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DhcpServer: socket implementation redesigned to resolve cross platform issues with consistent behavior on windows and linux. FindScope() implementation changed to use IPPacketInformation for scope selection. BindUdpListener() updated with SocketOptionName.ReuseAddress to work on Unix platforms.

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This commit is contained in:
Shreyas Zare
2019-06-16 21:26:34 +05:30
parent 5c3be88616
commit 6fa2c5406b
1 changed files with 99 additions and 111 deletions
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210
DnsServerCore/Dhcp/DhcpServer.cs
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@@ -61,7 +61,7 @@ namespace DnsServerCore.Dhcp
readonly string _configFolder;
readonly List<Socket> _udpListeners = new List<Socket>();
readonly ConcurrentDictionary<IPAddress, Socket> _udpListeners = new ConcurrentDictionary<IPAddress, Socket>();
readonly List<Thread> _listenerThreads = new List<Thread>();
readonly ConcurrentDictionary<string, Scope> _scopes = new ConcurrentDictionary<string, Scope>();
@@ -69,9 +69,10 @@ namespace DnsServerCore.Dhcp
Zone _authoritativeZoneRoot;
LogManager _log;
int _serverAnyAddressScopeCount;
volatile ServiceState _state = ServiceState.Stopped;
readonly IPEndPoint _dhcpDefaultEP = new IPEndPoint(IPAddress.Any, 67);
Timer _maintenanceTimer;
const int MAINTENANCE_TIMER_INTERVAL = 10000;
@@ -128,14 +129,18 @@ namespace DnsServerCore.Dhcp
EndPoint remoteEP = new IPEndPoint(IPAddress.Any, 0);
byte[] recvBuffer = new byte[576];
int bytesRecv;
bool processOnlyUnicastMessages = !(udpListener.LocalEndPoint as IPEndPoint).Address.Equals(IPAddress.Any); //only 0.0.0.0 ip should process broadcast to avoid duplicate offers on Windows
try
{
while (true)
{
SocketFlags flags = SocketFlags.None;
IPPacketInformation ipPacketInformation;
try
{
bytesRecv = udpListener.ReceiveFrom(recvBuffer, ref remoteEP);
bytesRecv = udpListener.ReceiveMessageFrom(recvBuffer, 0, recvBuffer.Length, ref flags, ref remoteEP, out ipPacketInformation);
}
catch (SocketException ex)
{
@@ -155,13 +160,16 @@ namespace DnsServerCore.Dhcp
if (bytesRecv > 0)
{
if (processOnlyUnicastMessages && ipPacketInformation.Address.Equals(IPAddress.Broadcast))
continue;
switch ((remoteEP as IPEndPoint).Port)
{
case 67:
case 68:
try
{
ThreadPool.QueueUserWorkItem(ProcessUdpRequestAsync, new object[] { udpListener, remoteEP, new DhcpMessage(new MemoryStream(recvBuffer, 0, bytesRecv, false)) });
ThreadPool.QueueUserWorkItem(ProcessUdpRequestAsync, new object[] { udpListener, remoteEP, ipPacketInformation, new DhcpMessage(new MemoryStream(recvBuffer, 0, bytesRecv, false)) });
}
catch (Exception ex)
{
@@ -209,11 +217,12 @@ namespace DnsServerCore.Dhcp
Socket udpListener = parameters[0] as Socket;
EndPoint remoteEP = parameters[1] as EndPoint;
DhcpMessage request = parameters[2] as DhcpMessage;
IPPacketInformation ipPacketInformation = (IPPacketInformation)parameters[2];
DhcpMessage request = parameters[3] as DhcpMessage;
try
{
DhcpMessage response = ProcessDhcpMessage(request, remoteEP as IPEndPoint, udpListener.LocalEndPoint as IPEndPoint);
DhcpMessage response = ProcessDhcpMessage(request, remoteEP as IPEndPoint, ipPacketInformation);
//send response
if (response != null)
@@ -236,8 +245,11 @@ namespace DnsServerCore.Dhcp
}
else
{
//send response as broadcast on port 68
udpListener.SendTo(sendBuffer, 0, (int)sendBufferStream.Position, SocketFlags.None, new IPEndPoint(IPAddress.Broadcast, 68));
//send response as broadcast on port 68 on appropriate interface bound socket
