more stuff

ex/fks-shield/cache.go

@@ -4,11 +4,13 @@ import (
 	"dns"
 	"fmt"
 	"log"
-	"radix"
+	"github.com/miekg/radix"
 	"strings"
 	"time"
 )
 
+const TTL time.Duration = 30 * 1e9 // 30 seconds
+
 // Cache elements, we using to key (toRadixKey) to distinguish between dns and dnssec
 type Packet struct {
 	ttl time.Time // insertion time
@@ -43,11 +45,28 @@ func NewCache() *Cache {
 	return &Cache{Radix: radix.New()}
 }
 
+func (c *Cache) Evict() {
+	// A bit tedious, keys() -> find() -> remove()
+	for _, key := range c.Radix.Keys() {
+		log.Printf("look for key %s\n", key)
+		node := c.Radix.Find(key)
+		if node == nil {
+			continue
+		}
+		if time.Since(node.Value.(*Packet).ttl) > TTL {
+			c.Radix.Remove(key)
+			if *flaglog {
+				log.Printf("fsk-shield: evicting %s\n", key)
+			}
+		}
+	}
+}
+
 func (c *Cache) Find(d *dns.Msg) []byte {
 	p := c.Radix.Find(toRadixKey(d))
 	if p == nil {
-		if *verbose {
+		if *flaglog {
-			log.Printf("Cache miss for " + toRadixKey(d))
+			log.Printf("fsk-shield: cache miss for " + toRadixKey(d))
 		}
 		return nil
 	}
@@ -55,10 +74,10 @@ func (c *Cache) Find(d *dns.Msg) []byte {
 }
 
 func (c *Cache) Insert(d *dns.Msg) {
-	if *verbose {
+	if *flaglog {
-		log.Printf("Inserting " + toRadixKey(d))
+		log.Printf("fsk-shield: inserting " + toRadixKey(d))
 	}
-	buf, _ := d.Pack()	// Should always work
+	buf, _ := d.Pack() // Should always work
 	c.Radix.Insert(toRadixKey(d), &Packet{d: buf, ttl: time.Now().UTC()})
 }
 

ex/fks-shield/shield.go

@@ -1,22 +1,19 @@
-/* 
- * Funkensturm, a versatile DNS proxy
- * Miek Gieben <miek@miek.nl> (c) 2011
- * GPLv2
- */
-
 package main
 
+// TODO: locking
+
 import (
 	"dns"
 	"flag"
 	"log"
 	"os"
+	"time"
 )
 
 var (
 	listen  = flag.String("listen", "127.0.0.1:8053", "set the listener address")
-	server  = flag.String("server", "127.0.0.1:53", "remote server address(es), seperate with commas")
+	server  = flag.String("server", "127.0.0.1:53", "remote server address")
-	verbose = flag.Bool("verbose", false, "be more verbose")
+	flaglog = flag.Bool("log", false, "be more verbose")
 )
 
 func serve(w dns.ResponseWriter, r *dns.Msg, c *Cache) {
@@ -29,7 +26,7 @@ func serve(w dns.ResponseWriter, r *dns.Msg, c *Cache) {
 	// Cache miss
 	client := new(dns.Client)
 	if p, e := client.Exchange(r, *server); e == nil {
-		if *verbose {
+		if *flaglog {
 			log.Printf("fks-shield: cache miss")
 		}
 		// TODO(mg): If r has edns0 and p has not we create a mismatch here
@@ -38,7 +35,9 @@ func serve(w dns.ResponseWriter, r *dns.Msg, c *Cache) {
 		return
 	} else {
 		log.Printf("fks-shield: failed to get answer " + e.Error())
-		// w.Write(SERFVAIL)
+		m := new(dns.Msg)
+		m.SetRcode(r, dns.RcodeServerFailure)
+		w.Write(m)
 	}
 }
 
@@ -54,9 +53,16 @@ func main() {
 	// Only listen on UDP
 	go func() {
 		if err := dns.ListenAndServe(*listen, "udp", nil); err != nil {
-			log.Fatal("fks-shield: failed to setup %s %s", net, add)
+			log.Fatal("fks-shield: failed to setup %s %s", *listen, "udp")
 		}
-	}
+	}()
+	go func() {
+		for {
+			// Every 10 sec run the cache cleaner
+			time.Sleep(10 * 1e9)
+			cache.Evict()
+		}
+	}()
 
 	sig := make(chan os.Signal)
 forever: