ManifestProxyController.cs

// -----------------------------------------------------------------------------
//  Copyright (C) Microsoft Corporation.  All rights reserved.
// -----------------------------------------------------------------------------

namespace Microsoft.Azure.CloudVideo.VideoManagementService.Cms.Controllers
{
	using System;
	using System.Collections.Generic;
	using System.Collections.Specialized;
	using System.Diagnostics.CodeAnalysis;
	using System.Globalization;
	using System.IO;
	using System.Linq;
	using System.Net;
	using System.Net.Cache;
	using System.Net.Http;
	using System.Text;
	using System.Text.RegularExpressions;
	using System.Web;
	using System.Web.Http;
	using CloudVideo.Common;

	public class ManifestProxyController : ApiController
	{
		/// <summary>
		///     Support for: GET /api/Manifest(playbackUrl, token)
		/// </summary>
		[SuppressMessage("Microsoft.Reliability", "CA2000:Dispose objects before losing scope", Justification = "Web API request will dispose of this object when thread completes")]
		[SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", Justification = "These are format strings, not URIs")]
		public HttpResponseMessage Get(string playbackUrl, string token)
		{
			Check.NotNullOrWhiteSpace(playbackUrl, "playbackUrl");
			Check.NotNullOrWhiteSpace(token, "token");

			if (token.StartsWith("Bearer=", StringComparison.OrdinalIgnoreCase))
			{
				token = token.Substring("Bearer=".Length);
			}
			var collection = HttpUtility.ParseQueryString(token);
			var authToken = collection.ToQueryString();
			string armoredAuthToken = HttpUtility.UrlEncode(authToken);

			var httpRequest = (HttpWebRequest)WebRequest.Create(new Uri(playbackUrl));
			httpRequest.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
			httpRequest.Timeout = 30000;
			var httpResponse = httpRequest.GetResponse();
			var response = this.Request.CreateResponse();

			try
			{
				var stream = httpResponse.GetResponseStream();
				if (stream != null)
				{
					using (var reader = new StreamReader(stream))
					{
						const string qulityLevelRegex = @"(QualityLevels\(\d+\))";
						const string fragmentsRegex = @"(Fragments\([\w\d=-]+,[\w\d=-]+\))";
						const string urlRegex = @"("")(https?:\/\/[\da-z\.-]+\.[a-z\.]{2,6}[\/\w \.-]*\/?[\?&][^&=]+=[^&=#]*)("")";

						var baseUrl = playbackUrl.Substring(0, playbackUrl.IndexOf(".ism", System.StringComparison.OrdinalIgnoreCase)) + ".ism";
						var content = reader.ReadToEnd();

						var newContent = Regex.Replace(content, urlRegex, string.Format(CultureInfo.InvariantCulture, "$1$2&token={0}$3", armoredAuthToken));
						var match = Regex.Match(playbackUrl, qulityLevelRegex);
						if (match.Success)
						{
							var qulityLevel = match.Groups[0].Value;
							newContent = Regex.Replace(newContent, fragmentsRegex, m => string.Format(CultureInfo.InvariantCulture, baseUrl + "/" + qulityLevel + "/" + m.Value));
						}

						response.Content = new StringContent(newContent, Encoding.UTF8, "application/vnd.apple.mpegurl");
					}
				}
			}
			finally
			{
				httpResponse.Close();
			}
			return response;
		}
	}

	public static class QueryExtensions
	{
		public static string ToQueryString(this NameValueCollection collection)
		{
			Check.NotNull(collection, "collection");

			IEnumerable<string> segments = from key in collection.AllKeys
										   from value in collection.GetValues(key)
										   select string.Format(CultureInfo.InvariantCulture, "{0}={1}", HttpUtility.UrlEncode(key), HttpUtility.UrlEncode(value));

			return string.Join("&", segments);
		}
	}
}