[Dnsmasq-discuss] [PATCH] Fix dns query retransmission when --strict-order active

Hans Dedecker dedeckeh at gmail.com
Mon Dec 4 09:15:27 GMT 2017


Commit 9396752c115b3ab733fa476b30da73237e12e7ba added support for dns query
retransmission in case a server returns refused in strict-order mode.
The patch did not cover the case when all servers return refused triggering
a dns query retransmission storm resulting into a high cpu load by dnsmasq.
Fix the problem by checking in strict-order mode if a next dns server is
available in the dns server list before forwarding the query again.

Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
---
 src/forward.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/forward.c b/src/forward.c
index 4824759..3d58571 100644
--- a/src/forward.c
+++ b/src/forward.c
@@ -799,11 +799,23 @@ void reply_query(int fd, int family, time_t now)
     {
       unsigned char *pheader;
       size_t plen;
-      int is_sign;
-      
+      int is_sign, fwd_query = 0;
+
+      if (option_bool(OPT_ORDER))
+        {
+	  /* try to find a good server to which the query can be forwarded */
+	  for (server = forward->sentto->next; server; server = server->next)
+	    if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_HAS_DOMAIN | SERV_FOR_NODOTS | SERV_NO_ADDR | SERV_LOOP)))
+	      {
+                fwd_query = 1;
+                break;
+	      }
+        } else
+          fwd_query = 1;
+
       /* recreate query from reply */
       pheader = find_pseudoheader(header, (size_t)n, &plen, NULL, &is_sign, NULL);
-      if (!is_sign)
+      if (!is_sign && fwd_query)
 	{
 	  header->ancount = htons(0);
 	  header->nscount = htons(0);
-- 
1.9.1




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