chore: expose original length when serving slim binaries (#17735)

This will be used in the extensions and desktop apps to enable
compression AND progress reporting for the download by comparing the
original content length to the amount of bytes written to disk.

Closes #16340

site/site.go

@@ -108,46 +108,8 @@ func New(opts *Options) *Handler {
 		panic(fmt.Sprintf("Failed to parse html files: %v", err))
 	}
 
-	binHashCache := newBinHashCache(opts.BinFS, opts.BinHashes)
-
 	mux := http.NewServeMux()
-	mux.Handle("/bin/", http.StripPrefix("/bin", http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+	mux.Handle("/bin/", binHandler(opts.BinFS, newBinMetadataCache(opts.BinFS, opts.BinHashes)))
-		// Convert underscores in the filename to hyphens. We eventually want to
-		// change our hyphen-based filenames to underscores, but we need to
-		// support both for now.
-		r.URL.Path = strings.ReplaceAll(r.URL.Path, "_", "-")
-
-		// Set ETag header to the SHA1 hash of the file contents.
-		name := filePath(r.URL.Path)
-		if name == "" || name == "/" {
-			// Serve the directory listing. This intentionally allows directory listings to
-			// be served. This file system should not contain anything sensitive.
-			http.FileServer(opts.BinFS).ServeHTTP(rw, r)
-			return
-		}
-		if strings.Contains(name, "/") {
-			// We only serve files from the root of this directory, so avoid any
-			// shenanigans by blocking slashes in the URL path.
-			http.NotFound(rw, r)
-			return
-		}
-		hash, err := binHashCache.getHash(name)
-		if xerrors.Is(err, os.ErrNotExist) {
-			http.NotFound(rw, r)
-			return
-		}
-		if err != nil {
-			http.Error(rw, err.Error(), http.StatusInternalServerError)
-			return
-		}
-
-		// ETag header needs to be quoted.
-		rw.Header().Set("ETag", fmt.Sprintf(`%q`, hash))
-
-		// http.FileServer will see the ETag header and automatically handle
-		// If-Match and If-None-Match headers on the request properly.
-		http.FileServer(opts.BinFS).ServeHTTP(rw, r)
-	})))
 	mux.Handle("/", http.FileServer(
 		http.FS(
 			// OnlyFiles is a wrapper around the file system that prevents directory
@@ -172,6 +134,60 @@ func New(opts *Options) *Handler {
 	return handler
 }
 
+func binHandler(binFS http.FileSystem, binMetadataCache *binMetadataCache) http.Handler {
+	return http.StripPrefix("/bin", http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		// Convert underscores in the filename to hyphens. We eventually want to
+		// change our hyphen-based filenames to underscores, but we need to
+		// support both for now.
+		r.URL.Path = strings.ReplaceAll(r.URL.Path, "_", "-")
+
+		// Set ETag header to the SHA1 hash of the file contents.
+		name := filePath(r.URL.Path)
+		if name == "" || name == "/" {
+			// Serve the directory listing. This intentionally allows directory listings to
+			// be served. This file system should not contain anything sensitive.
+			http.FileServer(binFS).ServeHTTP(rw, r)
+			return
+		}
+		if strings.Contains(name, "/") {
+			// We only serve files from the root of this directory, so avoid any
+			// shenanigans by blocking slashes in the URL path.
+			http.NotFound(rw, r)
+			return
+		}
+
+		metadata, err := binMetadataCache.getMetadata(name)
+		if xerrors.Is(err, os.ErrNotExist) {
+			http.NotFound(rw, r)
+			return
+		}
+		if err != nil {
+			http.Error(rw, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		// http.FileServer will not set Content-Length when performing chunked
+		// transport encoding, which is used for large files like our binaries
+		// so stream compression can be used.
+		//
+		// Clients like IDE extensions and the desktop apps can compare the
+		// value of this header with the amount of bytes written to disk after
+		// decompression to show progress. Without this, they cannot show
+		// progress without disabling compression.
+		//
+		// There isn't really a spec for a length header for the "inner" content
+		// size, but some nginx modules use this header.
+		rw.Header().Set("X-Original-Content-Length", fmt.Sprintf("%d", metadata.sizeBytes))
+
+		// Get and set ETag header. Must be quoted.
+		rw.Header().Set("ETag", fmt.Sprintf(`%q`, metadata.sha1Hash))
+
+		// http.FileServer will see the ETag header and automatically handle
+		// If-Match and If-None-Match headers on the request properly.
+		http.FileServer(binFS).ServeHTTP(rw, r)
+	}))
+}
+
 type Handler struct {
 	opts *Options
 
@@ -217,7 +233,7 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 		h.handler.ServeHTTP(rw, r)
 		return
 	// If requesting assets, serve straight up with caching.
-	case reqFile == "assets" || strings.HasPrefix(reqFile, "assets/"):
+	case reqFile == "assets" || strings.HasPrefix(reqFile, "assets/") || strings.HasPrefix(reqFile, "icon/"):
 		// It could make sense to cache 404s, but the problem is that during an
 		// upgrade a load balancer may route partially to the old server, and that
 		// would make new asset paths get cached as 404s and not load even once the
@@ -952,68 +968,95 @@ func RenderStaticErrorPage(rw http.ResponseWriter, r *http.Request, data ErrorPa
 	}
 }
 
