Add middleware reverse (#452)

9 files changed, 804 insertions, 0 deletions

diff --git a/core/coredns.go b/core/coredns.go
index d7043c804..b621f2c27 100644
--- a/core/coredns.go
+++ b/core/coredns.go
@@ -25,6 +25,7 @@ import (
 	_ "github.com/miekg/coredns/middleware/metrics"
 	_ "github.com/miekg/coredns/middleware/pprof"
 	_ "github.com/miekg/coredns/middleware/proxy"
+	_ "github.com/miekg/coredns/middleware/reverse"
 	_ "github.com/miekg/coredns/middleware/rewrite"
 	_ "github.com/miekg/coredns/middleware/root"
 	_ "github.com/miekg/coredns/middleware/secondary"
diff --git a/core/dnsserver/zdirectives.go b/core/dnsserver/zdirectives.go
index a55461854..ff6722998 100644
--- a/core/dnsserver/zdirectives.go
+++ b/core/dnsserver/zdirectives.go
@@ -29,6 +29,7 @@ var directives = []string{
 		"secondary",
 		"etcd",
 		"kubernetes",
+		"reverse",
 		"proxy",
 		"httpprox",
 		"whoami",
diff --git a/middleware.cfg b/middleware.cfg
index 71434ffd8..0a9527e5c 100644
--- a/middleware.cfg
+++ b/middleware.cfg
@@ -37,6 +37,7 @@
 160:secondary:
 170:etcd:
 180:kubernetes:
+185:reverse:
 190:proxy:
 200:httpprox:
 210:whoami:
diff --git a/middleware/reverse/README.md b/middleware/reverse/README.md
new file mode 100644
index 000000000..7437a3079
--- /dev/null
+++ b/middleware/reverse/README.md
@@ -0,0 +1,97 @@
+# reverse
+
+The *reverse* middleware allows CoreDNS to respond dynamic to an PTR request and the related A/AAAA request.
+
+## Syntax
+
+~~~
+reverse NETWORK.. {
+    hostname TEMPLATE
+    [ttl TTL]
+    [fallthrough]
+~~~
+
+* **NETWORK** one or more CIDR formatted networks to respond on.
+* `hostname` inject the ip and zone to an template for the hostname. Defaults to "ip-{ip}.{zone[0]}". See below for template.
+* `ttl` defaults to 60
+* `fallthrough` If zone matches and no record can be generated, pass request to the next middleware.
+
+### Template Syntax
+The template for the hostname is used for generating the PTR for an reverse lookup and matching the forward lookup back to an ip.
+
+#### `{ip}`
+This symbol is **required** to work.
+V4 network replaces the "." with an "-". 10.1.1.1 results in "10-1-1-1"
+V6 network removes the ":" and fills the zeros. "ffff::ffff" results in "ffff000000000000000000000000ffff"
+
+#### `{zone[i]}`
+This symbol is **optional** to use and can be replaced by a fix zone string.
+The zone will be matched by the configured listener on the server block key.
+`i` needs to be replaced to the index of the configured listener zones, starting with 0.
+
+`arpa.:53 domain.com.:8053` will resolve `zone{0}` to `arpa.` and `zone{1}` to `domain.com.`
+
+## Examples
+
+~~~
+# Serve on port 53
+# match arpa. and compute.internal. to resolv reverse and forward lookup 
+.arpa.:53 compute.internal.:53 {
+    # proxy unmatched requests
+    proxy . 8.8.8.8
+
+    # answer requests for IPs in this networks
+    # PTR 1.0.32.10.in-addr.arpa. 3600 ip-10-0-32-1.compute.internal.
+    # A ip-10-0-32-1.compute.internal. 3600 10.0.32.1
+    # v6 is also possible
+    # PTR 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.d.f.ip6.arpa. 3600 ip-fd010000000000000000000000000001.compute.internal.
+    # AAAA ip-fd010000000000000000000000000001.compute.internal. 3600 fd01::1
+    reverse 10.32.0.0/16 fd01::/16 {
+        # template of the ip injection to hostname, zone resolved to compute.internal.
+        hostname ip-{ip}.{zone[1]}
+
+        # set time-to-live of the RR
+        ttl 3600
+
+        # forward unanswered or unmatched requests to proxy
+        # without this flag, requesting A/AAAA records on compute.internal. will end here
+        fallthrough
+    }
+
+    # cache with ttl timeout
+    cache
+}
+~~~
+
+
+~~~
+# Serve on port 53
+# listen only on the specific network
+32.10.in-addr.arpa.arpa.:53 arpa.company.org.:53 {
+
+    reverse 10.32.0.0/16 {
+        # template of the ip injection to hostname, zone resolved to arpa.company.org.
