So, the client can have an old idea of the object properties for the object when it goes to buy. This can cause a problem in the buy process. Additionally Hazim mentioned that the buy packets are spoofable. The core modules are the crowing glory example of best practice :P, so therefore, setting the example here, Validate Client sent Buy Data. WebAppSecurity 101, Never trust a client. Validate Validate Validate! Or you'll have problems whether intentional or not.

1 files changed, 24 insertions, 0 deletions

diff --git a/OpenSim/Region/OptionalModules/World/MoneyModule/SampleMoneyModule.cs b/OpenSim/Region/OptionalModules/World/MoneyModule/SampleMoneyModule.cs
index d364df6..e42dbf2 100644
--- a/OpenSim/Region/OptionalModules/World/MoneyModule/SampleMoneyModule.cs
+++ b/OpenSim/Region/OptionalModules/World/MoneyModule/SampleMoneyModule.cs
@@ -805,6 +805,16 @@ namespace OpenSim.Region.OptionalModules.World.MoneyModule
             }
 
             Scene s = LocateSceneClientIn(remoteClient.AgentId);
+
+            // Implmenting base sale data checking here so the default OpenSimulator implementation isn't useless 
+            // combined with other implementations.  We're actually validating that the client is sending the data
+            // that it should.   In theory, the client should already know what to send here because it'll see it when it
+            // gets the object data.   If the data sent by the client doesn't match the object, the viewer probably has an 
+            // old idea of what the object properties are.   Viewer developer Hazim informed us that the base module 
+            // didn't check the client sent data against the object do any.   Since the base modules are the 
+            // 'crowning glory' examples of good practice..    
+
+            // Validate that the object exists in the scene the user is in
             SceneObjectPart part = s.GetSceneObjectPart(localID);
             if (part == null)
             {
@@ -812,6 +822,20 @@ namespace OpenSim.Region.OptionalModules.World.MoneyModule
                 return;
             }
             
+            // Validate that the client sent the price that the object is being sold for 
+            if (part.SalePrice != salePrice)
+            {
+                remoteClient.SendAgentAlertMessage("Cannot buy at this price. Buy Failed. If you continue to get this relog.", false);
+                return;
+            }
+
+            // Validate that the client sent the proper sale type the object has set 
+            if (part.ObjectSaleType != saleType)
+            {
+                remoteClient.SendAgentAlertMessage("Cannot buy this way. Buy Failed. If you continue to get this relog.", false);
+                return;
+            }
+
             IBuySellModule module = s.RequestModuleInterface<IBuySellModule>();
             if (module != null)
                 module.BuyObject(remoteClient, categoryID, localID, saleType, salePrice);