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.

1 files changed, 4 insertions, 45 deletions

diff --git a/source/namedbname.c b/source/namedbname.c
index 51571d786a8..f126b4651c9 100644
--- a/source/namedbname.c
+++ b/source/namedbname.c
@@ -166,8 +166,8 @@ struct name_record *find_name(struct name_record *n,
       {
         continue;
       }
-      DEBUG(9,("find_name: found name %s(%02x)\n", 
-                name->name, name->name_type));
+      DEBUG(9,("find_name: found name %s(%02x) source=%d\n", 
+                name->name, name->name_type, ret->source));
       return ret;
     }
   }
@@ -185,8 +185,8 @@ struct name_record *find_name(struct name_record *n,
   FIND_WINS - look for names in the WINS record
   **************************************************************************/
 struct name_record *find_name_search(struct subnet_record **d,
-			struct nmb_name *name,
-			int search, struct in_addr ip)
+				     struct nmb_name *name,
+				     int search, struct in_addr ip)
 {
   if (d == NULL) return NULL; /* bad error! */
 	
@@ -558,44 +558,3 @@ void expire_names(time_t t)
 }
 
 
-/***************************************************************************
-  assume a WINS name is a dns name, and do a gethostbyname() on it.
-  ****************************************************************************/
-struct name_record *dns_name_search(struct nmb_name *question, int Time)
-{
-  int name_type = question->name_type;
-  char *qname = question->name;
-  BOOL dns_type = (name_type == 0x20 || name_type == 0);
-  struct in_addr dns_ip;
-
-  if (wins_subnet == NULL) 
-    return NULL;
-
-  DEBUG(3,("Search for %s - ", namestr(question)));
-
-  /* only do DNS lookups if the query is for type 0x20 or type 0x0 */
-  if (!dns_type)
-  {
-    DEBUG(3,("types 0x20 0x0 only: name not found\n"));
-    return NULL;
-  }
-
-  /* look it up with DNS */      
-  dns_ip.s_addr = interpret_addr(qname);
-
-  if (!dns_ip.s_addr)
-  {
-    /* no luck with DNS. We could possibly recurse here XXXX */
-    DEBUG(3,("not found. no recursion.\n"));
-    /* add the fail to WINS cache of names. give it 1 hour in the cache */
-    add_netbios_entry(wins_subnet,qname,name_type,NB_ACTIVE,60*60,DNSFAIL,dns_ip,
-                  True, True);
-    return NULL;
-  }
-
-  DEBUG(3,("found with DNS: %s\n", inet_ntoa(dns_ip)));
-
-  /* add it to our WINS cache of names. give it 2 hours in the cache */
-  return add_netbios_entry(wins_subnet,qname,name_type,NB_ACTIVE,2*60*60,DNS,dns_ip,
-                         True,True);
-}