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appview,knotserver: use ETag based caching for blobs #511

merged

opened by

oppi.li 3 months ago targeting master from push-pwqwlvnsqtqr

this avoids stale raw content from being sent to clients.

Signed-off-by: oppiliappan me@oppi.li

options

unified split

Changed files

+34 -9

appview

repo

repo.go

knotserver

routes.go

+22 -2

appview/repo/repo.go

···

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       	if !rp.config.Core.Dev {

     

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       		protocol = "https"

     

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       	}

     

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       +
       

     

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       	blobURL := fmt.Sprintf("%s://%s/%s/%s/raw/%s/%s", protocol, f.Knot, f.OwnerDid(), f.Repo.Name, ref, filePath)

     

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       -
       	resp, err := http.Get(blobURL)

     

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       +
       

     

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       +
       	req, err := http.NewRequest("GET", blobURL, nil)

     

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       +
       	if err != nil {

     

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       +
       		log.Println("failed to create request", err)

     

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       +
       		return

     

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       +
       	}

     

       623
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       +
       

     

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       +
       	// forward the If-None-Match header

     

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       +
       	if clientETag := r.Header.Get("If-None-Match"); clientETag != "" {

     

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       +
       		req.Header.Set("If-None-Match", clientETag)

     

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       +
       	}

     

       628
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       +
       

     

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       +
       	client := &http.Client{}

     

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       +
       	resp, err := client.Do(req)

     

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       	if err != nil {

     

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       -
       		log.Println("failed to reach knotserver:", err)

     

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       +
       		log.Println("failed to reach knotserver", err)

     

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       		rp.pages.Error503(w)

     

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       		return

     

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       	}

     

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       	defer resp.Body.Close()

     

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       +
       	// forward 304 not modified

     

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       +
       	if resp.StatusCode == http.StatusNotModified {

     

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       +
       		w.WriteHeader(http.StatusNotModified)

     

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       +
       		return

     

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       +
       	}

     

       643
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       +
       

     

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       	if resp.StatusCode != http.StatusOK {

     

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       		log.Printf("knotserver returned non-OK status for raw blob %s: %d", blobURL, resp.StatusCode)

     

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       		w.WriteHeader(resp.StatusCode)

+12 -7

knotserver/routes.go

···

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       		mimeType = "image/svg+xml"

     

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       	}

     

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       +
       	contentHash := sha256.Sum256(contents)

     

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       +
       	eTag := fmt.Sprintf("\"%x\"", contentHash)

     

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       +
       

     

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       	// allow image, video, and text/plain files to be served directly

     

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       	switch {

     

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       -
       	case strings.HasPrefix(mimeType, "image/"):

     

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       -
       		// allowed

     

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       -
       	case strings.HasPrefix(mimeType, "video/"):

     

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       -
       		// allowed

     

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       +
       	case strings.HasPrefix(mimeType, "image/"), strings.HasPrefix(mimeType, "video/"):

     

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       +
       		if clientETag := r.Header.Get("If-None-Match"); clientETag == eTag {

     

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       +
       			w.WriteHeader(http.StatusNotModified)

     

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       +
       			return

     

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       +
       		}

     

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       +
       		w.Header().Set("ETag", eTag)

     

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       +
       

     

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       	case strings.HasPrefix(mimeType, "text/plain"):

     

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       -
       		// allowed

     

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       +
       		w.Header().Set("Cache-Control", "public, no-cache")

     

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       +
       

     

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       	default:

     

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       		l.Error("attempted to serve disallowed file type", "mimetype", mimeType)

     

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       		writeError(w, "only image, video, and text files can be accessed directly", http.StatusForbidden)

     

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       		return

     

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       	}

     

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       -
       	w.Header().Set("Cache-Control", "public, max-age=86400") // cache for 24 hours

     

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       -
       	w.Header().Set("ETag", fmt.Sprintf("%x", sha256.Sum256(contents)))

     

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       	w.Header().Set("Content-Type", mimeType)

     

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       	w.Write(contents)

     

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       }