Make PTR more magical (#148)

* Initial code and tests

docs/_functions/domain/PTR.md

@@ -0,0 +1,40 @@
+---
+name: PTR
+parameters:
+  - name
+  - target
+  - modifiers...
+---
+
+PTR adds a PTR record to the domain.
+
+The name should be the relative label for the domain, or may be a FQDN that ends with `.`.
+
+* If the name is a valid IP address, DNSControl will *magically* replace it with a string that is appropriate for the domain. That is, if the domain ends with `in-addr.arpa` it will generate the IPv4-style reverse name; if the domain ends with `ipv6.arpa` it will generate the IPv6-style reverse name.  DNSControl will truncate it as appropriate for the netmask.
+* If the name ends with `in-addr.arpa.` or `ipv6.arpa.` (not the `.` at the end), DNSControl will truncate it as appropriate for the domain. If the FQDN does not fit within the domain, this will raise an error.
+
+Target should be a string representing the FQDN of a host.  Like all FQDNs in DNSControl, it must end with a `.`.
+
+{% include startExample.html %}
+{% highlight js %}
+D(REV('1.2.3.0/24'), REGISTRAR, DnsProvider(BIND),
+  PTR('1', 'foo.example.com.'),
+  PTR('2', 'bar.example.com.'),
+  PTR('3', 'baz.example.com.'),
+  // If the first parameter is a valid IP address, DNSControl will generate the correct name:
+  PTR('1.2.3.10', 'ten.example.com.'),    // '10'
+);
+
+D(REV('2001:db8:302::/48'), REGISTRAR, DnsProvider(BIND),
+  PTR('1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0', 'foo.example.com.'),  // 2001:db8:302::1
+  // If the first parameter is a valid IP address, DNSControl will generate the correct name:
+  PTR('2001:db8:302::2', 'two.example.com.'),                          // '2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0'
+  PTR('2001:db8:302::3', 'three.example.com.'),                        // '3.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0'
+);
+
+{%endhighlight%}
+{% include endExample.html %}
+
+In the future we plan on adding a flag to `A()` which will insert
+the correct PTR() record if the approprate `.arpa` domain has been
+defined.

docs/_functions/global/REV.md

@@ -22,11 +22,21 @@ D(REV('1.2.3.0/24'), REGISTRAR, DnsProvider(BIND),
   PTR("1", 'foo.example.com.'),
   PTR("2", 'bar.example.com.'),
   PTR("3", 'baz.example.com.'),
+  // These take advantage of DNSControl's ability to generate the right name:
+  PTR("1.2.3.10", 'ten.example.com.'),
 );
 
 D(REV('2001:db8:302::/48'), REGISTRAR, DnsProvider(BIND),
   PTR("1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0", 'foo.example.com.'),  // 2001:db8:302::1
+  // These take advantage of DNSControl's ability to generate the right name:
+  PTR("2001:db8:302::2", 'two.example.com.'),                          // 2.0.0. etc. etc.
+  PTR("2001:db8:302::3", 'three.example.com.'),                        // 
 );
 
+
 {%endhighlight%}
 {% include endExample.html %}
+
+In the future we plan on adding a flag to `A()` which will insert 
+the correct PTR() record if the approprate `D(REV()` domain (i.e. `.arpa` domain) has been
+defined.

integrationTest/integration_test.go

@@ -219,6 +219,10 @@ func mx(name string, prio uint16, target string) *rec {
 	return r
 }
 
+func ptr(name, target string) *rec {
+	return makeRec(name, target, "PTR")
+}
+
 func makeRec(name, target, typ string) *rec {
 	return &rec{
 		Name:   name,
@@ -288,6 +292,11 @@ var tests = []*TestCase{
 	tc("Change to other name", mx("@", 5, "foo2.com."), mx("mail", 15, "foo3.com.")),
 	tc("Change Priority", mx("@", 7, "foo2.com."), mx("mail", 15, "foo3.com.")),
 
