BaseUriHelper.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ Dotnetfx_Vista_SP2 / Dotnetfx_Vista_SP2 / 8.0.50727.4016 / DEVDIV / depot / DevDiv / releases / Orcas / QFE / wpf / src / Core / CSharp / System / Windows / Navigation / BaseUriHelper.cs / 1 / BaseUriHelper.cs

                            //  Copyright (c) Microsoft Corporation, 2001 
//
//  File:           BaseUriHelper.cs
//
// 
//  History:        06/21/05 - erichar - created
//                  07/20/05 - weibz - Move the place 
//                                     Move the BaseUri helper from Framework 
//                                     down to core.
//                  01/31/06: brucemac - Change PreloadedPackages.AddPackage() to pass a boolean indicating 
//                                     that SiteOfOriginContainer is thread-safe
//
//------------------------------------------------------------------------------
 
using System;
using System.Diagnostics; 
using System.IO.Packaging; 
using System.Globalization;
using System.Net; 
using System.Security;
using System.Windows;
using System.Windows.Markup;
using System.Windows.Media; 
using System.Reflection;
using System.IO; 
 
using MS.Internal;
using MS.Internal.AppModel; 
using MS.Internal.IO.Packaging;
using MS.Internal.PresentationCore;

// In order to avoid generating warnings about unknown message numbers and 
// unknown pragmas when compiling your C# source code with the actual C# compiler,
// you need to disable warnings 1634 and 1691. (Presharp Documentation) 
#pragma warning disable 1634, 1691 

namespace System.Windows.Navigation 
{
    /// 
    /// BaseUriHelper class provides BaseUri related property, methods.
    ///  
    public static class BaseUriHelper
    { 
        private const string SOOBASE = "SiteOfOrigin://"; 
        private static readonly Uri _siteOfOriginBaseUri = PackUriHelper.Create(new Uri(SOOBASE));
        private const string APPBASE = "application://"; 
        private static readonly Uri _packAppBaseUri = PackUriHelper.Create(new Uri(APPBASE));

        private static SecurityCriticalDataForSet _baseUri;
 
        // Cached result of calling
        // PackUriHelper.GetPackageUri(BaseUriHelper.PackAppBaseUri).GetComponents( 
        // UriComponents.AbsoluteUri, 
        // UriFormat.UriEscaped);
        private const string _packageApplicationBaseUriEscaped = "application:///"; 
        private const string _packageSiteOfOriginBaseUriEscaped = "siteoforigin:///";

        /// 
        /// Critical: because it sets critical data. 
        ///         Adds SiteOfOriginContainer to PreloadedPackages.
        /// TreatAsSafe: because it is the static ctor, and the data doesn't go anywhere. 
        ///         SiteOfOriginContainer is a well-known package and allowed to be added 
        ///         to PreloadedPackages. Also, the package is not going to be handed out
        ///         from this API surface and as such will be protected 
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        static BaseUriHelper()
        { 
            _baseUri = new SecurityCriticalDataForSet(_packAppBaseUri);
            // Add an instance of the ResourceContainer to PreloadedPackages so that PackWebRequestFactory can find it 
            // and mark it as thread-safe so PackWebResponse won't protect returned streams with a synchronizing wrapper 
            PreloadedPackages.AddPackage(PackUriHelper.GetPackageUri(SiteOfOriginBaseUri), new SiteOfOriginContainer(), true);
        } 

        #region public property and method

        ///  
        ///     The DependencyProperty for BaseUri of current Element.
        /// 
        ///     Flags: None 
        ///     Default Value: null.
        ///  
        public static readonly DependencyProperty BaseUriProperty =
                    DependencyProperty.RegisterAttached(
                                "BaseUri",
                                typeof(Uri), 
                                typeof(BaseUriHelper),
                                new PropertyMetadata((object)null)); 
 

        ///  
        /// Get BaseUri for a dependency object inside a tree.
        ///
        /// 
        /// Dependency Object 
        /// BaseUri for the element
        ///  
        ///     Callers must have FileIOPermission(FileIOPermissionAccess.PathDiscovery) for the given Uri to call this API. 
        /// 
        ///  
        /// Critical: as it access the BaseUri, which is critcal
        /// PublicOK: calls GetBaseUriCore that does a demand
        /// Not available from the Internet zone
        ///  
        [SecurityCritical]
        public static Uri GetBaseUri(DependencyObject element) 
        { 
            Uri baseUri = GetBaseUriCore(element);
 
            //
            // Manipulate BaseUri after tree searching is done.
            //
 
            if (baseUri == null)
            { 
                // If no BaseUri information is found from the current tree, 
                // just take the Application's BaseUri.
                // Application's BaseUri must be an absolute Uri. 

                baseUri = BaseUriHelper.BaseUri;
            }
            else 
            {
                if (baseUri.IsAbsoluteUri == false) 
                { 
                    // Most likely the BaseUriDP in element or IUriContext.BaseUri
                    // is set to a relative Uri programmatically in user's code. 
                    // For this case, we should resolve this relative Uri to PackAppBase
                    // to generate an absolute Uri.

