public async Task ServeResource(HttpResponse response)
{
if (response == null)
{
return;
}
// Read all the file properties needed ---------------------------------------------------
// the file-name and last modified date
// and the content-type (mime mapping)
if (!File.Exists(filePath))
{
Log.Error("FileInfo doesn't exist at URI : {0}", filePath);
response.StatusCode = (int)HttpStatusCode.NotFound;
return;
}
long length = new FileInfo(filePath).Length;
string fileName = StringUtils.RemoveNonAsciiCharactersFast(Path.GetFileName(filePath));
DateTime lastModifiedDateTime = File.GetLastWriteTimeUtc(filePath);
if (string.IsNullOrEmpty(fileName) || lastModifiedDateTime == null)
{
response.StatusCode = (int)HttpStatusCode.InternalServerError;
return;
}
// convert the datetime to date time offset
DateTimeOffset lastModifiedDateTimeOffset = DateTime.SpecifyKind(lastModifiedDateTime, DateTimeKind.Utc);
// Since the 'Last-Modified' and other similar http date headers are rounded down to whole seconds,
// round down current file's last modified to whole seconds for correct comparison.
lastModifiedDateTimeOffset = RoundDownToWholeSeconds(lastModifiedDateTimeOffset);
// compare date times using milliseconds since UNIX epoch (January 1, 1970 00:00:00 UTC)
long lastModified = lastModifiedDateTimeOffset.ToUnixTimeMilliseconds();
// read in stored Content-Type
string contentType = ContentType;
// Validate request headers for caching ---------------------------------------------------
// If-None-Match header should contain "*" or ETag. If so, then return 304.
string ifNoneMatch = response.HttpContext.Request.Headers[HeaderNames.IfNoneMatch];
if (ifNoneMatch != null && HttpUtils.Matches(ifNoneMatch, fileName))
{
response.Headers.Add(HeaderNames.ETag, fileName); // Required in 304.
response.StatusCode = (int)HttpStatusCode.NotModified;
return;
}
// If-Modified-Since header should be greater than LastModified. If so, then return 304.
// This header is ignored if any If-None-Match header is specified.
long ifModifiedSince = GetDateHeader(response, HeaderNames.IfModifiedSince);
if (ifNoneMatch == null && ifModifiedSince != -1 && ifModifiedSince + 1000 > lastModified)
{
response.Headers.Add(HeaderNames.ETag, fileName); // Required in 304.
response.StatusCode = (int)HttpStatusCode.NotModified;
return;
}
// Validate request headers for resume ----------------------------------------------------
// If-Match header should contain "*" or ETag. If not, then return 412.
string ifMatch = response.HttpContext.Request.Headers[HeaderNames.IfMatch];
if (ifMatch != null && !HttpUtils.Matches(ifMatch, fileName))
{
response.StatusCode = (int)HttpStatusCode.PreconditionFailed;
return;
}
// If-Unmodified-Since header should be greater than LastModified. If not, then return 412.
long ifUnmodifiedSince = GetDateHeader(response, HeaderNames.IfUnmodifiedSince);
if (ifUnmodifiedSince != -1 && ifUnmodifiedSince + 1000 <= lastModified)
{
response.StatusCode = (int)HttpStatusCode.PreconditionFailed;
return;
}
// Validate and process range -------------------------------------------------------------
// Prepare some variables. The full Range represents the complete file.
Range full = new Range(0, length - 1, length);
List <Range> ranges = new List <Range>();
// Validate and process Range and If-Range headers.
string range = response.HttpContext.Request.Headers["Range"];
if (range != null)
{
// Range header should match format "bytes=n-n,n-n,n-n...". If not, then return 416.
if (!RangeRegex.IsMatch(range))
{
response.Headers.Add(HeaderNames.ContentRange, $"bytes */{length}"); // Required in 416.
response.StatusCode = (int)HttpStatusCode.RequestedRangeNotSatisfiable;
return;
}
string ifRange = response.HttpContext.Request.Headers[HeaderNames.IfRange];
if (ifRange != null && !ifRange.Equals(fileName))
{
long ifRangeTime = GetDateHeader(response, HeaderNames.IfRange);
if (ifRangeTime != -1)
{
ranges.Add(full);
}
}
// If any valid If-Range header, then process each part of byte range.
if (ranges.Count == 0)
{
// Remove "Ranges" and break up the ranges
string[] rangeArray = range.Replace("bytes=", string.Empty)
.Split(",".ToCharArray());
foreach (string part in rangeArray)
{
// Assuming a file with length of 100, the following examples returns bytes at:
// 50-80 (50 to 80), 40- (40 to length=100), -20 (length-20=80 to length=100).
long start = Range.SubstringLong(part, 0, part.IndexOf("-"));
long end = Range.SubstringLong(part, part.IndexOf("-") + 1, part.Length);
if (start == -1)
{
start = length - end;
end = length - 1;
}
else if (end == -1 || end > length - 1)
{
end = length - 1;
}
// Check if Range is syntactically valid. If not, then return 416.
