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DomainTree: implemented independent class to traverse domain name to be reuseable.

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Shreyas Zare
2020-06-27 15:35:35 +05:30
parent 7301c2ea65
commit 2db9337d36
1 changed files with 195 additions and 0 deletions
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195
DnsServerCore/Dns/Zones/DomainTree.cs Normal file
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/*
Technitium DNS Server
Copyright (C) 2020 Shreyas Zare (shreyas@technitium.com)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
using System;
using System.Text;
using TechnitiumLibrary.ByteTree;
using TechnitiumLibrary.Net.Dns;
namespace DnsServerCore.Dns.Zones
{
class DomainTree<T> : ByteTree<string, T> where T : class
{
#region variables
readonly static byte[] _keyMap;
readonly static byte[] _reverseKeyMap;
#endregion
#region constructor
static DomainTree()
{
_keyMap = new byte[256];
_reverseKeyMap = new byte[40];
for (int i = 0; i < _keyMap.Length; i++)
{
if ((i >= 97) && (i <= 122)) //[a-z]
{
_keyMap[i] = (byte)(i - 97);
_reverseKeyMap[_keyMap[i]] = (byte)i;
}
else if ((i >= 65) && (i <= 90)) //[a-z]
{
_keyMap[i] = (byte)(i - 65);
_reverseKeyMap[_keyMap[i]] = (byte)i;
}
else if ((i >= 48) && (i <= 57)) //[0-9]
{
_keyMap[i] = (byte)(26 + i - 48);
_reverseKeyMap[_keyMap[i]] = (byte)i;
}
else if (i == 45) //[-]
{
_keyMap[i] = 36;
_reverseKeyMap[36] = 45;
}
else if (i == 95) //[_]
{
_keyMap[i] = 37;
_reverseKeyMap[37] = 95;
}
else if (i == 42) //[*]
{
_keyMap[i] = 0xff; //skipped value 38 for optimization
_reverseKeyMap[38] = 42;
}
else if (i == 46) //[.]
{
_keyMap[i] = 39;
_reverseKeyMap[39] = 46;
}
else
{
_keyMap[i] = 0xff;
}
}
}
public DomainTree()
: base(40)
{ }
#endregion
#region protected
protected override byte[] ConvertToByteKey(string domain)
{
if (domain.Length == 0)
return Array.Empty<byte>();
if (domain.Length > 255)
throw new DnsClientException("Invalid domain name [" + domain + "]: length cannot exceed 255 bytes.");
byte[] key = new byte[domain.Length + 1];
int keyOffset = 0;
int labelStart;
int labelEnd = domain.Length - 1;
int labelLength;
int labelChar;
byte labelKeyCode;
int i;
do
{
if (labelEnd < 0)
labelEnd = 0;
labelStart = domain.LastIndexOf('.', labelEnd);
labelLength = labelEnd - labelStart;
if (labelLength == 0)
throw new DnsClientException("Invalid domain name [" + domain + "]: label length cannot be 0 byte.");
if (labelLength > 63)
throw new DnsClientException("Invalid domain name [" + domain + "]: label length cannot exceed 63 bytes.");
if (domain[labelStart + 1] == '-')
throw new DnsClientException("Invalid domain name [" + domain + "]: label cannot start with hyphen.");
if (domain[labelEnd] == '-')
throw new DnsClientException("Invalid domain name [" + domain + "]: label cannot end with hyphen.");
if ((labelLength == 1) && (domain[labelStart + 1] == '*'))
{
key[keyOffset++] = 38;
}
else
{
for (i = labelStart + 1; i <= labelEnd; i++)
{
labelChar = domain[i];
if (labelChar >= _keyMap.Length)
throw new DnsClientException("Invalid domain name [" + domain + "]: invalid character [" + labelChar + "] was found.");
labelKeyCode = _keyMap[labelChar];
if (labelKeyCode == 0xff)
throw new DnsClientException("Invalid domain name [" + domain + "]: invalid character [" + labelChar + "] was found.");
key[keyOffset++] = labelKeyCode;
}
}
key[keyOffset++] = 39;
labelEnd = labelStart - 1;
}
while (labelStart > -1);
return key;
}
protected static string ConvertKeyToLabel(byte[] key, int startIndex)
{
byte[] domain = new byte[key.Length - startIndex];
int i;
int k;
for (i = 0; i < domain.Length; i++)
{
k = key[i + startIndex];
if (k == 39)
break;
domain[i] = _reverseKeyMap[k];
}
return Encoding.ASCII.GetString(domain, 0, i);
}
#endregion
#region public
public override bool TryRemove(string key, out T value)
{
if (TryRemove(key, out value, out Node closestNode))
{
closestNode.CleanThisBranch();
return true;
}
return false;
}
#endregion
}
}