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SplitHorizon.AddressTranslation: Added support to specify network address for external to internal translation.

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This commit is contained in:
Shreyas Zare
2023-10-29 20:34:45 +05:30
parent 335d69e205
commit 7f34ccd3c6
1 changed files with 152 additions and 39 deletions
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191
Apps/SplitHorizonApp/AddressTranslation.cs
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@@ -22,6 +22,7 @@ using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text.Json;
using System.Threading.Tasks;
using TechnitiumLibrary;
@@ -78,7 +79,7 @@ namespace SplitHorizon
"enabled": true,
"translateReverseLookups": true,
"externalToInternalTranslation": {
"1.2.3.4": "10.0.0.4",
"1.2.3.0/24": "10.0.0.0/24",
"5.6.7.8": "10.0.0.5"
}
},
@@ -132,7 +133,7 @@ namespace SplitHorizon
"enabled": true,
"translateReverseLookups": true,
"externalToInternalTranslation": {
"1.2.3.4": "10.0.0.4",
"1.2.3.0/24": "10.0.0.0/24",
"5.6.7.8": "10.0.0.5"
}
},
@@ -189,9 +190,6 @@ namespace SplitHorizon
if (!_enableAddressTranslation)
return Task.FromResult(response);
if (request.DnssecOk)
return Task.FromResult(response);
if (response.RCODE != DnsResponseCode.NoError)
return Task.FromResult(response);
@@ -236,7 +234,7 @@ namespace SplitHorizon
{
IPAddress externalIp = (answer.RDATA as DnsARecordData).Address;
if (group.ExternalToInternalTranslation.TryGetValue(externalIp, out IPAddress internalIp))
if (group.TryExternalToInternalTranslation(externalIp, out IPAddress internalIp))
newAnswer.Add(new DnsResourceRecord(answer.Name, answer.Type, answer.Class, answer.TTL, new DnsARecordData(internalIp)));
else
newAnswer.Add(answer);
@@ -247,7 +245,7 @@ namespace SplitHorizon
{
IPAddress externalIp = (answer.RDATA as DnsAAAARecordData).Address;
if (group.ExternalToInternalTranslation.TryGetValue(externalIp, out IPAddress internalIp))
if (group.TryExternalToInternalTranslation(externalIp, out IPAddress internalIp))
newAnswer.Add(new DnsResourceRecord(answer.Name, answer.Type, answer.Class, answer.TTL, new DnsAAAARecordData(internalIp)));
else
newAnswer.Add(answer);
@@ -268,9 +266,6 @@ namespace SplitHorizon
if (!_enableAddressTranslation)
return Task.FromResult<DnsDatagram>(null);
if (request.DnssecOk)
return Task.FromResult<DnsDatagram>(null);
DnsQuestionRecord question = request.Question[0];
if (question.Type != DnsResourceRecordType.PTR)
return Task.FromResult<DnsDatagram>(null);
@@ -293,7 +288,7 @@ namespace SplitHorizon
IPAddress ptrIpAddress = IPAddressExtensions.ParseReverseDomain(question.Name);
if (!group.InternalToExternalTranslation.TryGetValue(ptrIpAddress, out IPAddress externalIp))
if (!group.TryInternalToExternalTranslation(ptrIpAddress, out IPAddress externalIp))
return Task.FromResult<DnsDatagram>(null);
IReadOnlyList<DnsResourceRecord> answer = new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.CNAME, question.Class, 600, new DnsCNAMERecordData(externalIp.GetReverseDomain())) };
@@ -319,6 +314,7 @@ namespace SplitHorizon
readonly bool _translateReverseLookups;
readonly IReadOnlyDictionary<IPAddress, IPAddress> _externalToInternalTranslation;
readonly IReadOnlyDictionary<IPAddress, IPAddress> _internalToExternalTranslation;
readonly IReadOnlyList<KeyValuePair<NetworkAddress, NetworkAddress>> _externalToInternalNetworkTranslation;
