/// <summary>
/// Construct the question reading from a DNS Server response.
/// </summary>
/// <param name="pointer">A logical pointer to the Question in byte array form.</param>
internal Question(RecordPointer pointer)
{
// extract from the pointer
domain_ = pointer.GetDomain();
dns_type_ = (DnsType)pointer.GetShort();
dns_class_ = (DnsClass)pointer.GetShort();
}
/// <summary>
/// Initializes a new instance_ of the Response class by parsing the message reponse.
/// </summary>
/// <param name="message">A byte array that contains the response message.</param>
internal Response(byte[] message) {
if (message == null)
throw new ArgumentException("message");
// ID - 16 bits
// QR - 1 bit
// Opcode - 4 bits
// AA, TC, RD - 3 bits
byte flags1 = message[2];
// RA, Z - 2 bits
// RCODE - 4 bits
byte flags2 = message[3];
long counts = message[3];
// adjust the return code
int return_code = (flags2 & (byte)0x3c) >> 2;
return_code_ = (return_code > 6) ? ReturnCode.Other : (ReturnCode)return_code;
// other bit flags
authoritative_answer_ = ((flags1 & 4) != 0);
recursion_available_ = ((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)];
name_servers_ = new NameServer[GetShort(message, 8)];
additional_records_ = new AdditionalRecord[GetShort(message, 10)];
// need a pointer to do this, position just after the header
RecordPointer pointer = new RecordPointer(message, 12);
// and now populate them, they always follow this order
for (int i = 0; i < questions_.Length; i++) {
try {
questions_[i] = new Question(pointer);
} catch(Exception ex) {
throw new InvalidResponseException(ex);
}
}
for (int i = 0; i < answers_.Length; i++) {
answers_[i] = new Answer(pointer);
}
for (int i = 0; i < name_servers_.Length; i++) {
name_servers_[i] = new NameServer(pointer);
}
for (int i = 0; i < additional_records_.Length; i++) {
additional_records_[i] = new AdditionalRecord(pointer);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="ResourceRecord"/> class by using the specified
/// pointer.
/// </summary>
/// <param name="pointer">The position in the byte array of the record.</param>
internal ResourceRecord(RecordPointer pointer) {
domain_ = pointer.GetDomain();
dns_type_ = (DnsType)pointer.GetShort();
dns_class_ = (DnsClass)pointer.GetShort();
ttl_ = pointer.GetInt();
// the next short is the record length, we only use it for unrecognised record types.
int length = pointer.GetShort();
switch(dns_type_) {
case DnsType.MX:
record_ = new MXRecord(pointer);
break;
default:
// move the pointer over this unrecognised record
pointer += length;
break;
}
}
/// <summary>
/// Initializes a new instance of the <see cref="ResourceRecord"/> class by using the specified
/// pointer.
/// </summary>
/// <param name="pointer">The position in the byte array of the record.</param>
internal ResourceRecord(RecordPointer pointer)
{
domain_ = pointer.GetDomain();
dns_type_ = (DnsType)pointer.GetShort();
dns_class_ = (DnsClass)pointer.GetShort();
ttl_ = pointer.GetInt();
// the next short is the record length, we only use it for unrecognised record types.
int length = pointer.GetShort();
switch (dns_type_)
{
case DnsType.MX:
record_ = new MXRecord(pointer);
break;
default:
// move the pointer over this unrecognised record
pointer += length;
break;
}
}
internal AdditionalRecord(RecordPointer pointer) : base(pointer)
{
}
internal AdditionalRecord(RecordPointer pointer) : base(pointer) { }
/// <summary>
/// Initializes a new instance_ of the Response class by parsing the message reponse.
/// </summary>
/// <param name="message">A byte array that contains the response message.</param>
internal Response(byte[] message)
{
if (message == null)
{
throw new ArgumentException("message");
}
// ID - 16 bits
// QR - 1 bit
// Opcode - 4 bits
// AA, TC, RD - 3 bits
byte flags1 = message[2];
// RA, Z - 2 bits
// RCODE - 4 bits
byte flags2 = message[3];
long counts = message[3];
// adjust the return code
int return_code = (flags2 & (byte)0x3c) >> 2;
return_code_ = (return_code > 6) ? ReturnCode.Other : (ReturnCode)return_code;
// other bit flags
authoritative_answer_ = ((flags1 & 4) != 0);
recursion_available_ = ((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)];
name_servers_ = new NameServer[GetShort(message, 8)];
additional_records_ = new AdditionalRecord[GetShort(message, 10)];
// need a pointer to do this, position just after the header
RecordPointer pointer = new RecordPointer(message, 12);
// and now populate them, they always follow this order
for (int i = 0; i < questions_.Length; i++)
{
try {
questions_[i] = new Question(pointer);
} catch (Exception ex) {
throw new InvalidResponseException(ex);
}
}
for (int i = 0; i < answers_.Length; i++)
{
answers_[i] = new Answer(pointer);
}
for (int i = 0; i < name_servers_.Length; i++)
{
name_servers_[i] = new NameServer(pointer);
}
for (int i = 0; i < additional_records_.Length; i++)
{
additional_records_[i] = new AdditionalRecord(pointer);
}
}
internal Answer(RecordPointer pointer) : base(pointer) { }
internal NameServer(RecordPointer pointer) : base(pointer)
{
}
/// <summary>
/// Construct the question reading from a DNS Server response.
/// </summary>
/// <param name="pointer">A logical pointer to the Question in byte array form.</param>
internal Question(RecordPointer pointer) {
// extract from the pointer
domain_ = pointer.GetDomain();
dns_type_ = (DnsType)pointer.GetShort();
dns_class_ = (DnsClass)pointer.GetShort();
}
internal Answer(RecordPointer pointer) : base(pointer)
{
}
/// <summary>
/// Initializes a nes instance_ of the MXRecord class by using the specified pointer.
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
internal MXRecord(RecordPointer pointer)
{
preference_ = pointer.GetShort();
domain_name_ = pointer.GetDomain();
}
internal NameServer(RecordPointer pointer) : base(pointer) { }
