jellyfin/Emby.Server.Implementations/HttpServer/HttpResultFactory.cs
2017-05-31 15:21:32 -04:00

841 lines
31 KiB
C#

using MediaBrowser.Common.Extensions;
using MediaBrowser.Controller.Net;
using MediaBrowser.Model.Logging;
using MediaBrowser.Model.Serialization;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.IO.Compression;
using System.Net;
using System.Runtime.Serialization;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using Emby.Server.Implementations.HttpServer;
using Emby.Server.Implementations.Services;
using MediaBrowser.Model.IO;
using MediaBrowser.Model.Services;
using IRequest = MediaBrowser.Model.Services.IRequest;
using MimeTypes = MediaBrowser.Model.Net.MimeTypes;
using StreamWriter = Emby.Server.Implementations.HttpServer.StreamWriter;
namespace Emby.Server.Implementations.HttpServer
{
/// <summary>
/// Class HttpResultFactory
/// </summary>
public class HttpResultFactory : IHttpResultFactory
{
/// <summary>
/// The _logger
/// </summary>
private readonly ILogger _logger;
private readonly IFileSystem _fileSystem;
private readonly IJsonSerializer _jsonSerializer;
private readonly IMemoryStreamFactory _memoryStreamFactory;
/// <summary>
/// Initializes a new instance of the <see cref="HttpResultFactory" /> class.
/// </summary>
public HttpResultFactory(ILogManager logManager, IFileSystem fileSystem, IJsonSerializer jsonSerializer, IMemoryStreamFactory memoryStreamFactory)
{
_fileSystem = fileSystem;
_jsonSerializer = jsonSerializer;
_memoryStreamFactory = memoryStreamFactory;
_logger = logManager.GetLogger("HttpResultFactory");
}
/// <summary>
/// Gets the result.
/// </summary>
/// <param name="content">The content.</param>
/// <param name="contentType">Type of the content.</param>
/// <param name="responseHeaders">The response headers.</param>
/// <returns>System.Object.</returns>
public object GetResult(object content, string contentType, IDictionary<string, string> responseHeaders = null)
{
return GetHttpResult(content, contentType, true, responseHeaders);
}
public object GetRedirectResult(string url)
{
var responseHeaders = new Dictionary<string, string>();
responseHeaders["Location"] = url;
var result = new HttpResult(new byte[] { }, "text/plain", HttpStatusCode.Redirect);
AddResponseHeaders(result, responseHeaders);
return result;
}
/// <summary>
/// Gets the HTTP result.
/// </summary>
private IHasHeaders GetHttpResult(object content, string contentType, bool addCachePrevention, IDictionary<string, string> responseHeaders = null)
{
IHasHeaders result;
var stream = content as Stream;
if (stream != null)
{
result = new StreamWriter(stream, contentType, _logger);
}
else
{
var bytes = content as byte[];
if (bytes != null)
{
result = new StreamWriter(bytes, contentType, _logger);
}
else
{
var text = content as string;
if (text != null)
{
result = new StreamWriter(Encoding.UTF8.GetBytes(text), contentType, _logger);
}
else
{
result = new HttpResult(content, contentType, HttpStatusCode.OK);
}
}
}
if (responseHeaders == null)
{
responseHeaders = new Dictionary<string, string>();
}
string expires;
if (addCachePrevention && !responseHeaders.TryGetValue("Expires", out expires))
{
responseHeaders["Expires"] = "-1";
}
AddResponseHeaders(result, responseHeaders);
return result;
}
/// <summary>
/// Gets the optimized result.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="requestContext">The request context.</param>
/// <param name="result">The result.</param>
/// <param name="responseHeaders">The response headers.</param>
/// <returns>System.Object.</returns>
/// <exception cref="System.ArgumentNullException">result</exception>
public object GetOptimizedResult<T>(IRequest requestContext, T result, IDictionary<string, string> responseHeaders = null)
where T : class
{
return GetOptimizedResultInternal<T>(requestContext, result, true, responseHeaders);
}
private object GetOptimizedResultInternal<T>(IRequest requestContext, T result, bool addCachePrevention, IDictionary<string, string> responseHeaders = null)
where T : class
{
if (result == null)
{
throw new ArgumentNullException("result");
}
var optimizedResult = ToOptimizedResult(requestContext, result);
if (responseHeaders == null)
{
responseHeaders = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
}
if (addCachePrevention)
{
responseHeaders["Expires"] = "-1";
}
// Apply headers
var hasHeaders = optimizedResult as IHasHeaders;
if (hasHeaders != null)
{
AddResponseHeaders(hasHeaders, responseHeaders);
}
return optimizedResult;
}
public static string GetCompressionType(IRequest request)
{
var acceptEncoding = request.Headers["Accept-Encoding"];
if (!string.IsNullOrWhiteSpace(acceptEncoding))
{
if (acceptEncoding.Contains("deflate"))
return "deflate";
if (acceptEncoding.Contains("gzip"))
return "gzip";
}
return null;
}
/// <summary>
/// Returns the optimized result for the IRequestContext.
