About the noddiest thing that works.

dns/main.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"github.com/miekg/dns"
+	"net"
+	"weavedns"
+	"log"
+)
+
+var zone = new(weavedns.ZoneDb)
+
+func handleLocal(w dns.ResponseWriter, r *dns.Msg) {
+	m := new(dns.Msg)
+	m.SetReply(r)
+	q := r.Question[0]
+	ip, err := zone.MatchLocal(q.Name)
+	if err == nil {
+		hdr := dns.RR_Header{Name: q.Name, Rrtype: dns.TypeA,
+			Class: dns.ClassINET, Ttl: 3600}
+		a := &dns.A{hdr, net.ParseIP(ip)}
+		m.Answer = append(m.Answer, a)
+	} else {
+		log.Printf("Failed lookup for %s", q.Name)
+	}
+	w.WriteMsg(m)
+	return
+}
+
+func main() {
+	LocalServeMux := dns.NewServeMux()
+	LocalServeMux.HandleFunc("local", handleLocal)
+	go weavedns.ListenHttp(zone)
+	dns.ListenAndServe(":5300", "udp", LocalServeMux)
+}

src/weavedns/http.go

@@ -0,0 +1,26 @@
+package weavedns
+
+import (
+	"net/http"
+	"fmt"
+	"log"
+)
+
+const (
+	UPDATE_PORT = 6785
+)
+
+func ListenHttp(db Zone) {
+	http.HandleFunc("/add", func(w http.ResponseWriter, r *http.Request) {
+		name := r.FormValue("name")
+		addr := r.FormValue("ip")
+		weave_ip := r.FormValue("weave_ip")
+		log.Printf("Adding %s %s %s", name, addr, weave_ip)
+		db.AddRecord(name, addr, weave_ip)
+	})
+	address := fmt.Sprintf(":%d", UPDATE_PORT)
+	err := http.ListenAndServe(address, nil)
+	if err != nil {
+		log.Fatal("Unable to create http listener: ", err)
+	}
+}

src/weavedns/zone.go

@@ -0,0 +1,60 @@
+package weavedns
+
+import (
+	"sync"
+	"log"
+	"github.com/miekg/dns"
+)
+
+type Zone interface {
+	AddRecord(name string, ip string, weave_ip string) error
+	MatchLocal(name string) (string, error)
+	MatchGlobal(name string) (string, error)
+}
+
+type Record struct {
+	Name string
+	Ip string
+	WeaveIp string
+}
+
+type ZoneDb struct {
+	mx sync.RWMutex
+	recs []Record
+}
+
+type LookupError string
+
+func (ops LookupError) Error() string {
+	return string(ops)
+}
+
+// Stop gap.
+func (zone ZoneDb) match(name string) (string, error) {
+	for _, r := range zone.recs {
+		log.Printf("%s == %s ?", r.Name, name)
+		if r.Name == name {
+			return r.WeaveIp, nil
+		}
+	}
+	return "", LookupError(name)
+}
+
+func (zone *ZoneDb) MatchLocal(name string) (string, error) {
+	zone.mx.Lock()
+	defer zone.mx.Unlock()
+	return zone.match(name)
+}
+
+func (zone *ZoneDb) MatchGlobal(name string) (string, error) {
+	zone.mx.Lock()
+	defer zone.mx.Unlock()
+	return zone.match(name)
+}
+
+func (zone *ZoneDb) AddRecord(name string, ip string, weave_ip string) error {
+	zone.mx.Lock()
+	defer zone.mx.Unlock()
+	zone.recs = append(zone.recs, Record{dns.Fqdn(name), ip, weave_ip})
+	return nil
+}