look for dhcp lease file in multiple locations (#41016)

Author: wfurt

src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/LinuxIPInterfaceProperties.cs

@@ -69,8 +69,12 @@ public GatewayIPAddressInformationCollection GetGatewayAddresses(LinuxNetworkInt
 
         private IPAddressCollection GetDhcpServerAddresses()
         {
-            List<IPAddress> internalCollection
-                = StringParsingHelpers.ParseDhcpServerAddressesFromLeasesFile(NetworkFiles.DHClientLeasesFile, _linuxNetworkInterface.Name);
+            List<IPAddress> internalCollection = new List<IPAddress>();
+
+            StringParsingHelpers.ParseDhcpServerAddressesFromLeasesFile(internalCollection, NetworkFiles.DHClientLeasesFile, _linuxNetworkInterface.Name);
+            StringParsingHelpers.ParseDhcpServerAddressesFromLeasesFile(internalCollection, string.Format(NetworkFiles.DHClientInterfaceLeasesFile, _linuxNetworkInterface.Name), _linuxNetworkInterface.Name);
+            StringParsingHelpers.ParseDhcpServerAddressesFromLeasesFile(internalCollection, string.Format(NetworkFiles.DHClientSecondaryInterfaceLeasesFile, _linuxNetworkInterface.Name), _linuxNetworkInterface.Name);
+
             return new InternalIPAddressCollection(internalCollection);
         }
 

src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/NetworkFiles.cs

@@ -23,6 +23,8 @@ internal static class NetworkFiles
         public const string Udp4ConnectionsFile = "/proc/net/udp";
         public const string Udp6ConnectionsFile = "/proc/net/udp6";
         public const string DHClientLeasesFile = "/var/lib/dhcp/dhclient.leases";
+        public const string DHClientInterfaceLeasesFile = "/var/lib/dhcp/dhclient.{0}.leases";
+        public const string DHClientSecondaryInterfaceLeasesFile = "/var/lib/dhcp/dhclient6.{0}.leases";
         public const string SmbConfFile = "/etc/samba/smb.conf";
 
         // Individual file names

src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/StringParsingHelpers.Addresses.cs

@@ -79,12 +79,11 @@ internal static void ParseIPv6GatewayAddressesFromRouteFile(List<GatewayIPAddres
             }
         }
 
-        internal static List<IPAddress> ParseDhcpServerAddressesFromLeasesFile(string filePath, string name)
+        internal static void ParseDhcpServerAddressesFromLeasesFile(List<IPAddress> collection, string filePath, string name)
         {
             // Parse the /var/lib/dhcp/dhclient.leases file, if it exists.
             // If any errors occur, like the file not existing or being
             // improperly formatted, just bail and return an empty collection.
-            List<IPAddress> collection = new List<IPAddress>();
             try
             {
                 if (File.Exists(filePath)) // avoid an exception in most cases if path doesn't already exist
@@ -123,8 +122,6 @@ internal static List<IPAddress> ParseDhcpServerAddressesFromLeasesFile(string fi
             {
                 // If any parsing or file reading exception occurs, just ignore it and return the collection.
             }
-
-            return collection;
         }
 
         internal static List<IPAddress> ParseWinsServerAddressesFromSmbConfFile(string smbConfFilePath)

src/libraries/System.Net.NetworkInformation/tests/FunctionalTests/AddressParsingTests.cs

@@ -69,7 +69,8 @@ public void DhcpServerAddressParsing()
         {
             string fileName = GetTestFilePath();
             FileUtil.NormalizeLineEndings("NetworkFiles/dhclient.leases", fileName);
-            List<IPAddress> dhcpServerAddresses = StringParsingHelpers.ParseDhcpServerAddressesFromLeasesFile(fileName, "wlan0");
+            List<IPAddress> dhcpServerAddresses = new List<IPAddress>();
+            StringParsingHelpers.ParseDhcpServerAddressesFromLeasesFile(dhcpServerAddresses, fileName, "wlan0");
             Assert.Equal(1, dhcpServerAddresses.Count);
             Assert.Equal(IPAddress.Parse("10.105.128.4"), dhcpServerAddresses[0]);
         }