/// Does not use or store results in any cache.
/// </summary>
/// <param name="request"></param>
/// <param name="dto"></param>
/// <returns></returns>
public object ToOptimizedResult<T>(IRequest request, T dto)
{
var compressionType = GetCompressionType(request);
if (compressionType == null)
{
var contentType = request.ResponseContentType;
switch (GetRealContentType(contentType))
{
case "application/xml":
case "text/xml":
case "text/xml; charset=utf-8": //"text/xml; charset=utf-8" also matches xml
return SerializeToXmlString(dto);
case "application/json":
case "text/json":
return _jsonSerializer.SerializeToString(dto);
}
}
// Do not use the memoryStreamFactory here, they don't place nice with compression
using (var ms = new MemoryStream())
{
var contentType = request.ResponseContentType;
var writerFn = RequestHelper.GetResponseWriter(HttpListenerHost.Instance, contentType);
writerFn(dto, ms);
ms.Position = 0;
var responseHeaders = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
return GetCompressedResult(ms, compressionType, responseHeaders, false, request.ResponseContentType).Result;
}
}
private static Stream GetCompressionStream(Stream outputStream, string compressionType)
{
if (compressionType == "deflate")
return new DeflateStream(outputStream, CompressionMode.Compress, true);
if (compressionType == "gzip")
return new GZipStream(outputStream, CompressionMode.Compress, true);
throw new NotSupportedException(compressionType);
}
public static string GetRealContentType(string contentType)
{
return contentType == null
? null
: contentType.Split(';')[0].ToLower().Trim();
}
private string SerializeToXmlString(object from)
{
using (var ms = new MemoryStream())
{
var xwSettings = new XmlWriterSettings();
xwSettings.Encoding = new UTF8Encoding(false);
xwSettings.OmitXmlDeclaration = false;
using (var xw = XmlWriter.Create(ms, xwSettings))
{
var serializer = new DataContractSerializer(from.GetType());
serializer.WriteObject(xw, from);
xw.Flush();
ms.Seek(0, SeekOrigin.Begin);
var reader = new StreamReader(ms);
return reader.ReadToEnd();
}
}
}
/// <summary>
/// Gets the optimized result using cache.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="requestContext">The request context.</param>
/// <param name="cacheKey">The cache key.</param>
/// <param name="lastDateModified">The last date modified.</param>
/// <param name="cacheDuration">Duration of the cache.</param>
/// <param name="factoryFn">The factory fn.</param>
/// <param name="responseHeaders">The response headers.</param>
/// <returns>System.Object.</returns>
/// <exception cref="System.ArgumentNullException">cacheKey
/// or
/// factoryFn</exception>
public object GetOptimizedResultUsingCache<T>(IRequest requestContext, Guid cacheKey, DateTime? lastDateModified, TimeSpan? cacheDuration, Func<T> factoryFn, IDictionary<string, string> responseHeaders = null)
where T : class
{
if (cacheKey == Guid.Empty)
{
throw new ArgumentNullException("cacheKey");
}
if (factoryFn == null)
{
throw new ArgumentNullException("factoryFn");
}
var key = cacheKey.ToString("N");
if (responseHeaders == null)
{
responseHeaders = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
}
// See if the result is already cached in the browser
var result = GetCachedResult(requestContext, responseHeaders, cacheKey, key, lastDateModified, cacheDuration, null);
if (result != null)
{
return result;
}
return GetOptimizedResultInternal(requestContext, factoryFn(), false, responseHeaders);
}
/// <summary>
/// To the cached result.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="requestContext">The request context.</param>