if (start > end)
{
// check https://github.com/dotnet/corefx/blob/master/src/System.Net.Http/src/System/Net/Http/Headers/ContentRangeHeaderValue.cs
// 14.16 Content-Range - A server sending a response with status code 416 (Requested range not satisfiable)
// SHOULD include a Content-Range field with a byte-range-resp-spec of "*". The instance-length specifies
// the current length of the selected resource. e.g. */length
response.Headers.Add(HeaderNames.ContentRange, $"bytes */{length}"); // Required in 416.
response.StatusCode = (int)HttpStatusCode.RequestedRangeNotSatisfiable;
return;
}
// Add range.
ranges.Add(new Range(start, end, length));
}
}
}
// Prepare and Initialize response --------------------------------------------------------
// disable response buffering
var bufferingFeature = response.HttpContext.Features.Get <IHttpResponseBodyFeature>();
bufferingFeature?.DisableBuffering();
// Get content type by file name and Set content disposition.
string disposition = "inline";
// If content type is unknown, then Set the default value.
// For all content types, see: http://www.w3schools.com/media/media_mimeref.asp
// To add new content types, add new mime-mapping entry in web.xml.
if (contentType == null)
{
contentType = "application/octet-stream";
}
else if (!contentType.StartsWith("image"))
{
// Else, expect for images, determine content disposition. If content type is supported by
// the browser, then Set to inline, else attachment which will pop a 'save as' dialogue.
string accept = response.HttpContext.Request.Headers[HeaderNames.Accept];
disposition = accept != null && HttpUtils.Accepts(accept, contentType) ? "inline" : "attachment";
}
// Initialize response.
try
{
response.Headers.Add(HeaderNames.ContentType, contentType);
response.Headers.Add(HeaderNames.ContentDisposition, disposition + $";filename=\"{fileName}\"");
Log.Debug($"{HeaderNames.ContentType} : {contentType}");
Log.Debug($"{HeaderNames.ContentDisposition} : {disposition}");
response.Headers.Add(HeaderNames.AcceptRanges, "bytes");
// Check SetLastModifiedAndEtagHeaders() in FileResultExecutorBase.cs for info about adding headers
response.Headers.Add(HeaderNames.ETag, fileName);
SetDateHeader(response, HeaderNames.LastModified, lastModifiedDateTimeOffset);
// set expiration header (remove milliseconds)
var expires = DateTimeOffset
.UtcNow
.AddSeconds(DEFAULT_EXPIRE_TIME_SECONDS);
SetDateHeader(response, HeaderNames.Expires, expires);
}
catch (System.Exception e)
{
Log.Error("Failed adding response headers: {0}", e.Message);
}
// Send requested file (part(s)) to client ------------------------------------------------
// Prepare streams.
Stream input = FileStream;
Stream output = response.Body;
if (ranges.Count == 0 || ranges[0] == full)
{
// Return full file.
Log.Information("Return full file : from ({0}) to ({1}) of ({2})", full.Start, full.End, full.Total);
response.ContentType = contentType;
response.Headers.Add(HeaderNames.ContentRange, $"bytes {full.Start}-{full.End}/{full.Total}");
response.Headers.Add(HeaderNames.ContentLength, full.Length.ToString());
await Range.CopyStream(input, output, length, full.Start, full.Length);
}
else if (ranges.Count == 1)
{
// Return single part of file.
Range r = ranges[0];
Log.Information("Return 1 part of file : from ({0}) to ({1}) of ({2})", r.Start, r.End, r.Total);
response.ContentType = contentType;
response.Headers.Add(HeaderNames.ContentRange, $"bytes {r.Start}-{r.End}/{r.Total}");
response.Headers.Add(HeaderNames.ContentLength, r.Length.ToString());
response.StatusCode = (int)HttpStatusCode.PartialContent; // 206
// Copy single part range.
await Range.CopyStream(input, output, length, r.Start, r.Length);
}
else
{
// Return multiple parts of file.
// check https://stackoverflow.com/questions/38069730/how-to-create-a-multipart-http-response-with-asp-net-core
// and https://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html
response.ContentType = $"multipart/byteranges; boundary={MULTIPART_BOUNDARY}";
response.StatusCode = (int)HttpStatusCode.PartialContent; // 206
// Copy multi part range.
foreach (Range r in ranges)
{
Log.Information("Return multi part of file : from ({0}) to ({1}) of ({2})", r.Start, r.End, r.Total);
// Add multipart boundary and header fields for every range.
await response.WriteAsync(CrLf);
await response.WriteAsync($"--{MULTIPART_BOUNDARY}");
await response.WriteAsync(CrLf);
await response.WriteAsync($"{HeaderNames.ContentType}: {contentType}");
await response.WriteAsync(CrLf);
await response.WriteAsync($"{HeaderNames.ContentRange}: bytes {r.Start}-{r.End}/{r.Total}");
await response.WriteAsync(CrLf);
// Copy single part range of multi part range.
await Range.CopyStream(input, output, length, r.Start, r.Length);
}
// End with multipart boundary.
await response.WriteAsync(CrLf);
await response.WriteAsync($"--{MULTIPART_BOUNDARY}");
await response.WriteAsync(CrLf);
}
}