Commit f7e6e852 authored by Mike Perry's avatar Mike Perry Committed by Nick Mathewson
Browse files

Fix 1108: Handle corrupt or large build times state. 

1108 was actually just a fencepost error in an assert,
but making the state file handling code resilient is a
good idea.
parent 2e70642c

ChangeLog

+5 −0
Original line number Diff line number Diff line 
Changes in version 0.2.2.4-alpha - 2009-??-??

  o Major bugfixes:

    - Fix another assert in the circuit_build_times code that causes Tor

	  to fail to start once we have accumulated 5000 build times in the

	  state file. Bugfix on 0.2.2.2-alpha; fixes bug 1108.



  o Minor features:

    - Log SSL state transitions at debug level during handshake, and

      include SSL states in error messages.  This may help debug

src/or/circuitbuild.c

+45 −20
Original line number Diff line number Diff line
@@ -372,17 +372,28 @@ circuit_build_times_update_state(circuit_build_times_t *cbt, 
 * Stolen from http://en.wikipedia.org/wiki/Fisher\u2013Yates_shuffle

 */

static void

circuit_build_times_shuffle_array(circuit_build_times_t *cbt)

circuit_build_times_shuffle_and_store_array(circuit_build_times_t *cbt,

                                            build_time_t *raw_times,

                                            int num_times)

{

   int n = cbt->total_build_times;

  int n = num_times;

  if (num_times > NCIRCUITS_TO_OBSERVE) {

    log_notice(LD_CIRC, "Decreasing circuit_build_times size from %d to %d",

               num_times, NCIRCUITS_TO_OBSERVE);

  }



  /* This code can only be run on a compact array */

   tor_assert(cbt->total_build_times == cbt->build_times_idx);

  while (n-- > 1) {

    int k = crypto_rand_int(n + 1); /* 0 <= k <= n. */

     build_time_t tmp = cbt->circuit_build_times[k];

     cbt->circuit_build_times[k] = cbt->circuit_build_times[n];

     cbt->circuit_build_times[n] = tmp;

    build_time_t tmp = raw_times[k];

    raw_times[k] = raw_times[n];

    raw_times[n] = tmp;

  }



  /* Since the times are now shuffled, take a random NCIRCUITS_TO_OBSERVE

   * subset (ie the first NCIRCUITS_TO_OBSERVE values) */

  for (n = 0; n < MIN(num_times, NCIRCUITS_TO_OBSERVE); n++) {

    circuit_build_times_add_time(cbt, raw_times[n]);

  }

}
@@ -397,14 +408,14 @@ int 
circuit_build_times_parse_state(circuit_build_times_t *cbt,

                                or_state_t *state, char **msg)

{

  int tot_values = 0, N = 0;

  int tot_values = 0;

  uint32_t loaded_cnt = 0, N = 0;

  config_line_t *line;

  int i;

  *msg = NULL;

  build_time_t *loaded_times = tor_malloc(sizeof(build_time_t)

                                          * state->TotalBuildTimes);

  circuit_build_times_init(cbt);



  /* We don't support decreasing the table size yet */

  tor_assert(state->TotalBuildTimes <= NCIRCUITS_TO_OBSERVE);

  *msg = NULL;



  for (line = state->BuildtimeHistogram; line; line = line->next) {

    smartlist_t *args = smartlist_create();
@@ -441,17 +452,30 @@ circuit_build_times_parse_state(circuit_build_times_t *cbt, 
        break;

      }



      if (loaded_cnt+count > state->TotalBuildTimes) {

        log_warn(LD_CIRC,

                 "Too many build times in state file. "

                 "Stopping short before %d",

                 loaded_cnt+count);

        break;

      }



      for (k = 0; k < count; k++) {

        circuit_build_times_add_time(cbt, ms);

        loaded_times[loaded_cnt++] = ms;

      }

      N++;

      SMARTLIST_FOREACH(args, char*, cp, tor_free(cp));

      smartlist_free(args);

    }

  }



  if (loaded_cnt != state->TotalBuildTimes) {

    log_warn(LD_CIRC,

            "Corrupt state file? Build times count mismatch. "

            "Read %d, file says %d", loaded_cnt, state->TotalBuildTimes);

  }



  circuit_build_times_shuffle_array(cbt);

  circuit_build_times_shuffle_and_store_array(cbt, loaded_times, loaded_cnt);



  /* Verify that we didn't overwrite any indexes */

  for (i=0; i < NCIRCUITS_TO_OBSERVE; i++) {
@@ -462,9 +486,10 @@ circuit_build_times_parse_state(circuit_build_times_t *cbt, 
  log_info(LD_CIRC,

           "Loaded %d/%d values from %d lines in circuit time histogram",

           tot_values, cbt->total_build_times, N);

  tor_assert(cbt->total_build_times == state->TotalBuildTimes);

  tor_assert(tot_values == cbt->total_build_times);

  tor_assert(cbt->total_build_times == tot_values);

  tor_assert(cbt->total_build_times <= NCIRCUITS_TO_OBSERVE);

  circuit_build_times_set_timeout(cbt);

  tor_free(loaded_times);

  return *msg ? -1 : 0;

}