From de69041f1d1abcfd4b98f8b7b3f7043809bfd433 Mon Sep 17 00:00:00 2001
From: Peter Rabbitson <ribasushi@leporine.io>
Date: Sun, 23 Jun 2019 21:17:39 +0200
Subject: [PATCH] Include the git blob id of the dir-index bundle in the ETag

While the content of raw files retrieved via the gateway should never
change, the look and feel of the directory index can and will change
between versions of go-ipfs.

Incorporate the hash of assets/bindata.go into the ETag when appropriate


This commit was moved from ipfs/kubo@2d5f8b4ebe015817b2ea285a4d589e5d796bf8a3
---
 gateway/core/corehttp/gateway_handler.go | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/gateway/core/corehttp/gateway_handler.go b/gateway/core/corehttp/gateway_handler.go
index ba264c095..a1549efdd 100644
--- a/gateway/core/corehttp/gateway_handler.go
+++ b/gateway/core/corehttp/gateway_handler.go
@@ -19,6 +19,7 @@ import (
 	"github.com/gabriel-vasile/mimetype"
 	"github.com/ipfs/go-cid"
 	files "github.com/ipfs/go-ipfs-files"
+	assets "github.com/ipfs/go-ipfs/assets"
 	dag "github.com/ipfs/go-merkledag"
 	mfs "github.com/ipfs/go-mfs"
 	path "github.com/ipfs/go-path"
@@ -222,16 +223,26 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 
 	defer dr.Close()
 
-	// Check etag send back to us
-	etag := "\"" + resolvedPath.Cid().String() + "\""
-	if r.Header.Get("If-None-Match") == etag || r.Header.Get("If-None-Match") == "W/"+etag {
+	var responseEtag string
+
+	// we need to figure out whether this is a directory before doing most of the heavy lifting below
+	_, ok := dr.(files.Directory)
+
+	if ok && assets.BindataVersionHash != "" {
+		responseEtag = `"DirIndex-` + assets.BindataVersionHash + `_CID-` + resolvedPath.Cid().String() + `"`
+	} else {
+		responseEtag = `"` + resolvedPath.Cid().String() + `"`
+	}
+
+	// Check etag sent back to us
+	if r.Header.Get("If-None-Match") == responseEtag || r.Header.Get("If-None-Match") == `W/`+responseEtag {
 		w.WriteHeader(http.StatusNotModified)
 		return
 	}
 
 	i.addUserHeaders(w) // ok, _now_ write user's headers.
 	w.Header().Set("X-IPFS-Path", urlPath)
-	w.Header().Set("Etag", etag)
+	w.Header().Set("Etag", responseEtag)
 
 	// set these headers _after_ the error, for we may just not have it
 	// and don't want the client to cache a 500 response...