if (!_udpListeners.TryGetValue(response.NextServerIpAddress, out Socket udpSocket))
udpSocket = udpListener; //no appropriate socket found so use default socket
udpSocket.SendTo(sendBuffer, 0, (int)sendBufferStream.Position, SocketFlags.None, new IPEndPoint(IPAddress.Broadcast, 68));
}
}
}
@@ -252,7 +264,7 @@ namespace DnsServerCore.Dhcp
}
}
private DhcpMessage ProcessDhcpMessage(DhcpMessage request, IPEndPoint remoteEP, IPEndPoint interfaceEP)
private DhcpMessage ProcessDhcpMessage(DhcpMessage request, IPEndPoint remoteEP, IPPacketInformation ipPacketInformation)
{
if (request.OpCode != DhcpMessageOpCode.BootRequest)
return null;
@@ -261,7 +273,7 @@ namespace DnsServerCore.Dhcp
{
case DhcpMessageType.Discover:
{
Scope scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
return null; //no scope available; do nothing
@@ -272,7 +284,7 @@ namespace DnsServerCore.Dhcp
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, interfaceEP.Address);
List<DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
if (options == null)
return null;
@@ -281,13 +293,16 @@ namespace DnsServerCore.Dhcp
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, interfaceEP.Address, options);
return new DhcpMessage(request, offer.Address, scope.InterfaceAddress, options);
}
case DhcpMessageType.Request:
{
//request ip address lease or extend existing lease
Scope scope;
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
return null; //no scope available; do nothing
Lease leaseOffer;
if (request.ServerIdentifier == null)
@@ -299,51 +314,38 @@ namespace DnsServerCore.Dhcp
if (request.ClientIpAddress.Equals(IPAddress.Any))
return null; //client must set IP address in ciaddr; do nothing
scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
if (scope == null)
{
//no scope available; do nothing
return null;
}
leaseOffer = scope.GetExistingLeaseOrOffer(request);
if (leaseOffer == null)
{
//no existing lease or offer available for client
//send nak
return new DhcpMessage(request, IPAddress.Any, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
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, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
return new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() });
}
}
else
{
//init-reboot
scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
if (scope == null)
{
//no scope available; do nothing
return null;
}
leaseOffer = scope.GetExistingLeaseOrOffer(request);
if (leaseOffer == null)
{
//no existing lease or offer available for client
//send nak
return new DhcpMessage(request, IPAddress.Any, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
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, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
return new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(scope.InterfaceAddress), DhcpOption.CreateEndOption() });
}
}
}
@@ -354,34 +356,26 @@ namespace DnsServerCore.Dhcp
if (request.RequestedIpAddress == null)
return null; //client MUST include this option; do nothing
if (!request.ServerIdentifier.Address.Equals(interfaceEP.Address))
if (!request.ServerIdentifier.Address.Equals(scope.InterfaceAddress))
return null; //offer declined by client; do nothing
scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
if (scope == null)
{
//no scope available
//send nak
return new DhcpMessage(request, IPAddress.Any, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
}
leaseOffer = scope.GetExistingLeaseOrOffer(request);
if (leaseOffer == null)
{
//no existing lease or offer available for client