                    // 
                    // BamlRecordReader now always sets absolute Uri for UriContext
                    // element when the tree is generated from baml/xaml stream, this 
                    // code path would not run for parser-loaded tree. 
                    //
 
                    baseUri = new Uri(BaseUriHelper.BaseUri, baseUri);
                }
            }
 
            return baseUri;
        } 
 

       #endregion public property and method 

        #region internal properties and methods

        static internal Uri SiteOfOriginBaseUri 
        {
            [FriendAccessAllowed] 
            get 
            {
                return _siteOfOriginBaseUri; 
            }
        }

        static internal Uri PackAppBaseUri 
        {
            [FriendAccessAllowed] 
            get 
            {
                return _packAppBaseUri; 
            }
        }

        ///  
        /// Checks whether the input uri is in the "pack://application:,,," form
        ///  
        internal static bool IsPackApplicationUri(Uri uri) 
        {
            return 
                // Is the "outer" URI absolute?
                uri.IsAbsoluteUri &&

                // Does the "outer" URI have the pack: scheme? 
                SecurityHelper.AreStringTypesEqual(uri.Scheme, PackUriHelper.UriSchemePack) &&
 
                // Does the "inner" URI have the application: scheme 
                SecurityHelper.AreStringTypesEqual(
                    PackUriHelper.GetPackageUri(uri).GetComponents(UriComponents.AbsoluteUri, UriFormat.UriEscaped), 
                    _packageApplicationBaseUriEscaped);
        }

        // The method accepts a relative or absolute Uri and returns the appropriate assembly. 
        //
        // For absolute Uri, it accepts only "pack://application:,,,/...", throw exception for 
        // any other absolute Uri. 
        //
        // If the first segment of that Uri contains ";component", returns the assembly whose 
        // assembly name matches the text string in the first segment. otherwise, this method
        // would return EntryAssembly in the AppDomain.
        //
        [FriendAccessAllowed] 
        internal static void GetAssemblyAndPartNameFromPackAppUri(Uri uri, out Assembly assembly, out string partName)
        { 
            // The input Uri is assumed to be a valid absolute pack application Uri. 
            // The caller should guarantee that.
            // Perform a sanity check to make sure the assumption stays. 
            Debug.Assert(uri != null && uri.IsAbsoluteUri && SecurityHelper.AreStringTypesEqual(uri.Scheme, PackUriHelper.UriSchemePack) && IsPackApplicationUri(uri));

            // Generate a relative Uri which gets rid of the pack://application:,,, authority part.
            Uri partUri = new Uri(uri.AbsolutePath, UriKind.Relative); 

            string assemblyName; 
            string assemblyVersion; 
            string assemblyKey;
 
            GetAssemblyNameAndPart(partUri, out partName, out assemblyName, out assemblyVersion, out assemblyKey);

            if (String.IsNullOrEmpty(assemblyName))
            { 
                // The uri doesn't contain ";component". it should map to the enty application assembly.
                assembly = ResourceAssembly; 
 
                // The partName returned from GetAssemblyNameAndPart should be escaped.
                Debug.Assert(String.Compare(partName, uri.GetComponents(UriComponents.Path, UriFormat.UriEscaped), StringComparison.OrdinalIgnoreCase) == 0); 
            }
            else
            {
                assembly = GetLoadedAssembly(assemblyName, assemblyVersion, assemblyKey); 
            }
        } 
 

        // 
        //
        [FriendAccessAllowed]
        internal static Assembly GetLoadedAssembly(string assemblyName, string assemblyVersion, string assemblyKey)
        { 
            Assembly assembly;
            AssemblyName asmName = new AssemblyName(assemblyName); 
 
            // We always use the primary assembly (culture neutral) for resource manager.
            // if the required resource lives in satellite assembly, ResourceManager can find 
            // the right satellite assembly later.
            asmName.CultureInfo = new CultureInfo(String.Empty);

            if (!String.IsNullOrEmpty(assemblyVersion)) 
            {
                asmName.Version = new Version(assemblyVersion); 
            } 

            if (!String.IsNullOrEmpty(assemblyKey)) 
            {
                int byteCount = assemblyKey.Length / 2;
                byte[] keyToken = new byte[byteCount];
                for (int i = 0; i < byteCount; i++) 
                {
                    string byteString = assemblyKey.Substring(i * 2, 2); 
                    keyToken[i] = byte.Parse(byteString, NumberStyles.HexNumber, CultureInfo.InvariantCulture); 
                }
 
                asmName.SetPublicKeyToken(keyToken);
            }

            assembly = SafeSecurityHelper.GetLoadedAssembly(asmName); 

            if (assembly == null) 
            { 
                // The assembly is not yet loaded to the AppDomain, try to load it with information specified in resource Uri.
                assembly = Assembly.Load(asmName); 
            }

            return assembly;
        } 

        // 
        // Return assembly Name, Version, Key and package Part from a relative Uri. 
        //
        [FriendAccessAllowed] 
        internal static void GetAssemblyNameAndPart(Uri uri, out string partName, out string assemblyName, out string assemblyVersion, out string assemblyKey)
        {
            Invariant.Assert(uri != null && uri.IsAbsoluteUri == false, "This method accepts relative uri only.");
 
            string original = uri.ToString(); // only relative Uri here (enforced by Package)
 