#endregion
@@ -332,43 +328,166 @@ namespace SplitHorizon
JsonElement jsonExternalToInternalTranslation = jsonGroup.GetProperty("externalToInternalTranslation");
Dictionary<IPAddress, IPAddress> externalToInternalIpTranslation = new Dictionary<IPAddress, IPAddress>();
Dictionary<IPAddress, IPAddress> internalToExternalIpTranslation = new Dictionary<IPAddress, IPAddress>();
List<KeyValuePair<NetworkAddress, NetworkAddress>> externalToInternalNetworkTranslation = new List<KeyValuePair<NetworkAddress, NetworkAddress>>();
foreach (JsonProperty jsonProperty in jsonExternalToInternalTranslation.EnumerateObject())
{
string strExternal = jsonProperty.Name;
string strInternal = jsonProperty.Value.GetString();
NetworkAddress external = NetworkAddress.Parse(strExternal);
NetworkAddress @internal = NetworkAddress.Parse(strInternal);
if (external.AddressFamily != @internal.AddressFamily)
throw new InvalidDataException("External to internal translation entries must have same address family: " + strExternal + " - " + strInternal);
if (external.PrefixLength != @internal.PrefixLength)
throw new InvalidDataException("External to internal translation entries must have same prefix length: " + strExternal + " - " + strInternal);
if (
((external.AddressFamily == AddressFamily.InterNetwork) && (external.PrefixLength == 32)) ||
((external.AddressFamily == AddressFamily.InterNetworkV6) && (external.PrefixLength == 128))
)
{
externalToInternalIpTranslation.TryAdd(external.Address, @internal.Address);
if (_translateReverseLookups)
internalToExternalIpTranslation.TryAdd(@internal.Address, external.Address);
}
else
{
externalToInternalNetworkTranslation.Add(new KeyValuePair<NetworkAddress, NetworkAddress>(external, @internal));
}
}
_externalToInternalTranslation = externalToInternalIpTranslation;
if (_translateReverseLookups)
_internalToExternalTranslation = internalToExternalIpTranslation;
_externalToInternalNetworkTranslation = externalToInternalNetworkTranslation;
}
#endregion
#region public
public bool TryExternalToInternalTranslation(IPAddress externalIp, out IPAddress internalIp)
{
if (_externalToInternalTranslation.TryGetValue(externalIp, out internalIp))
return true;
foreach (KeyValuePair<NetworkAddress, NetworkAddress> networkEntry in _externalToInternalNetworkTranslation)
{
Dictionary<IPAddress, IPAddress> externalToInternalTranslation = new Dictionary<IPAddress, IPAddress>();
Dictionary<IPAddress, IPAddress> internalToExternalTranslation = new Dictionary<IPAddress, IPAddress>();
NetworkAddress external = networkEntry.Key;
foreach (JsonProperty jsonProperty in jsonExternalToInternalTranslation.EnumerateObject())
if (external.AddressFamily != externalIp.AddressFamily)
continue;
if (external.Contains(externalIp))
{
string strExternalIp = jsonProperty.Name;
string strInternalIp = jsonProperty.Value.GetString();
NetworkAddress @internal = networkEntry.Value;
IPAddress externalIp = IPAddress.Parse(strExternalIp);
IPAddress internalIp = IPAddress.Parse(strInternalIp);
switch (external.AddressFamily)
{
case AddressFamily.InterNetwork:
{
uint hostMask = ~(0xFFFFFFFFu << (32 - external.PrefixLength));
uint host = externalIp.ConvertIpToNumber() & hostMask;
uint addr = @internal.Address.ConvertIpToNumber();
uint internalAddr = addr | host;
externalToInternalTranslation.TryAdd(externalIp, internalIp);
internalToExternalTranslation.TryAdd(internalIp, externalIp);
