From 64e7356acc7326faafe8454d884d0c260642805d Mon Sep 17 00:00:00 2001
From: Denis Kirillov <d.kirillov@yadro.com>
Date: Fri, 17 Feb 2023 15:52:52 +0300
Subject: [PATCH] [TrueCloudLab#32] Add custom policy unmarshaler

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>
---
 api/handler/acl.go      | 84 +++++++++++++++++++++++++++++++++++++++++
 api/handler/acl_test.go | 79 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 163 insertions(+)

diff --git a/api/handler/acl.go b/api/handler/acl.go
index 60c49e2a..2c5ad128 100644
--- a/api/handler/acl.go
+++ b/api/handler/acl.go
@@ -158,6 +158,90 @@ func (s ServiceRecord) ToEACLRecord() *eacl.Record {
 	return serviceRecord
 }
 
+var (
+	errInvalidStatement = stderrors.New("invalid statement")
+	errInvalidPrincipal = stderrors.New("invalid principal")
+)
+
+func (s *statement) UnmarshalJSON(data []byte) error {
+	var statementMap map[string]interface{}
+	if err := json.Unmarshal(data, &statementMap); err != nil {
+		return err
+	}
+
+	sidField, ok := statementMap["Sid"]
+	if ok {
+		if s.Sid, ok = sidField.(string); !ok {
+			return errInvalidStatement
+		}
+	}
+
+	effectField, ok := statementMap["Effect"]
+	if ok {
+		if s.Effect, ok = effectField.(string); !ok {
+			return errInvalidStatement
+		}
+	}
+
+	principalField, ok := statementMap["Principal"]
+	if ok {
+		principalMap, ok := principalField.(map[string]interface{})
+		if !ok {
+			return errInvalidPrincipal
+		}
+
+		awsField, ok := principalMap["AWS"]
+		if ok {
+			if s.Principal.AWS, ok = awsField.(string); !ok {
+				return fmt.Errorf("%w: 'AWS' field must be string", errInvalidPrincipal)
+			}
+		}
+
+		canonicalUserField, ok := principalMap["CanonicalUser"]
+		if ok {
+			if s.Principal.CanonicalUser, ok = canonicalUserField.(string); !ok {
+				return errInvalidPrincipal
+			}
+		}
+	}
+
+	actionField, ok := statementMap["Action"]
+	if ok {
+		switch actionField := actionField.(type) {
+		case []interface{}:
+			s.Action = make([]string, len(actionField))
+			for i, action := range actionField {
+				if s.Action[i], ok = action.(string); !ok {
+					return errInvalidStatement
+				}
+			}
+		case string:
+			s.Action = []string{actionField}
+		default:
+			return errInvalidStatement
+		}
+	}
+
+	resourceField, ok := statementMap["Resource"]
+	if ok {
+		switch resourceField := resourceField.(type) {
+		case []interface{}:
+			s.Resource = make([]string, len(resourceField))
+			for i, action := range resourceField {
+				if s.Resource[i], ok = action.(string); !ok {
+					return errInvalidStatement
+				}
+			}
+		case string:
+			s.Resource = []string{resourceField}
+		default:
+			return errInvalidStatement
+		}
+	}
+
+	return nil
+}
+
 func (h *handler) GetBucketACLHandler(w http.ResponseWriter, r *http.Request) {
 	reqInfo := api.GetReqInfo(r.Context())
 
diff --git a/api/handler/acl_test.go b/api/handler/acl_test.go
index d2cd2e7b..8c25c934 100644
--- a/api/handler/acl_test.go
+++ b/api/handler/acl_test.go
@@ -1352,6 +1352,85 @@ func TestBucketPolicy(t *testing.T) {
 	}
 }
 
+func TestBucketPolicyUnmarshal(t *testing.T) {
+	for _, tc := range []struct {
+		name   string
+		policy string
+	}{
+		{
+			name: "action/resource array",
+			policy: `
+{
+	"Version": "2012-10-17",
+	"Statement": [{
+		"Principal": {
+			"AWS": "arn:aws:iam::111122223333:role/JohnDoe"
+		},
+		"Effect": "Allow",
+		"Action": [
+			"s3:GetObject", 
+			"s3:GetObjectVersion"
+		],
+		"Resource": [
+			"arn:aws:s3:::DOC-EXAMPLE-BUCKET/*",
+			"arn:aws:s3:::DOC-EXAMPLE-BUCKET2/*"
+		]
+	}]
+}
+`,
+		},
+		{
+			name: "action/resource string",
+			policy: `
+{
+	"Version": "2012-10-17",
+	"Statement": [{
+		"Principal": {
+			"AWS": "arn:aws:iam::111122223333:role/JohnDoe"
+		},
+		"Effect": "Deny",
+		"Action": "s3:GetObject",
+		"Resource": "arn:aws:s3:::DOC-EXAMPLE-BUCKET/*"
+	}]
+}
+`,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			bktPolicy := &bucketPolicy{}
+			err := json.Unmarshal([]byte(tc.policy), bktPolicy)
+			require.NoError(t, err)
+		})
+	}
+}
+
+func TestPutBucketPolicy(t *testing.T) {
+	bktPolicy := `
+{
+	"Version": "2012-10-17",
+	"Statement": [{
+		"Principal": {
+			"AWS": "*"
+		},
+		"Effect": "Deny",
+		"Action": "s3:GetObject",
+		"Resource": "arn:aws:s3:::bucket-for-policy/*"
+	}]
+}
+`
+	hc := prepareHandlerContext(t)
+	bktName := "bucket-for-policy"
+
+	box, _ := createAccessBox(t)
+	createBucket(t, hc, bktName, box)
+
+	w, r := prepareTestPayloadRequest(hc, bktName, "", bytes.NewReader([]byte(bktPolicy)))
+	ctx := context.WithValue(r.Context(), api.BoxData, box)
+	r = r.WithContext(ctx)
+	hc.Handler().PutBucketPolicyHandler(w, r)
+	assertStatus(hc.t, w, http.StatusOK)
+}
+
 func getBucketPolicy(hc *handlerContext, bktName string) *bucketPolicy {
 	w, r := prepareTestRequest(hc, bktName, "", nil)
 	hc.Handler().GetBucketPolicyHandler(w, r)