From fb29d181c33e7796847734ed50e4f30bd4f5b6df Mon Sep 17 00:00:00 2001
From: Shreyas Zare <shreyas@technitium.com>
Date: Sat, 27 Jul 2019 12:34:12 +0530
Subject: [PATCH] DhcpServer: updated no offer handling in ProcessDhcpMessage()
 for Discover request. Fixed issue with space in host name option. Removed
 using hostname from reserved lease since hostname field will be removed from
 UI. Added hostname check in UpdateDnsAuthZone() to fix  DHCP server failing
 to activate scope bug if client has not hostname. Added error handling in
 ActivateScope() to avoid partial binding of scope causing inconsistent state.

---
 DnsServerCore/Dhcp/DhcpServer.cs | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/DnsServerCore/Dhcp/DhcpServer.cs b/DnsServerCore/Dhcp/DhcpServer.cs
index 8dc71847..d7c1554e 100644
--- a/DnsServerCore/Dhcp/DhcpServer.cs
+++ b/DnsServerCore/Dhcp/DhcpServer.cs
@@ -305,7 +305,7 @@ namespace DnsServerCore.Dhcp
 
                         Lease offer = scope.GetOffer(request);
                         if (offer == null)
-                            throw new DhcpServerException("DHCP Server failed to offer address: address unavailable due to address pool exhaustion.");
+                            return null; //no offer available, do nothing
 
                         List<DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
                         if (options == null)
@@ -426,9 +426,7 @@ namespace DnsServerCore.Dhcp
                             if (clientDomainName == null)
                             {
                                 if (request.HostName != null)
-                                    clientDomainName = request.HostName.HostName + "." + scope.DomainName;
-                                else if ((leaseOffer.Type == LeaseType.Reserved) && !string.IsNullOrEmpty(leaseOffer.HostName) && !leaseOffer.HostName.EndsWith("." + scope.DomainName, StringComparison.OrdinalIgnoreCase))
-                                    clientDomainName = leaseOffer.HostName + "." + scope.DomainName; //use hostname from reserved lease
+                                    clientDomainName = request.HostName.HostName.Replace(' ', '-') + "." + scope.DomainName;
                             }
 
                             if (clientDomainName != null)
@@ -598,6 +596,9 @@ namespace DnsServerCore.Dhcp
             if (string.IsNullOrEmpty(scope.DomainName))
                 return;
 
+            if (string.IsNullOrEmpty(lease.HostName))
+                return;
+
             if (add)
             {
                 //update forward zone
@@ -720,7 +721,19 @@ namespace DnsServerCore.Dhcp
                 lock (_activeScopeLock)
                 {
                     if (_activeScopeCount < 1)
-                        BindUdpListener(_dhcpDefaultEP);
+                    {
+                        try
+                        {
+                            BindUdpListener(_dhcpDefaultEP);
+                        }
+                        catch
+                        {
+                            if (!interfaceAddress.Equals(IPAddress.Any))
+                                UnbindUdpListener(dhcpEP);
+
+                            throw;
+                        }
+                    }
 
                     _activeScopeCount++;
                 }
@@ -770,7 +783,10 @@ namespace DnsServerCore.Dhcp
                     _activeScopeCount--;
 
                     if (_activeScopeCount < 1)
+                    {
+                        _activeScopeCount = 0;
                         UnbindUdpListener(_dhcpDefaultEP);
+                    }
                 }
 
                 if (_authoritativeZoneRoot != null)