public EntityResponseSinglePart(IHttpResponseHeaderHelper httpResponseHeaderHelper, RangeItem range)
{
this.HttpResponseHeaderHelper = httpResponseHeaderHelper;
this.Range = range;
}
/// <summary>
/// Parses the Range Header from the http request.
/// </summary>
/// <param name="request"></param>
/// <param name="contentLength">The length of the content to serve.</param>
/// <param name="ranges">A list of ranges</param>
/// <returns>
/// Returns Null, if there is no Range Header in the http request
/// Return False, if there are unsatisfiable Range Headers in the http request (416 Requested Range Not Satisfiable)
/// Returns True, if there are Range Headers in the http request
/// </returns>
public bool? GetRanges(HttpRequestBase request, long contentLength, out IEnumerable<RangeItem> ranges)
{
var requestHeaderRange = GetHttpHeaderValue(request, HttpRequestHeader.Range, String.Empty);
var rangesResult = new List<RangeItem>();
if (string.IsNullOrEmpty(requestHeaderRange))
{
ranges = rangesResult;
return null;
}
var rangesString = requestHeaderRange.Replace(" ", "").Replace("bytes=", "").Split(",".ToCharArray());
// Check each found Range request for consistency
foreach (var rangeString in rangesString)
{
// Split this range request by the dash character,
// currentRange[0] contains the requested begin-value,
// currentRange[1] contains the requested end-value...
var currentRangeString = rangeString.Split("-".ToCharArray());
if (currentRangeString.Length != 2)
{
ranges = null;
return false;
}
var currentRange = new RangeItem();
// Determine the end of the requested range
if (string.IsNullOrEmpty(currentRangeString[1]))
{
// No end was specified, take the entire range
currentRange.EndRange = contentLength - 1;
}
else
{
// An end was specified...
int endRangeValue;
if (!int.TryParse(currentRangeString[1], out endRangeValue))
{
ranges = null;
return false;
}
currentRange.EndRange = endRangeValue;
}
// Determine the begin of the requested range
if (string.IsNullOrEmpty(currentRangeString[0]))
{
// No begin was specified, which means that
// the end value indicated to return the last n
// bytes of the file:
// Calculate the begin
currentRange.StartRange = contentLength - currentRange.EndRange;
// ... to the end of the file...
currentRange.EndRange = contentLength - 1;
}
else
{
// A normal begin value was indicated...
int beginRangeValue;
if (!int.TryParse(currentRangeString[0], out beginRangeValue))
{
ranges = null;
return false;
}
currentRange.StartRange = beginRangeValue;
}
// Check if the requested range values are valid,
// return False if they are not.
// Note:
// Do not clean invalid values up by fitting them into
// valid parameters using Math.Min and Math.Max, because
// some download clients (like Go!Zilla) might send invalid
// (e.g. too large) range requests to determine the file limits!
// Begin and end must not exceed the file size
if ((currentRange.StartRange > (contentLength - 1)) | (currentRange.EndRange > (contentLength - 1)))
{
ranges = null;
return false;
}
// Begin and end cannot be < 0
if ((currentRange.StartRange < 0) | (currentRange.EndRange < 0))
{
ranges = null;
return false;
}
// End must be larger or equal to begin value
if (currentRange.EndRange < currentRange.StartRange)
{
// The requested Range is invalid...
ranges = null;
return false;
}
//We reached here so its a valid range, so add it to the list of ranges
rangesResult.Add(currentRange);
}
ranges = rangesResult;
return true;
}
