bring back support for byte ranged requests

MediaBrowser.Server.Implementations/HttpServer/RangeRequestWriter.cs

@@ -0,0 +1,172 @@
+using ServiceStack.Service;
+using System;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Threading.Tasks;
+
+namespace MediaBrowser.Server.Implementations.HttpServer
+{
+    public class RangeRequestWriter : IStreamWriter
+    {
+        /// <summary>
+        /// Gets or sets the source stream.
+        /// </summary>
+        /// <value>The source stream.</value>
+        public Stream SourceStream { get; set; }
+        public HttpListenerResponse Response { get; set; }
+        public NameValueCollection RequestHeaders { get; set; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StreamWriter" /> class.
+        /// </summary>
+        /// <param name="requestHeaders">The request headers.</param>
+        /// <param name="response">The response.</param>
+        /// <param name="source">The source.</param>
+        public RangeRequestWriter(NameValueCollection requestHeaders, HttpListenerResponse response, Stream source)
+        {
+            RequestHeaders = requestHeaders;
+            Response = response;
+            SourceStream = source;
+        }
+
+        /// <summary>
+        /// The _requested ranges
+        /// </summary>
+        private List<KeyValuePair<long, long?>> _requestedRanges;
+        /// <summary>
+        /// Gets the requested ranges.
+        /// </summary>
+        /// <value>The requested ranges.</value>
+        protected IEnumerable<KeyValuePair<long, long?>> RequestedRanges
+        {
+            get
+            {
+                if (_requestedRanges == null)
+                {
+                    _requestedRanges = new List<KeyValuePair<long, long?>>();
+
+                    // Example: bytes=0-,32-63
+                    var ranges = RequestHeaders["Range"].Split('=')[1].Split(',');
+
+                    foreach (var range in ranges)
+                    {
+                        var vals = range.Split('-');
+
+                        long start = 0;
+                        long? end = null;
+
+                        if (!string.IsNullOrEmpty(vals[0]))
+                        {
+                            start = long.Parse(vals[0]);
+                        }
+                        if (!string.IsNullOrEmpty(vals[1]))
+                        {
+                            end = long.Parse(vals[1]);
+                        }
+
+                        _requestedRanges.Add(new KeyValuePair<long, long?>(start, end));
+                    }
+                }
+
+                return _requestedRanges;
+            }
+        }
+
+        /// <summary>
+        /// Writes to.
+        /// </summary>
+        /// <param name="responseStream">The response stream.</param>
+        public void WriteTo(Stream responseStream)
+        {
+            Response.Headers["Accept-Ranges"] = "bytes";
+            Response.StatusCode = 206;
+            
+            var task = WriteToAsync(responseStream);
+
+            Task.WaitAll(task);
+        }
+
+        /// <summary>
+        /// Writes to async.
+        /// </summary>
+        /// <param name="responseStream">The response stream.</param>
+        /// <returns>Task.</returns>
+        private Task WriteToAsync(Stream responseStream)
+        {
+            var requestedRange = RequestedRanges.First();
+
+            var totalLength = SourceStream.Length;
+
+            // If the requested range is "0-", we can optimize by just doing a stream copy
+            if (!requestedRange.Value.HasValue)
+            {
+                return ServeCompleteRangeRequest(requestedRange, responseStream, totalLength);
+            }
+
+            // This will have to buffer a portion of the content into memory
+            return ServePartialRangeRequest(requestedRange.Key, requestedRange.Value.Value, responseStream, totalLength);
+        }
+
+        /// <summary>
+        /// Handles a range request of "bytes=0-"
+        /// This will serve the complete content and add the content-range header
+        /// </summary>
+        /// <param name="requestedRange">The requested range.</param>
+        /// <param name="responseStream">The response stream.</param>
+        /// <param name="totalContentLength">Total length of the content.</param>
+        /// <returns>Task.</returns>
+        private Task ServeCompleteRangeRequest(KeyValuePair<long, long?> requestedRange, Stream responseStream, long totalContentLength)
+        {
+            var rangeStart = requestedRange.Key;
+            var rangeEnd = totalContentLength - 1;
+            var rangeLength = 1 + rangeEnd - rangeStart;
+
+            // Content-Length is the length of what we're serving, not the original content
+            Response.ContentLength64 = rangeLength;
+            Response.Headers["Content-Range"] = string.Format("bytes {0}-{1}/{2}", rangeStart, rangeEnd, totalContentLength);
+
+            if (rangeStart > 0)
+            {
+                SourceStream.Position = rangeStart;
+            }
+
+            return SourceStream.CopyToAsync(responseStream);
+        }
+
+        /// <summary>
+        /// Serves a partial range request
+        /// </summary>
+        /// <param name="rangeStart">The range start.</param>
+        /// <param name="rangeEnd">The range end.</param>
+        /// <param name="responseStream">The response stream.</param>
+        /// <param name="totalContentLength">Total length of the content.</param>
+        /// <returns>Task.</returns>
+        private async Task ServePartialRangeRequest(long rangeStart, long rangeEnd, Stream responseStream, long totalContentLength)
+        {
+            var rangeLength = 1 + rangeEnd - rangeStart;
+
+            // Content-Length is the length of what we're serving, not the original content
+            Response.ContentLength64 = rangeLength;
+            Response.Headers["Content-Range"] = string.Format("bytes {0}-{1}/{2}", rangeStart, rangeEnd, totalContentLength);
+
+            SourceStream.Position = rangeStart;
+
+            // Fast track to just copy the stream to the end
+            if (rangeEnd == totalContentLength - 1)
+            {
+                await SourceStream.CopyToAsync(responseStream).ConfigureAwait(false);
+            }
+            else
+            {
+                // Read the bytes we need
+                var buffer = new byte[Convert.ToInt32(rangeLength)];
+                await SourceStream.ReadAsync(buffer, 0, buffer.Length).ConfigureAwait(false);
+
+                await responseStream.WriteAsync(buffer, 0, Convert.ToInt32(rangeLength)).ConfigureAwait(false);
+            }
+        }
+    }
+}