            // Start and end points for the first segment in the Uri. 
            int start = 0;
            int end; 

            if (original[0] == '/')
            {
                start = 1; 
            }
 
            partName = original.Substring(start); 

            assemblyName = string.Empty; 
            assemblyVersion = string.Empty;
            assemblyKey = string.Empty;

            end = original.IndexOf('/', start); 

            string firstSegment = String.Empty; 
            bool fHasComponent = false; 

            if (end > 0) 
            {
                // get the first section
                firstSegment = original.Substring(start, end - start);
 
                // The resource comes from dll
                if (firstSegment.EndsWith(COMPONENT, StringComparison.OrdinalIgnoreCase)) 
                { 
                    partName = original.Substring(end + 1);
                    fHasComponent = true; 
                }
            }

            if (fHasComponent) 
            {
                string[] assemblyInfo = firstSegment.Split(new char[] { COMPONENT_DELIMITER }); 
 
                int count = assemblyInfo.Length;
 
                if ((count > 4) || (count < 2))
                {
                    throw new UriFormatException(SR.Get(SRID.WrongFirstSegment));
                } 

                // 
                // if the uri contains escaping character, 
                // Convert it back to normal unicode string
                // so that the string as assembly name can be 
                // recognized by Assembly.Load later.
                //
                assemblyName = Uri.UnescapeDataString(assemblyInfo[0]);
 
                for (int i = 1; i < count - 1; i++)
                { 
                    if (assemblyInfo[i].StartsWith(VERSION, StringComparison.OrdinalIgnoreCase)) 
                    {
                        if (string.IsNullOrEmpty(assemblyVersion)) 
                        {
                            assemblyVersion = assemblyInfo[i].Substring(1);  // Get rid of the leading "v"
                        }
                        else 
                        {
                            throw new UriFormatException(SR.Get(SRID.WrongFirstSegment)); 
                        } 
                    }
                    else 
                    {
                        if (string.IsNullOrEmpty(assemblyKey))
                        {
                            assemblyKey = assemblyInfo[i]; 
                        }
                        else 
                        { 
                            throw new UriFormatException(SR.Get(SRID.WrongFirstSegment));
                        } 
                    }
                } // end of for loop

            } // end of if fHasComponent 
        }
 
        [FriendAccessAllowed] 
        static internal bool IsComponentEntryAssembly(string component)
        { 
            if (component.EndsWith(COMPONENT, StringComparison.OrdinalIgnoreCase))
            {
                string[] assemblyInfo = component.Split(new Char[] { COMPONENT_DELIMITER });
                // Check whether the assembly name is the same as the EntryAssembly. 
                int count = assemblyInfo.Length;
                if ((count >= 2) && (count <= 4)) 
                { 
                    string assemblyName = Uri.UnescapeDataString(assemblyInfo[0]);
 
                    Assembly assembly = ResourceAssembly;

                    if (assembly != null)
                    { 
                        return (String.Compare(SafeSecurityHelper.GetAssemblyPartialName(assembly), assemblyName, StringComparison.OrdinalIgnoreCase) == 0);
                    } 
                    else 
                    {
                        return false; 
                    }
                }
            }
            return false; 
        }
 
        [FriendAccessAllowed] 
        static internal Uri GetResolvedUri(Uri baseUri, Uri orgUri)
        { 
            return new Uri(baseUri, orgUri);
        }

        [FriendAccessAllowed] 
        static internal Uri MakeRelativeToSiteOfOriginIfPossible(Uri sUri)
        { 
            if (Uri.Compare(sUri, SiteOfOriginBaseUri, UriComponents.Scheme, UriFormat.UriEscaped, StringComparison.OrdinalIgnoreCase) == 0) 
            {
                Uri packageUri; 
                Uri partUri;
                PackUriHelper.ValidateAndGetPackUriComponents(sUri, out packageUri, out partUri);

                if (String.Compare(packageUri.GetComponents(UriComponents.AbsoluteUri, UriFormat.UriEscaped), _packageSiteOfOriginBaseUriEscaped, StringComparison.OrdinalIgnoreCase) == 0) 
                {
                    return (new Uri(sUri.GetComponents(UriComponents.SchemeAndServer, UriFormat.UriEscaped))).MakeRelativeUri(sUri); 
                } 
            }
 
            return sUri;
        }

        [FriendAccessAllowed] 
        static internal Uri ConvertPackUriToAbsoluteExternallyVisibleUri(Uri packUri)
        { 
            Invariant.Assert(packUri.IsAbsoluteUri && SecurityHelper.AreStringTypesEqual(packUri.Scheme, PackAppBaseUri.Scheme)); 

