Stop IGridService from throwing a fatal exception when an IPEndPoint cannot be resolved, and add some handlers to deal with this cleanly; a condition was observed on OSGrid where a neighbouring region with an invalid (unresolveable) hostname would prevent a region from starting. This is bad.

OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs

@@ -261,7 +261,7 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
             // This may be a costly operation. The reg.ExternalEndPoint field is not a passive field,
             // it's actually doing a lot of work.
             IPEndPoint endPoint = finalDestination.ExternalEndPoint;
-            if (endPoint.Address != null)
+            if (endPoint != null && endPoint.Address != null)
             {
                 // Fixing a bug where teleporting while sitting results in the avatar ending up removed from
                 // both regions
@@ -825,16 +825,20 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
                 m_log.DebugFormat("[ENTITY TRANSFER MODULE]: Sending new CAPS seed url {0} to client {1}", capsPath, agent.UUID);
 
                 IEventQueue eq = agent.Scene.RequestModuleInterface<IEventQueue>();
+                IPEndPoint neighbourExternal = neighbourRegion.ExternalEndPoint;
+                if (neighbourExternal != null)
+                {
                     if (eq != null)
                     {
-                    eq.CrossRegion(neighbourHandle, pos, agent.Velocity, neighbourRegion.ExternalEndPoint,
+                        eq.CrossRegion(neighbourHandle, pos, agent.Velocity, neighbourExternal,
                                        capsPath, agent.UUID, agent.ControllingClient.SessionId);
                     }
                     else
                     {
-                    agent.ControllingClient.CrossRegion(neighbourHandle, pos, agent.Velocity, neighbourRegion.ExternalEndPoint,
+                        agent.ControllingClient.CrossRegion(neighbourHandle, pos, agent.Velocity, neighbourExternal,
                                                     capsPath);
                     }
+                }
 
                 if (!WaitForCallback(agent.UUID))
                 {
@@ -906,11 +910,15 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
             agent.child = true;
             agent.Appearance = sp.Appearance;
 
+            IPEndPoint external = region.ExternalEndPoint;
+            if (external != null)
+            {
                 InformClientOfNeighbourDelegate d = InformClientOfNeighbourAsync;
-            d.BeginInvoke(sp, agent, region, region.ExternalEndPoint, true,
+                d.BeginInvoke(sp, agent, region, external, true,
                           InformClientOfNeighbourCompleted,
                           d);
             }
+        }
         #endregion
 
         #region Enable Child Agents
@@ -1038,6 +1046,7 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
                     InformClientOfNeighbourDelegate d = InformClientOfNeighbourAsync;
                     try
                     {
+                        //neighbour.ExternalEndPoint may return null, which will be caught
                         d.BeginInvoke(sp, cagents[count], neighbour, neighbour.ExternalEndPoint, newAgent,
                                       InformClientOfNeighbourCompleted,
                                       d);

OpenSim/Services/Connectors/Hypergrid/GatekeeperServiceConnector.cs

@@ -87,7 +87,12 @@ namespace OpenSim.Services.Connectors.Hypergrid
             paramList.Add(hash);
 
             XmlRpcRequest request = new XmlRpcRequest("link_region", paramList);
-            string uri = "http://" + info.ExternalEndPoint.Address + ":" + info.HttpPort + "/";
+            IPEndPoint ext = info.ExternalEndPoint;
+            string uri = "";
+            if (ext != null)
+            {
+                uri = "http://" + ext.Address + ":" + info.HttpPort + "/";
+            }
             //m_log.Debug("[GATEKEEPER SERVICE CONNECTOR]: Linking to " + uri);
             XmlRpcResponse response = null;
             try
@@ -189,7 +194,12 @@ namespace OpenSim.Services.Connectors.Hypergrid
             paramList.Add(hash);
 
             XmlRpcRequest request = new XmlRpcRequest("get_region", paramList);
-            string uri = "http://" + gatekeeper.ExternalEndPoint.Address + ":" + gatekeeper.HttpPort + "/";
+            IPEndPoint ext = gatekeeper.ExternalEndPoint;
+            string uri = "";
+            if (ext != null)
+            {
+                uri = "http://" + ext.Address + ":" + gatekeeper.HttpPort + "/";
+            }
             m_log.Debug("[GATEKEEPER SERVICE CONNECTOR]: contacting " + uri);
             XmlRpcResponse response = null;
             try

OpenSim/Services/Connectors/Land/LandServiceConnector.cs

@@ -83,6 +83,8 @@ namespace OpenSim.Services.Connectors
                 if (info != null) // just to be sure
                 {
                     XmlRpcRequest request = new XmlRpcRequest("land_data", paramList);
+                    
+                    //Possible nullref from info.externalendpoint will be caught here
                     string uri = "http://" + info.ExternalEndPoint.Address + ":" + info.HttpPort + "/";
                     XmlRpcResponse response = request.Send(uri, 10000);
                     if (response.IsFault)

