Propagate ETag from gitea (#93)

close #15

Co-authored-by: 6543 <6543@obermui.de>
Reviewed-on: https://codeberg.org/Codeberg/pages-server/pulls/93

server/gitea/client.go

@@ -25,6 +25,7 @@ type Client struct {
 
 type FileResponse struct {
 	Exists   bool
+	ETag     []byte
 	MimeType string
 	Body     []byte
 }

server/upstream/const.go

@@ -12,6 +12,7 @@ var branchExistenceCacheTimeout = 5 * time.Minute
 
 // fileCacheTimeout specifies the timeout for the file content cache - you might want to make this quite long, depending
 // on your available memory.
+// TODO: move as option into cache interface
 var fileCacheTimeout = 5 * time.Minute
 
 // fileCacheSizeLimit limits the maximum file size that will be cached, and is set to 1 MB by default.

server/upstream/upstream.go

@@ -161,6 +161,14 @@ func (o *Options) Upstream(ctx *fasthttp.RequestCtx, giteaClient *gitea.Client,
 	mimeType := o.getMimeTypeByExtension()
 	ctx.Response.Header.SetContentType(mimeType)
 
+	// Set ETag
+	if cachedResponse.Exists {
+		ctx.Response.Header.SetBytesV(fasthttp.HeaderETag, cachedResponse.ETag)
+	} else if res != nil {
+		cachedResponse.ETag = res.Header.Peek(fasthttp.HeaderETag)
+		ctx.Response.Header.SetBytesV(fasthttp.HeaderETag, cachedResponse.ETag)
+	}
+
 	if ctx.Response.StatusCode() != fasthttp.StatusNotFound {
 		// Everything's okay so far
 		ctx.Response.SetStatusCode(fasthttp.StatusOK)