/**
* <summary>This provides a mechanism for a node to get a lease by using the
* Dht. This uses Dht.Create which provides an atomic operation on the Dht,
* where this node is the first to store a value at a specific key. The idea
* being that, this node being the first to store the IP, all nodes doing a
* lookup for that IP Address would be directed to this node.</summary>
* <remarks>Working with the Dht is a little tricky as transient errors could
* be misrepresented as a failed Create. It is that reason why there is a
* Renew parameter. If that is set, the algorithm for obtaining an address
* is slightly changed with more weight on reobtaining the RequestedAddr.
* </remarks>
* <param name="RequestedAddr">Optional parameter if the node would like to
* request a specific address.</param>
* <param name="Renew">Is the RequestedAddr a renewal?</param>
* <param name="node_address">The Brunet.Address where the DhtIpopNode resides
* </param>
* <param name="para">Optional, position 0 should hold the hostname.</param>
*/
public override byte[] RequestLease(byte[] RequestedAddr, bool Renew,
string node_address, params object[] para)
{
int max_renew_attempts = 1;
int renew_attempts = max_renew_attempts;
int attempts = 2;
if (Renew)
{
if (!ValidIP(RequestedAddr))
{
throw new Exception("Invalid requested address: " +
Utils.BytesToString(RequestedAddr, '.'));
}
MemBlock request_addr = MemBlock.Reference(RequestedAddr);
renew_attempts = 2;
attempts = 1;
if (request_addr.Equals(_current_ip) && DateTime.UtcNow < _current_quarter_lifetime)
{
return(_current_ip);
}
}
else if (RequestedAddr == null || !ValidIP(RequestedAddr))
{
RequestedAddr = MemBlock.Reference(RandomIPAddress());
}
byte[] hostname = null;
if (para.Length > 0 && para[0] is string)
{
string shostname = para[0] as string;
if (!shostname.Equals(string.Empty))
{
hostname = Encoding.UTF8.GetBytes(Config.Namespace + "." + shostname + "." + Dns.DomainName);
}
}
byte[] multicast_key = null;
if (_multicast)
{
multicast_key = Encoding.UTF8.GetBytes(Config.Namespace + ".multicast.ipop");
}
byte[] node_addr = Encoding.UTF8.GetBytes(node_address);
bool res = false;
while (attempts-- > 0)
{
string str_addr = Utils.BytesToString(RequestedAddr, '.');
ProtocolLog.WriteIf(IpopLog.DhcpLog, "Attempting to allocate IP Address:" + str_addr);
byte[] dhcp_key = Encoding.UTF8.GetBytes("dhcp:" + Config.Namespace + ":" + str_addr);
byte[] ip_addr = Encoding.UTF8.GetBytes(str_addr);
while (renew_attempts-- > 0)
{
try {
res = _dht.Create(dhcp_key, node_addr, Config.LeaseTime);
if (hostname != null)
{
_dht.Put(hostname, ip_addr, Config.LeaseTime);
}
if (_multicast)
{
_dht.Put(multicast_key, node_addr, Config.LeaseTime);
}
// _dht.Put(node_addr, dhcp_key, Config.LeaseTime);
}
catch (Exception e) {
ProtocolLog.WriteIf(IpopLog.DhcpLog, "Unable to allocate: " + e.Message);
res = false;
}
}
if (res)
{
_current_ip = MemBlock.Reference(RequestedAddr);
_current_quarter_lifetime = DateTime.UtcNow.AddSeconds(Config.LeaseTime / 4.0);
break;
}
else
{
// Failure! Guess a new IP address
RequestedAddr = RandomIPAddress();
renew_attempts = max_renew_attempts;
}
}
if (!res)
{
throw new Exception("Unable to get an IP Address!");
}
return(RequestedAddr);
}