private DhcpMessage ProcessDhcpMessage(DhcpMessage request, IPEndPoint remoteEP, IPPacketInformation ipPacketInformation)
{
if (request.OpCode != DhcpMessageOpCode.BootRequest)
{
return(null);
}
switch (request.DhcpMessageType?.Type)
{
case DhcpMessageType.Discover:
{
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
{
return(null); //no scope available; do nothing
}
if (scope.OfferDelayTime > 0)
{
Thread.Sleep(scope.OfferDelayTime); //delay sending offer
}
Lease offer = scope.GetOffer(request);
if (offer == null)
{
throw new DhcpServerException("DHCP Server failed to offer address: address unavailable due to address pool exhaustion.");
}
List <DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
if (options == null)
{
return(null);
}
//log ip offer
LogManager log = _log;
if (log != null)
{
log.Write(remoteEP as IPEndPoint, "DHCP Server offered IP address [" + offer.Address.ToString() + "] to " + request.GetClientFullIdentifier() + ".");
}
return(new DhcpMessage(request, offer.Address, scope.InterfaceAddress, options));
}
case DhcpMessageType.Request:
{
//request ip address lease or extend existing lease
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
{
return(null); //no scope available; do nothing
}
Lease leaseOffer;
if (request.ServerIdentifier == null)
{
if (request.RequestedIpAddress == null)
{
//renewing or rebinding
if (request.ClientIpAddress.Equals(IPAddress.Any))
{
return(null); //client must set IP address in ciaddr; do nothing
}
leaseOffer = scope.GetExistingLeaseOrOffer(request);
if (leaseOffer == null)
{
//no existing lease or offer available for client
//send nak
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() }));
}
if (!request.ClientIpAddress.Equals(leaseOffer.Address))
{
//client ip is incorrect
//send nak
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() }));
}
}
else
{
//init-reboot
leaseOffer = scope.GetExistingLeaseOrOffer(request);
if (leaseOffer == null)
{
//no existing lease or offer available for client
//send nak
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() }));
}
if (!request.RequestedIpAddress.Address.Equals(leaseOffer.Address))
{
//the client's notion of its IP address is not correct - RFC 2131
//send nak
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() }));
}
}
}
else
{
//selecting offer
if (request.RequestedIpAddress == null)
{
return(null); //client MUST include this option; do nothing
}
if (!request.ServerIdentifier.Address.Equals(scope.InterfaceAddress))
{
return(null); //offer declined by client; do nothing
}
leaseOffer = scope.GetExistingLeaseOrOffer(request);
if (leaseOffer == null)
{
//no existing lease or offer available for client
//send nak
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() }));
}
if (!request.RequestedIpAddress.Address.Equals(leaseOffer.Address))
{
//requested ip is incorrect
//send nak
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() }));
}
}
List <DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
if (options == null)
{
return(null);
}
scope.CommitLease(leaseOffer);
//log ip lease
LogManager log = _log;
if (log != null)
{
log.Write(remoteEP as IPEndPoint, "DHCP Server leased IP address [" + leaseOffer.Address.ToString() + "] to " + request.GetClientFullIdentifier() + ".");
}
if (!string.IsNullOrEmpty(scope.DomainName))
{
//update dns
string clientDomainName = null;
foreach (DhcpOption option in options)
{
if (option.Code == DhcpOptionCode.ClientFullyQualifiedDomainName)
{
clientDomainName = (option as ClientFullyQualifiedDomainNameOption).DomainName;
break;
}
}
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
}
}
if (clientDomainName != null)
{
leaseOffer.SetHostName(clientDomainName.ToLower());
UpdateDnsAuthZone(true, scope, leaseOffer);
}
}
return(new DhcpMessage(request, leaseOffer.Address, scope.InterfaceAddress, options));
}
case DhcpMessageType.Decline:
{
//ip address is already in use as detected by client via ARP
if ((request.ServerIdentifier == null) || (request.RequestedIpAddress == null))
{
return(null); //client MUST include these option; do nothing
}
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
{
return(null); //no scope available; do nothing
}
if (!request.ServerIdentifier.Address.Equals(scope.InterfaceAddress))
{
return(null); //request not for this server; do nothing
}
Lease lease = scope.GetExistingLeaseOrOffer(request);
if (lease == null)
{
return(null); //no existing lease or offer available for client; do nothing
}
if (!lease.Address.Equals(request.RequestedIpAddress.Address))
{
return(null); //the client's notion of its IP address is not correct; do nothing
}
//remove lease since the IP address is used by someone else
scope.ReleaseLease(lease);
//log issue
LogManager log = _log;
if (log != null)
{
