serveFile method

void serveFile (File file, HttpRequest request)

Serve the content of file to request.

This is useful when e.g. overriding directoryHandler to redirect to some index file.

In the request contains the HttpHeaders.ifModifiedSince header, serveFile will send a HttpStatus.notModified response if the file was not changed.

Note that if it was unable to read from file, the requests response is closed with error-code HttpStatus.notFound.

Implementation

void serveFile(File file, HttpRequest request) {
  var response = request.response;
  // TODO(ajohnsen): Set up Zone support for these errors.
  file.lastModified().then((lastModified) {
    if (request.headers.ifModifiedSince != null &&
        !lastModified.isAfter(request.headers.ifModifiedSince)) {
      response.statusCode = HttpStatus.notModified;
      response.close();
      return null;
    }

    response.headers.set(HttpHeaders.lastModifiedHeader, lastModified);
    response.headers.set(HttpHeaders.acceptRangesHeader, "bytes");

    return file.length().then((length) {
      var range = request.headers.value(HttpHeaders.rangeHeader);
      if (range != null) {
        // We only support one range, where the standard support several.
        var matches = RegExp(r"^bytes=(\d*)\-(\d*)$").firstMatch(range);
        // If the range header have the right format, handle it.
        if (matches != null &&
            (matches[1].isNotEmpty || matches[2].isNotEmpty)) {
          // Serve sub-range.
          int start; // First byte position - inclusive.
          int end; // Last byte position - inclusive.
          if (matches[1].isEmpty) {
            start = length - int.parse(matches[2]);
            if (start < 0) start = 0;
            end = length - 1;
          } else {
            start = int.parse(matches[1]);
            end = matches[2].isEmpty ? length - 1 : int.parse(matches[2]);
          }
          // If the range is syntactically invalid the Range header
          // MUST be ignored (RFC 2616 section 14.35.1).
          if (start <= end) {
            if (end >= length) {
              end = length - 1;
            }

            if (start >= length) {
              response
                ..statusCode = HttpStatus.requestedRangeNotSatisfiable
                ..close();
              return;
            }

            // Override Content-Length with the actual bytes sent.
            response.headers
                .set(HttpHeaders.contentLengthHeader, end - start + 1);

            // Set 'Partial Content' status code.
            response
              ..statusCode = HttpStatus.partialContent
              ..headers.set(HttpHeaders.contentRangeHeader,
                  'bytes $start-$end/$length');

            // Pipe the 'range' of the file.
            if (request.method == 'HEAD') {
              response.close();
            } else {
              file
                  .openRead(start, end + 1)
                  .cast<List<int>>()
                  .pipe(_VirtualDirectoryFileStream(response, file.path))
                  .catchError((_) {
                // TODO(kevmoo): log errors
              });
            }
            return;
          }
        }
      }

      response.headers.set(HttpHeaders.contentLengthHeader, length);
      if (request.method == 'HEAD') {
        response.close();
      } else {
        file
            .openRead()
            .cast<List<int>>()
            .pipe(_VirtualDirectoryFileStream(response, file.path))
            .catchError((_) {
          // TODO(kevmoo): log errors
        });
      }
    });
  }).catchError((_) {
    response.statusCode = HttpStatus.notFound;
    response.close();
  });
}