            Uri relative = MakeRelativeToSiteOfOriginIfPossible(packUri); 

            if (! relative.IsAbsoluteUri)
            {
                return new Uri(SiteOfOriginContainer.SiteOfOrigin, relative); 
            }
            else 
            { 
               throw new InvalidOperationException(SR.Get(SRID.CannotNavigateToApplicationResourcesInWebBrowser, packUri));
            } 
        }

        // If a Uri is constructed with a legacy path such as c:\foo\bar then the Uri
        // object will not correctly resolve relative Uris in some cases.  This method 
        // detects and fixes this by constructing a new Uri with an original string
        // that contains the scheme file://. 
        [FriendAccessAllowed] 
        static internal Uri FixFileUri(Uri uri)
        { 
            if (uri != null && uri.IsAbsoluteUri && SecurityHelper.AreStringTypesEqual(uri.Scheme, Uri.UriSchemeFile) &&
                string.Compare(uri.OriginalString, 0, Uri.UriSchemeFile, 0, Uri.UriSchemeFile.Length, StringComparison.OrdinalIgnoreCase) != 0)
            {
                return new Uri(uri.AbsoluteUri); 
            }
 
            return uri; 
        }
 
        /// 
        /// Critical: as it sets the baseUri
        /// 
        static internal Uri BaseUri 
        {
            [FriendAccessAllowed] 
            get 
            {
                return _baseUri.Value; 
            }
            [FriendAccessAllowed]
            [SecurityCritical]
            set 
            {
                // This setter should only be called from Framework through 
                // BindUriHelper.set_BaseUri. 
                _baseUri.Value = value;
            } 
        }

        static internal Assembly ResourceAssembly
        { 
            get
            { 
                if (_resourceAssembly == null) 
                {
                    _resourceAssembly = Assembly.GetEntryAssembly(); 
                }
                return _resourceAssembly;
            }
            [FriendAccessAllowed] 
            set
            { 
                // This should only be called from Framework through Application.ResourceAssembly setter. 
                _resourceAssembly = value;
            } 
        }

        #endregion internal properties and methods
 
        #region private methods
 
        ///  
        /// Get BaseUri for a dependency object inside a tree.
        /// 
        /// 
        /// Dependency Object
        /// BaseUri for the element
        ///  
        ///     Callers must have FileIOPermission(FileIOPermissionAccess.PathDiscovery) for the given Uri to call this API.
        ///  
        ///  
        /// Critical: as it access the BaseUri, which is critcal
        /// TreatAsSafe: since it demands File read write and path dicovery  permission. 
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        internal static Uri GetBaseUriCore(DependencyObject element)
        { 
            Uri baseUri = null;
            DependencyObject doCurrent; 
 
            if (element == null)
            { 
                throw new ArgumentNullException("element");
            }

            try 
            {
                // 
                // Search the tree to find the closest parent which implements 
                // IUriContext or have set value for BaseUri property.
                // 
                doCurrent = element;

                while (doCurrent != null)
                { 
                    // Try to get BaseUri property value from current node.
                    baseUri = doCurrent.GetValue(BaseUriProperty) as Uri; 
 
                    if (baseUri != null)
                    { 
                        // Got the right node which is the closest to original element.
                        // Stop searching here.
                        break;
                    } 

                    IUriContext uriContext = doCurrent as IUriContext; 
 
                    if (uriContext != null)
                    { 
                        // If the element implements IUriContext, and if the BaseUri
                        // is not null, just take the BaseUri from there.
                        // and stop the search loop.
                        baseUri = uriContext.BaseUri; 

                        if (baseUri != null) 
                            break; 
                    }
 
                    //
                    // The current node doesn't contain BaseUri value,
                    // try its parent node in the tree.
 
                    UIElement uie = doCurrent as UIElement;
 
                    if (uie != null) 
                    {
                        // Do the tree walk up 
                        doCurrent = uie.GetUIParent(true);
                    }
                    else
                    { 
                        ContentElement ce = doCurrent as ContentElement;
 
                        if (ce != null) 
                        {
                            doCurrent = ce.Parent; 
                        }
                        else
                        {
                            Visual vis = doCurrent as Visual; 

