* Adds new NetworkUtil class, contains methods for handling IP resolution when located on the same subnet. (Eg, can be used to avoid NAT Loopback requirements if fully utilized.)

* Adds a few new network-related methods to Util.

1 files changed, 122 insertions, 0 deletions

diff --git a/OpenSim/Framework/NetworkUtil.cs b/OpenSim/Framework/NetworkUtil.cs
new file mode 100644
index 0000000..1abf0d8
--- /dev/null
+++ b/OpenSim/Framework/NetworkUtil.cs
@@ -0,0 +1,122 @@
+using System.Collections.Generic;

+using System.Net.Sockets;

+using System.Net;

+using System.Net.NetworkInformation;

+

+namespace OpenSim.Framework

+{

+    /// <summary>

+    /// Handles NAT translation in a 'manner of speaking'

+    /// Allows you to return multiple different external

+    /// hostnames depending on the requestors network

+    /// 

+    /// This enables standard port forwarding techniques

+    /// to work correctly with OpenSim.

+    /// </summary>

+    static class NetworkUtil

+    {

+        // IPv4Address, Subnet

+        static readonly Dictionary<IPAddress,IPAddress> m_subnets = new Dictionary<IPAddress, IPAddress>();

+

+        private static IPAddress GetExternalIPFor(IPAddress destination, string defaultHostname)

+        {

+            // Adds IPv6 Support (Not that any of the major protocols supports it...)

+            if (destination.AddressFamily == AddressFamily.InterNetworkV6)

+            {

+                foreach (IPAddress host in Dns.GetHostAddresses(defaultHostname))

+                {

+                    if (host.AddressFamily == AddressFamily.InterNetworkV6)

+                        return host;

+                }

+            }

+

+            if(destination.AddressFamily != AddressFamily.InterNetwork)

+                return null;

+

+            // Check if we're accessing localhost.

+            foreach (IPAddress host in Dns.GetHostAddresses(Dns.GetHostName()))

+            {

+                if (host.Equals(destination))

+                    return destination;

+            }

+

+            // Check for same LAN segment

+            foreach (KeyValuePair<IPAddress, IPAddress> subnet in m_subnets)

+            {

+                byte[] subnetBytes = subnet.Value.GetAddressBytes();

+                byte[] localBytes = subnet.Key.GetAddressBytes();

+                byte[] destBytes = destination.GetAddressBytes();

+                

+                if(subnetBytes.Length != destBytes.Length || subnetBytes.Length != localBytes.Length)

+                    return null;

+

+                bool valid = true;

+

+                for(int i=0;i<subnetBytes.Length;i++)

+                {

+                    if ((localBytes[i] & subnetBytes[i]) != (destBytes[i] & subnetBytes[i]))

+                    {

+                        valid = false;

+                        break;

+                    }

+                }

+

+                if (valid)

+                    return subnet.Key;

+            }

+

+            // None found. Assume outside network.

+            return null;

+        }

+

+        static NetworkUtil()

+        {

+            foreach (NetworkInterface ni in NetworkInterface.GetAllNetworkInterfaces())

+            {

+                foreach (UnicastIPAddressInformation address in ni.GetIPProperties().UnicastAddresses)

+                {

+                    if (address.Address.AddressFamily == AddressFamily.InterNetwork)

+                    {

+                        m_subnets.Add(address.Address, address.IPv4Mask);

+                    }

+                }

+            }

+        }

+

+        public static IPAddress GetIPFor(IPEndPoint user, string defaultHostname)

+        {

+            // Try subnet matching

+            IPAddress rtn = GetExternalIPFor(user.Address, defaultHostname);

+            if (rtn != null)

+                return rtn;

+

+            // Otherwise use the old algorithm

+            IPAddress ia;

+

+            if (IPAddress.TryParse(defaultHostname, out ia))

+                return ia;

+

+            ia = null;

+

+            foreach (IPAddress Adr in Dns.GetHostAddresses(defaultHostname))

+            {

+                if (Adr.AddressFamily == AddressFamily.InterNetwork)

+                {

+                    ia = Adr;

+                    break;

+                }

+            }

+

+            return ia;

+        }

+

+        public static string GetHostFor(IPAddress user, string defaultHostname)

+        {

+            IPAddress rtn = GetExternalIPFor(user, defaultHostname);

+            if(rtn != null)

+                return rtn.ToString();

+

+            return defaultHostname;

+        }

+    }

+}