//send nak
return new DhcpMessage(request, IPAddress.Any, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
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, interfaceEP.Address, new DhcpOption[] { new DhcpMessageTypeOption(DhcpMessageType.Nak), new ServerIdentifierOption(interfaceEP.Address), DhcpOption.CreateEndOption() });
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, interfaceEP.Address);
List<DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
if (options == null)
return null;
@@ -419,7 +413,7 @@ namespace DnsServerCore.Dhcp
}
}
return new DhcpMessage(request, leaseOffer.Address, interfaceEP.Address, options);
return new DhcpMessage(request, leaseOffer.Address, scope.InterfaceAddress, options);
}
case DhcpMessageType.Decline:
@@ -429,13 +423,13 @@ namespace DnsServerCore.Dhcp
if ((request.ServerIdentifier == null) || (request.RequestedIpAddress == null))
return null; //client MUST include these option; do nothing
if (!request.ServerIdentifier.Address.Equals(interfaceEP.Address))
return null; //request not for this server; do nothing
Scope scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
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
@@ -465,13 +459,13 @@ namespace DnsServerCore.Dhcp
if (request.ServerIdentifier == null)
return null; //client MUST include this option; do nothing
if (!request.ServerIdentifier.Address.Equals(interfaceEP.Address))
return null; //request not for this server; do nothing
Scope scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
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
@@ -498,11 +492,11 @@ namespace DnsServerCore.Dhcp
{
//need only local config; already has ip address assigned externally/manually
Scope scope = FindScope(request, remoteEP.Address, interfaceEP.Address);
Scope scope = FindScope(request, remoteEP.Address, ipPacketInformation);
if (scope == null)
return null; //no scope available; do nothing
List<DhcpOption> options = scope.GetOptions(request, interfaceEP.Address);
List<DhcpOption> options = scope.GetOptions(request, scope.InterfaceAddress);
if (options == null)
return null;
@@ -511,7 +505,7 @@ namespace DnsServerCore.Dhcp
if (log != null)
log.Write(remoteEP as IPEndPoint, "DHCP Server received INFORM message from " + request.GetClientFullIdentifier() + ".");
return new DhcpMessage(request, IPAddress.Any, interfaceEP.Address, options);
return new DhcpMessage(request, IPAddress.Any, scope.InterfaceAddress, options);
}
default:
@@ -519,23 +513,26 @@ namespace DnsServerCore.Dhcp
}
}
private Scope FindScope(DhcpMessage request, IPAddress remoteAddress, IPAddress interfaceAddress)
private Scope FindScope(DhcpMessage request, IPAddress remoteAddress, IPPacketInformation ipPacketInformation)
{
IPAddress address;
bool broadcast;
if (request.RelayAgentIpAddress.Equals(IPAddress.Any))
{
//no relay agent
if (request.ClientIpAddress.Equals(IPAddress.Any))
{
address = interfaceAddress; //broadcast request
if (!ipPacketInformation.Address.Equals(IPAddress.Broadcast))
return null; //message destination address must be broadcast address
broadcast = true; //broadcast request
}
else
{
if (!remoteAddress.Equals(request.ClientIpAddress))
return null; //client ip must match udp src addr
address = request.ClientIpAddress; //unicast request
broadcast = false; //unicast request
}
}
else
@@ -545,13 +542,24 @@ namespace DnsServerCore.Dhcp
if (!remoteAddress.Equals(request.RelayAgentIpAddress))
return null; //relay ip must match udp src addr
address = request.RelayAgentIpAddress;
broadcast = false; //unicast request
}