/// <param name="cacheKey">The cache key.</param>
/// <param name="lastDateModified">The last date modified.</param>
/// <param name="cacheDuration">Duration of the cache.</param>
/// <param name="factoryFn">The factory fn.</param>
/// <param name="contentType">Type of the content.</param>
/// <param name="responseHeaders">The response headers.</param>
/// <returns>System.Object.</returns>
/// <exception cref="System.ArgumentNullException">cacheKey</exception>
public object GetCachedResult<T>(IRequest requestContext, Guid cacheKey, DateTime? lastDateModified, TimeSpan? cacheDuration, Func<T> factoryFn, string contentType, IDictionary<string, string> responseHeaders = null)
where T : class
{
if (cacheKey == Guid.Empty)
{
throw new ArgumentNullException("cacheKey");
}
if (factoryFn == null)
{
throw new ArgumentNullException("factoryFn");
}
var key = cacheKey.ToString("N");
if (responseHeaders == null)
{
responseHeaders = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
}
// See if the result is already cached in the browser
var result = GetCachedResult(requestContext, responseHeaders, cacheKey, key, lastDateModified, cacheDuration, contentType);
if (result != null)
{
return result;
}
result = factoryFn();
// Apply caching headers
var hasHeaders = result as IHasHeaders;
if (hasHeaders != null)
{
AddResponseHeaders(hasHeaders, responseHeaders);
return hasHeaders;
}
return GetHttpResult(result, contentType, false, responseHeaders);
}
/// <summary>
/// Pres the process optimized result.
/// </summary>
private object GetCachedResult(IRequest requestContext, IDictionary<string, string> responseHeaders, Guid cacheKey, string cacheKeyString, DateTime? lastDateModified, TimeSpan? cacheDuration, string contentType)
{
responseHeaders["ETag"] = string.Format("\"{0}\"", cacheKeyString);
var noCache = (requestContext.Headers.Get("Cache-Control") ?? string.Empty).IndexOf("no-cache", StringComparison.OrdinalIgnoreCase) != -1;
if (!noCache)
{
if (IsNotModified(requestContext, cacheKey, lastDateModified, cacheDuration))
{
AddAgeHeader(responseHeaders, lastDateModified);
AddExpiresHeader(responseHeaders, cacheKeyString, cacheDuration, noCache);
var result = new HttpResult(new byte[] { }, contentType ?? "text/html", HttpStatusCode.NotModified);
AddResponseHeaders(result, responseHeaders);
return result;
}
}
AddCachingHeaders(responseHeaders, cacheKeyString, lastDateModified, cacheDuration, noCache);
return null;
}
public Task<object> GetStaticFileResult(IRequest requestContext,
string path,
FileShareMode fileShare = FileShareMode.Read)
{
if (string.IsNullOrEmpty(path))
{
throw new ArgumentNullException("path");
}
return GetStaticFileResult(requestContext, new StaticFileResultOptions
{
Path = path,
FileShare = fileShare
});
}
public Task<object> GetStaticFileResult(IRequest requestContext,
StaticFileResultOptions options)
{
var path = options.Path;
var fileShare = options.FileShare;
if (string.IsNullOrEmpty(path))
{
throw new ArgumentNullException("path");
}
if (fileShare != FileShareMode.Read && fileShare != FileShareMode.ReadWrite)
{
throw new ArgumentException("FileShare must be either Read or ReadWrite");
}
if (string.IsNullOrWhiteSpace(options.ContentType))
{
options.ContentType = MimeTypes.GetMimeType(path);
}
if (!options.DateLastModified.HasValue)
{
options.DateLastModified = _fileSystem.GetLastWriteTimeUtc(path);
}
var cacheKey = path + options.DateLastModified.Value.Ticks;
options.CacheKey = cacheKey.GetMD5();
options.ContentFactory = () => Task.FromResult(GetFileStream(path, fileShare));
return GetStaticResult(requestContext, options);
}
/// <summary>
/// Gets the file stream.
