Performance issues with deadwood

[Sam Trenholme]

> $:> time $(for h in $(cat hosts.txt); do printf "\n\n\n"; dig $h; done > test.log)
>
> The result is rather disappointing, the mean value over several runs
> is around
>
>  8 min for deadwood and
>  1 min for unbound.

OK, I’ve found and fixed a bug in Deadwood which accounted for about
two thirds of the slowdown compared to unbound.

I just did the same test you did, and this the timings I saw:

* 7 minutes 29 seconds without the bug patched (about the same you
saw, with a fairly large cache in place)

* 2 minutes 57 seconds with the bug patched (from a “cold start”: No cache)

Now, the reason I’m getting slower numbers than you may be caused by
me having a slower internet connection than you.  Or, it may be caused
because there are other bugs slowing down resolution which I still
need to stamp out.

Anyway, deadwood-H-20100906-2.tar.bz2 at
http://maradns.org/deadwood/snap/ has the bug patched.  In addition, I
will add the patch after my rather long sig.

Thank you for the bug report and let me know how much of a speedup you see.

- Sam

Note: I do not answer MaraDNS (including Deadwood) support requests
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security bug you think you found can reasonably be exploited.

--- deadwood-H-20100906-1/src/DwUdpSocket.c.orig        2010-09-06
20:01:26.000000000 -0700
+++ deadwood-H-20100906-1/src/DwUdpSocket.c     2010-09-06
20:03:49.000000000 -0700
@@ -179,8 +179,9 @@
      dw_str *query, SOCKET x_socket_num) {
         sockaddr_all_T server;
         SOCKET s = 0;
-        int32_t rnum = -1;
+        int_fast32_t rnum = -1;
         ip_addr_T addr = {0,{0,0},0,0};
+       int counter = 0;
         socklen_t inet_len = sizeof(struct sockaddr_in);

         if(rem[n].socket != x_socket_num || /* Already used (sanity check) */
@@ -195,7 +196,12 @@
         }

         /* Get IP of remote server and open a socket to them */
-        addr = get_upstream_ip(query,n);
+       for(counter = 0; counter < 7; counter++) { /* Don't stop on bad IP */
+               addr = get_upstream_ip(query,n);
+               if(addr.len > 0) {
+                       break;
+               }
+       }
         dw_log_ip("Making connection to IP",&addr,128);
         if(addr.len == 0) { /* Failed to get upstream IP */
                 return;