From 65db7054815f4efcdd1c6c9638b6e7f05950f481 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sun, 14 Jun 2015 21:31:44 +0200
Subject: ndb/dns: cleanup forwarding code (redistrib())

instead of copying the whole packet, just save the
udp header and restore it aftwards. dont call redistrib()
when there are no forwards (this should be almost always
the case).
---
 sys/src/cmd/ndb/dns.h         |  1 -
 sys/src/cmd/ndb/dnudpserver.c | 27 +++++++++++++++------------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/sys/src/cmd/ndb/dns.h b/sys/src/cmd/ndb/dns.h
index 51feb5739..51c1f7953 100644
--- a/sys/src/cmd/ndb/dns.h
+++ b/sys/src/cmd/ndb/dns.h
@@ -523,7 +523,6 @@ void	initdnsmsg(DNSmsg *mp, RR *rp, int flags, ushort reqno);
 /* dnserver.c */
 void	dnserver(DNSmsg*, DNSmsg*, Request*, uchar *, int);
 void	dnudpserver(char*);
-void	dntcpserver(char*);
 
 /* dnnotify.c */
 void	dnnotify(DNSmsg*, DNSmsg*, Request*);
diff --git a/sys/src/cmd/ndb/dnudpserver.c b/sys/src/cmd/ndb/dnudpserver.c
index ea6185a33..eef88e983 100644
--- a/sys/src/cmd/ndb/dnudpserver.c
+++ b/sys/src/cmd/ndb/dnudpserver.c
@@ -29,7 +29,7 @@ struct Forwtarg {
 	ulong	lastdial;
 };
 Forwtarg forwtarg[10];
-int currtarg;
+int forwtcount;
 
 static char *hmsg = "headers";
 
@@ -75,11 +75,11 @@ addforwtarg(char *host)
 {
 	Forwtarg *tp;
 
-	if (currtarg >= nelem(forwtarg)) {
+	if (forwtcount >= nelem(forwtarg)) {
 		dnslog("too many forwarding targets");
 		return -1;
 	}
-	tp = forwtarg + currtarg;
+	tp = forwtarg + forwtcount;
 	if (parseip(tp->addr, host) < 0) {
 		dnslog("can't parse ip %s", host);
 		return -1;
@@ -91,7 +91,7 @@ addforwtarg(char *host)
 
 	free(tp->host);
 	tp->host = estrdup(host);
-	currtarg++;
+	forwtcount++;
 	return 0;
 }
 
@@ -102,18 +102,18 @@ addforwtarg(char *host)
 static void
 redistrib(uchar *buf, int len)
 {
-	static uchar outpkt[Udphdrsize + Maxudp + 1024];
+	uchar save[Udphdrsize];
 	Forwtarg *tp;
 	Udphdr *uh;
 
-	assert(len <= sizeof outpkt);
-	memmove(outpkt, buf, len);
-	uh = (Udphdr *)outpkt;
-	for (tp = forwtarg; tp < forwtarg + currtarg; tp++)
+	memmove(save, buf, Udphdrsize);
+
+	uh = (Udphdr *)buf;
+	for (tp = forwtarg; tp < forwtarg + forwtcount; tp++)
 		if (tp->fd > 0) {
-			memmove(outpkt, tp->addr, sizeof tp->addr);
+			memmove(uh->raddr, tp->addr, sizeof tp->addr);
 			hnputs(uh->rport, 53);		/* dns port */
-			if (write(tp->fd, outpkt, len) != len) {
+			if (write(tp->fd, buf, len) != len) {
 				close(tp->fd);
 				tp->fd = -1;
 			}
@@ -121,6 +121,8 @@ redistrib(uchar *buf, int len)
 			tp->lastdial = time(nil);
 			tp->fd = udpport(mntpt);
 		}
+
+	memmove(buf, save, Udphdrsize);
 }
 
 /*
@@ -180,7 +182,8 @@ restart:
 		if(len <= Udphdrsize)
 			goto restart;
 
-		redistrib(buf, len);
+		if(forwtcount > 0)
+			redistrib(buf, len);
 
 		uh = (Udphdr*)buf;
 		len -= Udphdrsize;
-- 
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