1 files changed, 251 insertions, 0 deletions
diff --git a/vendor/github.com/docker/distribution/registry/client/transport/http_reader.go b/vendor/github.com/docker/distribution/registry/client/transport/http_reader.go
new file mode 100644
index 000000000..e5ff09d75
--- /dev/null
+++ b/vendor/github.com/docker/distribution/registry/client/transport/http_reader.go
@@ -0,0 +1,251 @@
+package transport
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"regexp"
+	"strconv"
+)
+
+var (
+	contentRangeRegexp = regexp.MustCompile(`bytes ([0-9]+)-([0-9]+)/([0-9]+|\\*)`)
+
+	// ErrWrongCodeForByteRange is returned if the client sends a request
+	// with a Range header but the server returns a 2xx or 3xx code other
+	// than 206 Partial Content.
+	ErrWrongCodeForByteRange = errors.New("expected HTTP 206 from byte range request")
+)
+
+// ReadSeekCloser combines io.ReadSeeker with io.Closer.
+type ReadSeekCloser interface {
+	io.ReadSeeker
+	io.Closer
+}
+
+// NewHTTPReadSeeker handles reading from an HTTP endpoint using a GET
+// request. When seeking and starting a read from a non-zero offset
+// the a "Range" header will be added which sets the offset.
+// TODO(dmcgowan): Move this into a separate utility package
+func NewHTTPReadSeeker(client *http.Client, url string, errorHandler func(*http.Response) error) ReadSeekCloser {
+	return &httpReadSeeker{
+		client:       client,
+		url:          url,
+		errorHandler: errorHandler,
+	}
+}
+
+type httpReadSeeker struct {
+	client *http.Client
+	url    string
+
+	// errorHandler creates an error from an unsuccessful HTTP response.
+	// This allows the error to be created with the HTTP response body
+	// without leaking the body through a returned error.
+	errorHandler func(*http.Response) error
+
+	size int64
+
+	// rc is the remote read closer.
+	rc io.ReadCloser
+	// readerOffset tracks the offset as of the last read.
+	readerOffset int64
+	// seekOffset allows Seek to override the offset. Seek changes
+	// seekOffset instead of changing readOffset directly so that
+	// connection resets can be delayed and possibly avoided if the
+	// seek is undone (i.e. seeking to the end and then back to the
+	// beginning).
+	seekOffset int64
+	err        error
+}
+
+func (hrs *httpReadSeeker) Read(p []byte) (n int, err error) {
+	if hrs.err != nil {
+		return 0, hrs.err
+	}
+
+	// If we sought to a different position, we need to reset the
+	// connection. This logic is here instead of Seek so that if
+	// a seek is undone before the next read, the connection doesn't
+	// need to be closed and reopened. A common example of this is
+	// seeking to the end to determine the length, and then seeking
+	// back to the original position.
+	if hrs.readerOffset != hrs.seekOffset {
+		hrs.reset()
+	}
+
+	hrs.readerOffset = hrs.seekOffset
+
+	rd, err := hrs.reader()
+	if err != nil {
+		return 0, err
+	}
+
+	n, err = rd.Read(p)
+	hrs.seekOffset += int64(n)
+	hrs.readerOffset += int64(n)
+
+	return n, err
+}
+
+func (hrs *httpReadSeeker) Seek(offset int64, whence int) (int64, error) {
+	if hrs.err != nil {
+		return 0, hrs.err
+	}
+
+	lastReaderOffset := hrs.readerOffset
+
+	if whence == os.SEEK_SET && hrs.rc == nil {
+		// If no request has been made yet, and we are seeking to an
+		// absolute position, set the read offset as well to avoid an
+		// unnecessary request.
