From fe275467e8f6bed1f5b688776f54a4f6a3922c49 Mon Sep 17 00:00:00 2001
From: AliveDevil <AliveDevil@users.noreply.github.com>
Date: Sat, 6 Jan 2024 23:57:15 +0100
Subject: [PATCH] Add Opt-Out of unique hostname enforcing

---
 src/pdns-dhcp/Dns/DnsRepository.cs       | 19 ++++++++++++++-----
 src/pdns-dhcp/Options/PowerDnsOptions.cs |  4 +++-
 src/pdns-dhcp/appsettings.json           |  1 +
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/pdns-dhcp/Dns/DnsRepository.cs b/src/pdns-dhcp/Dns/DnsRepository.cs
index 6044460..ea4dba1 100644
--- a/src/pdns-dhcp/Dns/DnsRepository.cs
+++ b/src/pdns-dhcp/Dns/DnsRepository.cs
@@ -2,6 +2,10 @@ using System.Net;
 using System.Net.NetworkInformation;
 using System.Net.Sockets;
 
+using Microsoft.Extensions.Options;
+
+using pdns_dhcp.Options;
+
 using Timeout = System.Threading.Timeout;
 
 namespace pdns_dhcp.Dns;
@@ -10,10 +14,16 @@ public class DnsRepository
 {
 	private static ReadOnlySpan<int> Lifetimes => [600, 3600];
 
+	private readonly PowerDnsOptions _options;
 	private readonly ReaderWriterLockSlim _recordLock = new();
 	private readonly List<DnsRecord> _records = [];
 	private readonly SemaphoreSlim _syncLock = new(1, 1);
 
+	public DnsRepository(IOptions<PowerDnsOptions> options)
+	{
+		_options = options.Value;
+	}
+
 	public List<DnsRecord> Find(Predicate<DnsRecord> query)
 	{
 		bool enteredLock = false;
@@ -124,11 +134,10 @@ public class DnsRepository
 				{
 					list.AddLast(i);
 				}
-				// Opt-In to disallow duplicate FQDN?
-				//else if (StringComparer.InvariantCultureIgnoreCase.Equals(record.FQDN, query.FQDN))
-				//{
-				//	list.AddLast(i);
-				//}
+				else if (_options.UniqueHostnames && StringComparer.OrdinalIgnoreCase.Equals(record.FQDN, query.FQDN))
+				{
+					list.AddLast(i);
+				}
 			}
 
 			return list;
diff --git a/src/pdns-dhcp/Options/PowerDnsOptions.cs b/src/pdns-dhcp/Options/PowerDnsOptions.cs
index 003db55..a9da9c8 100644
--- a/src/pdns-dhcp/Options/PowerDnsOptions.cs
+++ b/src/pdns-dhcp/Options/PowerDnsOptions.cs
@@ -2,7 +2,9 @@ namespace pdns_dhcp.Options;
 
 public class PowerDnsOptions
 {
-	public PowerDnsListenerOptions Listener { get; set; } = default!;
+	public PowerDnsListenerOptions Listener { get; init; } = default!;
+
+	public bool UniqueHostnames { get; init; } = true;
 }
 
 public record class PowerDnsListenerOptions(string Socket);
diff --git a/src/pdns-dhcp/appsettings.json b/src/pdns-dhcp/appsettings.json
index cc80ee3..e345227 100644
--- a/src/pdns-dhcp/appsettings.json
+++ b/src/pdns-dhcp/appsettings.json
@@ -10,6 +10,7 @@
 		}
 	},
 	"PowerDns": {
+		"UniqueHostnames": true,
 		"Listener": {
 			"Socket": "/run/pdns-dhcp/pdns.sock"
 		}