From 4358e46b02ba60e435df6f908ae1afe6516c16c5 Mon Sep 17 00:00:00 2001
From: Johann Wagner <johann.wagner@wobcom.de>
Date: Mon, 4 Jul 2022 14:59:46 +0200
Subject: [PATCH] Introducing data source for PTR record generation

---
 powerdns/provider.go                   |  4 +-
 powerdns/resource_powerdns_ptr.go      | 79 ++++++++++++++++++++++++++
 powerdns/resource_powerdns_ptr_test.go | 43 ++++++++++++++
 3 files changed, 125 insertions(+), 1 deletion(-)
 create mode 100644 powerdns/resource_powerdns_ptr.go
 create mode 100644 powerdns/resource_powerdns_ptr_test.go

diff --git a/powerdns/provider.go b/powerdns/provider.go
index d8d2040..d400754 100644
--- a/powerdns/provider.go
+++ b/powerdns/provider.go
@@ -52,7 +52,9 @@ func Provider() terraform.ResourceProvider {
 				Description: "Set cache TTL in seconds",
 			},
 		},
-
+		DataSourcesMap: map[string]*schema.Resource{
+			"powerdns_ptr": resourcePDNSPTR(),
+		},
 		ResourcesMap: map[string]*schema.Resource{
 			"powerdns_zone":   resourcePDNSZone(),
 			"powerdns_record": resourcePDNSRecord(),
diff --git a/powerdns/resource_powerdns_ptr.go b/powerdns/resource_powerdns_ptr.go
new file mode 100644
index 0000000..34d302d
--- /dev/null
+++ b/powerdns/resource_powerdns_ptr.go
@@ -0,0 +1,79 @@
+package powerdns
+
+import (
+	"fmt"
+	"github.com/hashicorp/terraform-plugin-sdk/helper/schema"
+	"net"
+	"strings"
+)
+
+func expandIPv6Address(ip net.IP) string {
+	b := make([]byte, 0, len(ip))
+
+	// Print with possible :: in place of run of zeros
+	for i := 0; i < len(ip); i += 2 {
+		if i > 0 {
+			b = append(b, ':')
+		}
+		s := (uint32(ip[i]) << 8) | uint32(ip[i+1])
+		bHex := fmt.Sprintf("%04x", s)
+		b = append(b, bHex...)
+	}
+	return string(b)
+}
+
+func resourcePDNSPTR() *schema.Resource {
+	return &schema.Resource{
+		Read: resourcePDNSPTRRead,
+		Schema: map[string]*schema.Schema{
+			"ip_address": {
+				Type:     schema.TypeString,
+				Required: true,
+				ForceNew: true,
+			},
+			"ptr_address": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+		},
+	}
+}
+
+func resourcePDNSPTRRead(d *schema.ResourceData, meta interface{}) error {
+	ipAddressStr := d.Get("ip_address").(string)
+
+	ipAddress := net.ParseIP(ipAddressStr)
+	if ipAddress == nil {
+		return fmt.Errorf("%v is not a valid IP address", ipAddressStr)
+	}
+
+	d.SetId(ipAddressStr)
+
+	ipAddress4 := ipAddress.To4()
+
+	if ipAddress4 != nil {
+		// IPv4
+		addressStringSplitted := strings.Split(ipAddress4.String(), ".")
+		reverseAddressParts := make([]string, 0)
+		for i := len(addressStringSplitted) - 1; i >= 0; i-- {
+			reverseAddressParts = append(reverseAddressParts, addressStringSplitted[i])
+		}
+		reverseAddress := strings.Join(reverseAddressParts, ".")
+
+		ptrRecord := fmt.Sprintf("%v.in-addr.arpa.", reverseAddress)
+		return d.Set("ptr_address", ptrRecord)
+	}
+
+	expandedAddress := expandIPv6Address(ipAddress)
+
+	addressStringSplitted := strings.Split(strings.ReplaceAll(expandedAddress, ":", ""), "")
+	reverseAddressParts := []string{}
+	for i := len(addressStringSplitted) - 1; i >= 0; i-- {
+		reverseAddressParts = append(reverseAddressParts, addressStringSplitted[i])
+	}
+	reverseAddress := strings.Join(reverseAddressParts, ".")
+
+	ptrRecord := fmt.Sprintf("%v.ip6.arpa.", reverseAddress)
+	return d.Set("ptr_address", ptrRecord)
+
+}
diff --git a/powerdns/resource_powerdns_ptr_test.go b/powerdns/resource_powerdns_ptr_test.go
new file mode 100644
index 0000000..f4c8c44
--- /dev/null
+++ b/powerdns/resource_powerdns_ptr_test.go
@@ -0,0 +1,43 @@
+package powerdns
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-sdk/helper/resource"
+)
+
+func TestAccPDNSPTR_v4(t *testing.T) {
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			{
+				Config: testPDNSPtrConfig4,
+				Check:  resource.TestCheckResourceAttr("data.powerdns_ptr.test4", "ptr_address", "4.3.2.1.in-addr.arpa."),
+			},
+		},
+	})
+}
+
+func TestAccPDNSPTR_v6(t *testing.T) {
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			{
+				Config: testPDNSPtrConfig6,
+				Check:  resource.TestCheckResourceAttr("data.powerdns_ptr.test6", "ptr_address", "1.1.b.6.f.a.d.1.5.e.6.7.c.0.6.d.5.9.2.0.0.c.a.8.8.0.1.8.2.0.a.2.ip6.arpa."),
+			},
+		},
+	})
+}
+
+const testPDNSPtrConfig4 = `
+data "powerdns_ptr" "test4" {
+	ip_address = "1.2.3.4"
+}`
+
+const testPDNSPtrConfig6 = `
+data "powerdns_ptr" "test6" {
+	ip_address = "2a02:8108:8ac0:295:d60c:76e5:1daf:6b11"
+}`