+        hostname "ip-{ip}.v4.{zone[1]}"
+
+        # set time-to-live of the RR
+        ttl 3600
+
+        # fallthrough is not required, v4.arpa.company.org. will be only answered here
+    }
+
+    # cidr closer to the ip wins, so we can overwrite the "default"
+    reverse 10.32.2.0/24 {
+        # its also possible to set fix domain suffix
+        hostname ip-{ip}.fix.arpa.company.org.
+
+        # set time-to-live of the RR
+        ttl 3600
+    }
+
+    # cache with ttl timeout
+    cache
+}
+~~~
+
+
+
diff --git a/middleware/reverse/network.go b/middleware/reverse/network.go
new file mode 100644
index 000000000..7f408326b
--- /dev/null
+++ b/middleware/reverse/network.go
@@ -0,0 +1,123 @@
+package reverse
+
+import (
+	"net"
+	"regexp"
+	"bytes"
+	"strings"
+)
+
+type network struct {
+	IPnet        *net.IPNet
+	Zone 	     string // forward lookup zone
+	Template     string
+	TTL          uint32
+	RegexMatchIP *regexp.Regexp
+	Fallthrough  bool
+}
+
+const hexDigit = "0123456789abcdef"
+const templateNameIP = "{ip}"
+const regexMatchV4 = "((?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\-){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))"
+const regexMatchV6 = "([0-9a-fA-F]{32})"
+
+// For forward lookup
+// converts the hostname back to an ip, based on the template
+// returns nil if there is no ip found
+func (network *network) hostnameToIP(rname string) net.IP {
+	var matchedIP net.IP
+
+	// use precompiled regex by setup
+	match := network.RegexMatchIP.FindStringSubmatch(rname)
+	// regex did not matched
+	if (len(match) != 2) {
+		return nil
+	}
+
+	if network.IPnet.IP.To4() != nil {
+		matchedIP = net.ParseIP(strings.Replace(match[1], "-", ".", 4))
+	} else {
+		var buf bytes.Buffer
+		// convert back to an valid ipv6 string with colons
+		for i := 0; i < 8 * 4; i += 4 {
+			buf.WriteString(match[1][i:i + 4])
+			if (i < 28) {
+				buf.WriteString(":")
+			}
+		}
+		matchedIP = net.ParseIP(buf.String())
+	}
+
+	// No valid ip or it does not belong to this network
+	if matchedIP == nil || !network.IPnet.Contains(matchedIP) {
+		return nil
+	}
+
+	return matchedIP
+}
+
+// For reverse lookup
+// Converts an Ip to an dns compatible hostname and injects it into the template.domain
+func (network *network) ipToHostname(ip net.IP) string {
+	var name string
+
+	ipv4 := ip.To4()
+	if ipv4 != nil {
+		// replace . to -
+		name = uitoa(ipv4[0]) + "-" +
+			uitoa(ipv4[1]) + "-" +
+			uitoa(ipv4[2]) + "-" +
+			uitoa(ipv4[3])
+	} else {
+		// assume v6
+		// ensure zeros are present in string
+		buf := make([]byte, 0, len(ip) * 4)
+		for i := 0; i < len(ip); i++ {
+			v := ip[i]
+			buf = append(buf, hexDigit[v >> 4])
+			buf = append(buf, hexDigit[v & 0xF])
+		}
+		name = string(buf)
+	}
+	// inject the converted ip into the fqdn template
+	return strings.Replace(network.Template, templateNameIP, name, 1)
+}
+
+// just the same from net.ip package, but with uint8
+func uitoa(val uint8) string {
+	if val == 0 {
+		// avoid string allocation
+		return "0"
+	}
+	var buf [20]byte // big enough for 64bit value base 10
+	i := len(buf) - 1
+	for val >= 10 {
+		q := val / 10
+		buf[i] = byte('0' + val - q * 10)
+		i--
+		val = q
+	}
+	// val < 10
+	buf[i] = byte('0' + val)
+	return string(buf[i:])
+}
+
+type networks []network
+
+// implements the sort interface
+func (slice networks) Len() int {
+	return len(slice)
+}
+
+// implements the sort interface
+// cidr closer to the ip wins (by netmask)
+func (slice networks) Less(i, j int) bool {
+	isize, _ := slice[i].IPnet.Mask.Size()
+	jsize, _ := slice[j].IPnet.Mask.Size()
+	return isize > jsize
+}
+
+// implements the sort interface
+func (slice networks) Swap(i, j int) {
+	slice[i], slice[j] = slice[j], slice[i]
+}
\ No newline at end of file
diff --git a/middleware/reverse/network_test.go b/middleware/reverse/network_test.go