                            if (vis != null) 
                            { 
                                // Try the Visual tree search
                                doCurrent = VisualTreeHelper.GetParent(vis); 
                            }
                            else
                            {
                                // Not a Visual. 
                                // Stop here for the tree searching to aviod an infinite loop.
                                break; 
                            } 
                        }
                    } 
                }
            }
            finally
            { 
                //
                // Putting the permission demand in finally block can prevent from exposing a bogus 
                // and dangerous uri to the code in upper frame. 
                //
                if (baseUri != null) 
                {
                    SecurityHelper.DemandUriDiscoveryPermission(baseUri);
                }
            } 

            return baseUri; 
        } 

        #endregion 

        private const string COMPONENT = ";component";
        private const string VERSION = "v";
        private const char COMPONENT_DELIMITER = ';'; 

        private static Assembly _resourceAssembly; 
    } 
}
 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
//  Copyright (c) Microsoft Corporation, 2001 
//
//  File:           BaseUriHelper.cs
//
// 
//  History:        06/21/05 - erichar - created
//                  07/20/05 - weibz - Move the place 
//                                     Move the BaseUri helper from Framework 
//                                     down to core.
//                  01/31/06: brucemac - Change PreloadedPackages.AddPackage() to pass a boolean indicating 
//                                     that SiteOfOriginContainer is thread-safe
//
//------------------------------------------------------------------------------
 
using System;
using System.Diagnostics; 
using System.IO.Packaging; 
using System.Globalization;
using System.Net; 
using System.Security;
using System.Windows;
using System.Windows.Markup;
using System.Windows.Media; 
using System.Reflection;
using System.IO; 
 
using MS.Internal;
using MS.Internal.AppModel; 
using MS.Internal.IO.Packaging;
using MS.Internal.PresentationCore;

// In order to avoid generating warnings about unknown message numbers and 
// unknown pragmas when compiling your C# source code with the actual C# compiler,
// you need to disable warnings 1634 and 1691. (Presharp Documentation) 
#pragma warning disable 1634, 1691 

namespace System.Windows.Navigation 
{
    /// 
    /// BaseUriHelper class provides BaseUri related property, methods.
    ///  
    public static class BaseUriHelper
    { 
        private const string SOOBASE = "SiteOfOrigin://"; 
        private static readonly Uri _siteOfOriginBaseUri = PackUriHelper.Create(new Uri(SOOBASE));
        private const string APPBASE = "application://"; 
        private static readonly Uri _packAppBaseUri = PackUriHelper.Create(new Uri(APPBASE));

        private static SecurityCriticalDataForSet _baseUri;
 
        // Cached result of calling
        // PackUriHelper.GetPackageUri(BaseUriHelper.PackAppBaseUri).GetComponents( 
        // UriComponents.AbsoluteUri, 
        // UriFormat.UriEscaped);
        private const string _packageApplicationBaseUriEscaped = "application:///"; 
        private const string _packageSiteOfOriginBaseUriEscaped = "siteoforigin:///";

        /// 
        /// Critical: because it sets critical data. 
        ///         Adds SiteOfOriginContainer to PreloadedPackages.
        /// TreatAsSafe: because it is the static ctor, and the data doesn't go anywhere. 
        ///         SiteOfOriginContainer is a well-known package and allowed to be added 
        ///         to PreloadedPackages. Also, the package is not going to be handed out
        ///         from this API surface and as such will be protected 
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        static BaseUriHelper()
        { 
            _baseUri = new SecurityCriticalDataForSet(_packAppBaseUri);
            // Add an instance of the ResourceContainer to PreloadedPackages so that PackWebRequestFactory can find it 
            // and mark it as thread-safe so PackWebResponse won't protect returned streams with a synchronizing wrapper 
            PreloadedPackages.AddPackage(PackUriHelper.GetPackageUri(SiteOfOriginBaseUri), new SiteOfOriginContainer(), true);
        } 

        #region public property and method

        ///  
        ///     The DependencyProperty for BaseUri of current Element.
        /// 
        ///     Flags: None 
        ///     Default Value: null.
        ///  
        public static readonly DependencyProperty BaseUriProperty =
                    DependencyProperty.RegisterAttached(
                                "BaseUri",
                                typeof(Uri), 
                                typeof(BaseUriHelper),
                                new PropertyMetadata((object)null)); 
 

        ///  
        /// Get BaseUri for a dependency object inside a tree.
        ///
        /// 
        /// Dependency Object 
        /// BaseUri for the element
        ///  
        ///     Callers must have FileIOPermission(FileIOPermissionAccess.PathDiscovery) for the given Uri to call this API. 
        /// 
        ///  
        /// Critical: as it access the BaseUri, which is critcal
        /// PublicOK: calls GetBaseUriCore that does a demand
        /// Not available from the Internet zone
        ///  
        [SecurityCritical]
        public static Uri GetBaseUri(DependencyObject element) 
        { 
            Uri baseUri = GetBaseUriCore(element);
 
            //
            // Manipulate BaseUri after tree searching is done.
            //
 
            if (baseUri == null)
            { 
                // If no BaseUri information is found from the current tree, 
                // just take the Application's BaseUri.
                // Application's BaseUri must be an absolute Uri. 

                baseUri = BaseUriHelper.BaseUri;
            }
            else 
            {
                if (baseUri.IsAbsoluteUri == false) 
                { 
                    // Most likely the BaseUriDP in element or IUriContext.BaseUri
                    // is set to a relative Uri programmatically in user's code. 
                    // For this case, we should resolve this relative Uri to PackAppBase
                    // to generate an absolute Uri.

