/// <summary>
/// Received network packet (contains entity name, message,
/// </summary>
/// <returns>The entity.</returns>
/// <param name="packet">Packet.</param>
public ValidationError ValidateEntity(ClientMessage packet, byte[] hmac, byte[] packetRaw, bool ignoreConnected = false)
{
string ts = Helpers.GetTimestamp(DateTime.Now);
if (ts != packet.Timestamp)
{
return(ValidationError.InvalidTime);
}
byte[] key = GenKey(seed1, selector);
byte[] iv = GenIV(seed2, selector);
if (entities == null)
{
return(ValidationError.NotFound);
}
bool dbValidation = ValidateDecryption(entities, key, iv);
if (!dbValidation)
{
return(ValidationError.NotFound);
}
if (ignoreConnected)
{
if (Program.server.clientHandlers.Contains(packet.Entity))
{
return(ValidationError.AlreadyConnected);
}
}
byte[] decripted = DecryptData(entities, key, iv);
List <EntityClass> _entities = Helpers.FromByteArray <List <EntityClass> >(decripted);
decripted = null;
if (_entities.Any(m => m.EntityName == packet.Entity))
{
EntityClass storedEntity = _entities.First(m => m.EntityName == packet.Entity);
byte[] calcHMAC = SHA256hmac.ComputeHMAC(packetRaw, storedEntity.Key);
return(!SHA256hmac.CompareHMAC(hmac, calcHMAC) ? ValidationError.InvalidKey : ValidationError.NoError);
}
_entities = null;
return(ValidationError.NotFound);
}
/// <summary>
/// Handles all messages received by the client (except the first one)
/// </summary>
/// <param name="m">Packet without the byte length</param>
/// <param name="clientHandler">Client handler.</param>
static void Server_MessageReceived(byte[] m, ClientHandler clientHandler)
{
IPAddress ip = ((IPEndPoint)clientHandler.Socket.Client.RemoteEndPoint).Address;
PacketType packetType = Server.DecodePacketType(m);
Server.DeconstructPacket(m, out byte[] hmac, out ClientMessage message, out byte[] raw);
if (enableDebug)
{
ReplaceWith("");
}
ProcessDebugMessage(string.Format("Message received from {0} ({1})", message.Entity, ip));
// This step allows the verification of:
// 1. if the entity is still accepted by the server
// 2. if the hmac is corect
Database.ValidationError validation = database.ValidateEntity(message, hmac, raw);
switch (validation)
{
case Database.ValidationError.NoError:
if (ClientOperations.RequestConnectedEntities.Value == message.Operation)
{
RequestedEntitiesList(clientHandler);
}
else if (ClientOperations.Disconnect.Value == message.Operation)
{
server.UserDisconnected(clientHandler.Entity);
}
else if (ClientOperations.RequestKeyNegotiation.Value == message.Operation)
{
NegotiateKey(message, clientHandler);
}
else
{
ServerCommand sv_cmd_invalid_operation = new ServerCommand
{
Command = ServerOperations.InvalidComand.Value
};
server.SendMessage(sv_cmd_invalid_operation,
PacketType.ServerCommand,
database.RetreiveEntityKey(clientHandler.Entity),
clientHandler.Socket);
}
break;
case Database.ValidationError.InvalidKey:
ProcessDebugMessage(string.Format("HMAC for message from {0} ({1}) failed!", message.Entity, ip));
ServerCommand sv_cmd_invalid_hmac = new ServerCommand
{
Command = ServerOperations.InvalidHMAC.Value,
Message = string.Format("RECEIVED_HMAC={0}|COMPUTED_HMAC={1}", hmac.FromByteArrayToHex(), SHA256hmac.ComputeHMAC(raw, database.RetreiveEntityKey(clientHandler.Entity)).FromByteArrayToHex())
};
server.SendMessage(sv_cmd_invalid_hmac,
PacketType.ServerCommand,
DEFAULT_KEY.FromHexToByteArray(),
clientHandler.Socket);
break;
case Database.ValidationError.NotFound:
ProcessDebugMessage(string.Format("Entity {0} at {1} not found!", message.Entity, ip));
ServerCommand sv_cmd_entity_not_found = new ServerCommand
{
Command = ServerOperations.EntityNoLongerAvailable.Value
};
server.SendMessage(sv_cmd_entity_not_found,
PacketType.ServerCommand,
database.RetreiveEntityKey(clientHandler.Entity),
clientHandler.Socket);
break;
case Database.ValidationError.InvalidTime:
ProcessDebugMessage("Packet time missmatch");
ServerCommand sv_cmd_ts_missmatch = new ServerCommand
{
Command = ServerOperations.InvalidTime.Value
};
server.SendMessage(sv_cmd_ts_missmatch,
PacketType.ClientMessage,
database.RetreiveEntityKey(clientHandler.Entity),
clientHandler.Socket);
break;
}
if (enableDebug)
{
Console.WriteLine("");
Console.Write("\r" + menuManager.commandPrefix);
}
}
