/// <summary>
/// Constructs an MX record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Srv(Pointer pointer)
{
this.priority = pointer.ReadShort();
this.weight = pointer.ReadShort();
this.port = pointer.ReadShort();
this.hostname = pointer.ReadDomain();
}
/// <summary>
/// Constructs an SOA record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Soa(Pointer pointer)
{
// read all fields RFC1035 3.3.13
primaryNameServer = pointer.ReadDomain();
responsibleMailAddress = pointer.ReadDomain();
serial = pointer.ReadInt();
refresh = pointer.ReadInt();
retry = pointer.ReadInt();
expire = pointer.ReadInt();
defaultTtl = pointer.ReadInt();
}
/// <summary>
/// Construct a Response object from the supplied byte array
/// </summary>
/// <param name="message">a byte array returned from a DNS server query</param>
internal Response(byte[] message)
{
// the bit flags are in bytes 2 and 3
byte flags1 = message[2];
byte flags2 = message[3];
// get return code from lowest 4 bits of byte 3
int returnCode_ = flags2 & 15;
// if its in the reserved section, set to other
if (returnCode_ > 6) returnCode_ = 6;
returnCode = (ReturnCode)returnCode_;
// other bit flags
authoritativeAnswer = ((flags1 & 4) != 0);
recursionAvailable = ((flags2 & 128) != 0);
truncated = ((flags1 & 2) != 0);
// create the arrays of response objects
questions = new Question[GetShort(message, 4)];
answers = new Answer[GetShort(message, 6)];
nameServers = new NameServer[GetShort(message, 8)];
additionalRecords = new AdditionalRecord[GetShort(message, 10)];
// need a pointer to do this, position just after the header
Pointer pointer = new Pointer(message, 12);
// and now populate them, they always follow this order
for (int index = 0; index < questions.Length; index++)
{
try
{
// try to build a quesion from the response
questions[index] = new Question(pointer);
}
catch (Exception ex)
{
// something grim has happened, we can't continue
throw new InvalidResponseException(ex);
}
}
for (int index = 0; index < answers.Length; index++)
{
answers[index] = new Answer(pointer);
}
for (int index = 0; index < nameServers.Length; index++)
{
nameServers[index] = new NameServer(pointer);
}
for (int index = 0; index < additionalRecords.Length; index++)
{
additionalRecords[index] = new AdditionalRecord(pointer);
}
}
/// <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 = (DnsType)pointer.ReadShort();
dnsClass = (DnsClass)pointer.ReadShort();
ttl = pointer.ReadInt();
// the next short is the record length
length = pointer.ReadShort();
// and create the appropriate RDATA record based on the dnsType
switch (dnsType)
{
case DnsType.A: record = new A(pointer); break;
case DnsType.AAAA: record = new Aaaa(pointer); break;
case DnsType.Cname: record = new Cname(pointer); break;
case DnsType.HINFO: record = new HInfo(pointer); break;
case DnsType.LOC: record = new Loc(pointer); break;
case DnsType.MX: record = new MX(pointer); break;
case DnsType.NS: record = new NS(pointer); break;
case DnsType.PTR: record = new Ptr(pointer); break;
case DnsType.SOA: record = new Soa(pointer); break;
case DnsType.SRV: record = new Srv(pointer); break;
case DnsType.SSHFP: record = new SshFP(pointer); break;
case DnsType.TXT: record = new Txt(pointer, length); break;
case DnsType.NULL: record = new Null(pointer, length); break;
//mail related RR types
case DnsType.MB: record = new MB(pointer); break;
case DnsType.MD: record = new MD(pointer); break;
case DnsType.MF: record = new MF(pointer); break;
case DnsType.MG: record = new MG(pointer); break;
case DnsType.MINFO: record = new MInfo(pointer); break;
//RFC 1183 RR types
case DnsType.AFSDB: record = new Afsdb(pointer); break;
case DnsType.RP: record = new Rp(pointer); break;
default:
{
// move the pointer over this unrecognised record
pointer += length;
break;
