From 3866bd5e6337534080cc19e5d3f7c866b708b30f Mon Sep 17 00:00:00 2001
From: Michael Bridgen <mikeb@squaremobius.net>
Date: Wed, 7 Jan 2015 14:29:35 +0000
Subject: [PATCH] Parse reverse address lookup IPs in the Zone

.. rather than making clients of the zone do it. At the minute there's
only one call site, but soon there will be more.
---
 nameserver/server.go    | 25 ++++++++-----------------
 nameserver/zone.go      | 32 ++++++++++++++++++++++++--------
 nameserver/zone_test.go |  2 +-
 3 files changed, 33 insertions(+), 26 deletions(-)

diff --git a/nameserver/server.go b/nameserver/server.go
index 896f9e26..61540836 100644
--- a/nameserver/server.go
+++ b/nameserver/server.go
@@ -9,12 +9,8 @@ import (
 
 const (
 	LOCAL_DOMAIN = "weave.local."
-	RDNS_DOMAIN  = "in-addr.arpa."
 )
 
-// +1 to also exclude a dot
-var rdnsDomainLen = len(RDNS_DOMAIN) + 1
-
 func checkFatal(e error) {
 	if e != nil {
 		Error.Fatal(e)
@@ -77,19 +73,14 @@ func rdnsHandler(zone Zone, mdnsClient *MDNSClient) dns.HandlerFunc {
 		q := r.Question[0]
 		Debug.Printf("Local rdns query: %+v", q)
 		if q.Qtype == dns.TypePTR {
-			if ip := net.ParseIP(q.Name[:len(q.Name)-rdnsDomainLen]); ip != nil {
-				ip4 := ip.To4()
-				revIP := []byte{ip4[3], ip4[2], ip4[1], ip4[0]}
-				Debug.Printf("Looking for address: %+v", revIP)
-				if name, err := zone.ReverseLookupLocal(revIP); err == nil {
-					Debug.Printf("Found name: %s", name)
-					m := makePTRReply(r, &q, []string{name})
-					w.WriteMsg(m)
-				} else {
-					Debug.Printf("Failed lookup for %s; sending mDNS query", q.Name)
-					// We don't know the answer; see if someone else does
-					// TODO
-				}
+			if name, err := zone.ReverseLookupLocal(q.Name); err == nil {
+				Debug.Printf("Found name: %s", name)
+				m := makePTRReply(r, &q, []string{name})
+				w.WriteMsg(m)
+			} else {
+				Debug.Printf("Failed lookup for %s; sending mDNS query", q.Name)
+				// We don't know the answer; see if someone else does
+				// TODO
 			}
 		}
 	}
diff --git a/nameserver/zone.go b/nameserver/zone.go
index 44c194b9..82f28f38 100644
--- a/nameserver/zone.go
+++ b/nameserver/zone.go
@@ -2,16 +2,24 @@ package nameserver
 
 import (
 	"github.com/miekg/dns"
+	. "github.com/zettio/weave/common"
 	"net"
 	"sync"
 )
 
+const (
+	RDNS_DOMAIN = "in-addr.arpa."
+)
+
+// +1 to also exclude a dot
+var rdnsDomainLen = len(RDNS_DOMAIN) + 1
+
 type Zone interface {
 	AddRecord(ident string, name string, ip net.IP) error
 	DeleteRecord(ident string, ip net.IP) error
 	DeleteRecordsFor(ident string) error
 	LookupLocal(name string) (net.IP, error)
-	ReverseLookupLocal(ip net.IP) (string, error)
+	ReverseLookupLocal(inaddr string) (string, error)
 }
 
 type Record struct {
@@ -60,15 +68,23 @@ func (zone *ZoneDb) LookupLocal(name string) (net.IP, error) {
 	return nil, LookupError(name)
 }
 
-func (zone *ZoneDb) ReverseLookupLocal(ip net.IP) (string, error) {
-	zone.mx.RLock()
-	defer zone.mx.RUnlock()
-	for _, r := range zone.recs {
-		if r.IP.Equal(ip) {
-			return r.Name, nil
+func (zone *ZoneDb) ReverseLookupLocal(inaddr string) (string, error) {
+	if revIP := net.ParseIP(inaddr[:len(inaddr)-rdnsDomainLen]); revIP != nil {
+		revIP4 := revIP.To4()
+		ip := []byte{revIP4[3], revIP4[2], revIP4[1], revIP4[0]}
+		Debug.Printf("Looking for address: %+v", ip)
+		zone.mx.RLock()
+		defer zone.mx.RUnlock()
+		for _, r := range zone.recs {
+			if r.IP.Equal(ip) {
+				return r.Name, nil
+			}
 		}
+		return "", LookupError(inaddr)
+	} else {
+		Warning.Printf("Asked to reverse lookup %s", inaddr)
+		return "", LookupError(inaddr)
 	}
-	return "", LookupError(ip.String())
 }
 
 func (zone *ZoneDb) AddRecord(ident string, name string, ip net.IP) error {
diff --git a/nameserver/zone_test.go b/nameserver/zone_test.go
index 6d99cf2a..86db36ec 100644
--- a/nameserver/zone_test.go
+++ b/nameserver/zone_test.go
@@ -35,7 +35,7 @@ func TestZone(t *testing.T) {
 	}
 
 	// See if we can find the address by IP.
-	foundName, err := zone.ReverseLookupLocal(ip)
+	foundName, err := zone.ReverseLookupLocal("1.2.0.10.in-addr.arpa.")
 	wt.AssertNoErr(t, err)
 
 	if foundName != successTestName {