new file mode 100644
index 000000000..ee4db1206
--- /dev/null
+++ b/middleware/reverse/network_test.go
@@ -0,0 +1,135 @@
+package reverse
+
+import (
+	"testing"
+	"net"
+	"reflect"
+	"regexp"
+)
+
+// Test converting from hostname to IP and back again to hostname
+func TestNetworkConversion(t *testing.T) {
+
+	_, net4, _ := net.ParseCIDR("10.1.1.0/24")
+	_, net6, _ := net.ParseCIDR("fd01::/64")
+
+	regexIP4, _ := regexp.Compile("^dns-" + regexMatchV4 + "\\.domain\\.internal\\.$")
+	regexIP6, _ := regexp.Compile("^dns-" + regexMatchV6 + "\\.domain\\.internal\\.$")
+
+	tests := []struct {
+		network    network
+		resultHost string
+		resultIP   net.IP
+	}{
+		{
+			network{
+				IPnet:net4,
+				Template: "dns-{ip}.domain.internal.",
+				RegexMatchIP:regexIP4,
+			},
+			"dns-10-1-1-23.domain.internal.",
+			net.ParseIP("10.1.1.23"),
+		},
+		{
+			network{
+				IPnet:net6,
+				Template: "dns-{ip}.domain.internal.",
+				RegexMatchIP:regexIP6,
+			},
+			"dns-fd01000000000000000000000000a32f.domain.internal.",
+			net.ParseIP("fd01::a32f"),
+		},
+	}
+
+	for i, test := range tests {
+		resultIP := test.network.hostnameToIP(test.resultHost)
+		if !reflect.DeepEqual(test.resultIP, resultIP) {
+			t.Fatalf("Test %d expected %v, got %v", i, test.resultIP, resultIP)
+		}
+
+		resultHost := test.network.ipToHostname(test.resultIP)
+		if !reflect.DeepEqual(test.resultHost, resultHost) {
+			t.Fatalf("Test %d expected %v, got %v", i, test.resultHost, resultHost)
+		}
+	}
+}
+
+func TestNetworkHostnameToIP(t *testing.T) {
+
+	_, net4, _ := net.ParseCIDR("10.1.1.0/24")
+	_, net6, _ := net.ParseCIDR("fd01::/64")
+
+	regexIP4, _ := regexp.Compile("^dns-" + regexMatchV4 + "\\.domain\\.internal\\.$")
+	regexIP6, _ := regexp.Compile("^dns-" + regexMatchV6 + "\\.domain\\.internal\\.$")
+
+	// Test regex does NOT match
+	// All this test should return nil
+	testsNil := []struct {
+		network  network
+		hostname string
+	}{
+		{
+			network{
+				IPnet:net4,
+				RegexMatchIP:regexIP4,
+			},
+			// domain does not match
+			"dns-10-1-1-23.domain.internals.",
+		},
+		{
+			network{
+				IPnet:net4,
+				RegexMatchIP:regexIP4,
+			},
+			// IP does match / contain in subnet
+			"dns-200-1-1-23.domain.internals.",
+		},
+		{
+			network{
+				IPnet:net4,
+				RegexMatchIP:regexIP4,
+			},
+			// template does not match
+			"dns-10-1-1-23-x.domain.internal.",
+		},
+		{
+			network{
+				IPnet:net4,
+				RegexMatchIP:regexIP4,
+			},
+			// template does not match
+			"IP-dns-10-1-1-23.domain.internal.",
+		},
+		{
+			network{
+				IPnet:net6,
+				RegexMatchIP:regexIP6,
+			},
+			// template does not match
+			"dnx-fd01000000000000000000000000a32f.domain.internal.",
+		},
+		{
+			network{
+				IPnet:net6,
+				RegexMatchIP:regexIP6,
+			},
+			// no valid v6 (missing one 0, only 31 chars)
+			"dns-fd0100000000000000000000000a32f.domain.internal.",
+		},
+		{
+			network{
+				IPnet:net6,
+				RegexMatchIP:regexIP6,
+			},
+			// IP does match / contain in subnet
+			"dns-ed01000000000000000000000000a32f.domain.internal.",
+		},
+	}
+
+	for i, test := range testsNil {
+		resultIP := test.network.hostnameToIP(test.hostname)
+		if resultIP != nil {
+			t.Fatalf("Test %d expected nil, got %v", i, resultIP)
+		}
+	}
+}
diff --git a/middleware/reverse/reverse.go b/middleware/reverse/reverse.go
new file mode 100644
index 000000000..9cf7d751a
--- /dev/null
+++ b/middleware/reverse/reverse.go
@@ -0,0 +1,114 @@
+package reverse
+
+import (
+	"net"
+
+	"github.com/miekg/coredns/request"
+	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/pkg/dnsutil"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+// Reverse provides dynamic reverse dns and the related forward rr
+type Reverse struct {
+	Next     middleware.Handler
+	Networks networks
+}
+
+// ServeDNS implements the middleware.Handler interface.
