Implemented asynchronous DNS lookups in nmbd.

I realised this afternoon just how easy it is to add this, so I
thought I'd implement it while the idea was fresh.

nmbd forks at startup and uses a pipe to talk to its child. The child
does the DNS lookups and the file descriptor of the child is added to
the main select loop.

While I was doing this I discovered a bug in nmbd that explains why
the dns proxy option has been so expensive. The DNS cache entries in
the WINS list were never being checked, which means we always did a
DNS lookup even if we have done it before and it is in cache. I'm sure
this used to work (I tested the DNS cache when I added it) so someone
broke it :-(

Anyway, the async DNS gets rid of the problem completely. I'll commit
just the fix to the DNS cache bug to the 1.9.17 tree.

You can disable async DNS by adding -DSYNC_DNS to the compile flags.
(This used to be commit 178e27de0791c1ff3268cb456ed5c5efc9ac2a01)

1 files changed, 6 insertions, 3 deletions

diff --git a/source3/libsmb/nmblib.c b/source3/libsmb/nmblib.c
index e8f281bc25..121008685b 100644
--- a/source3/libsmb/nmblib.c
+++ b/source3/libsmb/nmblib.c
@@ -482,9 +482,11 @@ void free_nmb_packet(struct nmb_packet *nmb)
   ******************************************************************/
 void free_packet(struct packet_struct *packet)
 {  
-  if (packet->packet_type == NMB_PACKET)
-    free_nmb_packet(&packet->packet.nmb);
-  free(packet);
+	if (packet->locked) 
+		return;
+	if (packet->packet_type == NMB_PACKET)
+		free_nmb_packet(&packet->packet.nmb);
+	free(packet);
 }
 
 /*******************************************************************
@@ -511,6 +513,7 @@ struct packet_struct *read_packet(int fd,enum packet_type packet_type)
   packet->ip = lastip;
   packet->port = lastport;
   packet->fd = fd;
+  packet->locked = False;
   packet->timestamp = time(NULL);
   packet->packet_type = packet_type;
   switch (packet_type)