/// <summary>
/// Gets the equality indicator of another MX record class.
/// </summary>
/// <param name="obj">The object to compare to.</param>
/// <returns>True if the specified object is equal to this object.</returns>
public override bool Equals(object obj)
{
// this object isn't null
if (obj == null)
{
return(false);
}
// must be of same type
if (this.GetType() != obj.GetType())
{
return(false);
}
MXRecord mxOther = (MXRecord)obj;
// preference must match
if (mxOther._preference != _preference)
{
return(false);
}
// and so must the domain name
if (mxOther._domainName != _domainName)
{
return(false);
}
// its a match
return(true);
}
/// <summary>
/// Construct a resource record from a pointer to a byte array
/// </summary>
/// <param name="pointer">the position in the byte array of the record</param>
internal ResourceRecord(Pointer pointer)
{
// extract the domain, question type, question class and Ttl
_domain = pointer.ReadDomain();
_dnsType = (Nequeo.Net.Dns.DnsType)pointer.ReadShort();
_dnsClass = (Nequeo.Net.Dns.DnsClass)pointer.ReadShort();
_Ttl = pointer.ReadInt();
// the next short is the record length, we only use it for unrecognised record types
int recordLength = pointer.ReadShort();
// and create the appropriate RDATA record based on the dnsType
switch (_dnsType)
{
case Nequeo.Net.Dns.DnsType.NS:
// Set the name server record.
_record = new NSRecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.MX:
// Set the name mail exchange record.
_record = new MXRecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.A:
// Set the name A name record.
_record = new ARecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.SOA:
// Set the name SOA record.
_record = new SoaRecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.TXT:
// Set the name TXT record.
_record = new TxtRecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.WKS:
// Set the name WKS record.
_record = new WksRecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.PTR:
// Set the name PTR record.
_record = new PtrRecord(pointer);
break;
case Nequeo.Net.Dns.DnsType.HINFO:
// Set the name HINFO record.
_record = new HInfoRecord(pointer);
break;
default:
// move the pointer over this unrecognised record
pointer += recordLength;
break;
}
}
/// <summary>
/// Shorthand form to make MX querying easier, essentially wraps up the retreival
/// of the MX records, and sorts them by preference
/// </summary>
/// <param name="domain">domain name to retreive MX RRs for</param>
/// <param name="port">the port number used by the domain name server.</param>
/// <param name="ipAddress">the ip address of the domain name server.</param>
/// <param name="protocolType">the protocol type used by the domain name server.</param>
/// <param name="useIPv4EndPoint">use only an IPv4 connection and disregard all other address families (IPv6).</param>
/// <returns>An array of MXRecords</returns>
internal MXRecord[] MXLookup(string domain, int port,
string ipAddress, Nequeo.Net.Dns.ProtocolType protocolType, bool useIPv4EndPoint)
{
// check the inputs
if (domain == null)
{
throw new ArgumentNullException("domain");
}
if (port < 1)
{
throw new IndexOutOfRangeException("port");
}
// create a request for this
Request request = new Request();
// add one question - the MX IN lookup for the supplied domain
request.AddQuestion(new Question(domain, Nequeo.Net.Dns.DnsType.MX, Nequeo.Net.Dns.DnsClass.IN));
// fire it off
Response response = Lookup(request, domain, port, ipAddress, protocolType, useIPv4EndPoint);
// if we didn't get a response, then return null
if (response == null)
{
return(null);
}
// create a growable array of MX records
ArrayList resourceRecords = new ArrayList();
// add each of the answers to the array
foreach (Answer answer in response.Answers)
{
// if the answer is an MX record
if (answer.Record.GetType() == typeof(MXRecord))
{
// add it to our array
resourceRecords.Add(answer.Record);
}
}
// create array of MX records
MXRecord[] mxRecords = new MXRecord[resourceRecords.Count];
// copy from the array list
resourceRecords.CopyTo(mxRecords);
// sort into lowest preference order
Array.Sort(mxRecords);
// and return
return(mxRecords);
}
/// <summary>
/// Implements the IComparable interface so that we can sort the MX records by their
/// lowest preference
/// </summary>
/// <param name="obj">the other MxRecord to compare against</param>
/// <returns>1, 0, -1</returns>
public int CompareTo(object obj)
{
MXRecord mxOther = (MXRecord)obj;
// we want to be able to sort them by preference
if (mxOther._preference < _preference)
{
return(1);
}
if (mxOther._preference > _preference)
{
return(-1);
}
// order mail servers of same preference by name
return(-mxOther._domainName.CompareTo(_domainName));
}