/// </summary>
/// <param name="path">The path.</param>
/// <param name="fileShare">The file share.</param>
/// <returns>Stream.</returns>
private Stream GetFileStream(string path, FileShareMode fileShare)
{
return _fileSystem.GetFileStream(path, FileOpenMode.Open, FileAccessMode.Read, fileShare);
}
public Task<object> GetStaticResult(IRequest requestContext,
Guid cacheKey,
DateTime? lastDateModified,
TimeSpan? cacheDuration,
string contentType,
Func<Task<Stream>> factoryFn,
IDictionary<string, string> responseHeaders = null,
bool isHeadRequest = false)
{
return GetStaticResult(requestContext, new StaticResultOptions
{
CacheDuration = cacheDuration,
CacheKey = cacheKey,
ContentFactory = factoryFn,
ContentType = contentType,
DateLastModified = lastDateModified,
IsHeadRequest = isHeadRequest,
ResponseHeaders = responseHeaders
});
}
public async Task<object> GetStaticResult(IRequest requestContext, StaticResultOptions options)
{
var cacheKey = options.CacheKey;
options.ResponseHeaders = options.ResponseHeaders ?? new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
var contentType = options.ContentType;
if (cacheKey == Guid.Empty)
{
throw new ArgumentNullException("cacheKey");
}
var key = cacheKey.ToString("N");
// See if the result is already cached in the browser
var result = GetCachedResult(requestContext, options.ResponseHeaders, cacheKey, key, options.DateLastModified, options.CacheDuration, contentType);
if (result != null)
{
return result;
}
var compress = ShouldCompressResponse(requestContext, contentType);
var hasHeaders = await GetStaticResult(requestContext, options, compress).ConfigureAwait(false);
AddResponseHeaders(hasHeaders, options.ResponseHeaders);
return hasHeaders;
}
/// <summary>
/// Shoulds the compress response.
/// </summary>
/// <param name="requestContext">The request context.</param>
/// <param name="contentType">Type of the content.</param>
/// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
private bool ShouldCompressResponse(IRequest requestContext, string contentType)
{
// It will take some work to support compression with byte range requests
if (!string.IsNullOrWhiteSpace(requestContext.Headers.Get("Range")))
{
return false;
}
// Don't compress media
if (contentType.StartsWith("audio/", StringComparison.OrdinalIgnoreCase) || contentType.StartsWith("video/", StringComparison.OrdinalIgnoreCase))
{
return false;
}
// Don't compress images
if (contentType.StartsWith("image/", StringComparison.OrdinalIgnoreCase))
{
return false;
}
if (contentType.StartsWith("font/", StringComparison.OrdinalIgnoreCase))
{
return false;
}
if (contentType.StartsWith("application/", StringComparison.OrdinalIgnoreCase))
{
if (string.Equals(contentType, "application/x-javascript", StringComparison.OrdinalIgnoreCase))
{
return true;
}
if (string.Equals(contentType, "application/xml", StringComparison.OrdinalIgnoreCase))
{
return true;
}
return false;
}
return true;
}
/// <summary>
/// The us culture
/// </summary>
private static readonly CultureInfo UsCulture = new CultureInfo("en-US");
private async Task<IHasHeaders> GetStaticResult(IRequest requestContext, StaticResultOptions options, bool compress)
{
var isHeadRequest = options.IsHeadRequest;
var factoryFn = options.ContentFactory;
var contentType = options.ContentType;
var responseHeaders = options.ResponseHeaders;
var requestedCompressionType = GetCompressionType(requestContext);
if (!compress || string.IsNullOrEmpty(requestedCompressionType))
{
var rangeHeader = requestContext.Headers.Get("Range");
if (!isHeadRequest && !string.IsNullOrWhiteSpace(options.Path))
{
return new FileWriter(options.Path, contentType, rangeHeader, _logger, _fileSystem)
