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tpurschketpurschke
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Merge pull request #3922 from tpurschke/fix/revers-lookup-with-multiple-PTRs
Fix/revers lookup with multiple ptrs
2 parents 0ab7065 + 182173c commit 6840119

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6 files changed

+97
-229
lines changed

6 files changed

+97
-229
lines changed

‎roles/lib/files/FWO.Basics/FWO.Basics.csproj‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,7 @@
77
</PropertyGroup>
88

99
<ItemGroup>
10+
<PackageReference Include="DnsClient" Version="1.8.0" />
1011
<PackageReference Include="IPAddressRange" Version="6.2.0" />
1112
</ItemGroup>
1213

‎roles/lib/files/FWO.Basics/IpOperations.cs‎

Lines changed: 59 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -2,18 +2,56 @@
22
using System.Net;
33
using NetTools;
44
using System;
5+
using DnsClient;
56

67
namespace FWO.Basics
78
{
89
public static class IpOperations
910
{
11+
12+
// reuse the client to avoid socket churn; disable client-side cache
13+
private static readonly LookupClient ReverseLookupClient = new(new LookupClientOptions
14+
{
15+
UseCache = false,
16+
ContinueOnDnsError = true,
17+
ThrowDnsErrors = false
18+
});
19+
20+
public static async Task<IReadOnlyList<string>> DnsReverseLookUpAllAsync(
21+
IPAddress address,
22+
CancellationToken cancellationToken = default)
23+
{
24+
// QueryReverseAsync issues a PTR query and returns all answers from the DNS server
25+
IDnsQueryResponse response = await ReverseLookupClient.QueryReverseAsync(address, cancellationToken)
26+
.ConfigureAwait(false);
27+
28+
if (response.HasError || response.Answers.Count == 0)
29+
{
30+
return Array.Empty<string>();
31+
}
32+
33+
return response.Answers
34+
.PtrRecords()
35+
.Select(ptr => ptr.PtrDomainName.Value.TrimEnd('.')) // drop trailing dot
36+
.Distinct(StringComparer.OrdinalIgnoreCase)
37+
.ToArray();
38+
}
39+
40+
public static async Task<string> DnsReverseLookUpPreferredAsync(IPAddress address)
41+
{
42+
IReadOnlyList<string> names = await DnsReverseLookUpAllAsync(address);
43+
return names.FirstOrDefault(name => !name.StartsWith("lx", StringComparison.OrdinalIgnoreCase))
44+
?? names.FirstOrDefault()
45+
?? string.Empty;
46+
}
47+
1048
public static async Task<string> DnsReverseLookUp(IPAddress address)
1149
{
1250
try
1351
{
1452
return (await Dns.GetHostEntryAsync(address)).HostName;
1553
}
16-
catch(Exception)
54+
catch (Exception)
1755
{
1856
return "";
1957
}
@@ -51,25 +89,25 @@ public static bool TryParseIPStringToRange(this string ipString, out (string Sta
5189
bool ipStartOK = IPAddress.TryParse(ipStart, out IPAddress? ipAdressStart);
5290
bool ipEndOK = IPAddress.TryParse(ipEnd, out IPAddress? ipAdressEnd);
5391

54-
if(ipAdressStart is null || ipAdressEnd is null)
92+
if (ipAdressStart is null || ipAdressEnd is null)
5593
{
5694
return false;
5795
}
5896

59-
if(strictv4Parse && ipAdressStart?.AddressFamily == AddressFamily.InterNetwork && ipAdressEnd?.AddressFamily == AddressFamily.InterNetwork)
97+
if (strictv4Parse && ipAdressStart?.AddressFamily == AddressFamily.InterNetwork && ipAdressEnd?.AddressFamily == AddressFamily.InterNetwork)
6098
{
61-
if(!IsValidIPv4(ipStart) || !IsValidIPv4(ipEnd))
99+
if (!IsValidIPv4(ipStart) || !IsValidIPv4(ipEnd))
62100
{
63101
return false;
64102
}
65103
}
66104

67-
if(!ipStartOK || !ipEndOK)
105+
if (!ipStartOK || !ipEndOK)
68106
{
69107
return false;
70108
}
71109

72-
if(!IPAddress.TryParse(ipStart, out _) || !IPAddress.TryParse(ipEnd, out _))
110+
if (!IPAddress.TryParse(ipStart, out _) || !IPAddress.TryParse(ipEnd, out _))
73111
{
74112
return false;
75113
}
@@ -79,51 +117,52 @@ public static bool TryParseIPStringToRange(this string ipString, out (string Sta
79117

