell_out</b> with a correctly formatted version of the
  * CREATED{,_FAST,2} cell in <b>cell_in</b>. Return 0 on success, -1 on
  * failure. */

src/or/onion.h

@@ -106,6 +106,7 @@ int extended_cell_parse(extended_cell_t *cell_out, uint8_t command,
                         const uint8_t *payload_in, size_t payload_len);
 
 int create_cell_format(cell_t *cell_out, const create_cell_t *cell_in);
+int create_cell_format_relayed(cell_t *cell_out, const create_cell_t *cell_in);
 int created_cell_format(cell_t *cell_out, const created_cell_t *cell_in);
 int extend_cell_format(uint8_t *command_out, uint16_t *len_out,
                        uint8_t *payload_out, const extend_cell_t *cell_in);

src/test/test_cell_formats.c

@@ -651,7 +651,7 @@ test_cfmt_extend_cells(void *arg)
   tt_int_op(p2_cmd, ==, RELAY_COMMAND_EXTEND);
   tt_int_op(p2_len, ==, 26+TAP_ONIONSKIN_CHALLENGE_LEN);
   test_memeq(p2, p, RELAY_PAYLOAD_SIZE);
-  tt_int_op(0, ==, create_cell_format(&cell, cc));
+  tt_int_op(0, ==, create_cell_format_relayed(&cell, cc));
 
   /* Now let's do a minimal ntor EXTEND2 cell. */
   memset(&ec, 0xff, sizeof(ec));
@@ -721,6 +721,7 @@ test_cfmt_extend_cells(void *arg)
                  /* Now the handshake prologue */
                  "01050063");
   test_memeq(p2+1+8+22+4, b, 99+20);
+  tt_int_op(0, ==, create_cell_format_relayed(&cell, cc));
 
   /* == Now try parsing some junk */