internal override DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length)
{
if (length < MinimumLength)
{
return(null);
}
byte prefixLength = dns[offsetInDns + Offset.PrefixLength];
if (prefixLength > MaxPrefixLength)
{
return(null);
}
offsetInDns += ConstantPartLength;
length -= ConstantPartLength;
int addressSuffixLength = CalculateAddressSuffixLength(prefixLength);
if (length < addressSuffixLength)
{
return(null);
}
IpV6Address addressSuffix = new IpV6Address((UInt128)dns.ReadUnsignedBigInteger(offsetInDns, addressSuffixLength, Endianity.Big));
offsetInDns += addressSuffixLength;
length -= addressSuffixLength;
if (IsAddressSuffixTooSmall(prefixLength, addressSuffix) || IsAddressSuffixTooBig(prefixLength, addressSuffix))
{
return(null);
}
DnsDomainName prefixName;
int prefixNameLength;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out prefixName, out prefixNameLength))
{
return(null);
}
if (prefixNameLength != length)
{
return(null);
}
return(new DnsResourceDataA6(prefixLength, addressSuffix, prefixName));
}
private static bool TryReadLabels(DnsDatagram dns, int offsetInDns, out int numBytesRead, List <DataSegment> labels)
{
numBytesRead = 0;
byte labelLength;
do
{
if (offsetInDns >= dns.Length)
{
return(false); // Can't read label's length.
}
labelLength = dns[offsetInDns];
++numBytesRead;
if (labelLength > MaxLabelLength)
{
// Compression.
if (offsetInDns + 1 >= dns.Length)
{
return(false); // Can't read compression pointer.
}
int newOffsetInDns = dns.ReadUShort(offsetInDns, Endianity.Big) & OffsetMask;
if (newOffsetInDns >= offsetInDns)
{
return(false); // Can't handle pointers that are not back pointers.
}
++numBytesRead;
int internalBytesRead;
return(TryReadLabels(dns, newOffsetInDns, out internalBytesRead, labels));
}
if (labelLength != 0)
{
++offsetInDns;
if (offsetInDns + labelLength >= dns.Length)
{
return(false); // Can't read label.
}
labels.Add(dns.Subsegment(offsetInDns, labelLength));
numBytesRead += labelLength;
offsetInDns += labelLength;
}
} while (labelLength != 0);
return(true);
}
internal override DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length)
{
int numBytesRead;
DnsDomainName domainName;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out domainName, out numBytesRead))
{
return(null);
}
length -= numBytesRead;
if (length != 0)
{
return(null);
}
return(new DnsResourceDataDomainName(domainName));
}
internal static List <DnsDomainName> ReadDomainNames(DnsDatagram dns, int offsetInDns, int length, int numExpected = 0)
{
List <DnsDomainName> domainNames = new List <DnsDomainName>(numExpected);
while (length != 0)
{
DnsDomainName domainName;
int domainNameLength;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out domainName, out domainNameLength))
{
return(null);
}
offsetInDns += domainNameLength;
length -= domainNameLength;
domainNames.Add(domainName);
}
return(domainNames);
}
internal static bool TryParseBase(DnsDatagram dns, int offsetInDns,
out DnsDomainName domainName, out DnsType type, out DnsClass dnsClass, out int numBytesRead)
{
type = DnsType.Any;
dnsClass = DnsClass.Any;
if (!DnsDomainName.TryParse(dns, offsetInDns, dns.Length - offsetInDns, out domainName, out numBytesRead))
{
return(false);
}
if (offsetInDns + numBytesRead + MinimumLengthAfterDomainName > dns.Length)
{
return(false);
}
type = (DnsType)dns.ReadUShort(offsetInDns + numBytesRead + OffsetAfterDomainName.Type, Endianity.Big);
dnsClass = (DnsClass)dns.ReadUShort(offsetInDns + numBytesRead + OffsetAfterDomainName.DnsClass, Endianity.Big);
numBytesRead += MinimumLengthAfterDomainName;
return(true);
}
internal override DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length)
{
if (length < ConstPartLength)
{
return(null);
}
byte precedence = dns[offsetInDns + Offset.Precedence];
DnsGatewayType gatewayType = (DnsGatewayType)dns[offsetInDns + Offset.GatewayType];
DnsPublicKeyAlgorithm algorithm = (DnsPublicKeyAlgorithm)dns[offsetInDns + Offset.Algorithm];
DnsGateway gateway = DnsGateway.CreateInstance(gatewayType, dns, offsetInDns + Offset.Gateway, length - ConstPartLength);
if (gateway == null)
{
return(null);
}
DataSegment publicKey = dns.Subsegment(offsetInDns + ConstPartLength + gateway.Length, length - ConstPartLength - gateway.Length);
return(new DnsResourceDataIpSecKey(precedence, gateway, algorithm, publicKey));
}
