1 files changed, 84 insertions, 0 deletions
diff --git a/workhorse/internal/staticpages/servefile.go b/workhorse/internal/staticpages/servefile.go
new file mode 100644
index 00000000000..c98bc030bc2
--- /dev/null
+++ b/workhorse/internal/staticpages/servefile.go
@@ -0,0 +1,84 @@
+package staticpages
+
+import (
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"gitlab.com/gitlab-org/labkit/log"
+	"gitlab.com/gitlab-org/labkit/mask"
+
+	"gitlab.com/gitlab-org/gitlab-workhorse/internal/helper"
+	"gitlab.com/gitlab-org/gitlab-workhorse/internal/urlprefix"
+)
+
+type CacheMode int
+
+const (
+	CacheDisabled CacheMode = iota
+	CacheExpireMax
+)
+
+// BUG/QUIRK: If a client requests 'foo%2Fbar' and 'foo/bar' exists,
+// handleServeFile will serve foo/bar instead of passing the request
+// upstream.
+func (s *Static) ServeExisting(prefix urlprefix.Prefix, cache CacheMode, notFoundHandler http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		file := filepath.Join(s.DocumentRoot, prefix.Strip(r.URL.Path))
+
+		// The filepath.Join does Clean traversing directories up
+		if !strings.HasPrefix(file, s.DocumentRoot) {
+			helper.Fail500(w, r, &os.PathError{
+				Op:   "open",
+				Path: file,
+				Err:  os.ErrInvalid,
+			})
+			return
+		}
+
+		var content *os.File
+		var fi os.FileInfo
+		var err error
+
+		// Serve pre-gzipped assets
+		if acceptEncoding := r.Header.Get("Accept-Encoding"); strings.Contains(acceptEncoding, "gzip") {
+			content, fi, err = helper.OpenFile(file + ".gz")
+			if err == nil {
+				w.Header().Set("Content-Encoding", "gzip")
+			}
+		}
+
+		// If not found, open the original file
+		if content == nil || err != nil {
+			content, fi, err = helper.OpenFile(file)
+		}
+		if err != nil {
+			if notFoundHandler != nil {
+				notFoundHandler.ServeHTTP(w, r)
+			} else {
+				http.NotFound(w, r)
+			}
+			return
+		}
+		defer content.Close()
+
+		switch cache {
+		case CacheExpireMax:
+			// Cache statically served files for 1 year
+			cacheUntil := time.Now().AddDate(1, 0, 0).Format(http.TimeFormat)
+			w.Header().Set("Cache-Control", "public")
+			w.Header().Set("Expires", cacheUntil)
+		}
+
+		log.WithContextFields(r.Context(), log.Fields{
+			"file":     file,
+			"encoding": w.Header().Get("Content-Encoding"),
+			"method":   r.Method,
+			"uri":      mask.URL(r.RequestURI),
+		}).Info("Send static file")
+
+		http.ServeContent(w, r, filepath.Base(file), fi.ModTime(), content)
+	})
+}