Skip duplicate networks when extracting multiple networks from a network

Author: RobThree

IPNetworkHelper.Tests/NetworkHelperTests.cs

@@ -147,6 +147,18 @@ public void ExtractIPv4()
             Assert.IsTrue(result.Select((n, i) => expected[i].Equals(n)).All(v => true));
         }
 
+        [TestMethod]
+        public void ExtractSelfReturnsSelfIPv4()
+        {
+            var network = NetworkHelper.Parse("192.168.0.0/16");
+            var desired = NetworkHelper.Parse("192.168.0.0/16");
+
+            var result = network.Extract(desired).ToArray();
+            var expected = new[] { NetworkHelper.Parse("192.168.0.0/16") };
+
+            Assert.IsTrue(result.Select((n, i) => expected[i].Equals(n)).All(v => true));
+        }
+
         [TestMethod]
         public void ExtractIPv6()
         {
@@ -159,6 +171,18 @@ public void ExtractIPv6()
             Assert.IsTrue(result.Select((n, i) => expected[i].Equals(n)).All(v => true));
         }
 
+        [TestMethod]
+        public void ExtractSelfReturnsSelfIPv6()
+        {
+            var network = NetworkHelper.Parse("1111:2222::/32");
+            var desired = NetworkHelper.Parse("1111:2222::/32");
+
+            var result = network.Extract(desired).ToArray();
+            var expected = new[] { NetworkHelper.Parse("1111:2222::/32") };
+
+            Assert.IsTrue(result.Select((n, i) => expected[i].Equals(n)).All(v => true));
+        }
+
         [TestMethod]
         public void ExtractMultipleIPv4()
         {
@@ -171,6 +195,19 @@ public void ExtractMultipleIPv4()
             Assert.IsTrue(result.Select((n, i) => expected[i].Equals(n)).All(v => true));
         }
 
+        [TestMethod]
+        public void ExtractMultipleSkipsCreated()
+        {
+            // See https://github.com/RobThree/IPNetworkHelper/issues/1#issuecomment-1034793979
+            var network = NetworkHelper.Parse("37.0.0.0/8");
+            var desired = new[] { "37.10.128.0/17", "37.12.128.0/18", "37.13.64.0/18", "37.13.128.0/17" }.Select(v => NetworkHelper.Parse(v)).ToArray();
+
+            var result = network.Extract(desired).ToArray();
+            var expected = new[] { "37.0.0.0/13", "37.8.0.0/15", "37.10.0.0/17", "37.10.128.0/17", "37.11.0.0/16", "37.12.0.0/17", "37.12.128.0/18", "37.12.192.0/18", "37.13.0.0/18", "37.13.64.0/18", "37.13.128.0/17", "37.14.0.0/15", "37.16.0.0/12", "37.32.0.0/11", "37.64.0.0/10", "37.128.0.0/9" }.Select(v => NetworkHelper.Parse(v)).ToArray();
+
+            Assert.IsTrue(result.Select((n, i) => expected[i].Equals(n)).All(v => true));
+        }
+
         [TestMethod]
         public void ExtractMultipleIPv6()
         {
@@ -191,7 +228,7 @@ public void ExtractMultipleThrowsOnNetworkOutsideOfStartingNetwork()
 
             try
             {
-                network.Extract(desired).ToArray();
+                network.Extract(desired);
                 Assert.Fail();
             }
             catch (IPNetworkNotInIPNetworkException ex)

IPNetworkHelper/IPNetworkHelper.csproj

@@ -15,8 +15,8 @@
     <RepositoryUrl>https://github.com/RobThree/IPNetworkHelper</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageTags>networking, csharp, ipv6, dotnet, network, ipv4, ip, cidr, extension-methods, dotnet-standard, ipv6-network, cidr-notation, ipv6-subnetting, ipv4-subnetting, ipv4-network, cidr-subnet</PackageTags>
-    <PackageReleaseNotes>Added overload to extract multiple networks from a starting network</PackageReleaseNotes>
-    <Version>1.0.4</Version>
+    <PackageReleaseNotes>Duplicate networks are now ignored/skipped when extracting multiple networks</PackageReleaseNotes>
+    <Version>1.0.5</Version>
     <Description>Provides helper (extension)methods for working with IPNetworks</Description>
   </PropertyGroup>
 

IPNetworkHelper/NetworkHelper.cs

@@ -197,7 +197,7 @@ private static IEnumerable<IPNetwork> ExtractImpl(IPNetwork network, IPNetwork d
                 throw new AddressFamilyMismatchException(network.Prefix.AddressFamily, desiredNetwork.Prefix.AddressFamily);
             }
 
-            if (desiredNetwork.PrefixLength <= network.PrefixLength)
+            if (desiredNetwork.PrefixLength < network.PrefixLength)
             {
                 throw new IPNetworkLargerThanIPNetworkException(network, desiredNetwork);
             }
@@ -219,5 +219,6 @@ private static IEnumerable<IPNetwork> ExtractImpl(IPNetwork network, IPNetwork d
             }
             yield return network;                               // Lastly, return the extracted network
         }
+
     }
 }