-type binHashCache struct {
+type binMetadata struct {
-	binFS http.FileSystem
+	sizeBytes int64 // -1 if not known yet
-
+	// SHA1 was chosen because it's fast to compute and reasonable for
-	hashes map[string]string
+	// determining if a file has changed. The ETag is not used a security
-	mut    sync.RWMutex
+	// measure.
-	sf     singleflight.Group
+	sha1Hash string // always set if in the cache
-	sem    chan struct{}
 }
 
-func newBinHashCache(binFS http.FileSystem, binHashes map[string]string) *binHashCache {
+type binMetadataCache struct {
-	b := &binHashCache{
+	binFS          http.FileSystem
-		binFS:  binFS,
+	originalHashes map[string]string
-		hashes: make(map[string]string, len(binHashes)),
+
-		mut:    sync.RWMutex{},
+	metadata map[string]binMetadata
-		sf:     singleflight.Group{},
+	mut      sync.RWMutex
-		sem:    make(chan struct{}, 4),
+	sf       singleflight.Group
+	sem      chan struct{}
+}
+
+func newBinMetadataCache(binFS http.FileSystem, binSha1Hashes map[string]string) *binMetadataCache {
+	b := &binMetadataCache{
+		binFS:          binFS,
+		originalHashes: make(map[string]string, len(binSha1Hashes)),
+
+		metadata: make(map[string]binMetadata, len(binSha1Hashes)),
+		mut:      sync.RWMutex{},
+		sf:       singleflight.Group{},
+		sem:      make(chan struct{}, 4),
 	}
-	// Make a copy since we're gonna be mutating it.
+
-	for k, v := range binHashes {
+	// Previously we copied binSha1Hashes to the cache immediately. Since we now
-		b.hashes[k] = v
+	// read other information like size from the file, we can't do that. Instead
+	// we copy the hashes to a different map that will be used to populate the
+	// cache on the first request.
+	for k, v := range binSha1Hashes {
+		b.originalHashes[k] = v
 	}
 
 	return b
 }
 
-func (b *binHashCache) getHash(name string) (string, error) {
+func (b *binMetadataCache) getMetadata(name string) (binMetadata, error) {
 	b.mut.RLock()
-	hash, ok := b.hashes[name]
+	metadata, ok := b.metadata[name]
 	b.mut.RUnlock()
 	if ok {
-		return hash, nil
+		return metadata, nil
 	}
 
 	// Avoid DOS by using a pool, and only doing work once per file.
-	v, err, _ := b.sf.Do(name, func() (interface{}, error) {
+	v, err, _ := b.sf.Do(name, func() (any, error) {
 		b.sem <- struct{}{}
 		defer func() { <-b.sem }()
 
 		f, err := b.binFS.Open(name)
 		if err != nil {
-			return "", err
+			return binMetadata{}, err
 		}
 		defer f.Close()
 
-		h := sha1.New() //#nosec // Not used for cryptography.
+		var metadata binMetadata
-		_, err = io.Copy(h, f)
+
+		stat, err := f.Stat()
 		if err != nil {
-			return "", err
+			return binMetadata{}, err
+		}
+		metadata.sizeBytes = stat.Size()
+
+		if hash, ok := b.originalHashes[name]; ok {
+			metadata.sha1Hash = hash
+		} else {
+			h := sha1.New() //#nosec // Not used for cryptography.
+			_, err := io.Copy(h, f)
+			if err != nil {
+				return binMetadata{}, err
+			}
+			metadata.sha1Hash = hex.EncodeToString(h.Sum(nil))
 		}
 
-		hash := hex.EncodeToString(h.Sum(nil))
 		b.mut.Lock()
-		b.hashes[name] = hash
+		b.metadata[name] = metadata
 		b.mut.Unlock()
-		return hash, nil
+		return metadata, nil
 	})
 	if err != nil {
-		return "", err
+		return binMetadata{}, err
 	}
 
 	//nolint:forcetypeassert
-	return strings.ToLower(v.(string)), nil
+	return v.(binMetadata), nil
 }
 
 func applicationNameOrDefault(cfg codersdk.AppearanceConfig) string {

site/site_test.go

@@ -19,6 +19,7 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -373,11 +374,13 @@ func TestServingBin(t *testing.T) {
 	delete(sampleBinFSMissingSha256, binCoderSha1)
 
