Cancel still-active c-ares queries after 10 seconds to avoid chance of deadlock

1 files changed, 9 insertions, 1 deletions

diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
index 90bc88961d..4ebc2c8161 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
@@ -122,6 +122,8 @@ class AresDnsResolver : public Resolver {
   char* service_config_json_ = nullptr;
   // has shutdown been initiated
   bool shutdown_initiated_ = false;
+  // timeout in milliseconds for active DNS queries
+  int query_timeout_ms_;
 };
 
 AresDnsResolver::AresDnsResolver(const ResolverArgs& args)
@@ -159,6 +161,11 @@ AresDnsResolver::AresDnsResolver(const ResolverArgs& args)
                     grpc_combiner_scheduler(combiner()));
   GRPC_CLOSURE_INIT(&on_resolved_, OnResolvedLocked, this,
                     grpc_combiner_scheduler(combiner()));
+  const grpc_arg* query_timeout_ms_arg =
+      grpc_channel_args_find(channel_args_, GRPC_ARG_DNS_ARES_QUERY_TIMEOUT_MS);
+  query_timeout_ms_ = grpc_channel_arg_get_integer(
+      query_timeout_ms_arg,
+      {GRPC_DNS_ARES_DEFAULT_QUERY_TIMEOUT_MS, 0, INT_MAX});
 }
 
 AresDnsResolver::~AresDnsResolver() {
@@ -410,7 +417,8 @@ void AresDnsResolver::StartResolvingLocked() {
   pending_request_ = grpc_dns_lookup_ares_locked(
       dns_server_, name_to_resolve_, kDefaultPort, interested_parties_,
       &on_resolved_, &lb_addresses_, true /* check_grpclb */,
-      request_service_config_ ? &service_config_json_ : nullptr, combiner());
+      request_service_config_ ? &service_config_json_ : nullptr,
+      query_timeout_ms_, combiner());
   last_resolution_timestamp_ = grpc_core::ExecCtx::Get()->Now();
 }