Select random IO channel when sending request.

src/dns_private.h

@@ -41,6 +41,7 @@ static const unsigned initial_n = 128;
 static const unsigned initial_bias = 72;
 
 static const int dns_port = 53;
+static const int default_io_cnt = 8;
 
 #define UDP_PACKET_SIZE 4096
 
@@ -56,14 +57,10 @@ static const int dns_port = 53;
  */
 struct rdns_server {
  char *name; /**< name of DNS server */
-
  unsigned int port;
-
- struct rdns_io_channel *io_channels;
- struct rdns_io_channel *cur_io_channel;
-
  unsigned int io_cnt;
 
+ struct rdns_io_channel **io_channels;
  upstream_entry_t up;
 };
 
@@ -112,7 +109,6 @@ struct rdns_io_channel {
  int sock; /**< persistent socket */
  void *async_io; /** async opaque ptr */
  struct rdns_request *requests; /**< requests in flight */
- struct rdns_io_channel *prev, *next;
  bool want_reinit;
  UT_hash_handle hh;
  ref_entry_t ref;

src/resolver.c

@@ -431,7 +431,6 @@ rdns_make_request_full (
 
  req->retransmits = repeats;
  req->timeout = timeout;
- req->io = NULL;
  req->state = RDNS_REQUEST_NEW;
  req->async = resolver->async;
 
@@ -443,15 +442,8 @@ rdns_make_request_full (
  return NULL;
  }
 
- /* Now select IO channel */
-
- req->io = serv->cur_io_channel;
- if (req->io == NULL) {
- DNS_DEBUG ("cannot find suitable io channel for the server %s", serv->name);
- REF_RELEASE (req);
- return NULL;
- }
- serv->cur_io_channel = serv->cur_io_channel->next;
+ /* Select random IO channel */
+ req->io = serv->io_channels[ottery_rand_uint32 () % serv->io_cnt];
 
  /* Now send request to server */
  r = rdns_send_request (req, req->io->sock, true);
@@ -478,8 +470,13 @@ rdns_resolver_init (struct rdns_resolver *resolver)
  return false;
  }
 
+ if (resolver->servers == NULL) {
+ return false;
+ }
+
  /* Now init io channels to all servers */
  UPSTREAM_FOREACH (resolver->servers, serv) {
+ serv->io_channels = calloc (serv->io_cnt, sizeof (struct rdns_io_channel *));
  for (i = 0; i < serv->io_cnt; i ++) {
  ioc = calloc (1, sizeof (struct rdns_io_channel));
  ioc->sock = rdns_make_client_socket (serv->name, serv->port, SOCK_DGRAM);
@@ -491,10 +488,9 @@ rdns_resolver_init (struct rdns_resolver *resolver)
  ioc->resolver = resolver;
  ioc->async_io = resolver->async->add_read (resolver->async->data,
  ioc->sock, ioc);
- serv->cur_io_channel = ioc;
- CDL_PREPEND (serv->io_channels, ioc);
  HASH_ADD_INT (resolver->io_channels, sock, ioc);
  REF_INIT_RETAIN (ioc, rdns_ioc_free);
+ serv->io_channels[i] = ioc;
  }
  }
  }
@@ -567,7 +563,8 @@ static void
 rdns_resolver_free (struct rdns_resolver *resolver)
 {
  struct rdns_server *serv, *stmp;
- struct rdns_io_channel *ioc, *itmp1, *itmp2;
+ struct rdns_io_channel *ioc;
+ int i;
 
  if (resolver->initialized) {
  if (resolver->periodic != NULL) {
@@ -578,11 +575,13 @@ rdns_resolver_free (struct rdns_resolver *resolver)
  }
  /* Stop IO watch on all IO channels */
  UPSTREAM_FOREACH_SAFE (resolver->servers, serv, stmp) {
- CDL_FOREACH_SAFE (serv->io_channels, ioc, itmp1, itmp2) {
+ for (i = 0; i < serv->io_cnt; i ++) {
+ ioc = serv->io_channels[i];
  HASH_DELETE (hh, resolver->io_channels, ioc);
  REF_RELEASE (ioc);
  }
  UPSTREAM_DEL (resolver->servers, serv);
+ free (serv->io_channels);
  free (serv->name);
  free (serv);
  }

src/util.c

@@ -422,10 +422,10 @@ rdns_resolver_parse_resolv_conf (struct rdns_resolver *resolver, const char *pat
 
  while (!feof (in)) {
  if (fgets (buf, sizeof (buf), in) == NULL) {
- fclose (in);
- return false;
+ break;
  }
  if (!rdns_resolver_conf_process_line (resolver, buf)) {
+ DNS_DEBUG ("rdns_resolver_parse_resolv_conf: cannot parse line: %s", buf);
  fclose (in);
  return false;
  }