{
OnComplete = options.OnComplete,
OnError = options.OnError,
FileShare = options.FileShare
};
}
if (!string.IsNullOrWhiteSpace(rangeHeader))
{
var stream = await factoryFn().ConfigureAwait(false);
return new RangeRequestWriter(rangeHeader, stream, contentType, isHeadRequest, _logger)
{
OnComplete = options.OnComplete
};
}
else
{
var stream = await factoryFn().ConfigureAwait(false);
responseHeaders["Content-Length"] = stream.Length.ToString(UsCulture);
if (isHeadRequest)
{
stream.Dispose();
return GetHttpResult(new byte[] { }, contentType, true);
}
return new StreamWriter(stream, contentType, _logger)
{
OnComplete = options.OnComplete,
OnError = options.OnError
};
}
}
using (var stream = await factoryFn().ConfigureAwait(false))
{
return await GetCompressedResult(stream, requestedCompressionType, responseHeaders, isHeadRequest, contentType).ConfigureAwait(false);
}
}
private async Task<IHasHeaders> GetCompressedResult(Stream stream,
string requestedCompressionType,
IDictionary<string, string> responseHeaders,
bool isHeadRequest,
string contentType)
{
using (var reader = new MemoryStream())
{
await stream.CopyToAsync(reader).ConfigureAwait(false);
reader.Position = 0;
var content = reader.ToArray();
if (content.Length >= 1024)
{
content = Compress(content, requestedCompressionType);
responseHeaders["Content-Encoding"] = requestedCompressionType;
}
responseHeaders["Vary"] = "Accept-Encoding";
responseHeaders["Content-Length"] = content.Length.ToString(UsCulture);
if (isHeadRequest)
{
return GetHttpResult(new byte[] { }, contentType, true);
}
return GetHttpResult(content, contentType, true, responseHeaders);
}
}
private byte[] Compress(byte[] bytes, string compressionType)
{
if (compressionType == "deflate")
return Deflate(bytes);
if (compressionType == "gzip")
return GZip(bytes);
throw new NotSupportedException(compressionType);
}
private byte[] Deflate(byte[] bytes)
{
// In .NET FX incompat-ville, you can't access compressed bytes without closing DeflateStream
// Which means we must use MemoryStream since you have to use ToArray() on a closed Stream
using (var ms = new MemoryStream())
using (var zipStream = new DeflateStream(ms, CompressionMode.Compress))
{
zipStream.Write(bytes, 0, bytes.Length);
zipStream.Dispose();
return ms.ToArray();
}
}
private byte[] GZip(byte[] buffer)
{
using (var ms = new MemoryStream())
using (var zipStream = new GZipStream(ms, CompressionMode.Compress))
{
zipStream.Write(buffer, 0, buffer.Length);
zipStream.Dispose();
return ms.ToArray();
}
}
/// <summary>
/// Adds the caching responseHeaders.
/// </summary>
private void AddCachingHeaders(IDictionary<string, string> responseHeaders, string cacheKey, DateTime? lastDateModified, TimeSpan? cacheDuration, bool noCache)
{
// Don't specify both last modified and Etag, unless caching unconditionally. They are redundant
// https://developers.google.com/speed/docs/best-practices/caching#LeverageBrowserCaching
if (lastDateModified.HasValue && (string.IsNullOrEmpty(cacheKey) || cacheDuration.HasValue))
{
AddAgeHeader(responseHeaders, lastDateModified);
responseHeaders["Last-Modified"] = lastDateModified.Value.ToString("r");
}
if (!noCache && cacheDuration.HasValue)
{
responseHeaders["Cache-Control"] = "public, max-age=" + Convert.ToInt32(cacheDuration.Value.TotalSeconds);
}
else if (!noCache && !string.IsNullOrEmpty(cacheKey))
{
responseHeaders["Cache-Control"] = "public";
}
else
{
responseHeaders["Cache-Control"] = "no-cache, no-store, must-revalidate";
responseHeaders["pragma"] = "no-cache, no-store, must-revalidate";
}
AddExpiresHeader(responseHeaders, cacheKey, cacheDuration, noCache);
}
/// <summary>
/// Adds the expires header.
