From 5b270b2be5558634e1dd8355617dcc1e861d9d1d Mon Sep 17 00:00:00 2001
From: Henrique Dias <hacdias@gmail.com>
Date: Fri, 10 Jun 2022 14:50:10 +0200
Subject: [PATCH] feat: add .tar.gz gateway support

License: MIT
Signed-off-by: Henrique Dias <hacdias@gmail.com>
---
 core/corehttp/gateway_handler.go     | 10 ++++++++--
 core/corehttp/gateway_handler_tar.go | 23 ++++++++++++++++++++---
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/core/corehttp/gateway_handler.go b/core/corehttp/gateway_handler.go
index 3b41570eef8..903e17d1155 100644
--- a/core/corehttp/gateway_handler.go
+++ b/core/corehttp/gateway_handler.go
@@ -432,7 +432,11 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 		return
 	case "application/x-tar":
 		logger.Debugw("serving tar file", "path", contentPath)
-		i.serveTAR(r.Context(), w, r, resolvedPath, contentPath, begin, logger)
+		i.serveTAR(r.Context(), w, r, resolvedPath, contentPath, begin, logger, false)
+		return
+	case "application/x-tar+gzip":
+		logger.Debugw("serving tar file", "path", contentPath)
+		i.serveTAR(r.Context(), w, r, resolvedPath, contentPath, begin, logger, true)
 		return
 	default: // catch-all for unsuported application/vnd.*
 		err := fmt.Errorf("unsupported format %q", responseFormat)
@@ -878,7 +882,7 @@ func getEtag(r *http.Request, cid cid.Cid) string {
 		// Etag: "cid.foo" (gives us nice compression together with Content-Disposition in block (raw) and car responses)
 		suffix = `.` + f + suffix
 		// Since different TAR implementations may produce different byte-for-byte responses, we define a weak Etag.
-		if responseFormat == "application/x-tar" {
+		if strings.HasPrefix(responseFormat, "application/x-tar") {
 			prefix = "W/" + prefix
 		}
 	}
@@ -897,6 +901,8 @@ func customResponseFormat(r *http.Request) (mediaType string, params map[string]
 			return "application/vnd.ipld.car", nil, nil
 		case "tar":
 			return "application/x-tar", nil, nil
+		case "tar.gz":
+			return "application/x-tar+gzip", nil, nil
 		}
 	}
 	// Browsers and other user agents will send Accept header with generic types like:
diff --git a/core/corehttp/gateway_handler_tar.go b/core/corehttp/gateway_handler_tar.go
index bbf60cefeda..0abbe5136c8 100644
--- a/core/corehttp/gateway_handler_tar.go
+++ b/core/corehttp/gateway_handler_tar.go
@@ -1,8 +1,10 @@
 package corehttp
 
 import (
+	"compress/gzip"
 	"context"
 	"html"
+	"io"
 	"net/http"
 	"time"
 
@@ -16,7 +18,7 @@ import (
 
 var unixEpochTime = time.Unix(0, 0)
 
-func (i *gatewayHandler) serveTAR(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time, logger *zap.SugaredLogger) {
+func (i *gatewayHandler) serveTAR(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, begin time.Time, logger *zap.SugaredLogger, compressed bool) {
 	ctx, span := tracing.Span(ctx, "Gateway", "ServeTAR", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
 	defer span.End()
 
@@ -38,6 +40,9 @@ func (i *gatewayHandler) serveTAR(ctx context.Context, w http.ResponseWriter, r
 		name = urlFilename
 	} else {
 		name = resolvedPath.Cid().String() + ".tar"
+		if compressed {
+			name += ".gz"
+		}
 	}
 	setContentDispositionHeader(w, name, "attachment")
 
@@ -49,8 +54,19 @@ func (i *gatewayHandler) serveTAR(ctx context.Context, w http.ResponseWriter, r
 	}
 	defer file.Close()
 
+	// Define the output writer, maybe build a Gzip writer
+	var dstw io.Writer
+	if compressed {
+		gzipw := gzip.NewWriter(w)
+		defer gzipw.Close()
+
+		dstw = gzipw
+	} else {
+		dstw = w
+	}
+
 	// Construct the TAR writer
-	tarw, err := files.NewTarWriter(w)
+	tarw, err := files.NewTarWriter(dstw)
 	if err != nil {
 		webError(w, "could not build tar writer", err, http.StatusInternalServerError)
 		return
@@ -64,7 +80,8 @@ func (i *gatewayHandler) serveTAR(ctx context.Context, w http.ResponseWriter, r
 		w.Header().Set("Last-Modified", modtime.UTC().Format(http.TimeFormat))
 	}
 
-	w.Header().Set("Content-Type", "application/x-tar")
+	responseFormat, _, _ := customResponseFormat(r)
+	w.Header().Set("Content-Type", responseFormat)
 
 	if err := tarw.WriteFile(file, name); err != nil {
 		// We return error as a trailer, however it is not something browsers can access