 	type req struct {
-		url         string
+		url              string
-		ifNoneMatch string
+		ifNoneMatch      string
-		wantStatus  int
+		wantStatus       int
-		wantBody    []byte
+		wantBody         []byte
-		wantEtag    string
+		wantOriginalSize int
+		wantEtag         string
+		compression      bool
 	}
 	tests := []struct {
 		name    string
@@ -390,17 +393,27 @@ func TestServingBin(t *testing.T) {
 			fs:   sampleBinFS(),
 			reqs: []req{
 				{
-					url:        "/bin/coder-linux-amd64",
+					url:              "/bin/coder-linux-amd64",
-					wantStatus: http.StatusOK,
+					wantStatus:       http.StatusOK,
-					wantBody:   []byte("compressed"),
+					wantBody:         []byte("compressed"),
-					wantEtag:   fmt.Sprintf("%q", sampleBinSHAs["coder-linux-amd64"]),
+					wantOriginalSize: 10,
+					wantEtag:         fmt.Sprintf("%q", sampleBinSHAs["coder-linux-amd64"]),
 				},
 				// Test ETag support.
 				{
-					url:         "/bin/coder-linux-amd64",
+					url:              "/bin/coder-linux-amd64",
-					ifNoneMatch: fmt.Sprintf("%q", sampleBinSHAs["coder-linux-amd64"]),
+					ifNoneMatch:      fmt.Sprintf("%q", sampleBinSHAs["coder-linux-amd64"]),
-					wantStatus:  http.StatusNotModified,
+					wantStatus:       http.StatusNotModified,
-					wantEtag:    fmt.Sprintf("%q", sampleBinSHAs["coder-linux-amd64"]),
+					wantOriginalSize: 10,
+					wantEtag:         fmt.Sprintf("%q", sampleBinSHAs["coder-linux-amd64"]),
+				},
+				// Test compression support with X-Original-Content-Length
+				// header.
+				{
+					url:              "/bin/coder-linux-amd64",
+					wantStatus:       http.StatusOK,
+					wantOriginalSize: 10,
+					compression:      true,
 				},
 				{url: "/bin/GITKEEP", wantStatus: http.StatusNotFound},
 			},
@@ -462,9 +475,24 @@ func TestServingBin(t *testing.T) {
 			},
 			reqs: []req{
 				// We support both hyphens and underscores for compatibility.
-				{url: "/bin/coder-linux-amd64", wantStatus: http.StatusOK, wantBody: []byte("embed")},
+				{
-				{url: "/bin/coder_linux_amd64", wantStatus: http.StatusOK, wantBody: []byte("embed")},
+					url:              "/bin/coder-linux-amd64",
-				{url: "/bin/GITKEEP", wantStatus: http.StatusOK, wantBody: []byte("")},
+					wantStatus:       http.StatusOK,
+					wantBody:         []byte("embed"),
+					wantOriginalSize: 5,
+				},
+				{
+					url:              "/bin/coder_linux_amd64",
+					wantStatus:       http.StatusOK,
+					wantBody:         []byte("embed"),
+					wantOriginalSize: 5,
+				},
+				{
+					url:              "/bin/GITKEEP",
+					wantStatus:       http.StatusOK,
+					wantBody:         []byte(""),
+					wantOriginalSize: 0,
+				},
 			},
 		},
 	}
@@ -482,12 +510,14 @@ func TestServingBin(t *testing.T) {
 				require.Error(t, err, "extraction or read did not fail")
 			}
 
-			srv := httptest.NewServer(site.New(&site.Options{
+			site := site.New(&site.Options{
 				Telemetry: telemetry.NewNoop(),
 				BinFS:     binFS,
 				BinHashes: binHashes,
 				SiteFS:    rootFS,
-			}))
+			})
+			compressor := middleware.NewCompressor(1, "text/*", "application/*")
+			srv := httptest.NewServer(compressor.Handler(site))
 			defer srv.Close()
 
 			// Create a context
@@ -502,6 +532,9 @@ func TestServingBin(t *testing.T) {
 					if tr.ifNoneMatch != "" {
 						req.Header.Set("If-None-Match", tr.ifNoneMatch)
 					}
+					if tr.compression {
+						req.Header.Set("Accept-Encoding", "gzip")
+					}
 
 					resp, err := http.DefaultClient.Do(req)
 					require.NoError(t, err, "http do failed")
@@ -520,10 +553,28 @@ func TestServingBin(t *testing.T) {
 						assert.Empty(t, gotBody, "body is not empty")
 					}
 
+					if tr.compression {
+						assert.Equal(t, "gzip", resp.Header.Get("Content-Encoding"), "content encoding is not gzip")
+					} else {
+						assert.Empty(t, resp.Header.Get("Content-Encoding"), "content encoding is not empty")
+					}
+
 					if tr.wantEtag != "" {
 						assert.NotEmpty(t, resp.Header.Get("ETag"), "etag header is empty")
 						assert.Equal(t, tr.wantEtag, resp.Header.Get("ETag"), "etag did not match")
 					}
+
+					if tr.wantOriginalSize > 0 {
+						// This is a custom header that we set to help the
+						// client know the size of the decompressed data. See
+						// the comment in site.go.
+						headerStr := resp.Header.Get("X-Original-Content-Length")
+						assert.NotEmpty(t, headerStr, "X-Original-Content-Length header is empty")
+						originalSize, err := strconv.Atoi(headerStr)
+						if assert.NoErrorf(t, err, "could not parse X-Original-Content-Length header %q", headerStr) {
+							assert.EqualValues(t, tr.wantOriginalSize, originalSize, "X-Original-Content-Length did not match")
+						}
+					}
 				})
 			}
 		})