/// </summary>
private void AddExpiresHeader(IDictionary<string, string> responseHeaders, string cacheKey, TimeSpan? cacheDuration, bool noCache)
{
if (!noCache && cacheDuration.HasValue)
{
responseHeaders["Expires"] = DateTime.UtcNow.Add(cacheDuration.Value).ToString("r");
}
else if (string.IsNullOrEmpty(cacheKey))
{
responseHeaders["Expires"] = "-1";
}
}
/// <summary>
/// Adds the age header.
/// </summary>
/// <param name="responseHeaders">The responseHeaders.</param>
/// <param name="lastDateModified">The last date modified.</param>
private void AddAgeHeader(IDictionary<string, string> responseHeaders, DateTime? lastDateModified)
{
if (lastDateModified.HasValue)
{
responseHeaders["Age"] = Convert.ToInt64((DateTime.UtcNow - lastDateModified.Value).TotalSeconds).ToString(CultureInfo.InvariantCulture);
}
}
/// <summary>
/// Determines whether [is not modified] [the specified cache key].
/// </summary>
/// <param name="requestContext">The request context.</param>
/// <param name="cacheKey">The cache key.</param>
/// <param name="lastDateModified">The last date modified.</param>
/// <param name="cacheDuration">Duration of the cache.</param>
/// <returns><c>true</c> if [is not modified] [the specified cache key]; otherwise, <c>false</c>.</returns>
private bool IsNotModified(IRequest requestContext, Guid? cacheKey, DateTime? lastDateModified, TimeSpan? cacheDuration)
{
//var isNotModified = true;
var ifModifiedSinceHeader = requestContext.Headers.Get("If-Modified-Since");
if (!string.IsNullOrEmpty(ifModifiedSinceHeader))
{
DateTime ifModifiedSince;
if (DateTime.TryParse(ifModifiedSinceHeader, out ifModifiedSince))
{
if (IsNotModified(ifModifiedSince.ToUniversalTime(), cacheDuration, lastDateModified))
{
return true;
}
}
}
var ifNoneMatchHeader = requestContext.Headers.Get("If-None-Match");
// Validate If-None-Match
if ((cacheKey.HasValue || !string.IsNullOrEmpty(ifNoneMatchHeader)))
{
Guid ifNoneMatch;
ifNoneMatchHeader = (ifNoneMatchHeader ?? string.Empty).Trim('\"');
if (Guid.TryParse(ifNoneMatchHeader, out ifNoneMatch))
{
if (cacheKey.HasValue && cacheKey.Value == ifNoneMatch)
{
return true;
}
}
}
return false;
}
/// <summary>
/// Determines whether [is not modified] [the specified if modified since].
/// </summary>
/// <param name="ifModifiedSince">If modified since.</param>
/// <param name="cacheDuration">Duration of the cache.</param>
/// <param name="dateModified">The date modified.</param>
/// <returns><c>true</c> if [is not modified] [the specified if modified since]; otherwise, <c>false</c>.</returns>
private bool IsNotModified(DateTime ifModifiedSince, TimeSpan? cacheDuration, DateTime? dateModified)
{
if (dateModified.HasValue)
{
var lastModified = NormalizeDateForComparison(dateModified.Value);
ifModifiedSince = NormalizeDateForComparison(ifModifiedSince);
return lastModified <= ifModifiedSince;
}
if (cacheDuration.HasValue)
{
var cacheExpirationDate = ifModifiedSince.Add(cacheDuration.Value);
if (DateTime.UtcNow < cacheExpirationDate)
{
return true;
}
}
return false;
}
/// <summary>
/// When the browser sends the IfModifiedDate, it's precision is limited to seconds, so this will account for that
/// </summary>
/// <param name="date">The date.</param>
/// <returns>DateTime.</returns>
private DateTime NormalizeDateForComparison(DateTime date)
{
return new DateTime(date.Year, date.Month, date.Day, date.Hour, date.Minute, date.Second, date.Kind);
}
/// <summary>
/// Adds the response headers.
/// </summary>
/// <param name="hasHeaders">The has options.</param>
/// <param name="responseHeaders">The response headers.</param>
private void AddResponseHeaders(IHasHeaders hasHeaders, IEnumerable<KeyValuePair<string, string>> responseHeaders)
{
foreach (var item in responseHeaders)
{
hasHeaders.Headers[item.Key] = item.Value;
}
}
}
}