80118
return true;
81119
}
82-
catch(Exception)
120+
catch (Exception)
83121
{
84122
return false;
85123
}
86124
}
87125

88-
public static bool TryParseIPString<T>(this string ipString, out T? ipResult, bool strictv4Parse = false)
126+
public static bool TryParseIPString<T>(this string ipString, out T? ipResult, bool strictv4Parse = false)
89127
{
90128
ipResult = default;
91-
129+
92130
try
93131
{
94132
(string ipStart, string ipEnd) = SplitIpToRange(ipString);
95133

96134
bool ipStartOK = IPAddress.TryParse(ipStart, out IPAddress? ipAdressStart);
97135
bool ipEndOK = IPAddress.TryParse(ipEnd, out IPAddress? ipAdressEnd);
98136

99-
if(ipAdressStart is null || ipAdressEnd is null)
137+
if (ipAdressStart is null || ipAdressEnd is null)
100138
{
101139
return false;
102140
}
103141

104-
if(strictv4Parse && ipAdressStart?.AddressFamily == AddressFamily.InterNetwork && ipAdressEnd?.AddressFamily == AddressFamily.InterNetwork)
142+
if (strictv4Parse && ipAdressStart?.AddressFamily == AddressFamily.InterNetwork && ipAdressEnd?.AddressFamily == AddressFamily.InterNetwork)
105143
{
106-
if(!IsValidIPv4(ipStart) || !IsValidIPv4(ipEnd))
144+
if (!IsValidIPv4(ipStart) || !IsValidIPv4(ipEnd))
107145
{
108146
return false;
109147
}
110148
}
111149

112-
if(!ipStartOK || !ipEndOK)
150+
if (!ipStartOK || !ipEndOK)
113151
{
114152
return false;
115153
}
116154

117-
if(typeof(T) == typeof((string, string)))
155+
if (typeof(T) == typeof((string, string)))
118156
{
119157
ipResult = (T)Convert.ChangeType((ipAdressStart!.ToString(), ipAdressEnd!.ToString()), typeof(T));
120158
return true;
121159
}
122-
else if(typeof(T) == typeof(IPAddressRange) && IPAddressRange.TryParse(ipString, out IPAddressRange ipRange))
160+
else if (typeof(T) == typeof(IPAddressRange) && IPAddressRange.TryParse(ipString, out IPAddressRange ipRange))
123161
{
124162
ipResult = (T)Convert.ChangeType(ipRange, typeof(T));
125163
return true;
126-
}else if(typeof(T) == typeof((IPAddress, IPAddress)))
164+
}
165+
else if (typeof(T) == typeof((IPAddress, IPAddress)))
127166
{
128167
Tuple<IPAddress, IPAddress>? ipTuple = new(ipAdressStart!, ipAdressEnd!);
129168
ipResult = (T)Convert.ChangeType(ipTuple, typeof(T));
@@ -132,7 +171,7 @@ public static bool TryParseIPString<T>(this string ipString, out T? ipResult, bo
132171

133172
return false;
134173
}
135-
catch(Exception)
174+
catch (Exception)
136175
{
137176
return false;
138177
}
@@ -142,7 +181,7 @@ private static bool IsValidIPv4(string ipAddress)
142181
{
143182
byte[] addBytes = [.. ipAddress.Split('.').Where(_ => byte.Parse(_) <= 255 && byte.Parse(_) >= 0).Select(byte.Parse)];
144183

145-
return addBytes.Length == 4;
184+
return addBytes.Length == 4;
146185
}
147186

148187
public static string GetObjectType(string ip1, string ip2)
@@ -333,11 +372,11 @@ public static int CompareIpValues(IPAddress ip1, IPAddress ip2)
333372
/// </summary>
334373
public static int CompareIpFamilies(IPAddress ip1, IPAddress ip2)
335374
{
336-
if (ip1.AddressFamily == AddressFamily.InterNetwork && ip2.AddressFamily == AddressFamily.InterNetworkV6 )
375+
if (ip1.AddressFamily == AddressFamily.InterNetwork && ip2.AddressFamily == AddressFamily.InterNetworkV6)
337376
{
338377
return -1;
339378
}
340-
if (ip1.AddressFamily == AddressFamily.InterNetworkV6 && ip2.AddressFamily == AddressFamily.InterNetwork )
379+
if (ip1.AddressFamily == AddressFamily.InterNetworkV6 && ip2.AddressFamily == AddressFamily.InterNetwork)
341380
{
342381
return 1;
343382
}

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