commit f93f7e331be94114d82c17108e741eb2482e6bda Author: Andrea Shepard andrea@torproject.org Date: Mon Mar 18 11:15:21 2013 -0700

Ignore advertised bandwidths if we have enough measured bandwidths available --- changes/bug8435 | 4 ++ src/or/config.c | 1 + src/or/dirserv.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++---- src/or/or.h | 4 ++ 4 files changed, 99 insertions(+), 7 deletions(-)

diff --git a/changes/bug8435 b/changes/bug8435 new file mode 100644 index 0000000..da7ca7c --- /dev/null +++ b/changes/bug8435 @@ -0,0 +1,4 @@ + o Major bugfixes: + - When dirserv.c computes flags and thresholds, ignore advertised + bandwidths if we have more than a threshold number of routers with + measured bandwidths. diff --git a/src/or/config.c b/src/or/config.c index f888426..f3e4083 100644 --- a/src/or/config.c +++ b/src/or/config.c @@ -299,6 +299,7 @@ static config_var_t option_vars_[] = { V(MaxClientCircuitsPending, UINT, "32"), OBSOLETE("MaxOnionsPending"), V(MaxOnionQueueDelay, MSEC_INTERVAL, "1750 msec"), + V(MinMeasuredBWsForAuthToIgnoreAdvertised, INT, "500"), OBSOLETE("MonthlyAccountingStart"), V(MyFamily, STRING, NULL), V(NewCircuitPeriod, INTERVAL, "30 seconds"), diff --git a/src/or/dirserv.c b/src/or/dirserv.c index 37934a0..c769bed 100644 --- a/src/or/dirserv.c +++ b/src/or/dirserv.c @@ -66,6 +66,9 @@ static cached_dir_t *the_directory = NULL; /** For authoritative directories: the current (v1) network status. */ static cached_dir_t the_runningrouters;

+/** Total number of routers with measured bandwidth */ +static int routers_with_measured_bw = 0; + static void directory_remove_invalid(void); static cached_dir_t *dirserv_regenerate_directory(void); static char *format_versions_list(config_line_t *ln); @@ -86,6 +89,7 @@ static const signed_descriptor_t *get_signed_descriptor_by_fp( static was_router_added_t dirserv_add_extrainfo(extrainfo_t *ei, const char **msg); static uint32_t dirserv_get_bandwidth_for_router(const routerinfo_t *ri); +static uint32_t dirserv_get_credible_bandwidth(const routerinfo_t *ri);

/************** Fingerprint handling code ************/

@@ -1877,12 +1881,18 @@ dirserv_thinks_router_is_hs_dir(const routerinfo_t *router, * include a router in our calculations, and return true iff we should. */ static int router_counts_toward_thresholds(const node_t *node, time_t now, - const digestmap_t *omit_as_sybil) + const digestmap_t *omit_as_sybil, + int require_mbw) { + /* Have measured bw? */ + int have_mbw = + dirserv_query_measured_bw_cache(node->ri->cache_info.identity_digest, + NULL, NULL); + return node->ri && router_is_active(node->ri, node, now) && !digestmap_get(omit_as_sybil, node->ri->cache_info.identity_digest) && - (dirserv_get_bandwidth_for_router(node->ri) >= - ABSOLUTE_MIN_BW_VALUE_TO_CONSIDER); + (dirserv_get_credible_bandwidth(node->ri) >= + ABSOLUTE_MIN_BW_VALUE_TO_CONSIDER) && (have_mbw || !require_mbw); }

/** Look through the routerlist, the Mean Time Between Failure history, and @@ -1904,6 +1914,11 @@ dirserv_compute_performance_thresholds(routerlist_t *rl, time_t now = time(NULL); const or_options_t *options = get_options();

+ /* Require mbw? */ + int require_mbw = + (routers_with_measured_bw > + options->MinMeasuredBWsForAuthToIgnoreAdvertised) ? 1 : 0; + /* initialize these all here, in case there are no routers */ stable_uptime = 0; stable_mtbf = 0; @@ -1936,7 +1951,8 @@ dirserv_compute_performance_thresholds(routerlist_t *rl,

/* Now, fill in the arrays. */ SMARTLIST_FOREACH_BEGIN(nodelist_get_list(), node_t *, node) { - if (router_counts_toward_thresholds(node, now, omit_as_sybil)) { + if (router_counts_toward_thresholds(node, now, omit_as_sybil, + require_mbw)) { routerinfo_t *ri = node->ri; const char *id = ri->cache_info.identity_digest; uint32_t bw; @@ -1945,7 +1961,7 @@ dirserv_compute_performance_thresholds(routerlist_t *rl, uptimes[n_active] = (uint32_t)real_uptime(ri, now); mtbfs[n_active] = rep_hist_get_stability(id, now); tks [n_active] = rep_hist_get_weighted_time_known(id, now); - bandwidths[n_active] = bw = dirserv_get_bandwidth_for_router(ri); + bandwidths[n_active] = bw = dirserv_get_credible_bandwidth(ri); total_bandwidth += bw; if (node->is_exit && !node->is_bad_exit) { total_exit_bandwidth += bw; @@ -2001,7 +2017,8 @@ dirserv_compute_performance_thresholds(routerlist_t *rl, n_familiar = 0;

