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Fix 1108: Handle corrupt or large build times state.

Browse Source 
1108 was actually just a fencepost error in an assert,
but making the state file handling code resilient is a
good idea.
This commit is contained in:
Mike Perry 2009-09-29 03:41:23 -07:00 committed by Nick Mathewson
parent 2e70642c3a
commit f7e6e852e8
2 changed files with 50 additions and 20 deletions
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5
ChangeLog
View File

@ -1,4 +1,9 @@
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

65
src/or/circuitbuild.c
View File

@ -372,18 +372,29 @@ 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;
}
/* This code can only be run on a compact array */
while (n-- > 1) {
int k = crypto_rand_int(n + 1); /* 0 <= k <= n. */
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);
}
}
circuit_build_times_shuffle_array(cbt);
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_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;
}