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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>
private Stream SourceStream { get; set; }
private HttpListenerResponse Response { get; set; }
private NameValueCollection RequestHeaders { get; set; }
private bool IsHeadRequest { 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>
/// <param name="isHeadRequest">if set to <c>true</c> [is head request].</param>
public RangeRequestWriter(NameValueCollection requestHeaders, HttpListenerResponse response, Stream source, bool isHeadRequest)
{
RequestHeaders = requestHeaders;
Response = response;
SourceStream = source;
IsHeadRequest = isHeadRequest;
}
/// <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 async Task WriteToAsync(Stream responseStream)
{
using (var source = SourceStream)
{
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)
{
await ServeCompleteRangeRequest(source, requestedRange, responseStream, totalLength).ConfigureAwait(false);
}
// This will have to buffer a portion of the content into memory
await ServePartialRangeRequest(source, requestedRange.Key, requestedRange.Value.Value, responseStream, totalLength).ConfigureAwait(false);
}
}
/// <summary>
/// Handles a range request of "bytes=0-"
/// This will serve the complete content and add the content-range header
/// </summary>
/// <param name="sourceStream">The source stream.</param>
/// <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(Stream sourceStream, 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);
// Headers only
if (IsHeadRequest)
{
return Task.FromResult(true);
}
if (rangeStart > 0)
{
sourceStream.Position = rangeStart;
}
return sourceStream.CopyToAsync(responseStream);
}
/// <summary>
/// Serves a partial range request
/// </summary>
/// <param name="sourceStream">The source stream.</param>
/// <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(Stream sourceStream, 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);
// Headers only
if (IsHeadRequest)
{
return;
}
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);
}
}
}
}
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