Use binary packets in the cache

ex/fks-shield/cache.go

@@ -3,6 +3,7 @@ package main
 import (
 	"dns"
 	"fmt"
+	"log"
 	"radix"
 	"strings"
 	"time"
@@ -11,7 +12,7 @@ import (
 // Cache elements, we using to key (toRadixKey) to distinguish between dns and dnssec
 type Packet struct {
 	ttl time.Time // insertion time
-	d   *dns.Msg  // packet
+	d   []byte    // raw packet
 }
 
 func toRadixKey(d *dns.Msg) string {
@@ -30,20 +31,36 @@ type Cache struct {
 	*radix.Radix
 }
 
+func quickCopy(p []byte) []byte {
+	q := make([]byte, 2)
+	q = append(q, p[2:]...)
+	return q
+}
+
 func NewCache() *Cache {
 	return &Cache{Radix: radix.New()}
 }
 
-func (c *Cache) Find(d *dns.Msg) *dns.Msg {
+func (c *Cache) Find(d *dns.Msg) []byte {
 	p := c.Radix.Find(toRadixKey(d))
 	if p == nil {
+		if *verbose {
+			log.Printf("Cache miss for " + toRadixKey(d))
+		}
 		return nil
 	}
-	return p.Value.(*Packet).d
+	if *verbose {
+		log.Printf("Cache hit for " + toRadixKey(d))
+	}
+	return quickCopy(p.Value.(*Packet).d)
 }
 
 func (c *Cache) Insert(d *dns.Msg) {
-	c.Radix.Insert(toRadixKey(d), &Packet{d: d, ttl: time.Now().UTC()})
+	if *verbose {
+		log.Printf("Inserting " + toRadixKey(d))
+	}
+	buf, _ := d.Pack()	// Should always work
+	c.Radix.Insert(toRadixKey(d), &Packet{d: buf, ttl: time.Now().UTC()})
 }
 
 func (c *Cache) Remove(d *dns.Msg) {

ex/fks-shield/shield.go

@@ -16,17 +16,22 @@ import (
 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")
-	verbose = flag.Bool("verbose", false, "Print packet as it flows through")
+	verbose = flag.Bool("verbose", false, "be more verbose")
 )
 
 func serve(w dns.ResponseWriter, r *dns.Msg, c *Cache) {
 	if p := c.Find(r); p != nil {
-		w.Write(p)
+		dns.RawSetId(p, r.MsgHdr.Id)
+		w.WriteBuf(p)
 		return
 	}
 	// Cache miss
 	client := new(dns.Client)
 	if p, e := client.Exchange(r, *server); e == nil {
+		if *verbose {
+			log.Printf("fks-shield: cache miss")
+		}
+		// TODO(mg): If r has edns0 and p has not we create a mismatch here
 		w.Write(p)
 		c.Insert(p)
 		return
@@ -38,7 +43,7 @@ func serve(w dns.ResponseWriter, r *dns.Msg, c *Cache) {
 
 func listenAndServe(add, net string) {
 	if err := dns.ListenAndServe(add, net, nil); err != nil {
-		log.Printf("fks-shield: failed to setup:", net, add)
+		log.Fatal("fks-shield: failed to setup %s %s", net, add)
 	}
 }
 

ex/fksd/serve.go

@@ -5,12 +5,24 @@ import (
 	"log"
 )
 
+// Create skeleton edns opt RR from the query and
+// add it to the message m
+func ednsFromRequest(req, m *dns.Msg) {
+	for _, r := range req.Extra {
+		if r.Header().Rrtype == dns.TypeOPT {
+			m.SetEdns0(4096, r.(*dns.RR_OPT).Do())
+			return
+		}
+	}
+	return
+}
+
 func serve(w dns.ResponseWriter, req *dns.Msg, z *dns.Zone) {
 	if z == nil {
 		panic("fks: no zone")
 	}
 	if *l {
-		log.Printf("fks: [zone %s] incoming %s %s %d\n", z.Origin, req.Question[0].Name, dns.Rr_str[req.Question[0].Qtype], req.MsgHdr.Id)
+		log.Printf("fks: [zone %s] incoming %s %s %d from %s\n", z.Origin, req.Question[0].Name, dns.Rr_str[req.Question[0].Qtype], req.MsgHdr.Id, w.RemoteAddr())
 	}
 	// Ds Handling
 	// Referral
@@ -36,6 +48,7 @@ func serve(w dns.ResponseWriter, req *dns.Msg, z *dns.Zone) {
 				}
 			}
 		}
+		ednsFromRequest(req, m)
 		w.Write(m)
 		return
 	}
@@ -45,6 +58,7 @@ func serve(w dns.ResponseWriter, req *dns.Msg, z *dns.Zone) {
 	node := z.Find(req.Question[0].Name)
 	if node == nil {
 		m.SetRcode(req, dns.RcodeNameError)
+		ednsFromRequest(req, m)
 		w.Write(m)
 		return
 	}
@@ -70,6 +84,7 @@ func serve(w dns.ResponseWriter, req *dns.Msg, z *dns.Zone) {
 				}
 			}
 		}
+		ednsFromRequest(req, m)
 		w.Write(m)
 		return
 	}
@@ -81,14 +96,17 @@ func serve(w dns.ResponseWriter, req *dns.Msg, z *dns.Zone) {
 		m.MsgHdr.Authoritative = true
 		m.Answer = rrs
 		m.Ns = apex.RR[dns.TypeNS]
+		ednsFromRequest(req, m)
 		w.Write(m)
 		return
 	} else { // NoData reply or CNAME
 		m.SetReply(req)
 		m.Ns = apex.RR[dns.TypeSOA]
+		ednsFromRequest(req, m)
 		w.Write(m)
 		return
 	}
 	m.SetRcode(req, dns.RcodeNameError)
+	ednsFromRequest(req, m)
 	w.Write(m)
 }