+func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	var rr dns.RR
+	nextHandler := true
+
+	state := request.Request{W: w, Req: r}
+	m := new(dns.Msg)
+	m.SetReply(r)
+	m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
+
+	switch state.QType(){
+	case dns.TypePTR:
+		address := dnsutil.ExtractAddressFromReverse(state.Name())
+
+		if address == "" {
+			// Not an reverse lookup, but can still be an pointer for an domain
+			break
+		}
+
+		ip := net.ParseIP(address)
+		// loop through the configured networks
+		for _, n := range reverse.Networks {
+			if (n.IPnet.Contains(ip)) {
+				nextHandler = n.Fallthrough
+				rr = &dns.PTR{
+					Hdr:  dns.RR_Header{Name: state.QName(), Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: n.TTL},
+					Ptr: n.ipToHostname(ip),
+				}
+				break
+			}
+		}
+
+	case dns.TypeA:
+		for _, n := range reverse.Networks {
+			if dns.IsSubDomain(n.Zone, state.Name()) {
+				nextHandler = n.Fallthrough
+
+				// skip if requesting an v4 address and network is not v4
+				if n.IPnet.IP.To4() == nil {
+					continue
+				}
+
+				result := n.hostnameToIP(state.Name())
+				if result != nil {
+					rr = &dns.A{
+						Hdr:  dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: n.TTL},
+						A: result,
+					}
+					break
+				}
+			}
+		}
+
+	case dns.TypeAAAA:
+		for _, n := range reverse.Networks {
+			if dns.IsSubDomain(n.Zone, state.Name()) {
+				nextHandler = n.Fallthrough
+
+				// Do not use To16 which tries to make v4 in v6
+				if n.IPnet.IP.To4() != nil {
+					continue
+				}
+
+				result := n.hostnameToIP(state.Name())
+				if result != nil {
+					rr = &dns.AAAA{
+						Hdr:  dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: n.TTL},
+						AAAA: result,
+					}
+					break
+				}
+			}
+		}
+
+	}
+
+	if rr == nil {
+		if reverse.Next == nil || !nextHandler {
+			// could not resolv
+			w.WriteMsg(m)
+			return dns.RcodeNameError, nil
+		}
+		return reverse.Next.ServeDNS(ctx, w, r)
+	}
+
+	m.Answer = append(m.Answer, rr)
+	state.SizeAndDo(m)
+	w.WriteMsg(m)
+	return dns.RcodeSuccess, nil
+}
+
+// Name implements the Handler interface.