internal override DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length)
{
DnsDomainName nextDomainName;
int nextDomainNameLength;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out nextDomainName, out nextDomainNameLength))
{
return(null);
}
offsetInDns += nextDomainNameLength;
length -= nextDomainNameLength;
DnsTypeBitmaps typeBitmaps = DnsTypeBitmaps.CreateInstance(dns.Buffer, dns.StartOffset + offsetInDns, length);
if (typeBitmaps == null)
{
return(null);
}
return(new DnsResourceDataNextDomainSecure(nextDomainName, typeBitmaps));
}
internal override DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length)
{
if (length < ConstantPartLength)
{
return(null);
}
int hostIdentityTagLength = dns[offsetInDns + Offset.HostIdentityTagLength];
DnsPublicKeyAlgorithm publicKeyAlgorithm = (DnsPublicKeyAlgorithm)dns[offsetInDns + Offset.PublicKeyAlgorithm];
int publicKeyLength = dns.ReadUShort(offsetInDns + Offset.PublicKeyLength, Endianity.Big);
if (length < ConstantPartLength + hostIdentityTagLength + publicKeyLength)
{
return(null);
}
DataSegment hostIdentityTag = dns.Subsegment(offsetInDns + Offset.HostIdentityTag, hostIdentityTagLength);
int publicKeyOffset = offsetInDns + ConstantPartLength + hostIdentityTagLength;
DataSegment publicKey = dns.Subsegment(publicKeyOffset, publicKeyLength);
offsetInDns += ConstantPartLength + hostIdentityTagLength + publicKeyLength;
length -= ConstantPartLength + hostIdentityTagLength + publicKeyLength;
List <DnsDomainName> rendezvousServers = new List <DnsDomainName>();
while (length != 0)
{
DnsDomainName rendezvousServer;
int rendezvousServerLength;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out rendezvousServer, out rendezvousServerLength))
{
return(null);
}
rendezvousServers.Add(rendezvousServer);
offsetInDns += rendezvousServerLength;
length -= rendezvousServerLength;
}
return(new DnsResourceDataHostIdentityProtocol(hostIdentityTag, publicKeyAlgorithm, publicKey, rendezvousServers));
}
internal static DnsDataResourceRecord Parse(DnsDatagram dns, int offsetInDns, out int numBytesRead)
{
DnsDomainName domainName;
DnsType type;
DnsClass dnsClass;
if (!TryParseBase(dns, offsetInDns, out domainName, out type, out dnsClass, out numBytesRead))
{
return(null);
}
if (offsetInDns + numBytesRead + MinimumLengthAfterBase > dns.Length)
{
return(null);
}
int ttl = dns.ReadInt(offsetInDns + numBytesRead + OffsetAfterBase.Ttl, Endianity.Big);
ushort dataLength = dns.ReadUShort(offsetInDns + numBytesRead + OffsetAfterBase.DataLength, Endianity.Big);
numBytesRead += MinimumLengthAfterBase;
if (offsetInDns + numBytesRead + dataLength > dns.Length)
{
return(null);
}
DnsResourceData data = DnsResourceData.Read(dns, type, offsetInDns + numBytesRead, dataLength);
if (data == null)
{
return(null);
}
numBytesRead += dataLength;
if (type == DnsType.Opt)
{
return(new DnsOptResourceRecord(domainName, dnsClass, ttl, data));
}
return(new DnsDataResourceRecord(domainName, type, dnsClass, ttl, data));
}
internal override DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length)
{
if (length < ConstantPartLength)
{
return(null);
}
ushort preference = dns.ReadUShort(offsetInDns + Offset.Preference, Endianity.Big);
offsetInDns += ConstantPartLength;
length -= ConstantPartLength;
DnsDomainName map822;
int map822Length;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out map822, out map822Length))
{
return(null);
}
offsetInDns += map822Length;
length -= map822Length;
DnsDomainName mapX400;
int mapX400Length;
if (!DnsDomainName.TryParse(dns, offsetInDns, length, out mapX400, out mapX400Length))
{
return(null);
}
length -= mapX400Length;
if (length != 0)
{
return(null);
}
return(new DnsResourceDataX400Pointer(preference, map822, mapX400));
}
internal abstract DnsResourceData CreateInstance(DnsDatagram dns, int offsetInDns, int length);
/// <summary>
/// Writes the layer to the buffer.
/// </summary>
/// <param name="buffer">The buffer to write the layer to.</param>
/// <param name="offset">The offset in the buffer to start writing the layer at.</param>
protected override void Write(byte[] buffer, int offset)
{
DnsDatagram.Write(buffer, offset,
Id, IsResponse, OpCode, IsAuthoritativeAnswer, IsTruncated, IsRecursionDesired, IsRecursionAvailable, FutureUse, IsAuthenticData,
IsCheckingDisabled, ResponseCode, Queries, Answers, Authorities, Additionals, DomainNameCompressionMode);
}
