Hello,
I have attached a patch to change the way upstream nameservers are
selected for new DNS resolution requests. This patch essentially gives
a new command line option that prefers nameservers in resolv.conf
(probably given by a DHCP server) and uses ( probably third party DNS
server) specified by -S as a last resort for every new incoming
request.
Hope this a feature, worthy of addition to dnsmasq. Feedback/critique
is welcome. I have attached a patch taken again dnsmasq-2.57 tarball.
Regards,
Harish Badrinath
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index a386a31..40be277 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -202,7 +202,8 @@ struct event_desc {
#define OPT_NO_REBIND 31
#define OPT_ADD_MAC 32
#define OPT_DNSSEC 33
-#define OPT_LAST 34
+#define OPT_BIASEDRR 34
+#define OPT_LAST 35
/* extra flags for my_syslog, we use a couple of facilities since they are known
not to occupy the same bits as priorities, no matter how syslog.h is set up. */
diff --git a/src/forward.c b/src/forward.c
index 92bc6b0..865ef87 100644
--- a/src/forward.c
+++ b/src/forward.c
@@ -336,7 +336,26 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
/* only send to servers dealing with our domain.
domain may be NULL, in which case server->domain
must be NULL also. */
-
+ if (option_bool(OPT_BIASEDRR))
+ #define BIASED_RESOLUTION
+ #ifdef BIASED_RESOLUTION
+ /* For new queires that have not timed out
+ forward->sentto is null.
+ start is the upstream server of interest in the current
+ iteration of the loop.
+ if(start->next) checks are done to prevent infinite loops *or* segfaulting
+ */
+ if((!(forward->sentto)) && (!(start->flags & SERV_FROM_RESOLV)))
+ if(start->next) start=start->next;
+ if((!(forward->sentto)) && (!(start->flags & SERV_FROM_RESOLV)))
+ if(start->next) continue;
+ if(forward->sentto && (sockaddr_isequal(&(forward->sentto->addr),&(start->addr))))
+ if(start->next) start=start->next;
+ if(forward->sentto && (sockaddr_isequal(&(forward->sentto->addr),&(start->addr))))
+ if(start->next) continue;
+ if((forward->sentto) || ((!(forward->sentto)) && (start->flags & SERV_FROM_RESOLV)))
+ {
+ #endif
if (type == (start->flags & SERV_TYPE) &&
(type != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) &&
!(start->flags & SERV_LITERAL_ADDRESS))
@@ -399,7 +418,9 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
forward->forwardall++;
}
}
-
+ #ifdef BIASED_RESOLUTION
+ }
+ #endif
if (!(start = start->next))
start = daemon->servers;
diff --git a/src/option.c b/src/option.c
index 4cee0a2..c42a0d7 100644
--- a/src/option.c
+++ b/src/option.c
@@ -110,6 +110,7 @@ struct myoption {
#define LOPT_LOC_REBND 299
#define LOPT_ADD_MAC 300
#define LOPT_DNSSEC 301
+#define LOPT_BIASEDRR 302
#ifdef HAVE_GETOPT_LONG
static const struct option opts[] =
@@ -225,6 +226,7 @@ static const struct myoption opts[] =
{ "rebind-localhost-ok", 0, 0, LOPT_LOC_REBND },
{ "add-mac", 0, 0, LOPT_ADD_MAC },
{ "proxy-dnssec", 0, 0, LOPT_DNSSEC },
+ { "biased-resolution",0 ,0, LOPT_BIASEDRR},
{ NULL, 0, 0, 0 }
};
@@ -347,6 +349,7 @@ static struct {
{ LOPT_TEST, 0, NULL, gettext_noop("Check configuration syntax."), NULL },
{ LOPT_ADD_MAC, OPT_ADD_MAC, NULL, gettext_noop("Add requestor's MAC address to forwarded DNS queries"), NULL },
{ LOPT_DNSSEC, OPT_DNSSEC, NULL, gettext_noop("Proxy DNSSEC validation results from upstream nameservers"), NULL },
+ { LOPT_BIASEDRR, OPT_BIASEDRR, NULL, gettext_noop("Be partial towards upstream nameservers present in resolv.conf (defaults to %s)."),RESOLVFILE},
{ 0, 0, NULL, NULL, NULL }
};
