diff options
| author | Florian Obser <florian@cvs.openbsd.org> | 2019-11-14 08:32:31 +0000 |
|---|---|---|
| committer | Florian Obser <florian@cvs.openbsd.org> | 2019-11-14 08:32:31 +0000 |
| commit | 41dff51c79fd37dda973dd31745e0ad6cbb65357 (patch) | |
| tree | c6b269922b29d7303631db8af184fd2ca1171613 /sbin | |
| parent | e875c869adefdeaed5e57f53bc0781fe530c4225 (diff) | |
Checking a resolver that we are already checking can lead to a
self-DoS under high query rate and constant failures.
Diffstat (limited to 'sbin')
| -rw-r--r-- | sbin/unwind/resolver.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/sbin/unwind/resolver.c b/sbin/unwind/resolver.c index cc2939c44d6..c525e72e55a 100644 --- a/sbin/unwind/resolver.c +++ b/sbin/unwind/resolver.c @@ -1,4 +1,4 @@ -/* $OpenBSD: resolver.c,v 1.63 2019/11/14 08:30:10 florian Exp $ */ +/* $OpenBSD: resolver.c,v 1.64 2019/11/14 08:32:30 florian Exp $ */ /* * Copyright (c) 2018 Florian Obser <florian@openbsd.org> @@ -88,6 +88,7 @@ struct uw_resolver { enum uw_resolver_state state; enum uw_resolver_type type; int oppdot; + int check_running; char *why_bogus; int64_t histogram[nitems(histogram_limits)]; }; @@ -1258,6 +1259,12 @@ check_resolver(struct uw_resolver *resolver_to_check) { struct uw_resolver *res; + if (resolver_to_check->check_running) { + log_debug("%s: already checking: %s", __func__, + uw_resolver_type_str[resolver_to_check->type]); + return; + } + log_debug("%s: create_resolver", __func__); if ((res = create_resolver(resolver_to_check->type, 0)) == NULL) fatal("%s", __func__); @@ -1276,7 +1283,8 @@ check_resolver(struct uw_resolver *resolver_to_check) resolver_to_check->check_tv.tv_sec, uw_resolver_type_str[resolver_to_check->type], uw_resolver_state_str[resolver_to_check->state]); - } + } else + resolver_to_check->check_running++; if (!(resolver_to_check->type == UW_RES_DHCP || resolver_to_check->type == UW_RES_FORWARDER)) @@ -1302,7 +1310,8 @@ check_resolver(struct uw_resolver *resolver_to_check) resolver_to_check->check_tv.tv_sec, uw_resolver_type_str[resolver_to_check->type], uw_resolver_state_str[resolver_to_check->state]); - } + } else + resolver_to_check->check_running++; } void @@ -1314,6 +1323,8 @@ check_resolver_done(struct uw_resolver *res, void *arg, int rcode, enum uw_resolver_state prev_state; char *str; + checked_resolver->check_running--; + log_debug("%s: %s rcode: %d", __func__, uw_resolver_type_str[checked_resolver->type], rcode); |