Use If-Modified-Since for downloading images

1 files changed, 120 insertions, 0 deletions

diff --git a/libvirt/utils_volume.go b/libvirt/utils_volume.go
new file mode 100644
index 00000000..6793124c
--- /dev/null
+++ b/libvirt/utils_volume.go
@@ -0,0 +1,120 @@
+package libvirt
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// network transparent image
+type image interface {
+	Size() (uint64, error)
+	Import(func(io.Reader) error, defVolume) error
+	String() string
+}
+
+type localImage struct {
+	path string
+}
+
+func (i *localImage) String() string {
+	return i.path
+}
+
+func (i *localImage) Size() (uint64, error) {
+	file, err := os.Open(i.path)
+	if err != nil {
+		return 0, err
+	}
+
+	fi, err := file.Stat()
+	if err != nil {
+		return 0, err
+	}
+	return uint64(fi.Size()), nil
+}
+
+func (i *localImage) Import(copier func(io.Reader) error, vol defVolume) error {
+
+	file, err := os.Open(i.path)
+	defer file.Close()
+	if err != nil {
+		return fmt.Errorf("Error while opening %s: %s", i.path, err)
+	}
+
+	if fi, err := file.Stat(); err != nil {
+		return err
+	} else {
+		// we can skip the upload if the modification times are the same
+		if vol.Target.Timestamps != nil && vol.Target.Timestamps.Modification != nil {
+			modTime := UnixTimestamp{fi.ModTime()}
+			if modTime == *vol.Target.Timestamps.Modification {
+				log.Printf("Modification time is the same: skipping image copy")
+				return nil
+			}
+		}
+	}
+
+	return copier(file)
+}
+
+type httpImage struct {
+	url *url.URL
+}
+
+func (i *httpImage) String() string {
+	return i.url.String()
+}
+
+func (i *httpImage) Size() (uint64, error) {
+	response, err := http.Head(i.url.String())
+	if err != nil {
+		return 0, err
+	}
+	length, err := strconv.Atoi(response.Header.Get("Content-Length"))
+	if err != nil {
+		return 0, err
+	}
+	return uint64(length), nil
+}
+
+func (i *httpImage) Import(copier func(io.Reader) error, vol defVolume) error {
+	client := &http.Client{}
+	req, _ := http.NewRequest("GET", i.url.String(), nil)
+
+	if vol.Target.Timestamps != nil && vol.Target.Timestamps.Modification != nil {
+		t := vol.Target.Timestamps.Modification.UTC().Format(http.TimeFormat)
+		req.Header.Set("If-Modified-Since", t)
+	}
+	response, err := client.Do(req)
+	defer response.Body.Close()
+
+	if err != nil {
+		return fmt.Errorf("Error while downloading %s: %s", i.url.String(), err)
+	}
+	if response.StatusCode == http.StatusNotModified {
+		return nil
+	}
+
+	return copier(response.Body)
+}
+
+func newImage(source string) (image, error) {
+	url, err := url.Parse(source)
+	if err != nil {
+		return nil, fmt.Errorf("Can't parse source '%s' as url: %s", source, err)
+	}
+
+	if strings.HasPrefix(url.Scheme, "http") {
+		return &httpImage{url: url}, nil
+	} else if url.Scheme == "file" || url.Scheme == "" {
+		return &localImage{path: url.Path}, nil
+	} else {
+		return nil, fmt.Errorf("Don't know how to read from '%s': %s", url.String(), err)
+	}
+}