protected void TXTRecordCheck(DnsResourceRecord record, ref bool spfRecordExists)
{
if (spfRecordExists == false && record.ToString().Contains("spf"))
{
spfRecordExists = true;
}
WriteLineInvoke("Found TXT record " + record.ToString(), Color.Gainsboro);
Invoke(new Finished(WriteEmptyLine));
}
public static IEnumerable <string> ValueAsStrings(this DnsResourceRecord drr)
{
switch (drr)
{
case TxtRecord txt:
return(txt.Text);
default:
return(new[] { drr.ToString() });
}
}
protected void ARecordCheck(DnsResourceRecord record, ARecord arecord)
{
bool online = false;
bool acc80 = false;
bool acc443 = false;
if (InvokeRequired)
{
WriteLineInvoke("Found A record " + record.ToString(), Color.Gainsboro);
if (arecord == null || arecord.Address == null)
{
Invoke(new Finished(WriteEmptyLine));
return;
}
UpdateStatusInvoke("Attempting to ping host " + arecord.Address);
if (CanPingHost(arecord.Address))
{
online = true;
UpdateStatusInvoke("Attempting to acess host on port 80...");
if (CanReachHost(arecord.Address, 80))
{
acc80 = true;
}
UpdateStatusInvoke("Attempting to acess host on port 443...");
if (CanReachHost(arecord.Address, 443))
{
acc443 = true;
}
}
if (!online)
{
WriteStringInvoke("Host appears offline!", Color.OrangeRed);
}
else
{
WriteStringInvoke("Host online! ", Color.YellowGreen);
WriteStringInvoke("80 ", Color.Gainsboro);
if (acc80)
{
WriteStringInvoke("Open ", Color.YellowGreen);
}
else
{
WriteStringInvoke("Closed ", Color.OrangeRed);
}
WriteStringInvoke("443 ", Color.Gainsboro);
if (acc443)
{
WriteLineInvoke("Open", Color.YellowGreen);
}
else
{
WriteLineInvoke("Closed", Color.OrangeRed);
}
}
Invoke(new Finished(WriteEmptyLine));
}
}
protected void MXRecordCheck(DnsResourceRecord record, MxRecord mxrecord)
{
bool online = false;
bool acc25 = false;
bool acc465 = false;
bool acc587 = false;
bool allowsRelay = false;
if (InvokeRequired)
{
WriteLineInvoke("Found MX record " + record.ToString(), Color.Gainsboro);
if (mxrecord == null || mxrecord.Exchange == null)
{
Invoke(new Finished(WriteEmptyLine));
return;
}
UpdateStatusInvoke("Attempting to ping host " + mxrecord.Exchange);
if (CanPingHost(mxrecord.Exchange))
{
online = true;
UpdateStatusInvoke("Attempting to acess host on port 25...");
if (CanReachHost(mxrecord.Exchange, 25))
{
acc25 = true;
}
UpdateStatusInvoke("Attempting to acess host on port 465...");
if (CanReachHost(mxrecord.Exchange, 465))
{
acc465 = true;
}
UpdateStatusInvoke("Attempting to acess host on port 587...");
if (CanReachHost(mxrecord.Exchange, 587))
{
acc587 = true;
}
if (acc25)
{
UpdateStatusInvoke("Attempting to communicate using SMTP on port 25...");
EmailServerStatus ess = CheckEmailServer(mxrecord.Exchange, 25);
if (ess.AllowsRelay)
{
allowsRelay = true;
}
}
}
if (!online)
{
WriteLineInvoke("Host appears offline!", Color.OrangeRed);
}
else
{
WriteStringInvoke("Host online! ", Color.YellowGreen);
WriteStringInvoke("25 ", Color.Gainsboro);
if (acc25)
{
WriteStringInvoke("Open ", Color.YellowGreen);
}
else
{
WriteStringInvoke("Closed ", Color.OrangeRed);
}
WriteStringInvoke("465 ", Color.Gainsboro);
if (acc465)
{
WriteStringInvoke("Open ", Color.YellowGreen);
}
else
{
WriteStringInvoke("Closed ", Color.OrangeRed);
}
WriteStringInvoke("587 ", Color.Gainsboro);
