public void ChangeNetwork(IPAddress startingAddress, IPAddress endingAddress, IPAddress subnetMask)
{
if (startingAddress.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentException("Address family not supported.", nameof(startingAddress));
}
if (endingAddress.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentException("Address family not supported.", nameof(endingAddress));
}
if (subnetMask.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentException("Address family not supported.", nameof(subnetMask));
}
uint startingAddressNumber = startingAddress.ConvertIpToNumber();
uint endingAddressNumber = endingAddress.ConvertIpToNumber();
if (startingAddressNumber >= endingAddressNumber)
{
throw new ArgumentException("Ending address must be greater than starting address.");
}
_startingAddress = startingAddress;
_endingAddress = endingAddress;
_subnetMask = subnetMask;
//compute other parameters
uint subnetMaskNumber = _subnetMask.ConvertIpToNumber();
uint networkAddressNumber = startingAddressNumber & subnetMaskNumber;
uint broadcastAddressNumber = networkAddressNumber | ~subnetMaskNumber;
if (networkAddressNumber == startingAddressNumber)
{
throw new ArgumentException("Starting address cannot be same as the network address.");
}
if (broadcastAddressNumber == endingAddressNumber)
{
throw new ArgumentException("Ending address cannot be same as the broadcast address.");
}
_networkAddress = IPAddressExtension.ConvertNumberToIp(networkAddressNumber);
_broadcastAddress = IPAddressExtension.ConvertNumberToIp(broadcastAddressNumber);
_reverseZone = Zone.GetReverseZone(_networkAddress, _subnetMask);
lock (_lastAddressOfferedLock)
{
_lastAddressOffered = IPAddressExtension.ConvertNumberToIp(startingAddressNumber - 1u);
}
}
internal Lease GetOffer(DhcpMessage request)
{
if (_leases.TryGetValue(request.ClientIdentifier, out Lease existingLease))
{
//lease already exists
return(existingLease);
}
if (_reservedLeases != null)
{
ClientIdentifierOption clientIdentifierKey = new ClientIdentifierOption(1, request.ClientHardwareAddress);
foreach (Lease reservedLease in _reservedLeases)
{
if (reservedLease.ClientIdentifier.Equals(clientIdentifierKey))
{
//reserved address exists
IPAddress reservedLeaseAddress = reservedLease.Address;
if (!IsAddressAvailable(ref reservedLeaseAddress))
{
break; //reserved lease address is already allocated so ignore reserved lease
}
Lease reservedOffer = new Lease(LeaseType.Reserved, request.ClientIdentifier, request.HostName?.HostName, request.ClientHardwareAddress, reservedLease.Address, null, GetLeaseTime());
return(_offers.AddOrUpdate(request.ClientIdentifier, reservedOffer, delegate(ClientIdentifierOption key, Lease existingValue)
{
return reservedOffer;
}));
}
}
}
if (_allowOnlyReservedLeases)
{
throw new DhcpServerException("DHCP Server failed to offer IP address to " + request.GetClientFullIdentifier() + ": scope allows only reserved lease allocations.");
}
Lease dummyOffer = new Lease(LeaseType.None, null, null, null, null, null, 0);
Lease existingOffer = _offers.GetOrAdd(request.ClientIdentifier, dummyOffer);
if (dummyOffer != existingOffer)
{
if (existingOffer.Type == LeaseType.None)
{
return(null); //dummy offer so another thread is handling offer; do nothing
}
//offer already exists
existingOffer.ExtendLease(GetLeaseTime());
return(existingOffer);
}
//find offer ip address
IPAddress offerAddress = null;
if (request.RequestedIpAddress != null)
{
//client wish to get this address
IPAddress requestedAddress = request.RequestedIpAddress.Address;
if (IsAddressInRange(requestedAddress) && IsAddressAvailable(ref requestedAddress))
{
offerAddress = requestedAddress;
}
}
if (offerAddress == null)
{
lock (_lastAddressOfferedLock)
{
//find free address from scope
offerAddress = _lastAddressOffered;
uint endingAddressNumber = _endingAddress.ConvertIpToNumber();
bool offerAddressWasResetFromEnd = false;
while (true)
{
uint nextOfferAddressNumber = offerAddress.ConvertIpToNumber() + 1u;
if (nextOfferAddressNumber > endingAddressNumber)
{
if (offerAddressWasResetFromEnd)
{
throw new DhcpServerException("DHCP Server failed to offer IP address to " + request.GetClientFullIdentifier() + ": address unavailable due to address pool exhaustion.");
}
offerAddress = IPAddressExtension.ConvertNumberToIp(_startingAddress.ConvertIpToNumber() - 1u);
offerAddressWasResetFromEnd = true;
continue;
}
offerAddress = IPAddressExtension.ConvertNumberToIp(nextOfferAddressNumber);
if (IsAddressAvailable(ref offerAddress))
{
break;
}
}
_lastAddressOffered = offerAddress;
}
}
Lease offerLease = new Lease(LeaseType.Dynamic, request.ClientIdentifier, request.HostName?.HostName, request.ClientHardwareAddress, offerAddress, null, GetLeaseTime());
return(_offers.AddOrUpdate(request.ClientIdentifier, offerLease, delegate(ClientIdentifierOption key, Lease existingValue)
{
return offerLease;
}));
}