                    // 
                    // BamlRecordReader now always sets absolute Uri for UriContext
                    // element when the tree is generated from baml/xaml stream, this 
                    // code path would not run for parser-loaded tree. 
                    //
 
                    baseUri = new Uri(BaseUriHelper.BaseUri, baseUri);
                }
            }
 
            return baseUri;
        } 
 

       #endregion public property and method 

        #region internal properties and methods

        static internal Uri SiteOfOriginBaseUri 
        {
            [FriendAccessAllowed] 
            get 
            {
                return _siteOfOriginBaseUri; 
            }
        }

        static internal Uri PackAppBaseUri 
        {
            [FriendAccessAllowed] 
            get 
            {
                return _packAppBaseUri; 
            }
        }

        ///  
        /// Checks whether the input uri is in the "pack://application:,,," form
        ///  
        internal static bool IsPackApplicationUri(Uri uri) 
        {
            return 
                // Is the "outer" URI absolute?
                uri.IsAbsoluteUri &&

                // Does the "outer" URI have the pack: scheme? 
                SecurityHelper.AreStringTypesEqual(uri.Scheme, PackUriHelper.UriSchemePack) &&
 
                // Does the "inner" URI have the application: scheme 
                SecurityHelper.AreStringTypesEqual(
                    PackUriHelper.GetPackageUri(uri).GetComponents(UriComponents.AbsoluteUri, UriFormat.UriEscaped), 
                    _packageApplicationBaseUriEscaped);
        }

        // The method accepts a relative or absolute Uri and returns the appropriate assembly. 
        //
        // For absolute Uri, it accepts only "pack://application:,,,/...", throw exception for 
        // any other absolute Uri. 
        //
        // If the first segment of that Uri contains ";component", returns the assembly whose 
        // assembly name matches the text string in the first segment. otherwise, this method
        // would return EntryAssembly in the AppDomain.
        //
        [FriendAccessAllowed] 
        internal static void GetAssemblyAndPartNameFromPackAppUri(Uri uri, out Assembly assembly, out string partName)
        { 
            // The input Uri is assumed to be a valid absolute pack application Uri. 
            // The caller should guarantee that.
            // Perform a sanity check to make sure the assumption stays. 
            Debug.Assert(uri != null && uri.IsAbsoluteUri && SecurityHelper.AreStringTypesEqual(uri.Scheme, PackUriHelper.UriSchemePack) && IsPackApplicationUri(uri));

            // Generate a relative Uri which gets rid of the pack://application:,,, authority part.
            Uri partUri = new Uri(uri.AbsolutePath, UriKind.Relative); 

            string assemblyName; 
            string assemblyVersion; 
            string assemblyKey;
 
            GetAssemblyNameAndPart(partUri, out partName, out assemblyName, out assemblyVersion, out assemblyKey);

            if (String.IsNullOrEmpty(assemblyName))
            { 
                // The uri doesn't contain ";component". it should map to the enty application assembly.
                assembly = ResourceAssembly; 
 
                // The partName returned from GetAssemblyNameAndPart should be escaped.
                Debug.Assert(String.Compare(partName, uri.GetComponents(UriComponents.Path, UriFormat.UriEscaped), StringComparison.OrdinalIgnoreCase) == 0); 
            }
            else
            {
                assembly = GetLoadedAssembly(assemblyName, assemblyVersion, assemblyKey); 
            }
        } 
 

        // 
        //
        [FriendAccessAllowed]
        internal static Assembly GetLoadedAssembly(string assemblyName, string assemblyVersion, string assemblyKey)
        { 
            Assembly assembly;
            AssemblyName asmName = new AssemblyName(assemblyName); 
 
            // We always use the primary assembly (culture neutral) for resource manager.
            // if the required resource lives in satellite assembly, ResourceManager can find 
            // the right satellite assembly later.
            asmName.CultureInfo = new CultureInfo(String.Empty);

            if (!String.IsNullOrEmpty(assemblyVersion)) 
            {
                asmName.Version = new Version(assemblyVersion); 
            } 

            if (!String.IsNullOrEmpty(assemblyKey)) 
            {
                int byteCount = assemblyKey.Length / 2;
                byte[] keyToken = new byte[byteCount];
                for (int i = 0; i < byteCount; i++) 
                {
                    string byteString = assemblyKey.Substring(i * 2, 2); 
                    keyToken[i] = byte.Parse(byteString, NumberStyles.HexNumber, CultureInfo.InvariantCulture); 
                }
 
                asmName.SetPublicKeyToken(keyToken);
            }

            assembly = SafeSecurityHelper.GetLoadedAssembly(asmName); 

            if (assembly == null) 
            { 
                // The assembly is not yet loaded to the AppDomain, try to load it with information specified in resource Uri.
                assembly = Assembly.Load(asmName); 
            }

            return assembly;
        } 

        // 
        // Return assembly Name, Version, Key and package Part from a relative Uri. 
        //
        [FriendAccessAllowed] 
        internal static void GetAssemblyNameAndPart(Uri uri, out string partName, out string assemblyName, out string assemblyVersion, out string assemblyKey)
        {
            Invariant.Assert(uri != null && uri.IsAbsoluteUri == false, "This method accepts relative uri only.");
 
            string original = uri.ToString(); // only relative Uri here (enforced by Package)
 