foreach (KeyValuePair<string, Scope> scope in _scopes)
if (broadcast)
{
if (scope.Value.InterfaceAddress.Equals(interfaceAddress) && scope.Value.IsAddressInRange(address))
return scope.Value;
foreach (KeyValuePair<string, Scope> scope in _scopes)
{
if (scope.Value.Enabled && (scope.Value.InterfaceIndex == ipPacketInformation.Interface))
return scope.Value;
}
}
else
{
foreach (KeyValuePair<string, Scope> scope in _scopes)
{
if (scope.Value.Enabled && (scope.Value.IsAddressInRange(remoteAddress)))
return scope.Value;
}
}
return null;
@@ -626,13 +634,16 @@ namespace DnsServerCore.Dhcp
#endregion
//bind to interface address
if (Environment.OSVersion.Platform == PlatformID.Unix)
udpListener.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, 1); //to allow binding to same port with different addresses
udpListener.EnableBroadcast = true;
udpListener.ExclusiveAddressUse = false;
udpListener.Bind(dhcpEP);
lock (_udpListeners)
{
_udpListeners.Add(udpListener);
}
if (!_udpListeners.TryAdd(dhcpEP.Address, udpListener))
throw new DhcpServerException("Udp listener already exists for IP address: " + dhcpEP.Address);
//start reading dhcp packets
Thread listenerThread = new Thread(ReadUdpRequestAsync);
@@ -653,24 +664,10 @@ namespace DnsServerCore.Dhcp
private bool UnbindUdpListener(IPEndPoint dhcpEP)
{
lock (_udpListeners)
if (_udpListeners.TryRemove(dhcpEP.Address, out Socket socket))
{
Socket foundSocket = null;
foreach (Socket udpListener in _udpListeners)
{
if (dhcpEP.Equals(udpListener.LocalEndPoint))
{
foundSocket = udpListener;
break;
}
}
if (foundSocket != null)
{
foundSocket.Dispose();
return _udpListeners.Remove(foundSocket);
}
socket.Dispose();
return true;
}
return false;
@@ -682,21 +679,14 @@ namespace DnsServerCore.Dhcp
try
{
//find scope interface for binding socket
scope.FindInterface();
IPAddress interfaceAddress = scope.InterfaceAddress;
dhcpEP = new IPEndPoint(interfaceAddress, 67);
if (interfaceAddress.Equals(IPAddress.Any))
{
if (_serverAnyAddressScopeCount < 1)
BindUdpListener(dhcpEP);
_serverAnyAddressScopeCount++;
}
else
{
if (!interfaceAddress.Equals(IPAddress.Any))
BindUdpListener(dhcpEP);
}
if (_authoritativeZoneRoot != null)
{
@@ -735,22 +725,8 @@ namespace DnsServerCore.Dhcp
IPAddress interfaceAddress = scope.InterfaceAddress;
dhcpEP = new IPEndPoint(interfaceAddress, 67);
if (interfaceAddress.Equals(IPAddress.Any))
{
if (_serverAnyAddressScopeCount < 2)
{
UnbindUdpListener(dhcpEP);
_serverAnyAddressScopeCount = 0;
}
else
{
_serverAnyAddressScopeCount--;
}
}
else
{
if (!interfaceAddress.Equals(IPAddress.Any))
UnbindUdpListener(dhcpEP);
}
if (_authoritativeZoneRoot != null)
{
@@ -949,6 +925,8 @@ namespace DnsServerCore.Dhcp
_state = ServiceState.Starting;
BindUdpListener(_dhcpDefaultEP);
LoadAllScopeFiles();
StartMaintenanceTimer();
@@ -964,6 +942,8 @@ namespace DnsServerCore.Dhcp
StopMaintenanceTimer();
UnbindUdpListener(_dhcpDefaultEP);
foreach (KeyValuePair<string, Scope> scope in _scopes)
UnloadScope(scope.Value);
@@ -1008,7 +988,7 @@ namespace DnsServerCore.Dhcp
}
}
public void EnableScope(string name)
public bool EnableScope(string name)
{
if (_scopes.TryGetValue(name, out Scope scope))
{
@@ -1016,11 +996,15 @@ namespace DnsServerCore.Dhcp
{
scope.SetEnabled(true);
SaveScopeFile(scope);
return true;
}
}
return false;
}
public void DisableScope(string name)
public bool DisableScope(string name)
{
if (_scopes.TryGetValue(name, out Scope scope))
{
@@ -1028,8 +1012,12 @@ namespace DnsServerCore.Dhcp
{
scope.SetEnabled(false);
SaveScopeFile(scope);
return true;
}
}
return false;
}
public void SaveScope(string name)