OpenSim/Services/Connectors/Neighbour/NeighbourServiceConnector.cs

@@ -87,7 +87,9 @@ namespace OpenSim.Services.Connectors
 
         public bool DoHelloNeighbourCall(GridRegion region, RegionInfo thisRegion)
         {
-            string uri = "http://" + region.ExternalEndPoint.Address + ":" + region.HttpPort + "/region/" + thisRegion.RegionID + "/";
+            IPEndPoint ext = region.ExternalEndPoint;
+            if (ext == null) return false;
+            string uri = "http://" + ext.Address + ":" + region.HttpPort + "/region/" + thisRegion.RegionID + "/";
             //m_log.Debug("   >>> DoHelloNeighbourCall <<< " + uri);
 
             WebRequest HelloNeighbourRequest = WebRequest.Create(uri);

OpenSim/Services/Connectors/SimianGrid/SimianGridServiceConnector.cs

@@ -104,6 +104,8 @@ namespace OpenSim.Services.Connectors.SimianGrid
 
         public string RegisterRegion(UUID scopeID, GridRegion regionInfo)
         {
+            IPEndPoint ext = regionInfo.ExternalEndPoint;
+            if (ext == null) return "Region registration for " + regionInfo.RegionName + " failed: Could not resolve EndPoint";
             Vector3d minPosition = new Vector3d(regionInfo.RegionLocX, regionInfo.RegionLocY, 0.0);
             Vector3d maxPosition = minPosition + new Vector3d(Constants.RegionSize, Constants.RegionSize, 4096.0);
 
@@ -114,7 +116,7 @@ namespace OpenSim.Services.Connectors.SimianGrid
                 { "ServerURI", OSD.FromString(regionInfo.ServerURI) },
                 { "InternalAddress", OSD.FromString(regionInfo.InternalEndPoint.Address.ToString()) },
                 { "InternalPort", OSD.FromInteger(regionInfo.InternalEndPoint.Port) },
-                { "ExternalAddress", OSD.FromString(regionInfo.ExternalEndPoint.Address.ToString()) },
+                { "ExternalAddress", OSD.FromString(ext.Address.ToString()) },
                 { "ExternalPort", OSD.FromInteger(regionInfo.ExternalEndPoint.Port) },
                 { "MapTexture", OSD.FromUUID(regionInfo.TerrainImage) },
                 { "Access", OSD.FromInteger(regionInfo.Access) },

OpenSim/Services/Connectors/Simulation/SimulationServiceConnector.cs

@@ -348,9 +348,11 @@ namespace OpenSim.Services.Connectors.Simulation
 
         public bool RetrieveAgent(GridRegion destination, UUID id, out IAgentData agent)
         {
+            IPEndPoint ext = destination.ExternalEndPoint;
             agent = null;
+            if (ext == null) return false;
             // Eventually, we want to use a caps url instead of the agentID
-            string uri = "http://" + destination.ExternalEndPoint.Address + ":" + destination.HttpPort + AgentPath() + id + "/" + destination.RegionID.ToString() + "/";
+            string uri = "http://" + ext.Address + ":" + destination.HttpPort + AgentPath() + id + "/" + destination.RegionID.ToString() + "/";
             //Console.WriteLine("   >>> DoRetrieveRootAgentCall <<< " + uri);
 
             HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
@@ -514,8 +516,10 @@ namespace OpenSim.Services.Connectors.Simulation
 
         public bool CreateObject(GridRegion destination, ISceneObject sog, bool isLocalCall)
         {
+            IPEndPoint ext = destination.ExternalEndPoint;
+            if (ext == null) return false;
             string uri
-                = "http://" + destination.ExternalEndPoint.Address + ":" + destination.HttpPort + ObjectPath() + sog.UUID + "/";
+                = "http://" + ext.Address + ":" + destination.HttpPort + ObjectPath() + sog.UUID + "/";
             //m_log.Debug("   >>> DoCreateObjectCall <<< " + uri);
 
             WebRequest ObjectCreateRequest = WebRequest.Create(uri);

OpenSim/Services/Interfaces/IGridService.cs

@@ -259,9 +259,13 @@ namespace OpenSim.Services.Interfaces
                 }
                 catch (SocketException e)
                 {
-                    throw new Exception(
+                    /*throw new Exception(
                         "Unable to resolve local hostname " + m_externalHostName + " innerException of type '" +
-                        e + "' attached to this exception", e);
+                        e + "' attached to this exception", e);*/
+                    // Don't throw a fatal exception here, instead, return Null and handle it in the caller.
+                    // Reason is, on systems such as OSgrid it has occured that known hostnames stop
+                    // resolving and thus make surrounding regions crash out with this exception.
+                    return null;
                 }
 
                 return new IPEndPoint(ia, m_internalEndPoint.Port);

OpenSim/Services/LLLoginService/LLLoginResponse.cs

@@ -327,6 +327,7 @@ namespace OpenSim.Services.LLLoginService
         private void FillOutRegionData(GridRegion destination)
         {
             IPEndPoint endPoint = destination.ExternalEndPoint;
+            if (endPoint == null) return;
             SimAddress = endPoint.Address.ToString();
             SimPort = (uint)endPoint.Port;
             RegionX = (uint)destination.RegionLocX;