+func (reverse Reverse) Name() string {
+	return "reverse"
+}
diff --git a/middleware/reverse/setup.go b/middleware/reverse/setup.go
new file mode 100644
index 000000000..024f7a39e
--- /dev/null
+++ b/middleware/reverse/setup.go
@@ -0,0 +1,146 @@
+package reverse
+
+import (
+	"net"
+	"sort"
+	"strings"
+	"strconv"
+	"regexp"
+
+	"github.com/miekg/coredns/core/dnsserver"
+	"github.com/miekg/coredns/middleware"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("reverse", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setupReverse,
+	})
+}
+
+func setupReverse(c *caddy.Controller) error {
+	networks, err := reverseParse(c)
+	if err != nil {
+		return middleware.Error("reverse", err)
+	}
+
+	dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
+		return Reverse{Next: next, Networks:networks}
+	})
+
+	return nil
+}
+
+func reverseParse(c *caddy.Controller) (networks, error) {
+	var err error
+
+	// normalize zones, validation is almost done by dnsserver
+	zones := make([]string, len(c.ServerBlockKeys))
+	for i, str := range c.ServerBlockKeys {
+		host, _, _ := net.SplitHostPort(str)
+		zones[i] = strings.ToLower(host)
+	}
+
+	networks := networks{}
+	for c.Next() {
+		if c.Val() == "reverse" {
+
+			var cidrs []*net.IPNet
+
+			// parse all networks
+			for _, cidr :=  range c.RemainingArgs() {
+				if cidr == "{" {
+					break
+				}
+				_, ipnet, err := net.ParseCIDR(cidr)
+				if err != nil {
+					return nil, c.Errf("%v needs to be an CIDR formatted Network\n", cidr)
+				}
+				cidrs = append(cidrs, ipnet)
+			}
+			if len(cidrs) == 0 {
+				return nil, c.ArgErr()
+			}
+
+			// set defaults
+			var (
+				template = "ip-" + templateNameIP + ".{zone[0]}"
+				ttl = 60
+				fall = false
+			)
+			for c.NextBlock() {
+				switch c.Val() {
+				case "hostname":
+					if !c.NextArg() {
+						return nil, c.ArgErr()
+					}
+					template = c.Val()
+
+				case "ttl":
+					if !c.NextArg() {
+						return nil, c.ArgErr()
+					}
+					ttl, err = strconv.Atoi(c.Val())
+					if err != nil {
+						return nil, err
+					}
+
+				case "fallthrough":
+					fall = true
+
+				default:
+					return nil, c.ArgErr()
+				}
+			}
+
+			// prepare template
+			// replace {zone[index]} by the listen zone/domain of this config block
+			for i, zone := range zones {
+				template = strings.Replace(template, "{zone[" + string(i + 48) + "]}", zone, 1)
+			}
+			if !strings.HasSuffix(template, ".") {
+				template += "."
+			}
+
+			// extract zone from template
+			templateZone := strings.SplitAfterN(template, ".", 2)
+			if len(templateZone) != 2 || templateZone[1] == "" {
+				return nil, c.Errf("Cannot find domain in template '%v'", template)
+			}
+
+			// Create for each configured network in this stanza
+			for _, ipnet := range cidrs {
+				// precompile regex for hostname to ip matching
+				regexIP := regexMatchV4
+				if ipnet.IP.To4() == nil {
+					regexIP = regexMatchV6
+				}
+				regex, err := regexp.Compile(
+					"^" + strings.Replace( // inject ip regex into template
+						regexp.QuoteMeta(template), // escape dots
+						regexp.QuoteMeta(templateNameIP),
+						regexIP,
+						1, ) + "$")
+				if err != nil {
+					// invalid regex
+					return nil, err
+				}
+
+				networks = append(networks, network{
+					IPnet: ipnet,
+					Zone: templateZone[1],
+					Template: template,
+					RegexMatchIP: regex,
+					TTL: uint32(ttl),
+					Fallthrough: fall,
+				})
+			}
+		}
+	}
+
+	// sort by cidr
+	sort.Sort(networks)
+	return networks, nil
+}
diff --git a/middleware/reverse/setup_test.go b/middleware/reverse/setup_test.go
new file mode 100644
index 000000000..4ec9e8a55
--- /dev/null
+++ b/middleware/reverse/setup_test.go
@@ -0,0 +1,186 @@
+package reverse
+
+import (
+	"testing"
+	"net"
+	"reflect"
+	"regexp"
+
+	"github.com/mholt/caddy"
+)
+
+func TestSetupParse(t *testing.T) {
+
+	_, net4, _ := net.ParseCIDR("10.1.1.0/24")
+	_, net6, _ := net.ParseCIDR("fd01::/64")
+
+	regexIP6, _ := regexp.Compile("^ip-" + regexMatchV6 + "\\.domain\\.com\\.$")
+	regexIpv4dynamic, _ := regexp.Compile("^dynamic-" + regexMatchV4 + "-intern\\.dynamic\\.domain\\.com\\.$")
+	regexIpv6dynamic, _ := regexp.Compile("^dynamic-" + regexMatchV6 + "-intern\\.dynamic\\.domain\\.com\\.$")
+	regexIpv4vpndynamic, _ := regexp.Compile("^dynamic-" + regexMatchV4 + "-vpn\\.dynamic\\.domain\\.com\\.$")
+
+	serverBlockKeys := []string{"domain.com.:8053", "dynamic.domain.com.:8053" }
+
+	tests := []struct {
+		inputFileRules string
+		shouldErr      bool
+		networks       networks
+	}{
+		{
+			// with defaults
+			`reverse fd01::/64`,
+			false,
+			networks{network{
+				IPnet: net6,
+				Template: "ip-{ip}.domain.com.",
+				Zone: "domain.com.",
+				TTL: 60,
+				RegexMatchIP: regexIP6,
+				Fallthrough: false,
+			}},
+		},
+		{
+			`reverse`,
+			true,
+			networks{},
+		},
+		{
+			//no cidr
+			`reverse 10.1.1.1`,
+			true,
+			networks{},
+		},
+		{
+			//no cidr
+			`reverse 10.1.1.0/16 fd00::`,
+			true,
+			networks{},
+		},
+		{
+			// invalid key
+			`reverse 10.1.1.0/24 {
+				notavailable
+			}`,
+			true,
+			networks{},
+		},
+		{
+			// no domain suffix
+			`reverse 10.1.1.0/24 {
+				hostname ip-{ip}.
