fifo isn't really the right data structure for varying expirations.

convert to a simple rbtree ordered by expiration time.
ok anton

diff --git a/usr.sbin/rebound/rebound.c b/usr.sbin/rebound/rebound.c
index f2d028e..28b8649 100644 (file)
--- a/usr.sbin/rebound/rebound.c
+++ b/usr.sbin/rebound/rebound.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: rebound.c,v 1.106 2018/12/20 07:23:22 anton Exp $ */
+/* $OpenBSD: rebound.c,v 1.107 2018/12/27 18:00:15 tedu Exp $ */
 /*
  * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
  *
@@ -88,7 +88,7 @@ struct dnspacket {
  * after the response is set, the request must not free it.
  */
 struct dnscache {
-       TAILQ_ENTRY(dnscache) fifo;
+       RB_ENTRY(dnscache) expnode;
        RB_ENTRY(dnscache) cachenode;
        struct dnspacket *req;
        size_t reqlen;
@@ -98,7 +98,8 @@ struct dnscache {
        struct timespec basetime;
        int permanent;
 };
-static TAILQ_HEAD(, dnscache) cachefifo;
+static RB_HEAD(cacheexp, dnscache) cacheexp;
+RB_PROTOTYPE_STATIC(cacheexp, dnscache, expnode, expirycmp)
 static RB_HEAD(cachetree, dnscache) cachetree;
 RB_PROTOTYPE_STATIC(cachetree, dnscache, cachenode, cachecmp)
 
@@ -170,6 +171,17 @@ logerr(const char *msg, ...)
        exit(1);
 }
 
+static int
+expirycmp(struct dnscache *c1, struct dnscache *c2)
+{
+       if (timespeccmp(&c1->ts, &c2->ts, <))
+               return -1;
+       if (timespeccmp(&c1->ts, &c2->ts, >))
+               return 1;
+       return c1 < c2 ? -1 : 1;
+}
+RB_GENERATE_STATIC(cacheexp, dnscache, expnode, expirycmp)
+
 static int
 cachecmp(struct dnscache *c1, struct dnscache *c2)
 {
@@ -212,7 +224,7 @@ freecacheent(struct dnscache *ent)
 {
        cachecount -= 1;
        RB_REMOVE(cachetree, &cachetree, ent);
-       TAILQ_REMOVE(&cachefifo, ent, fifo);
+       RB_REMOVE(cacheexp, &cacheexp, ent);
        free(ent->req);
        free(ent->resp);
        free(ent);
@@ -562,8 +574,13 @@ sendreply(struct request *req, uint8_t *buf, size_t r)
                }
                memcpy(ent->resp, buf, r);
                ent->resplen = r;
+               if (RB_INSERT(cacheexp, &cacheexp, ent)) {
+                       free(ent->resp);
+                       ent->resp = NULL;
+                       RB_REMOVE(cachetree, &cachetree, ent);
+                       return;
+               }
                cachecount += 1;
-               TAILQ_INSERT_TAIL(&cachefifo, ent, fifo);
        }
 }
 
@@ -737,6 +754,7 @@ preloadcache(const char *name, uint16_t type, void *rdata, uint16_t rdatalen)
        ent->resplen = resplen;
        ent->permanent = 1;
 
+       /* not added to the cacheexp tree */
        RB_INSERT(cachetree, &cachetree, ent);
        return 0;
 
@@ -860,7 +878,7 @@ workerinit(void)
        cachemax = 10000; /* something big, but not huge */
 
        TAILQ_INIT(&reqfifo);
-       TAILQ_INIT(&cachefifo);
+       RB_INIT(&cacheexp);
        RB_INIT(&cachetree);
 
        https_init();
@@ -1037,10 +1055,10 @@ workerloop(int conffd, int udpfds[], int numudp, int tcpfds[], int numtcp)
                while (conncount > connmax)
                        freerequest(TAILQ_FIRST(&reqfifo));
                while (cachecount > cachemax)
-                       freecacheent(TAILQ_FIRST(&cachefifo));
+                       freecacheent(RB_MIN(cacheexp, &cacheexp));
 
                /* burn old cache entries */
-               while ((ent = TAILQ_FIRST(&cachefifo))) {
+               while ((ent = RB_MIN(cacheexp, &cacheexp))) {
                        if (timespeccmp(&ent->ts, &now, <=))
                                freecacheent(ent);
                        else