1 files changed, 88 insertions, 0 deletions
diff --git a/src/c-ares/ares_timeout.c b/src/c-ares/ares_timeout.c
new file mode 100644
index 000000000..293e4af02
--- /dev/null
+++ b/src/c-ares/ares_timeout.c
@@ -0,0 +1,88 @@
+
+/* Copyright 1998 by the Massachusetts Institute of Technology.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
+
+#include "ares.h"
+#include "ares_private.h"
+
+/* return time offset between now and (future) check, in milliseconds */
+static long timeoffset(struct timeval *now, struct timeval *check)
+{
+  return (check->tv_sec - now->tv_sec)*1000 +
+         (check->tv_usec - now->tv_usec)/1000;
+}
+
+/* WARNING: Beware that this is linear in the number of outstanding
+ * requests! You are probably far better off just calling ares_process()
+ * once per second, rather than calling ares_timeout() to figure out
+ * when to next call ares_process().
+ */
+struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,
+                             struct timeval *tvbuf)
+{
+  struct query *query;
+  struct list_node* list_head;
+  struct list_node* list_node;
+  struct timeval now;
+  struct timeval nextstop;
+  long offset, min_offset;
+
+  /* No queries, no timeout (and no fetch of the current time). */
+  if (ares__is_list_empty(&(channel->all_queries)))
+    return maxtv;
+
+  /* Find the minimum timeout for the current set of queries. */
+  now = ares__tvnow();
+  min_offset = -1;
+
+  list_head = &(channel->all_queries);
+  for (list_node = list_head->next; list_node != list_head;
+       list_node = list_node->next)
+    {
+      query = list_node->data;
+      if (query->timeout.tv_sec == 0)
+        continue;
+      offset = timeoffset(&now, &query->timeout);
+      if (offset < 0)
+        offset = 0;
+      if (min_offset == -1 || offset < min_offset)
+        min_offset = offset;
+    }
+
+  /* If we found a minimum timeout and it's sooner than the one specified in
+   * maxtv (if any), return it.  Otherwise go with maxtv.
+   */
+  if (min_offset != -1)
+    {
+      int ioffset = (min_offset > (long)INT_MAX) ? INT_MAX : (int)min_offset;
+
+      nextstop.tv_sec = ioffset/1000;
+      nextstop.tv_usec = (ioffset%1000)*1000;
+
+      if (!maxtv || ares__timedout(maxtv, &nextstop))
+        {
+          *tvbuf = nextstop;
+          return tvbuf;
+        }
+    }
+
+  return maxtv;
+}