}
}
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public SshFP(Pointer pointer)
{
//detect algorithm
byte a = pointer.ReadByte();
switch(a)
{
case 0: this.algorithm = "Reserved"; break;
case 1: this.algorithm = "RSA"; break;
case 2: this.algorithm = "DSS"; break;
default: this.algorithm = "Unknown"; break;
}
//detect fingerprint type
byte fpt = pointer.ReadByte();
switch(fpt)
{
case 0: this.fingerPrintType = "Reserved"; break;
case 1: this.fingerPrintType = "RSA-1"; break;
default: this.fingerPrintType = "Unknown"; break;
}
this.fingerPrint = pointer.ReadString(); //read the fingerprint (hex format)
}
internal NameServer(Pointer pointer)
: base(pointer)
{
}
internal Answer(Pointer pointer)
: base(pointer)
{
}
internal AdditionalRecord(Pointer pointer)
: base(pointer)
{
}
/// <summary>
/// Constructs an MX record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public MX(Pointer pointer)
{
preference = pointer.ReadShort();
hostname = pointer.ReadDomain();
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public MInfo(Pointer pointer)
{
this.ownerMailbox = pointer.ReadString();
this.errorMailbox = pointer.ReadString();
}
/// <summary>
/// Constructs an AAAA record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Aaaa(Pointer pointer)
{
byte[] b = pointer.ReadBytes(16);
ipAddress = new IPAddress(b);
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
internal Afsdb(Pointer pointer)
{
pref = pointer.ReadShort();
hostname = pointer.ReadDomain();
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Null(Pointer pointer, int length)
{
data = pointer.ReadBytes(length);
}
/// <summary>
/// Constructs a HINFO record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public HInfo(Pointer pointer)
{
this.cpu = pointer.ReadString();
this.os = pointer.ReadString();
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Txt(Pointer pointer, int length)
{
pointer.ReadByte(); //ignore first (NULL) byte
text = pointer.ReadString(length - 1);
}
/// <summary>
/// Constructs an ANAME record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public A(Pointer pointer)
{
byte[] bytes = pointer.ReadBytes(4);
ipAddress = new IPAddress(bytes);
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Ptr(Pointer pointer)
{
hostname = pointer.ReadDomain();
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public MD(Pointer pointer)
{
madname = pointer.ReadDomain();
}
/// <summary>
/// Constructs an LOC record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
public Loc(Pointer pointer)
{
int referenceAlt = 100000 * 100;
int latval, longval, altval;
version = pointer.ReadByte();
size = pointer.ReadByte();
hPrecision = pointer.ReadByte();
vPrecision = pointer.ReadByte();
latitude = pointer.ReadInt();
longitude = pointer.ReadInt();
altitude = pointer.ReadInt();
latval = latitude - (1 << 31);
longval = longitude - (1 << 31);
if (altitude < referenceAlt)
{
//below WGS 84 spheroid
altval = referenceAlt - altitude;
altsign = -1;
}
else
{
altval = altitude - referenceAlt;
altsign = 1;
}
if (latval < 0)
{
northsouth = 'S';
latval = -latval;
}
else
northsouth = 'N';
//latitude calculation
latsecfrag = latval % 1000;
latval /= 1000;
latsec = latval % 60;
latval /= 60;
latmin = latval % 60;
latval /= 60;
latdeg = latval;
if (longval < 0)
{
eastwest = 'W';
longval = -longval;
}
else
eastwest = 'E';
//longitude calculation
longsecfrag = longval % 1000;
longval /= 1000;
longsec = longval % 60;
longval /= 60;
longmin = longval % 60;
longval /= 60;
longdeg = longval;
//altitude
altfrag = altval % 100;
altmeters = (altval / 100) * altsign;
}
/// <summary>
/// Constructs a NS record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
internal Rp(Pointer pointer)
{
this.mailboxHostname = pointer.ReadDomain();
this.textHostname = pointer.ReadDomain();
}
