- Carlo Contavalli added support for the glibc "rotate" option, as documented

  in man resolv.conf:

  causes round robin selection of nameservers from among those listed.  This
  has the effect of spreading the query load among all listed servers, rather
  than having all clients try the first listed server first every time.

  You can enable it with ARES_OPT_ROTATE

1 files changed, 10 insertions, 1 deletions

diff --git a/ares/ares_init.c b/ares/ares_init.c
index 4d4ba1ea5..4a147fc42 100644
--- a/ares/ares_init.c
+++ b/ares/ares_init.c
@@ -144,6 +144,7 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
   channel->timeout = -1;
   channel->tries = -1;
   channel->ndots = -1;
+  channel->rotate = -1;
   channel->udp_port = -1;
   channel->tcp_port = -1;
   channel->socket_send_buffer_size = -1;
@@ -159,6 +160,7 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
   channel->sock_state_cb = NULL;
   channel->sock_state_cb_data = NULL;
 
+  channel->last_server = 0;
   channel->last_timeout_processed = (time_t)now.tv_sec;
 
   /* Initialize our lists of queries */
@@ -352,6 +354,8 @@ static int init_by_options(ares_channel channel,
     channel->tries = options->tries;
   if ((optmask & ARES_OPT_NDOTS) && channel->ndots == -1)
     channel->ndots = options->ndots;
+  if ((optmask & ARES_OPT_ROTATE) && channel->rotate == -1)
+    channel->rotate = options->rotate;
   if ((optmask & ARES_OPT_UDP_PORT) && channel->udp_port == -1)
     channel->udp_port = options->udp_port;
   if ((optmask & ARES_OPT_TCP_PORT) && channel->tcp_port == -1)
@@ -932,6 +936,8 @@ static int init_by_defaults(ares_channel channel)
     channel->tries = DEFAULT_TRIES;
   if (channel->ndots == -1)
     channel->ndots = 1;
+  if (channel->rotate == -1)
+    channel->rotate = 0;
   if (channel->udp_port == -1)
     channel->udp_port = htons(NAMESERVER_PORT);
   if (channel->tcp_port == -1)
@@ -1302,6 +1308,9 @@ static int set_options(ares_channel channel, const char *str)
       val = try_option(p, q, "retry:");
       if (val && channel->tries == -1)
         channel->tries = atoi(val);
+      val = try_option(p, q, "rotate");
+      if (val && channel->rotate == -1)
+        channel->rotate = 1;
       p = q;
       while (ISSPACE(*p))
         p++;
@@ -1374,7 +1383,7 @@ static char *try_config(char *s, const char *opt)
 static const char *try_option(const char *p, const char *q, const char *opt)
 {
   size_t len = strlen(opt);
-  return ((size_t)(q - p) > len && !strncmp(p, opt, len)) ? &p[len] : NULL;
+  return ((size_t)(q - p) >= len && !strncmp(p, opt, len)) ? &p[len] : NULL;
 }
 
 #ifndef WIN32