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Commit f203d85c authored by Bernie Innocenti's avatar Bernie Innocenti
Browse files

Move bug workaround for old resolvers past the Private DNS codepath 

There's an anecdotal bug where a buggy resolver might drop queries which are sent too close together. We have never observed this bug directly, but we assume that it might exist in very old resolvers. Private DNS resolvers implementing DoH and DoT are modern codebases and thus shouldn't need this workaround.

Change-Id: Id0242063791fd295fa584b7b46e8938a62c71f42
parent 509e3705

res_send.cpp

+6 −5
Original line number Diff line number Diff line
@@ -508,11 +508,6 @@ int res_nsend(ResState* statp, const uint8_t* buf, int buflen, uint8_t* ans, int 
        return -ESRCH;

    }



    // If parallel_lookup is enabled, it might be required to wait some time to avoid

    // gateways drop packets if queries are sent too close together

    if (sleepTimeMs != 0ms) {

        std::this_thread::sleep_for(sleepTimeMs);

    }

    // Private DNS

    if (!(statp->netcontext_flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS) &&

        !isMdnsResolution(statp->flags)) {
@@ -533,6 +528,12 @@ int res_nsend(ResState* statp, const uint8_t* buf, int buflen, uint8_t* ans, int 
        }

    }



    // If parallel_lookup is enabled, it might be required to wait some time to avoid

    // gateways from dropping packets if queries are sent too close together.

    if (sleepTimeMs != 0ms) {

        std::this_thread::sleep_for(sleepTimeMs);

    }



    res_stats stats[MAXNS]{};

    res_params params;

    int revision_id = resolv_cache_get_resolver_stats(statp->netid, &params, stats, statp->nsaddrs);