From: tedu <tedu@openbsd.org>
Date: Mon, 3 Jul 2017 09:39:48 +0000 (+0000)
Subject: check that a cachehit hasn't expired before using it.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=352aa418c7730f0804334d9ae77c604ad2c47fee;p=openbsd

check that a cachehit hasn't expired before using it.
---

diff --git a/usr.sbin/rebound/rebound.c b/usr.sbin/rebound/rebound.c
index 16d40381a2b..3b6d5144433 100644
--- a/usr.sbin/rebound/rebound.c
+++ b/usr.sbin/rebound/rebound.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: rebound.c,v 1.84 2017/05/31 04:52:11 deraadt Exp $ */
+/* $OpenBSD: rebound.c,v 1.85 2017/07/03 09:39:48 tedu Exp $ */
 /*
  * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
  *
@@ -190,6 +190,17 @@ randomcase(unsigned char *s)
 	}
 }
 
+static void
+freecacheent(struct dnscache *ent)
+{
+	cachecount -= 1;
+	RB_REMOVE(cachetree, &cachetree, ent);
+	TAILQ_REMOVE(&cachefifo, ent, fifo);
+	free(ent->req);
+	free(ent->resp);
+	free(ent);
+}
+
 static struct dnscache *
 cachelookup(struct dnspacket *dnsreq, size_t reqlen)
 {
@@ -212,8 +223,13 @@ cachelookup(struct dnspacket *dnsreq, size_t reqlen)
 	key.reqlen = reqlen;
 	key.req = dnsreq;
 	hit = RB_FIND(cachetree, &cachetree, &key);
-	if (hit)
-		cachehits += 1;
+	if (hit) {
+		if (timespeccmp(&hit->ts, &now, <=)) {
+			freecacheent(hit);
+			hit = NULL;
+		} else
+			cachehits += 1;
+	}
 
 	memcpy(dnsreq->qname, origname, namelen + 1);
 	dnsreq->id = origid;
@@ -242,17 +258,6 @@ freerequest(struct request *req)
 	free(req);
 }
 
-static void
-freecacheent(struct dnscache *ent)
-{
-	cachecount -= 1;
-	RB_REMOVE(cachetree, &cachetree, ent);
-	TAILQ_REMOVE(&cachefifo, ent, fifo);
-	free(ent->req);
-	free(ent->resp);
-	free(ent);
-}
-
 static void
 servfail(int ud, uint16_t id, struct sockaddr *fromaddr, socklen_t fromlen)
 {