middleware/secondary: multiple fixes (#745)

Fix transferring the zone from a master and the matching of notifies
to source and dst IP addresses.

Add `upstream` keyword as well, because it is needed for the same
reasons as in the *file* middlware.
Add some dire warning about upstream in the readme of both middlewares.

Out of band testing, hidden by net build tag was added. Integration
testing still needs to be setup.

middleware/file/README.md

@@ -38,7 +38,8 @@ file DBFILE [ZONES... ] {
 * `no_reload` by default CoreDNS will reload a zone from disk whenever it detects a change to the
   file. This option disables that behavior.
 * `upstream` defines upstream resolvers to be used resolve external names found (think CNAMEs)
-  pointing to external names.
+  pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for
+  normal authoritative serving you don't need *or* want to use this.
 
 ## Examples
 

middleware/file/notify.go

@@ -3,8 +3,8 @@ package file
 import (
 	"fmt"
 	"log"
+	"net"
 
-	"github.com/coredns/coredns/middleware"
 	"github.com/coredns/coredns/middleware/pkg/rcode"
 	"github.com/coredns/coredns/request"
 
@@ -21,8 +21,13 @@ func (z *Zone) isNotify(state request.Request) bool {
 	if len(z.TransferFrom) == 0 {
 		return false
 	}
-	remote := middleware.Addr(state.IP()).Normalize()
-	for _, from := range z.TransferFrom {
+	// If remote IP matches we accept.
+	remote := state.IP()
+	for _, f := range z.TransferFrom {
+		from, _, err := net.SplitHostPort(f)
+		if err != nil {
+			continue
+		}
 		if from == remote {
 			return true
 		}

middleware/file/secondary.go

@@ -26,19 +26,19 @@ Transfer:
 		t := new(dns.Transfer)
 		c, err := t.In(m, tr)
 		if err != nil {
-			log.Printf("[ERROR] Failed to setup transfer `%s' with `%s': %v", z.origin, tr, err)
+			log.Printf("[ERROR] Failed to setup transfer `%s' with `%q': %v", z.origin, tr, err)
 			Err = err
 			continue Transfer
 		}
 		for env := range c {
 			if env.Error != nil {
-				log.Printf("[ERROR] Failed to parse transfer `%s': %v", z.origin, env.Error)
+				log.Printf("[ERROR] Failed to transfer `%s' from %q: %v", z.origin, tr, env.Error)
 				Err = env.Error
 				continue Transfer
 			}
 			for _, rr := range env.RR {
 				if err := z1.Insert(rr); err != nil {
-					log.Printf("[ERROR] Failed to parse transfer `%s': %v", z.origin, err)
+					log.Printf("[ERROR] Failed to parse transfer `%s' from: %q: %v", z.origin, tr, err)
 					Err = err
 					continue Transfer
 				}
@@ -48,7 +48,6 @@ Transfer:
 		break
 	}
 	if Err != nil {
-		log.Printf("[ERROR] Failed to transfer %s: %s", z.origin, Err)
 		return Err
 	}
 

middleware/file/xfr.go

@@ -57,6 +57,6 @@ func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (in
 }
 
 // Name implements the middleware.Hander interface.
-func (x Xfr) Name() string { return "xfr" } // Or should we return "file" here?
+func (x Xfr) Name() string { return "xfr" }
 
 const transferLength = 1000 // Start a new envelop after message reaches this size in bytes. Intentionally small to test multi envelope parsing.

middleware/file/zone.go

@@ -2,6 +2,7 @@ package file
 
 import (
 	"fmt"
+	"net"
 	"path"
 	"strings"
 	"sync"
@@ -55,12 +56,12 @@ func NewZone(name, file string) *Zone {
 	return z
 }
 
-// Copy copies a zone *without* copying the zone's content. It is not a deep copy.
 func (z *Zone) Copy() *Zone {
 	z1 := NewZone(z.origin, z.file)
 	z1.TransferTo = z.TransferTo
 	z1.TransferFrom = z.TransferFrom
 	z1.Expired = z.Expired
+
 	z1.Apex = z.Apex
 	return z1
 }
@@ -113,11 +114,20 @@ func (z *Zone) Insert(r dns.RR) error {
 func (z *Zone) Delete(r dns.RR) { z.Tree.Delete(r) }
 
 // TransferAllowed checks if incoming request for transferring the zone is allowed according to the ACLs.
-func (z *Zone) TransferAllowed(req request.Request) bool {
+func (z *Zone) TransferAllowed(state request.Request) bool {
 	for _, t := range z.TransferTo {
 		if t == "*" {
 			return true
 		}
+		// If remote IP matches we accept.
+		remote := state.IP()
+		to, _, err := net.SplitHostPort(t)
+		if err != nil {
+			continue
+		}
+		if to == remote {
+			return true
+		}
 	}
 	// TODO(miek): future matching against IP/CIDR notations
 	return false

middleware/secondary/README.md

@@ -16,13 +16,17 @@ A working syntax would be:
 ~~~
 secondary [zones...] {
     transfer from ADDRESS
-    [transfer to ADDRESS]
+    transfer to ADDRESS
+    upstream ADDRESS...
 }
 ~~~
 
 * `transfer from` specifies from which address to fetch the zone. It can be specified multiple times;
     if one does not work, another will be tried.
 * `transfer to` can be enabled to allow this secondary zone to be transferred again.
+* `upstream` defines upstream resolvers to be used resolve external names found (think CNAMEs)
+  pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for
+  normal authoritative serving you don't need *or* want to use this.
 
 ## Examples
 

middleware/secondary/setup.go

@@ -4,6 +4,8 @@ import (
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/middleware"
 	"github.com/coredns/coredns/middleware/file"
+	"github.com/coredns/coredns/middleware/pkg/dnsutil"
+	"github.com/coredns/coredns/middleware/proxy"
 
 	"github.com/mholt/caddy"
 )
@@ -47,6 +49,7 @@ func secondaryParse(c *caddy.Controller) (file.Zones, error) {
 	z := make(map[string]*file.Zone)
 	names := []string{}
 	origins := []string{}
+	prxy := proxy.Proxy{}
 	for c.Next() {
 
 		if c.Val() == "secondary" {
@@ -74,6 +77,16 @@ func secondaryParse(c *caddy.Controller) (file.Zones, error) {
 					if e != nil {
 						return file.Zones{}, e
 					}
+				case "upstream":
+					args := c.RemainingArgs()
+					if len(args) == 0 {
+						return file.Zones{}, c.ArgErr()
+					}
+					ups, err := dnsutil.ParseHostPortOrFile(args...)
+					if err != nil {
+						return file.Zones{}, err
+					}
+					prxy = proxy.NewLookup(ups)
 				}
 
 				for _, origin := range origins {
@@ -83,6 +96,7 @@ func secondaryParse(c *caddy.Controller) (file.Zones, error) {
 					if f != nil {
 						z[origin].TransferFrom = append(z[origin].TransferFrom, f...)
 					}
+					z[origin].Proxy = prxy
 				}
 			}
 		}