Exemplo n.º 1
0
// serveBlobRef sends 'blobref' to 'conn' as directed by the Range header in 'req'
func serveBlobRef(conn http.ResponseWriter, req *http.Request,
	blobRef *blobref.BlobRef, fetcher blobref.StreamingFetcher) {

	if w, ok := fetcher.(blobserver.ContextWrapper); ok {
		fetcher = w.WrapContext(req)
	}

	file, size, err := fetcher.FetchStreaming(blobRef)
	switch err {
	case nil:
		break
	case os.ErrNotExist:
		conn.WriteHeader(http.StatusNotFound)
		fmt.Fprintf(conn, "Blob %q not found", blobRef)
		return
	default:
		httputil.ServerError(conn, req, err)
		return
	}

	defer file.Close()

	seeker, isSeeker := file.(io.Seeker)
	reqRange := httprange.FromRequest(req)
	if reqRange.SkipBytes() != 0 && isSeeker {
		// TODO: set the Range-specific response headers too,
		// acknowledging that we honored the content range
		// request.
		_, err = seeker.Seek(reqRange.SkipBytes(), 0)
		if err != nil {
			httputil.ServerError(conn, req, err)
			return
		}
	}

	var input io.Reader = file
	if reqRange.LimitBytes() != -1 {
		input = io.LimitReader(file, reqRange.LimitBytes())
	}

	remainBytes := size - reqRange.SkipBytes()
	if reqRange.LimitBytes() != -1 &&
		reqRange.LimitBytes() < remainBytes {
		remainBytes = reqRange.LimitBytes()
	}

	conn.Header().Set("Content-Type", "application/octet-stream")
	if reqRange.IsWholeFile() {
		conn.Header().Set("Content-Length", strconv.FormatInt(size, 10))
		// If it's small and all UTF-8, assume it's text and
		// just render it in the browser.  This is more for
		// demos/debuggability than anything else.  It isn't
		// part of the spec.
		if size <= 32<<10 {
			var buf bytes.Buffer
			_, err := io.Copy(&buf, input)
			if err != nil {
				httputil.ServerError(conn, req, err)
				return
			}
			if utf8.Valid(buf.Bytes()) {
				conn.Header().Set("Content-Type", "text/plain; charset=utf-8")
			}
			input = &buf
		}
	}

	if !reqRange.IsWholeFile() {
		conn.Header().Set("Content-Range",
			fmt.Sprintf("bytes %d-%d/%d", reqRange.SkipBytes(),
				reqRange.SkipBytes()+remainBytes,
				size))
		conn.WriteHeader(http.StatusPartialContent)
	}
	bytesCopied, err := io.Copy(conn, input)

	// If there's an error at this point, it's too late to tell the client,
	// as they've already been receiving bytes.  But they should be smart enough
	// to verify the digest doesn't match.  But we close the (chunked) response anyway,
	// to further signal errors.
	killConnection := func() {
		if hj, ok := conn.(http.Hijacker); ok {
			log.Printf("Force-closing TCP connection to signal error sending %q", blobRef)
			if closer, _, err := hj.Hijack(); err != nil {
				closer.Close()
			}
		}
	}

	if err != nil {
		fmt.Fprintf(os.Stderr, "Error sending file: %v, err=%v\n", blobRef, err)
		killConnection()
		return
	}

	if bytesCopied != remainBytes {
		fmt.Fprintf(os.Stderr, "Error sending file: %v, copied=%d, not %d\n", blobRef,
			bytesCopied, remainBytes)
		killConnection()
		return
	}
}
Exemplo n.º 2
0
// serveBlobRef sends 'blobref' to 'conn' as directed by the Range header in 'req'
func serveBlobRef(conn http.ResponseWriter, req *http.Request,
	blobRef *blobref.BlobRef, fetcher blobref.StreamingFetcher) {

	if w, ok := fetcher.(blobserver.ContextWrapper); ok {
		fetcher = w.WrapContext(req)
	}

	file, size, err := fetcher.FetchStreaming(blobRef)
	switch err {
	case nil:
		break
	case os.ErrNotExist:
		conn.WriteHeader(http.StatusNotFound)
		fmt.Fprintf(conn, "Blob %q not found", blobRef)
		return
	default:
		httputil.ServerError(conn, req, err)
		return
	}

	defer file.Close()

	seeker, isSeeker := file.(io.Seeker)
	reqRange := httprange.FromRequest(req)
	if reqRange.SkipBytes() != 0 && isSeeker {
		// TODO: set the Range-specific response headers too,
		// acknowledging that we honored the content range
		// request.
		_, err = seeker.Seek(reqRange.SkipBytes(), 0)
		if err != nil {
			httputil.ServerError(conn, req, err)
			return
		}
	}

	var input io.Reader = file
	if reqRange.LimitBytes() != -1 {
		input = io.LimitReader(file, reqRange.LimitBytes())
	}

	remainBytes := size - reqRange.SkipBytes()
	if reqRange.LimitBytes() != -1 &&
		reqRange.LimitBytes() < remainBytes {
		remainBytes = reqRange.LimitBytes()
	}

	// Assume this generic content type by default.  For better
	// demos we'll try to sniff and guess the "right" MIME type in
	// certain cases (no Range requests, etc) but this isn't part
	// of the Camli spec at all.  We just do it to ease demos.
	contentType := "application/octet-stream"
	if reqRange.IsWholeFile() {
		const peekSize = 1024
		bufReader := bufio.NewReaderSize(input, peekSize)
		header, _ := bufReader.Peek(peekSize)
		if len(header) >= 8 {
			switch {
			case utf8.Valid(header):
				contentType = "text/plain; charset=utf-8"
			case bytes.HasPrefix(header, []byte{0xff, 0xd8, 0xff, 0xe2}):
				contentType = "image/jpeg"
			case bytes.HasPrefix(header, []byte{0x89, 0x50, 0x4e, 0x47, 0xd, 0xa, 0x1a, 0xa}):
				contentType = "image/png"
			}
		}
		input = bufReader

		conn.Header().Set("Content-Length", strconv.FormatInt(size, 10))
	}

	conn.Header().Set("Content-Type", contentType)
	if !reqRange.IsWholeFile() {
		conn.Header().Set("Content-Range",
			fmt.Sprintf("bytes %d-%d/%d", reqRange.SkipBytes(),
				reqRange.SkipBytes()+remainBytes,
				size))
		conn.WriteHeader(http.StatusPartialContent)
	}
	bytesCopied, err := io.Copy(conn, input)

	// If there's an error at this point, it's too late to tell the client,
	// as they've already been receiving bytes.  But they should be smart enough
	// to verify the digest doesn't match.  But we close the (chunked) response anyway,
	// to further signal errors.
	killConnection := func() {
		if hj, ok := conn.(http.Hijacker); ok {
			log.Printf("Force-closing TCP connection to signal error sending %q", blobRef)
			if closer, _, err := hj.Hijack(); err != nil {
				closer.Close()
			}
		}
	}

	if err != nil {
		fmt.Fprintf(os.Stderr, "Error sending file: %v, err=%v\n", blobRef, err)
		killConnection()
		return
	}

	if bytesCopied != remainBytes {
		fmt.Fprintf(os.Stderr, "Error sending file: %v, copied=%d, not %d\n", blobRef,
			bytesCopied, remainBytes)
		killConnection()
		return
	}
}