+	//PTR
+	tc("Empty"),
+	tc("Create PTR record", ptr("4", "foo.com.")),
+	tc("Modify PTR record", ptr("4", "bar.com.")),
+
 	//ALIAS
 	tc("EMPTY"),
 	tc("ALIAS at root", alias("@", "foo.com.")).IfHasCapability(providers.CanUseAlias),

integrationTest/zones/example.com.zone

@@ -1,2 +1,4 @@
 $TTL 300
-@                IN SOA   DEFAULT_NOT_SET. DEFAULT_NOT_SET. 2017041717 3600 600 604800 1440
+@                IN SOA   DEFAULT_NOT_SET. DEFAULT_NOT_SET. 2017070632 3600 600 604800 1440
+                 IN NS    ns1.otherdomain.tld.
+                 IN NS    ns2.otherdomain.tld.

pkg/normalize/validate.go

@@ -273,6 +273,11 @@ func NormalizeAndValidateConfig(config *models.DNSConfig) (errs []error) {
 				rec.Target = dnsutil.AddOrigin(rec.Target, domain.Name+".")
 			} else if rec.Type == "A" || rec.Type == "AAAA" {
 				rec.Target = net.ParseIP(rec.Target).String()
+			} else if rec.Type == "PTR" {
+				var err error
+				if rec.Name, err = transform.PtrNameMagic(rec.Name, domain.Name); err != nil {
+					errs = append(errs, err)
+				}
 			}
 			// Populate FQDN:
 			rec.NameFQDN = dnsutil.AddOrigin(rec.Name, domain.Name)

pkg/transform/arpa.go

@@ -32,7 +32,7 @@ func ReverseDomainName(cidr string) (string, error) {
 		}
 		toTrim = (total - bits) / 4
 	} else {
-		return "", fmt.Errorf("Invalid mask bit size: %d", total)
+		return "", fmt.Errorf("Address is not IPv4 or IPv6: %v", cidr)
 	}
 
 	parts := strings.SplitN(base, ".", toTrim+1)

pkg/transform/ptr.go

@@ -0,0 +1,69 @@
+package transform
+
+import (
+	"net"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+func PtrNameMagic(name, domain string) (string, error) {
+	// Implement the PTR name magic.  If the name is a properly formed
+	// IPv4 or IPv6 address, we replace it with the right string (i.e
+	// reverse it and truncate it).
+
+	// If the name is already in-addr.arpa or ipv6.arpa,
+	// make sure the domain matches.
+	if strings.HasSuffix(name, ".in-addr.arpa.") || strings.HasSuffix(name, ".ip6.arpa.") {
+		if strings.HasSuffix(name, "."+domain+".") {
+			return strings.TrimSuffix(name, "."+domain+"."), nil
+		} else {
+			return name, errors.Errorf("PTR record %v in wrong domain (%v)", name, domain)
+		}
+	}
+
+	// If the domain is .arpa, we do magic.
+	if strings.HasSuffix(domain, ".in-addr.arpa") {
+		return ipv4magic(name, domain)
+	} else if strings.HasSuffix(domain, ".ip6.arpa") {
+		return ipv6magic(name, domain)
+	} else {
+		return name, nil
+	}
+}
+
+func ipv4magic(name, domain string) (string, error) {
+	// Not a valid IPv4 address. Leave it alone.
+	ip := net.ParseIP(name)
+	if ip == nil || ip.To4() == nil || !strings.Contains(name, ".") {
+		return name, nil
+	}
+
+	// Reverse it.
+	rev, err := ReverseDomainName(ip.String() + "/32")
+	if err != nil {
+		return name, err
+	}
+	if !strings.HasSuffix(rev, "."+domain) {
+		err = errors.Errorf("ERROR: PTR record %v in wrong IPv4 domain (%v)", name, domain)
+	}
+	return strings.TrimSuffix(rev, "."+domain), err
+}
+
+func ipv6magic(name, domain string) (string, error) {
+	// Not a valid IPv6 address. Leave it alone.
+	ip := net.ParseIP(name)
+	if ip == nil || len(ip) != 16 || !strings.Contains(name, ":") {
+		return name, nil
+	}
+
+	// Reverse it.
+	rev, err := ReverseDomainName(ip.String() + "/128")
+	if err != nil {
+		return name, err
+	}
+	if !strings.HasSuffix(rev, "."+domain) {
+		err = errors.Errorf("ERROR: PTR record %v in wrong IPv6 domain (%v)", name, domain)
+	}
+	return strings.TrimSuffix(rev, "."+domain), err
+}