+			}`,
+			true,
+			networks{},
+		},
+		{
+			// hostname requires an second arg
+			`reverse 10.1.1.0/24 {
+				hostname
+			}`,
+			true,
+			networks{},
+		},
+		{
+			// template breaks regex compile
+			`reverse 10.1.1.0/24 {
+				hostname ip-{[-x
+			}`,
+			true,
+			networks{},
+		},
+		{
+			// ttl requires an (u)int
+			`reverse 10.1.1.0/24 {
+				ttl string
+			}`,
+			true,
+			networks{},
+		},
+		{
+			`reverse fd01::/64 {
+				hostname dynamic-{ip}-intern.{zone[1]}
+				ttl 50
+			}
+			reverse 10.1.1.0/24 {
+				hostname dynamic-{ip}-vpn.{zone[1]}
+				fallthrough
+			}`,
+			false,
+			networks{network{
+				IPnet: net6,
+				Template: "dynamic-{ip}-intern.dynamic.domain.com.",
+				Zone: "dynamic.domain.com.",
+				TTL: 50,
+				RegexMatchIP:regexIpv6dynamic,
+				Fallthrough: false,
+			}, network{
+				IPnet: net4,
+				Template: "dynamic-{ip}-vpn.dynamic.domain.com.",
+				Zone: "dynamic.domain.com.",
+				TTL: 60,
+				RegexMatchIP: regexIpv4vpndynamic,
+				Fallthrough:true,
+			}},
+		},
+		{
+			// multiple networks in one stanza
+			`reverse fd01::/64 10.1.1.0/24 {
+				hostname dynamic-{ip}-intern.{zone[1]}
+				ttl 50
+				fallthrough
+			}`,
+			false,
+			networks{network{
+				IPnet: net6,
+				Template: "dynamic-{ip}-intern.dynamic.domain.com.",
+				Zone: "dynamic.domain.com.",
+				TTL: 50,
+				RegexMatchIP:regexIpv6dynamic,
+				Fallthrough: true,
+			}, network{
+				IPnet: net4,
+				Template: "dynamic-{ip}-intern.dynamic.domain.com.",
+				Zone: "dynamic.domain.com.",
+				TTL: 50,
+				RegexMatchIP: regexIpv4dynamic,
+				Fallthrough: true,
+			}},
+		},
+		{
+			// fix domain in template
+			`reverse fd01::/64 {
+				hostname dynamic-{ip}-intern.dynamic.domain.com
+				ttl 300
+				fallthrough
+			}`,
+			false,
+			networks{network{
+				IPnet: net6,
+				Template: "dynamic-{ip}-intern.dynamic.domain.com.",
+				Zone: "dynamic.domain.com.",
+				TTL: 300,
+				RegexMatchIP:regexIpv6dynamic,
+				Fallthrough: true,
+			}},
+		},
+
+	}
+	for i, test := range tests {
+		c := caddy.NewTestController("dns", test.inputFileRules)
+		c.ServerBlockKeys = serverBlockKeys
+		networks, err := reverseParse(c)
+
+		if err == nil && test.shouldErr {
+			t.Fatalf("Test %d expected errors, but got no error", i)
+		} else if err != nil && !test.shouldErr {
+			t.Fatalf("Test %d expected no errors, but got '%v'", i, err)
+		} else {
+			for j, n := range networks {
+				reflect.DeepEqual(test.networks[j], n)
+				if !reflect.DeepEqual(test.networks[j], n) {
+					t.Fatalf("Test %d/%d expected %v, got %v", i, j, test.networks[j], n)
+				}
+			}
+		}
+	}
+}
\ No newline at end of file