Implemented the ability to query the EnumerateSecurityPackages native API safely.

NSspi/NativeMethods.cs

@@ -33,5 +33,10 @@ namespace NSspi
         [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
         [DllImport( "Secur32.dll", EntryPoint = "QuerySecurityPackageInfo", CharSet = CharSet.Unicode )]
         internal static extern SecurityStatus QuerySecurityPackageInfo( string packageName, ref IntPtr pkgInfo );
+
+        [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
+        [DllImport( "Secur32.dll", EntryPoint = "EnumerateSecurityPackages", CharSet = CharSet.Unicode )]
+        internal static extern SecurityStatus EnumerateSecurityPackages( ref int numPackages, ref IntPtr pkgInfoArry );
+
     }
 }

NSspi/PackageSupport.cs

@@ -13,7 +13,7 @@ namespace NSspi
         internal static SecPkgInfo GetPackageCapabilities( string packageName )
         {
             SecPkgInfo info;
-            SecurityStatus status;
+            SecurityStatus status = SecurityStatus.InternalError;
             SecurityStatus freeStatus;
 
             IntPtr rawInfoPtr;
@@ -45,8 +45,71 @@ namespace NSspi
                 }
             }
 
+            if( status != SecurityStatus.OK )
+            {
+                throw new SSPIException( "Failed to query security package provider details", status );
+            }
+
             return info;
         }
 
+        public static SecPkgInfo[] EnumeratePackages()
+        {
+            SecurityStatus status = SecurityStatus.InternalError;
+            SecPkgInfo[] packages = null;
+            IntPtr pkgArrayPtr;
+            IntPtr pkgPtr;
+            int numPackages = 0;
+            int pkgSize = Marshal.SizeOf( typeof(SecPkgInfo) );
+
+            pkgArrayPtr = new IntPtr();
+
+            RuntimeHelpers.PrepareConstrainedRegions();
+            try { }
+            finally
+            {
+                status = NativeMethods.EnumerateSecurityPackages( ref numPackages, ref pkgArrayPtr );
+
+                if( pkgArrayPtr != IntPtr.Zero )
+                {
+                    try
+                    {
+                        if( status == SecurityStatus.OK )
+                        {
+                            // Bwooop Bwooop Alocation Alert
+                            // 1) We allocate the array
+                            // 2) We allocate the individual elements in the array (they're class objects).
+                            // 3) We allocate the strings in the individual elements in the array when we 
+                            //    call Marshal.PtrToStructure()
+
+                            packages = new SecPkgInfo[numPackages];
+
+                            for( int i = 0; i < numPackages; i++ )
+                            {
+                                packages[i] = new SecPkgInfo();
+                            }
+                            
+                            for( int i = 0; i < numPackages; i++ )
+                            {
+                                pkgPtr = IntPtr.Add( pkgArrayPtr, i * pkgSize );
+
+                                Marshal.PtrToStructure( pkgPtr, packages[i] );
+                            }
+                        }
+                    }
+                    finally
+                    {
+                        NativeMethods.FreeContextBuffer( pkgArrayPtr );
+                    }
+                }
+            }
+
+            if( status != SecurityStatus.OK )
+            {
+                throw new SSPIException( "Failed to enumerate security package providers", status );
+            }
+
+            return packages;
+        }
     }
 }