log.Write(remoteEP as IPEndPoint, "DHCP Server received DECLINE message: " + lease.GetClientFullIdentifier() + " detected that IP address [" + lease.Address + "] is already in use.");
}
//update dns
UpdateDnsAuthZone(false, scope, lease);
//do nothing
return(null);
}
case DhcpMessageType.Release:
{
//cancel ip address lease
if (request.ServerIdentifier == null)
{
return(null); //client MUST include this option; do nothing
}
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
{
return(null); //no scope available; do nothing
}
if (!request.ServerIdentifier.Address.Equals(scope.InterfaceAddress))
{
return(null); //request not for this server; do nothing
}
Lease lease = scope.GetExistingLeaseOrOffer(request);
if (lease == null)
{
return(null); //no existing lease or offer available for client; do nothing
}
if (!lease.Address.Equals(request.ClientIpAddress))
{
return(null); //the client's notion of its IP address is not correct; do nothing
}
//release lease
scope.ReleaseLease(lease);
//log ip lease release
LogManager log = _log;
if (log != null)
{
log.Write(remoteEP as IPEndPoint, "DHCP Server released IP address [" + lease.Address.ToString() + "] that was leased to " + lease.GetClientFullIdentifier() + ".");
}
//update dns
UpdateDnsAuthZone(false, scope, lease);
//do nothing
return(null);
}
case DhcpMessageType.Inform:
{
//need only local config; already has ip address assigned externally/manually
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
{
return(null); //no scope available; do nothing
}
List <DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
if (options == null)
{
return(null);
}
//log inform
LogManager log = _log;
if (log != null)
{
log.Write(remoteEP as IPEndPoint, "DHCP Server received INFORM message from " + request.GetClientFullIdentifier() + ".");
}
return(new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, options));
}
default:
return(null);
}
}
internal List <DhcpOption> GetOptions(DhcpMessage request, IPAddress serverIdentifierAddress)
{
List <DhcpOption> options = new List <DhcpOption>();
switch (request.DhcpMessageType.Type)
{
case DhcpMessageType.Discover:
options.Add(new DhcpMessageTypeOption(DhcpMessageType.Offer));
break;
case DhcpMessageType.Request:
case DhcpMessageType.Inform:
options.Add(new DhcpMessageTypeOption(DhcpMessageType.Ack));
break;
default:
return(null);
}
options.Add(new ServerIdentifierOption(serverIdentifierAddress));
switch (request.DhcpMessageType.Type)
{
case DhcpMessageType.Discover:
case DhcpMessageType.Request:
uint leaseTime = GetLeaseTime();
options.Add(new IpAddressLeaseTimeOption(leaseTime));
options.Add(new RenewalTimeValueOption(leaseTime / 2));
options.Add(new RebindingTimeValueOption(Convert.ToUInt32(leaseTime * 0.875)));
break;
}
if (request.ParameterRequestList == null)
{
options.Add(new SubnetMaskOption(_subnetMask));
options.Add(new BroadcastAddressOption(_broadcastAddress));
if (!string.IsNullOrEmpty(_domainName))
{
options.Add(new DomainNameOption(_domainName));
if (request.ClientFullyQualifiedDomainName != null)
{
options.Add(GetClientFullyQualifiedDomainNameOption(request));
}
}
if (_routerAddress != null)
{
options.Add(new RouterOption(new IPAddress[] { _routerAddress }));
}
if (_dnsServers != null)
{
options.Add(new DomainNameServerOption(_dnsServers));
}
if (_winsServers != null)
{
options.Add(new NetBiosNameServerOption(_winsServers));
}
if (_ntpServers != null)
{
options.Add(new NetworkTimeProtocolServersOption(_ntpServers));
}
if (_staticRoutes != null)
{
options.Add(new ClasslessStaticRouteOption(_staticRoutes));
}
}
else
{
foreach (DhcpOptionCode optionCode in request.ParameterRequestList.OptionCodes)
{
switch (optionCode)
{
case DhcpOptionCode.SubnetMask:
options.Add(new SubnetMaskOption(_subnetMask));
options.Add(new BroadcastAddressOption(_broadcastAddress));
break;
case DhcpOptionCode.DomainName:
if (!string.IsNullOrEmpty(_domainName))
{
options.Add(new DomainNameOption(_domainName));
if (request.ClientFullyQualifiedDomainName != null)
{
options.Add(GetClientFullyQualifiedDomainNameOption(request));
}
}
break;
case DhcpOptionCode.Router:
if (_routerAddress != null)
{
options.Add(new RouterOption(new IPAddress[] { _routerAddress }));
}
break;
case DhcpOptionCode.DomainNameServer:
if (_dnsServers != null)
{
options.Add(new DomainNameServerOption(_dnsServers));
}
break;
case DhcpOptionCode.NetBiosOverTcpIpNameServer:
if (_winsServers != null)
{
options.Add(new NetBiosNameServerOption(_winsServers));
}
break;
case DhcpOptionCode.NetworkTimeProtocolServers:
if (_ntpServers != null)
{
options.Add(new NetworkTimeProtocolServersOption(_ntpServers));
}
break;
case DhcpOptionCode.ClasslessStaticRoute:
if (_staticRoutes != null)
{
options.Add(new ClasslessStaticRouteOption(_staticRoutes));
}
break;
}
}
}
options.Add(DhcpOption.CreateEndOption());
return(options);
}