+		hrs.readerOffset = offset
+	}
+
+	_, err := hrs.reader()
+	if err != nil {
+		hrs.readerOffset = lastReaderOffset
+		return 0, err
+	}
+
+	newOffset := hrs.seekOffset
+
+	switch whence {
+	case os.SEEK_CUR:
+		newOffset += offset
+	case os.SEEK_END:
+		if hrs.size < 0 {
+			return 0, errors.New("content length not known")
+		}
+		newOffset = hrs.size + offset
+	case os.SEEK_SET:
+		newOffset = offset
+	}
+
+	if newOffset < 0 {
+		err = errors.New("cannot seek to negative position")
+	} else {
+		hrs.seekOffset = newOffset
+	}
+
+	return hrs.seekOffset, err
+}
+
+func (hrs *httpReadSeeker) Close() error {
+	if hrs.err != nil {
+		return hrs.err
+	}
+
+	// close and release reader chain
+	if hrs.rc != nil {
+		hrs.rc.Close()
+	}
+
+	hrs.rc = nil
+
+	hrs.err = errors.New("httpLayer: closed")
+
+	return nil
+}
+
+func (hrs *httpReadSeeker) reset() {
+	if hrs.err != nil {
+		return
+	}
+	if hrs.rc != nil {
+		hrs.rc.Close()
+		hrs.rc = nil
+	}
+}
+
+func (hrs *httpReadSeeker) reader() (io.Reader, error) {
+	if hrs.err != nil {
+		return nil, hrs.err
+	}
+
+	if hrs.rc != nil {
+		return hrs.rc, nil
+	}
+
+	req, err := http.NewRequest("GET", hrs.url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	if hrs.readerOffset > 0 {
+		// If we are at different offset, issue a range request from there.
+		req.Header.Add("Range", fmt.Sprintf("bytes=%d-", hrs.readerOffset))
+		// TODO: get context in here
+		// context.GetLogger(hrs.context).Infof("Range: %s", req.Header.Get("Range"))
+	}
+
+	req.Header.Add("Accept-Encoding", "identity")
+	resp, err := hrs.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	// Normally would use client.SuccessStatus, but that would be a cyclic
+	// import
+	if resp.StatusCode >= 200 && resp.StatusCode <= 399 {
+		if hrs.readerOffset > 0 {
+			if resp.StatusCode != http.StatusPartialContent {
+				return nil, ErrWrongCodeForByteRange
+			}
+
+			contentRange := resp.Header.Get("Content-Range")
+			if contentRange == "" {
+				return nil, errors.New("no Content-Range header found in HTTP 206 response")
+			}
+
+			submatches := contentRangeRegexp.FindStringSubmatch(contentRange)
+			if len(submatches) < 4 {
+				return nil, fmt.Errorf("could not parse Content-Range header: %s", contentRange)
+			}
+
+			startByte, err := strconv.ParseUint(submatches[1], 10, 64)
+			if err != nil {
+				return nil, fmt.Errorf("could not parse start of range in Content-Range header: %s", contentRange)
+			}
+
+			if startByte != uint64(hrs.readerOffset) {
+				return nil, fmt.Errorf("received Content-Range starting at offset %d instead of requested %d", startByte, hrs.readerOffset)
+			}
+
+			endByte, err := strconv.ParseUint(submatches[2], 10, 64)
+			if err != nil {
+				return nil, fmt.Errorf("could not parse end of range in Content-Range header: %s", contentRange)
+			}
+
+			if submatches[3] == "*" {
+				hrs.size = -1
+			} else {
+				size, err := strconv.ParseUint(submatches[3], 10, 64)
+				if err != nil {
+					return nil, fmt.Errorf("could not parse total size in Content-Range header: %s", contentRange)
+				}
+
+				if endByte+1 != size {
+					return nil, fmt.Errorf("range in Content-Range stops before the end of the content: %s", contentRange)
+				}
+
+				hrs.size = int64(size)
+			}
+		} else if resp.StatusCode == http.StatusOK {
+			hrs.size = resp.ContentLength
+		} else {
+			hrs.size = -1
+		}
+		hrs.rc = resp.Body
+	} else {
+		defer resp.Body.Close()
+		if hrs.errorHandler != nil {
+			return nil, hrs.errorHandler(resp)
+		}
+		return nil, fmt.Errorf("unexpected status resolving reader: %v", resp.Status)
+	}
+
+	return hrs.rc, nil
+}