From 45686c5bdf10423873d4e2fef77c14b243f313f1 Mon Sep 17 00:00:00 2001
From: Alex Vanin <a.vanin@yadro.com>
Date: Fri, 10 Feb 2023 15:19:29 +0300
Subject: [PATCH] [TrueCloudLab#25] Process allow and deny lists of zones in
 bucket head requests

Signed-off-by: Alex Vanin <a.vanin@yadro.com>
---
 api/handler/api.go        |  2 ++
 api/handler/head.go       | 29 ++++++++++++++++++++++++++++-
 api/handler/head_test.go  | 20 ++++++++++++++++++++
 api/headers.go            |  1 +
 cmd/s3-gw/app.go          |  6 ++++++
 cmd/s3-gw/app_settings.go |  4 ++++
 6 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/api/handler/api.go b/api/handler/api.go
index 5253af7..0b64b65 100644
--- a/api/handler/api.go
+++ b/api/handler/api.go
@@ -29,6 +29,8 @@ type (
 		DefaultMaxAge      int
 		NotificatorEnabled bool
 		CopiesNumber       uint32
+		ResolveZoneList    []string
+		IsResolveListAllow bool // True if ResolveZoneList contains allowed zones
 	}
 
 	PlacementPolicy interface {
diff --git a/api/handler/head.go b/api/handler/head.go
index 0bead4b..58d2d85 100644
--- a/api/handler/head.go
+++ b/api/handler/head.go
@@ -123,8 +123,13 @@ func (h *handler) HeadBucketHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.Header().Set(api.ContainerID, bktInfo.CID.EncodeToString())
-	w.Header().Set(api.ContainerName, bktInfo.Name)
 	w.Header().Set(api.AmzBucketRegion, bktInfo.LocationConstraint)
+
+	if isAvailableToResolve(bktInfo.Zone, h.cfg.ResolveZoneList, h.cfg.IsResolveListAllow) {
+		w.Header().Set(api.ContainerName, bktInfo.Name)
+		w.Header().Set(api.ContainerZone, bktInfo.Zone)
+	}
+
 	api.WriteResponse(w, http.StatusOK, nil, api.MimeNone)
 }
 
@@ -158,3 +163,25 @@ func writeLockHeaders(h http.Header, legalHold *data.LegalHold, retention *data.
 		h.Set(api.AmzObjectLockMode, retention.Mode)
 	}
 }
+
+func isAvailableToResolve(zone string, list []string, isAllowList bool) bool {
+	// empty zone means container doesn't have proper system name,
+	// so we don't have to resolve it
+	if len(zone) == 0 {
+		return false
+	}
+
+	var zoneInList bool
+	for _, t := range list {
+		if t == zone {
+			zoneInList = true
+			break
+		}
+	}
+	// InList | IsAllowList | Result
+	//    0         0          1
+	//    0         1          0
+	//    1         0          0
+	//    1         1          1
+	return zoneInList == isAllowList
+}
diff --git a/api/handler/head_test.go b/api/handler/head_test.go
index f9d01ad..40078f8 100644
--- a/api/handler/head_test.go
+++ b/api/handler/head_test.go
@@ -86,6 +86,26 @@ func TestInvalidAccessThroughCache(t *testing.T) {
 	assertStatus(t, w, http.StatusForbidden)
 }
 
+func TestIsAvailableToResolve(t *testing.T) {
+	list := []string{"container", "s3"}
+
+	for i, testCase := range [...]struct {
+		isAllowList bool
+		list        []string
+		zone        string
+		expected    bool
+	}{
+		{isAllowList: true, list: list, zone: "container", expected: true},
+		{isAllowList: true, list: list, zone: "sftp", expected: false},
+		{isAllowList: false, list: list, zone: "s3", expected: false},
+		{isAllowList: false, list: list, zone: "system", expected: true},
+		{isAllowList: true, list: list, zone: "", expected: false},
+	} {
+		result := isAvailableToResolve(testCase.zone, testCase.list, testCase.isAllowList)
+		require.Equal(t, testCase.expected, result, "case %d", i+1)
+	}
+}
+
 func newTestAccessBox(t *testing.T, key *keys.PrivateKey) *accessbox.Box {
 	var err error
 	if key == nil {
diff --git a/api/headers.go b/api/headers.go
index 8f5307e..db9fc2a 100644
--- a/api/headers.go
+++ b/api/headers.go
@@ -64,6 +64,7 @@ const (
 
 	ContainerID   = "X-Container-Id"
 	ContainerName = "X-Container-Name"
+	ContainerZone = "X-Container-Zone"
 
 	AccessControlAllowOrigin      = "Access-Control-Allow-Origin"
 	AccessControlAllowMethods     = "Access-Control-Allow-Methods"
diff --git a/cmd/s3-gw/app.go b/cmd/s3-gw/app.go
index b1c8c74..5a0b950 100644
--- a/cmd/s3-gw/app.go
+++ b/cmd/s3-gw/app.go
@@ -642,6 +642,12 @@ func (a *App) initHandler() {
 		cfg.CopiesNumber = val
 	}
 
+	cfg.ResolveZoneList = a.cfg.GetStringSlice(cfgResolveBucketAllow)
+	cfg.IsResolveListAllow = len(cfg.ResolveZoneList) > 0
+	if !cfg.IsResolveListAllow {
+		cfg.ResolveZoneList = a.cfg.GetStringSlice(cfgResolveBucketDeny)
+	}
+
 	var err error
 	a.api, err = handler.New(a.log, a.obj, a.nc, cfg)
 	if err != nil {
diff --git a/cmd/s3-gw/app_settings.go b/cmd/s3-gw/app_settings.go
index 3cb9fef..cd8a3af 100644
--- a/cmd/s3-gw/app_settings.go
+++ b/cmd/s3-gw/app_settings.go
@@ -130,6 +130,10 @@ const ( // Settings.
 	// List of allowed AccessKeyID prefixes.
 	cfgAllowedAccessKeyIDPrefixes = "allowed_access_key_id_prefixes"
 
+	// Bucket resolving options.
+	cfgResolveBucketAllow = "resolve_bucket.allow"
+	cfgResolveBucketDeny  = "resolve_bucket.deny"
+
 	// envPrefix is an environment variables prefix used for configuration.
 	envPrefix = "S3_GW"
 )