pkg/transform/ptr_test.go

@@ -0,0 +1,77 @@
+package transform
+
+import (
+	"fmt"
+	"testing"
+)
+
+// ptrmagic(name, domain string, al int) (string, error)
+
+func TestPtrMagic(t *testing.T) {
+	tests := []struct {
+		name   string
+		domain string
+		output string
+		fail   bool
+	}{
+		// Magic IPv4:
+		{"1.2.3.4", "3.2.1.in-addr.arpa", "4", false},
+		{"1.2.3.4", "2.1.in-addr.arpa", "4.3", false},
+		{"1.2.3.4", "1.in-addr.arpa", "4.3.2", false},
+
+		// No magic IPv4:
+		{"1", "2.3.4.in-addr.arpa", "1", false},
+		{"1.2", "3.4.in-addr.arpa", "1.2", false},
+		{"1.2.3", "4.in-addr.arpa", "1.2.3", false},
+		{"1.2.3.4", "in-addr.arpa", "1.2.3.4", false}, // Not supported, but it works.
+
+		// Magic IPv6:
+		{"1", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1", false},
+		{"1.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0", false},
+		{"1.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0", false},
+		{"1.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0", false},
+		{"1.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0", false},
+		{"1.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0.0.0.0.0", false},
+		{"1.0.0.0.0.0.0.0.0.0.0.0.0.0", "0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0.0.0.0.0.0", false},
+
+		// If it doesn't end in .arpa, the magic is disabled:
+		{"1.2.3.4", "example.com", "1.2.3.4", false},
+		{"1", "example.com", "1", false},
+		{"1.0.0.0", "example.com", "1.0.0.0", false},
+		{"1.0.0.0.0.0.0.0", "example.com", "1.0.0.0.0.0.0.0", false},
+
+		// User manually reversed addresses:
+		{"1.1.1.1.in-addr.arpa.", "1.1.in-addr.arpa", "1.1", false},
+		{"1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.",
+			"0.2.ip6.arpa", "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0", false},
+
+		// Error cases:
+		{"1.1.1.1.in-addr.arpa.", "2.2.in-addr.arpa", "", true},
+		{"1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.", "9.9.ip6.arpa", "", true},
+		{"3.3.3.3", "4.4.in-addr.arpa", "", true},
+		{"2001:db8::1", "9.9.ip6.arpa", "", true},
+
+		// These should be errors but we don't check for them at this time:
+		//{"blurg", "3.4.in-addr.arpa", "blurg", true},
+		//{"1", "3.4.in-addr.arpa", "1", true},
+	}
+	for _, tst := range tests {
+		t.Run(fmt.Sprintf("%s %s", tst.name, tst.domain), func(t *testing.T) {
+			o, errs := PtrNameMagic(tst.name, tst.domain)
+			if errs != nil && !tst.fail {
+				t.Errorf("Got error but expected none (%v)", errs)
+			} else if errs == nil && tst.fail {
+				t.Errorf("Expected error but got none (%v)", o)
+			} else if errs == nil && o != tst.output {
+				t.Errorf("Got (%v) expected (%v)", o, tst.output)
+			}
+		})
+	}
+}