From 2f2e7f2fd77ac264685d2e82f3e8538af857ab17 Mon Sep 17 00:00:00 2001
From: Henrique Dias <hacdias@gmail.com>
Date: Thu, 22 Jun 2023 14:23:36 +0200
Subject: [PATCH] feat(gateway): parse ipip-402 Accept Header params

---
 gateway/gateway.go          | 13 ++++++++++--
 gateway/handler_car.go      | 26 +++++++++++++++++++++--
 gateway/handler_car_test.go | 42 +++++++++++++++++++++++++++++++++++--
 3 files changed, 75 insertions(+), 6 deletions(-)

diff --git a/gateway/gateway.go b/gateway/gateway.go
index cc0babba13..d05d80e3ce 100644
--- a/gateway/gateway.go
+++ b/gateway/gateway.go
@@ -121,8 +121,10 @@ func (i ImmutablePath) IsValid() error {
 var _ path.Path = (*ImmutablePath)(nil)
 
 type CarParams struct {
-	Range *DagByteRange
-	Scope DagScope
+	Range      *DagByteRange
+	Scope      DagScope
+	Order      DagOrder
+	Duplicates *bool
 }
 
 // DagByteRange describes a range request within a UnixFS file. "From" and
@@ -189,6 +191,13 @@ const (
 	DagScopeBlock  DagScope = "block"
 )
 
+type DagOrder string
+
+const (
+	DagOrderDFS     DagOrder = "dfs"
+	DagOrderUnknown DagOrder = "unk"
+)
+
 type ContentPathMetadata struct {
 	PathSegmentRoots []cid.Cid
 	LastSegment      path.Resolved
diff --git a/gateway/handler_car.go b/gateway/handler_car.go
index bf7e0c5eb7..0f6f6e50dc 100644
--- a/gateway/handler_car.go
+++ b/gateway/handler_car.go
@@ -39,7 +39,7 @@ func (i *handler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.R
 		return false
 	}
 
-	params, err := getCarParams(r)
+	params, err := getCarParams(r, rq.responseParams)
 	if err != nil {
 		i.webError(w, r, err, http.StatusBadRequest)
 		return false
@@ -113,7 +113,7 @@ func (i *handler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.R
 	return true
 }
 
-func getCarParams(r *http.Request) (CarParams, error) {
+func getCarParams(r *http.Request, formatParams map[string]string) (CarParams, error) {
 	queryParams := r.URL.Query()
 	rangeStr, hasRange := queryParams.Get(carRangeBytesKey), queryParams.Has(carRangeBytesKey)
 	scopeStr, hasScope := queryParams.Get(carTerminalElementTypeKey), queryParams.Has(carTerminalElementTypeKey)
@@ -140,6 +140,28 @@ func getCarParams(r *http.Request) (CarParams, error) {
 		params.Scope = DagScopeAll
 	}
 
+	switch order := DagOrder(formatParams["order"]); order {
+	case DagOrderUnknown, DagOrderDFS:
+		params.Order = order
+	case "":
+		params.Order = DagOrderUnknown
+	default:
+		return CarParams{}, fmt.Errorf("unsupported order %s", order)
+	}
+
+	switch dups := formatParams["dups"]; dups {
+	case "y":
+		v := true
+		params.Duplicates = &v
+	case "n":
+		v := false
+		params.Duplicates = &v
+	case "":
+		// Acceptable, we do not set anything.
+	default:
+		return CarParams{}, fmt.Errorf("unsupported dups %s", dups)
+	}
+
 	return params, nil
 }
 
diff --git a/gateway/handler_car_test.go b/gateway/handler_car_test.go
index 858ccb85d9..54b71181d9 100644
--- a/gateway/handler_car_test.go
+++ b/gateway/handler_car_test.go
@@ -28,7 +28,7 @@ func TestCarParams(t *testing.T) {
 		}
 		for _, test := range tests {
 			r := mustNewRequest(t, http.MethodGet, "http://example.com/?"+test.query, nil)
-			params, err := getCarParams(r)
+			params, err := getCarParams(r, map[string]string{})
 			if test.expectedError {
 				assert.Error(t, err)
 			} else {
@@ -60,7 +60,7 @@ func TestCarParams(t *testing.T) {
 		}
 		for _, test := range tests {
 			r := mustNewRequest(t, http.MethodGet, "http://example.com/?"+test.query, nil)
-			params, err := getCarParams(r)
+			params, err := getCarParams(r, map[string]string{})
 			if test.hasError {
 				assert.Error(t, err)
 			} else {
@@ -73,6 +73,44 @@ func TestCarParams(t *testing.T) {
 			}
 		}
 	})
+
+	t.Run("order and duplicates parsing", func(t *testing.T) {
+		t.Parallel()
+
+		T := true
+		F := false
+
+		tests := []struct {
+			acceptHeader       string
+			expectedOrder      DagOrder
+			expectedDuplicates *bool
+		}{
+			{"application/vnd.ipld.car; order=dfs; dups=y", DagOrderDFS, &T},
+			{"application/vnd.ipld.car; order=unk; dups=n", DagOrderUnknown, &F},
+			{"application/vnd.ipld.car; order=unk", DagOrderUnknown, nil},
+			{"application/vnd.ipld.car; dups=y", DagOrderUnknown, &T},
+			{"application/vnd.ipld.car; dups=n", DagOrderUnknown, &F},
+			{"application/vnd.ipld.car", DagOrderUnknown, nil},
+		}
+		for _, test := range tests {
+			r := mustNewRequest(t, http.MethodGet, "http://example.com/", nil)
+			r.Header.Set("Accept", test.acceptHeader)
+
+			mediaType, formatParams, err := customResponseFormat(r)
+			assert.NoError(t, err)
+			assert.Equal(t, carResponseFormat, mediaType)
+
+			params, err := getCarParams(r, formatParams)
+			assert.NoError(t, err)
+			require.Equal(t, test.expectedOrder, params.Order)
+
+			if test.expectedDuplicates == nil {
+				require.Nil(t, params.Duplicates)
+			} else {
+				require.Equal(t, *test.expectedDuplicates, *params.Duplicates)
+			}
+		}
+	})
 }
 
 func TestGetCarEtag(t *testing.T) {