diff options
Diffstat (limited to 'ares/ares_process.c')
| -rw-r--r-- | ares/ares_process.c | 50 |
1 files changed, 27 insertions, 23 deletions
diff --git a/ares/ares_process.c b/ares/ares_process.c index 675af489d..b7f375e19 100644 --- a/ares/ares_process.c +++ b/ares/ares_process.c @@ -670,30 +670,33 @@ static void skip_server(ares_channel channel, struct query *query, static void next_server(ares_channel channel, struct query *query, struct timeval *now) { - /* Advance to the next server or try. */ - query->server++; - for (; query->try < channel->tries; query->try++) + /* We need to try each server channel->tries times. We have channel->nservers + * servers to try. In total, we need to do channel->nservers * channel->tries + * attempts. Use query->try to remember how many times we already attempted + * this query. Use modular arithmetic to find the next server to try. */ + while (++(query->try) < (channel->nservers * channel->tries)) { - for (; query->server < channel->nservers; query->server++) + struct server_state *server; + + /* Move on to the next server. */ + query->server = (query->server + 1) % channel->nservers; + server = &channel->servers[query->server]; + + /* We don't want to use this server if (1) we decided this + * connection is broken, and thus about to be closed, (2) + * we've decided to skip this server because of earlier + * errors we encountered, or (3) we already sent this query + * over this exact connection. + */ + if (!server->is_broken && + !query->server_info[query->server].skip_server && + !(query->using_tcp && + (query->server_info[query->server].tcp_connection_generation == + server->tcp_connection_generation))) { - struct server_state *server = &channel->servers[query->server]; - /* We don't want to use this server if (1) we decided this - * connection is broken, and thus about to be closed, (2) - * we've decided to skip this server because of earlier - * errors we encountered, or (3) we already sent this query - * over this exact connection. - */ - if (!server->is_broken && - !query->server_info[query->server].skip_server && - !(query->using_tcp && - (query->server_info[query->server].tcp_connection_generation == - server->tcp_connection_generation))) - { - ares__send_query(channel, query, now); - return; - } + ares__send_query(channel, query, now); + return; } - query->server = 0; /* You might think that with TCP we only need one try. However, * even when using TCP, servers can time-out our connection just @@ -702,6 +705,8 @@ static void next_server(ares_channel channel, struct query *query, * tickle a bug that drops our request. */ } + + /* If we are here, all attempts to perform query failed. */ end_query(channel, query, query->error_status, NULL, 0); } @@ -775,8 +780,7 @@ void ares__send_query(ares_channel channel, struct query *query, } query->timeout = *now; ares__timeadd(&query->timeout, - (query->try == 0) ? channel->timeout - : channel->timeout << query->try / channel->nservers); + channel->timeout << (query->try / channel->nservers)); /* Keep track of queries bucketed by timeout, so we can process * timeout events quickly. */ |