private void OnTimerElapsed(Object state)
{
// get next workstation to probe
Workstation workstation = null;
{
lock (_guard)
{
if (_workstations.Count > 0)
{
// get one
workstation = _workstations[0];
// and pop it
_workstations.RemoveAt(0);
}
}
}
// see if we were able to get something
if (workstation != null)
{
log.DebugFormat("Probing workstation {0}.", workstation.DnsHostName);
// ok we have a workstation to probe, do it
List <Address> addresses = WorkstationProber.Probe(workstation);
foreach (var address in addresses)
{
log.DebugFormat("Workstation {0} will be added with address {1}.", workstation.DnsHostName, address.AsString);
lock (_guard)
{
_storage.Insert(address);
}
}
}
else
{
log.DebugFormat("No workstations to probe remaining, getting the list of existing workstations from LDAP server...");
// we do not have any workstations left, issue a call to LDAP server
List <Workstation> workstations = WorkstationHarvester.Harvest();
log.DebugFormat("Got {0} workstations from LDAP server, adding them all to probe queue.", workstations.Count);
// and update the list in class
lock (_guard)
{
_workstations = workstations;
}
}
}
public static List <Address> Probe(Workstation workstation)
{
// this is the result
List <Address> result = new List <Address>();
try
{
log.DebugFormat("Resolving workstation {0}", workstation.DnsHostName);
// get host entry (this clears DNS cache in .net too)
var hostenry = Dns.GetHostEntry(workstation.DnsHostName);
// get addresses
var addresses = hostenry.AddressList;
{
log.DebugFormat("Workstation {0} was resolved into {1} IP addresses", workstation.DnsHostName, addresses.Length);
foreach (IPAddress ip in addresses)
{
log.DebugFormat("Workstation {0} has address {1}", workstation.DnsHostName, ip.ToString());
}
}
// resolve the workstation name, get all addresses from it
foreach (IPAddress ip in addresses)
{
Address address = Prober.Probe(ip);
if (address.Users.Count == 0)
{
// log it
log.DebugFormat("Probing of address {0} for workstation {1} indicated the number of logged in users are 0, skipping it.", ip.ToString(), workstation.DnsHostName);
// there are no one logged on on that IP, skip it then
continue;;
}
// debug check we have filled in the address itself
Debug.Assert(address.IP == ip);
Debug.Assert(address.Users.Count > 0);
// assign some other fields for reference
address.DistinguishedName = workstation.DistinguishedName;
address.CommonName = workstation.CommonName;
address.DnsHostName = workstation.DnsHostName;
address.LastLogon = workstation.LastLogon;
address.Name = workstation.Name;
// log it
log.DebugFormat("Address {0} was probed successfully, {1} users found. Adding it to the storage.", ip.ToString(), address.Users.Count);
// and add this address
result.Add(address);
}
}
catch (Exception e)
{
log.WarnFormat("Probe failed for workstation {0}. Error: {1}", workstation.DnsHostName, e.Message);
}
// and return (possibly empty) list
return(result);
}
public static List <Workstation> Harvest()
{
// trace it
log.Debug("Starting LDAP search for existing workstations in the Active Directory...");
// this is the value to return
List <Workstation> result = new List <Workstation>();
// connect to LDAP
using (DirectoryEntry root = new DirectoryEntry())
{
using (DirectorySearcher searcher = new DirectorySearcher(root))
{
searcher.PropertiesToLoad.AddRange(new[] { "cn", "distinguishedName", "dNSHostName", "lastLogon", "name" });
searcher.PageSize = 1000;
searcher.ClientTimeout = new TimeSpan(0, 0, 20);
searcher.Filter = "(objectCategory=computer)";
var entries = searcher.FindAll();
foreach (SearchResult entry in entries)
{
Workstation w = new Workstation();
{
if (entry.Properties["cn"].Count > 0)
{
w.CommonName = (string)entry.Properties["cn"][0];
}
if (entry.Properties["distinguishedName"].Count > 0)
{
w.DistinguishedName = (string)entry.Properties["distinguishedName"][0];
}
if (entry.Properties["dNSHostName"].Count > 0)
{
w.DnsHostName = (string)entry.Properties["dNSHostName"][0];
}
if (entry.Properties["lastLogon"].Count > 0)
{
w.LastLogon = (Int64)entry.Properties["lastLogon"][0];
}
if (entry.Properties["name"].Count > 0)
{
w.Name = (string)entry.Properties["name"][0];
}
log.DebugFormat("Found workstation {0}", w.DnsHostName);
}
result.Add(w);
}
}
}
// trace it
log.DebugFormat("LDAP search for workstations finished, got {0} workstations.", result.Count);
// and return
return(result);
}