if (acc587)
{
WriteLineInvoke("Open", Color.YellowGreen);
}
else
{
WriteLineInvoke("Closed", Color.OrangeRed);
}
if (allowsRelay)
{
WriteLineInvoke("Warning: Host allows relaying!", Color.OrangeRed);
}
}
Invoke(new Finished(WriteEmptyLine));
}
}
private void button1_Click(object sender, EventArgs e)
{
if (runThread != null && runThread.IsAlive)
{
runThread.Abort();
button1.Text = "Check";
return;
}
string host = Hostname;
bool checkA = CheckARecords;
bool checkAAAA = CheckAAAARecords;
bool checkMX = CheckMXRecords;
bool checkTXT = CheckTXTRecords;
bool checkSRV = CheckSRVRecords;
bool checkPTR = CheckPTRRecords;
bool validateSPF = ValidateSPFRecords;
runThread = new Thread(new ThreadStart(delegate()
{
LookupClient lookupClient = new LookupClient();
if (InvokeRequired)
{
Invoke(new WriteString(WriteStringColor), new object[] { "Checking host ", richTextBox1.ForeColor });
Invoke(new WriteString(WriteLineColor), new object[] { host, Color.YellowGreen });
Invoke(new Finished(WriteEmptyLine));
}
if (checkA)
{
var response = lookupClient.Query(host, QueryType.A);
if (response.HasError)
{
if (InvokeRequired)
{
WriteLineInvoke("Failed to retrieve A records for host", Color.OrangeRed);
Invoke(new Finished(WriteEmptyLine));
}
}
else
{
for (int i = 0; i < response.AllRecords.Count(); i++)
{
DnsResourceRecord record = response.AllRecords.ElementAt(i);
ARecord arecord = null;
if (response.Answers.Count > i)
{
arecord = response.Answers.OfType <ARecord>().ElementAt(i);
}
ARecordCheck(record, arecord);
}
}
}
if (checkMX)
{
var response = lookupClient.Query(host, QueryType.MX);
if (response.HasError)
{
if (InvokeRequired)
{
WriteLineInvoke("No MX records found for host", Color.Gainsboro);
Invoke(new Finished(WriteEmptyLine));
}
}
else
{
for (int i = 0; i < response.AllRecords.Count(); i++)
{
DnsResourceRecord record = response.AllRecords.ElementAt(i);
MxRecord mxrecord = null;
if (response.Answers.Count > i)
{
mxrecord = response.Answers.OfType <MxRecord>().ElementAt(i);
}
MXRecordCheck(record, mxrecord);
}
}
}
if (checkTXT)
{
var response = lookupClient.Query(host, QueryType.TXT);
if (response.HasError)
{
WriteLineInvoke("No TXT records found for host", Color.Gainsboro);
Invoke(new Finished(WriteEmptyLine));
}
else
{
bool foundSpfRecord = false;
bool spfIsValid = false;
for (int i = 0; i < response.AllRecords.Count(); i++)
{
DnsResourceRecord record = response.AllRecords.ElementAt(i);
TxtRecord txtrecord = null;
if (response.Answers.Count > i)
{
txtrecord = response.Answers.OfType <TxtRecord>().ElementAt(i);
}
TXTRecordCheck(record, ref foundSpfRecord);
if (record.ToString().Contains("spf1"))
{
spfIsValid = IsSPFValid(record.ToString());
}
}
if (!foundSpfRecord)
{
WriteLineInvoke("Warning: No SPF records found!", Color.OrangeRed);
}
else
{
if (!validateSPF)
{
WriteLineInvoke("Note: Use SPF Validation option to validate an SPF record", Color.Black);
}
else
{
if (spfIsValid)
{
WriteLineInvoke("SPF exists and is valid", Color.YellowGreen);
}
else
{
WriteLineInvoke("Warning: SPF exists, but doesn't appear valid", Color.OrangeRed);
}
}
}
}
}
if (InvokeRequired)
{
Invoke(new Finished(DnsCheckComplete));
UpdateStatusInvoke("Ready");
}
}));
runThread.Start();
button1.Text = "Cancel";
}