internalIp = IPAddressExtensions.ConvertNumberToIp(internalAddr);
return true;
}
case AddressFamily.InterNetworkV6:
{
byte[] externalIpBytes = externalIp.GetAddressBytes();
byte[] internalIpBytes = @internal.Address.GetAddressBytes();
int copyBytes = external.PrefixLength / 8;
int balanceBits = external.PrefixLength - (copyBytes * 8);
Buffer.BlockCopy(externalIpBytes, copyBytes + 1, internalIpBytes, copyBytes + 1, 16 - copyBytes - 1);
if (balanceBits > 0)
{
int mask = 0xFF << (8 - balanceBits);
internalIpBytes[copyBytes] = (byte)((internalIpBytes[copyBytes] & mask) | (externalIpBytes[copyBytes] & ~mask));
}
internalIp = new IPAddress(internalIpBytes);
return true;
}
default:
throw new InvalidOperationException();
}
}
_externalToInternalTranslation = externalToInternalTranslation;
_internalToExternalTranslation = internalToExternalTranslation;
}
else
internalIp = null;
return false;
}
public bool TryInternalToExternalTranslation(IPAddress internalIp, out IPAddress externalIp)
{
if (_internalToExternalTranslation.TryGetValue(internalIp, out externalIp))
return true;
foreach (KeyValuePair<NetworkAddress, NetworkAddress> networkEntry in _externalToInternalNetworkTranslation)
{
Dictionary<IPAddress, IPAddress> externalToInternalTranslation = new Dictionary<IPAddress, IPAddress>();
NetworkAddress @internal = networkEntry.Value;
foreach (JsonProperty jsonProperty in jsonExternalToInternalTranslation.EnumerateObject())
if (@internal.AddressFamily != internalIp.AddressFamily)
continue;
if (@internal.Contains(internalIp))
{
string strExternalIp = jsonProperty.Name;
string strInternalIp = jsonProperty.Value.GetString();
NetworkAddress external = networkEntry.Key;
IPAddress externalIp = IPAddress.Parse(strExternalIp);
IPAddress internalIp = IPAddress.Parse(strInternalIp);
switch (@internal.AddressFamily)
{
case AddressFamily.InterNetwork:
{
uint hostMask = ~(0xFFFFFFFFu << (32 - @internal.PrefixLength));
uint host = internalIp.ConvertIpToNumber() & hostMask;
uint addr = external.Address.ConvertIpToNumber();
uint externalAddr = addr | host;
externalToInternalTranslation.TryAdd(externalIp, internalIp);
externalIp = IPAddressExtensions.ConvertNumberToIp(externalAddr);
return true;
}
case AddressFamily.InterNetworkV6:
{
byte[] internalIpBytes = internalIp.GetAddressBytes();
byte[] externalIpBytes = external.Address.GetAddressBytes();
int copyBytes = @internal.PrefixLength / 8;
int balanceBits = @internal.PrefixLength - (copyBytes * 8);
Buffer.BlockCopy(internalIpBytes, copyBytes + 1, externalIpBytes, copyBytes + 1, 16 - copyBytes - 1);
if (balanceBits > 0)
{
int mask = 0xFF << (8 - balanceBits);
externalIpBytes[copyBytes] = (byte)((externalIpBytes[copyBytes] & mask) | (internalIpBytes[copyBytes] & ~mask));
}
externalIp = new IPAddress(externalIpBytes);
return true;
}
default:
throw new InvalidOperationException();
}
}
_externalToInternalTranslation = externalToInternalTranslation;
}
externalIp = null;
return false;
}
#endregion
@@ -384,12 +503,6 @@ namespace SplitHorizon
public bool TranslateReverseLookups
{ get { return _translateReverseLookups; } }
public IReadOnlyDictionary<IPAddress, IPAddress> ExternalToInternalTranslation
{ get { return _externalToInternalTranslation; } }
public IReadOnlyDictionary<IPAddress, IPAddress> InternalToExternalTranslation
{ get { return _internalToExternalTranslation; } }
#endregion
}
}