commit 165a92e33f3dc6123c1cd3326c6b183ac1c1d778 Author: Nick Mathewson nickm@torproject.org Date: Tue Jan 14 13:16:39 2020 -0500
Replace an assertion with a check-and-log
We hit this assertion with bug 32868, but I'm stymied figuring out how we wound up with a routerstatus like this. This patch is a diagnostic to attempt to figure out what is going on, and to avoid a crash in the meantime. --- changes/log_32868 | 4 +++ src/feature/nodelist/node_select.c | 54 +++++++++++++++++++++++++++++++++++--- 2 files changed, 54 insertions(+), 4 deletions(-)
diff --git a/changes/log_32868 b/changes/log_32868 new file mode 100644 index 000000000..34476078b --- /dev/null +++ b/changes/log_32868 @@ -0,0 +1,4 @@ + o Minor features (debugging, directory system): + - Don't crash when we find a non-guard with a guard-fraction value set. + Instead, log a bug warning, in an attempt to figure out how this + happened. Diagnostic for ticket 32868. diff --git a/src/feature/nodelist/node_select.c b/src/feature/nodelist/node_select.c index e31abb247..7b9e241e5 100644 --- a/src/feature/nodelist/node_select.c +++ b/src/feature/nodelist/node_select.c @@ -540,6 +540,51 @@ bridge_get_advertised_bandwidth_bounded(routerinfo_t *router) return result; }
+/** + * We have found an instance of bug 32868: log our best guess about where the + * routerstatus was found. + **/ +static void +log_buggy_rs_source(const routerstatus_t *rs) +{ + static ratelim_t buggy_rs_ratelim = RATELIM_INIT(1200); + char *m; + if ((m = rate_limit_log(&buggy_rs_ratelim, approx_time()))) { + log_warn(LD_BUG, + "Found a routerstatus %p with has_guardfraction=%u " + " and guardfraction_percentage=%u, but is_possible_guard=%u.%s", + rs, + rs->has_guardfraction, + rs->guardfraction_percentage, + rs->is_possible_guard, + m); + tor_free(m); + networkstatus_t *ns; + int in_ns_count = 0; + if ((ns = networkstatus_get_latest_consensus_by_flavor(FLAV_NS))) { + int pos = smartlist_pos(ns->routerstatus_list, rs); + if (pos >= 0) { + ++in_ns_count; + log_warn(LD_BUG, "Found the routerstatus at position %d of the " + "NS consensus.", pos); + } + } + if ((ns = networkstatus_get_latest_consensus_by_flavor(FLAV_MICRODESC))) { + int pos = smartlist_pos(ns->routerstatus_list, rs); + if (pos >= 0) { + ++in_ns_count; + log_warn(LD_BUG, "Found the routerstatus at position %d of the " + "MD consensus.", pos); + } + } + if (in_ns_count == 0) { + log_warn(LD_BUG, "Could not find the routerstatus in any " + "latest consensus."); + } + tor_assert_nonfatal_unreached(); + } +} + /** Given a list of routers and a weighting rule as in * smartlist_choose_node_by_bandwidth_weights, compute weighted bandwidth * values for each node and store them in a freshly allocated @@ -715,10 +760,11 @@ compute_weighted_bandwidths(const smartlist_t *sl, * choose N proportionally to F*Wpf*B + (1-F)*Wpn*B. */ if (node->rs && node->rs->has_guardfraction && rule != WEIGHT_FOR_GUARD) { - /* XXX The assert should actually check for is_guard. However, - * that crashes dirauths because of #13297. This should be - * equivalent: */ - tor_assert(node->rs->is_possible_guard); + /* We should only have guardfraction set if the node has the Guard + flag. */ + if (! node->rs->is_possible_guard) { + log_buggy_rs_source(node->rs); + }
guard_get_guardfraction_bandwidth(&guardfraction_bw, this_bw,