            // Start and end points for the first segment in the Uri. 
            int start = 0;
            int end; 

            if (original[0] == '/')
            {
                start = 1; 
            }
 
            partName = original.Substring(start); 

            assemblyName = string.Empty; 
            assemblyVersion = string.Empty;
            assemblyKey = string.Empty;

            end = original.IndexOf('/', start); 

            string firstSegment = String.Empty; 
            bool fHasComponent = false; 

            if (end > 0) 
            {
                // get the first section
                firstSegment = original.Substring(start, end - start);
 
                // The resource comes from dll
                if (firstSegment.EndsWith(COMPONENT, StringComparison.OrdinalIgnoreCase)) 
                { 
                    partName = original.Substring(end + 1);
                    fHasComponent = true; 
                }
            }

            if (fHasComponent) 
            {
                string[] assemblyInfo = firstSegment.Split(new char[] { COMPONENT_DELIMITER }); 
 
                int count = assemblyInfo.Length;
 
                if ((count > 4) || (count < 2))
                {
                    throw new UriFormatException(SR.Get(SRID.WrongFirstSegment));
                } 

                // 
                // if the uri contains escaping character, 
                // Convert it back to normal unicode string
                // so that the string as assembly name can be 
                // recognized by Assembly.Load later.
                //
                assemblyName = Uri.UnescapeDataString(assemblyInfo[0]);
 
                for (int i = 1; i < count - 1; i++)
                { 
                    if (assemblyInfo[i].StartsWith(VERSION, StringComparison.OrdinalIgnoreCase)) 
                    {
                        if (string.IsNullOrEmpty(assemblyVersion)) 
                        {
                            assemblyVersion = assemblyInfo[i].Substring(1);  // Get rid of the leading "v"
                        }
                        else 
                        {
                            throw new UriFormatException(SR.Get(SRID.WrongFirstSegment)); 
                        } 
                    }
                    else 
                    {
                        if (string.IsNullOrEmpty(assemblyKey))
                        {
                            assemblyKey = assemblyInfo[i]; 
                        }
                        else 
                        { 
                            throw new UriFormatException(SR.Get(SRID.WrongFirstSegment));
                        } 
                    }
                } // end of for loop

            } // end of if fHasComponent 
        }
 
        [FriendAccessAllowed] 
        static internal bool IsComponentEntryAssembly(string component)
        { 
            if (component.EndsWith(COMPONENT, StringComparison.OrdinalIgnoreCase))
            {
                string[] assemblyInfo = component.Split(new Char[] { COMPONENT_DELIMITER });
                // Check whether the assembly name is the same as the EntryAssembly. 
                int count = assemblyInfo.Length;
                if ((count >= 2) && (count <= 4)) 
                { 
                    string assemblyName = Uri.UnescapeDataString(assemblyInfo[0]);
 
                    Assembly assembly = ResourceAssembly;

                    if (assembly != null)
                    { 
                        return (String.Compare(SafeSecurityHelper.GetAssemblyPartialName(assembly), assemblyName, StringComparison.OrdinalIgnoreCase) == 0);
                    } 
                    else 
                    {
                        return false; 
                    }
                }
            }
            return false; 
        }
 
        [FriendAccessAllowed] 
        static internal Uri GetResolvedUri(Uri baseUri, Uri orgUri)
        { 
            return new Uri(baseUri, orgUri);
        }

        [FriendAccessAllowed] 
        static internal Uri MakeRelativeToSiteOfOriginIfPossible(Uri sUri)
        { 
            if (Uri.Compare(sUri, SiteOfOriginBaseUri, UriComponents.Scheme, UriFormat.UriEscaped, StringComparison.OrdinalIgnoreCase) == 0) 
            {
                Uri packageUri; 
                Uri partUri;
                PackUriHelper.ValidateAndGetPackUriComponents(sUri, out packageUri, out partUri);

                if (String.Compare(packageUri.GetComponents(UriComponents.AbsoluteUri, UriFormat.UriEscaped), _packageSiteOfOriginBaseUriEscaped, StringComparison.OrdinalIgnoreCase) == 0) 
                {
                    return (new Uri(sUri.GetComponents(UriComponents.SchemeAndServer, UriFormat.UriEscaped))).MakeRelativeUri(sUri); 
                } 
            }
 
            return sUri;
        }

        [FriendAccessAllowed] 
        static internal Uri ConvertPackUriToAbsoluteExternallyVisibleUri(Uri packUri)
        { 
            Invariant.Assert(packUri.IsAbsoluteUri && SecurityHelper.AreStringTypesEqual(packUri.Scheme, PackAppBaseUri.Scheme)); 