SMARTLIST_FOREACH_BEGIN(nodelist_get_list(), node_t *, node) { - if (router_counts_toward_thresholds(node, now, omit_as_sybil)) { + if (router_counts_toward_thresholds(node, now, + omit_as_sybil, require_mbw)) { routerinfo_t *ri = node->ri; const char *id = ri->cache_info.identity_digest; long tk = rep_hist_get_weighted_time_known(id, now); @@ -2182,6 +2199,59 @@ dirserv_get_bandwidth_for_router(const routerinfo_t *ri) return bw; }

+/** Look through the routerlist, and using the measured bandwidth cache count + * how many measured bandwidths we know. This is used to decide whether we + * ever trust advertised bandwidths for purposes of assigning flags. */ +static void +dirserv_count_measured_bws(routerlist_t *rl) +{ + /* Initialize this first */ + routers_with_measured_bw = 0; + + tor_assert(rl); + tor_assert(rl->routers); + + /* Iterate over the routerlist and count measured bandwidths */ + SMARTLIST_FOREACH_BEGIN(rl->routers, routerinfo_t *, ri) { + /* Check if we know a measured bandwidth for this one */ + if (dirserv_query_measured_bw_cache(ri->cache_info.identity_digest, + NULL, NULL)) { + ++routers_with_measured_bw; + } + } SMARTLIST_FOREACH_END(ri); +} + +/** Return the bandwidth we believe for assigning flags; prefer measured + * over advertised, and if we have above a threshold quantity of measured + * bandwidths, we don't want to ever give flags to unmeasured routers, so + * return 0. */ +static uint32_t +dirserv_get_credible_bandwidth(const routerinfo_t *ri) +{ + int threshold; + uint32_t bw = 0; + long mbw; + + tor_assert(ri); + /* Check if we have a measured bandwidth, and check the threshold if not */ + if (!(dirserv_query_measured_bw_cache(ri->cache_info.identity_digest, + &mbw, NULL))) { + threshold = get_options()->MinMeasuredBWsForAuthToIgnoreAdvertised; + if (routers_with_measured_bw > threshold) { + /* Return zero for unmeasured bandwidth if we are above threshold */ + bw = 0; + } else { + /* Return an advertised bandwidth otherwise */ + bw = router_get_advertised_bandwidth(ri); + } + } else { + /* We have the measured bandwidth in mbw */ + bw = (uint32_t)mbw; + } + + return bw; +} + /** Give a statement of our current performance thresholds for inclusion * in a vote document. */ char * @@ -2604,7 +2674,7 @@ set_routerstatus_from_routerinfo(routerstatus_t *rs, int listbaddirs, int vote_on_hsdirs) { const or_options_t *options = get_options(); - uint32_t routerbw = dirserv_get_bandwidth_for_router(ri); + uint32_t routerbw = dirserv_get_credible_bandwidth(ri);

memset(rs, 0, sizeof(routerstatus_t));

@@ -2927,6 +2997,14 @@ dirserv_generate_networkstatus_vote_obj(crypto_pk_t *private_key, */ if (options->V3BandwidthsFile) { dirserv_read_measured_bandwidths(options->V3BandwidthsFile, NULL); + } else { + /* + * No bandwidths file; clear the measured bandwidth cache in case we had + * one last time around. + */ + if (dirserv_get_measured_bw_cache_size() > 0) { + dirserv_clear_measured_bw_cache(); + } }

/* precompute this part, since we need it to decide what "stable" @@ -2945,6 +3023,10 @@ dirserv_generate_networkstatus_vote_obj(crypto_pk_t *private_key, rep_hist_make_router_pessimal(sybil_id, now); } DIGESTMAP_FOREACH_END;

+ /* Count how many have measured bandwidths so we know how to assign flags; + * this must come before dirserv_compute_performance_thresholds() */ + dirserv_count_measured_bws(rl); + dirserv_compute_performance_thresholds(rl, omit_as_sybil);

routerstatuses = smartlist_new(); @@ -2989,6 +3071,7 @@ dirserv_generate_networkstatus_vote_obj(crypto_pk_t *private_key, smartlist_free(routers); digestmap_free(omit_as_sybil, NULL);

+ /* This pass through applies the measured bw lines to the routerstatuses */ if (options->V3BandwidthsFile) { dirserv_read_measured_bandwidths(options->V3BandwidthsFile, routerstatuses); diff --git a/src/or/or.h b/src/or/or.h index 45eb467..f2605d6 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -3870,6 +3870,10 @@ typedef struct { * consensus vote on the 'params' line. */ char *ConsensusParams;

+ /** Authority only: minimum number of measured bandwidths we must see + * before we only beliee measured bandwidths to assign flags. */ + int MinMeasuredBWsForAuthToIgnoreAdvertised; + /** The length of time that we think an initial consensus should be fresh. * Only altered on testing networks. */ int TestingV3AuthInitialVotingInterval;