            Uri relative = MakeRelativeToSiteOfOriginIfPossible(packUri); 

            if (! relative.IsAbsoluteUri)
            {
                return new Uri(SiteOfOriginContainer.SiteOfOrigin, relative); 
            }
            else 
            { 
               throw new InvalidOperationException(SR.Get(SRID.CannotNavigateToApplicationResourcesInWebBrowser, packUri));
            } 
        }

        // If a Uri is constructed with a legacy path such as c:\foo\bar then the Uri
        // object will not correctly resolve relative Uris in some cases.  This method 
        // detects and fixes this by constructing a new Uri with an original string
        // that contains the scheme file://. 
        [FriendAccessAllowed] 
        static internal Uri FixFileUri(Uri uri)
        { 
            if (uri != null && uri.IsAbsoluteUri && SecurityHelper.AreStringTypesEqual(uri.Scheme, Uri.UriSchemeFile) &&
                string.Compare(uri.OriginalString, 0, Uri.UriSchemeFile, 0, Uri.UriSchemeFile.Length, StringComparison.OrdinalIgnoreCase) != 0)
            {
                return new Uri(uri.AbsoluteUri); 
            }
 
            return uri; 
        }
 
        /// 
        /// Critical: as it sets the baseUri
        /// 
        static internal Uri BaseUri 
        {
            [FriendAccessAllowed] 
            get 
            {
                return _baseUri.Value; 
            }
            [FriendAccessAllowed]
            [SecurityCritical]
            set 
            {
                // This setter should only be called from Framework through 
                // BindUriHelper.set_BaseUri. 
                _baseUri.Value = value;
            } 
        }

        static internal Assembly ResourceAssembly
        { 
            get
            { 
                if (_resourceAssembly == null) 
                {
                    _resourceAssembly = Assembly.GetEntryAssembly(); 
                }
                return _resourceAssembly;
            }
            [FriendAccessAllowed] 
            set
            { 
                // This should only be called from Framework through Application.ResourceAssembly setter. 
                _resourceAssembly = value;
            } 
        }

        #endregion internal properties and methods
 
        #region private methods
 
        ///  
        /// Get BaseUri for a dependency object inside a tree.
        /// 
        /// 
        /// Dependency Object
        /// BaseUri for the element
        ///  
        ///     Callers must have FileIOPermission(FileIOPermissionAccess.PathDiscovery) for the given Uri to call this API.
        ///  
        ///  
        /// Critical: as it access the BaseUri, which is critcal
        /// TreatAsSafe: since it demands File read write and path dicovery  permission. 
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        internal static Uri GetBaseUriCore(DependencyObject element)
        { 
            Uri baseUri = null;
            DependencyObject doCurrent; 
 
            if (element == null)
            { 
                throw new ArgumentNullException("element");
            }

            try 
            {
                // 
                // Search the tree to find the closest parent which implements 
                // IUriContext or have set value for BaseUri property.
                // 
                doCurrent = element;

                while (doCurrent != null)
                { 
                    // Try to get BaseUri property value from current node.
                    baseUri = doCurrent.GetValue(BaseUriProperty) as Uri; 
 
                    if (baseUri != null)
                    { 
                        // Got the right node which is the closest to original element.
                        // Stop searching here.
                        break;
                    } 

                    IUriContext uriContext = doCurrent as IUriContext; 
 
                    if (uriContext != null)
                    { 
                        // If the element implements IUriContext, and if the BaseUri
                        // is not null, just take the BaseUri from there.
                        // and stop the search loop.
                        baseUri = uriContext.BaseUri; 

                        if (baseUri != null) 
                            break; 
                    }
 
                    //
                    // The current node doesn't contain BaseUri value,
                    // try its parent node in the tree.
 
                    UIElement uie = doCurrent as UIElement;
 
                    if (uie != null) 
                    {
                        // Do the tree walk up 
                        doCurrent = uie.GetUIParent(true);
                    }
                    else
                    { 
                        ContentElement ce = doCurrent as ContentElement;
 
                        if (ce != null) 
                        {
                            doCurrent = ce.Parent; 
                        }
                        else
                        {
                            Visual vis = doCurrent as Visual; 

                            if (vis != null) 
                            { 
                                // Try the Visual tree search
                                doCurrent = VisualTreeHelper.GetParent(vis); 
                            }
                            else
                            {
                                // Not a Visual. 
                                // Stop here for the tree searching to aviod an infinite loop.
                                break; 
                            } 
                        }
                    } 
                }
            }
            finally
            { 
                //
                // Putting the permission demand in finally block can prevent from exposing a bogus 
                // and dangerous uri to the code in upper frame. 
                //
                if (baseUri != null) 
                {
                    SecurityHelper.DemandUriDiscoveryPermission(baseUri);
                }
            } 

            return baseUri; 
        } 

        #endregion 

        private const string COMPONENT = ";component";
        private const string VERSION = "v";
        private const char COMPONENT_DELIMITER = ';'; 

        private static Assembly _resourceAssembly; 
    } 
}
 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
                        

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