Migrate this project to minio micro services code

pkg/fs/postpolicyform.go

@@ -0,0 +1,157 @@
+/*
+ * Minio Cloud Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package fs
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"time"
+
+	"github.com/minio/minio-xl/pkg/probe"
+)
+
+// toString - Safely convert interface to string without causing panic.
+func toString(val interface{}) string {
+	switch v := val.(type) {
+	case string:
+		return v
+	}
+	return ""
+}
+
+// toInteger _ Safely convert interface to integer without causing panic.
+func toInteger(val interface{}) int {
+	switch v := val.(type) {
+	case int:
+		return v
+	}
+	return 0
+}
+
+// isString - Safely check if val is of type string without causing panic.
+func isString(val interface{}) bool {
+	switch val.(type) {
+	case string:
+		return true
+	}
+	return false
+}
+
+// PostPolicyForm provides strict static type conversion and validation for Amazon S3's POST policy JSON string.
+type PostPolicyForm struct {
+	Expiration time.Time // Expiration date and time of the POST policy.
+	Conditions struct {  // Conditional policy structure.
+		Policies map[string]struct {
+			Operator string
+			Value    string
+		}
+		ContentLengthRange struct {
+			Min int
+			Max int
+		}
+	}
+}
+
+// ParsePostPolicyForm - Parse JSON policy string into typed POostPolicyForm structure.
+func ParsePostPolicyForm(policy string) (PostPolicyForm, *probe.Error) {
+	// Convert po into interfaces and
+	// perform strict type conversion using reflection.
+	var rawPolicy struct {
+		Expiration string        `json:"expiration"`
+		Conditions []interface{} `json:"conditions"`
+	}
+
+	e := json.Unmarshal([]byte(policy), &rawPolicy)
+	if e != nil {
+		return PostPolicyForm{}, probe.NewError(e)
+	}
+
+	parsedPolicy := PostPolicyForm{}
+
+	// Parse expiry time.
+	parsedPolicy.Expiration, e = time.Parse(time.RFC3339Nano, rawPolicy.Expiration)
+	if e != nil {
+		return PostPolicyForm{}, probe.NewError(e)
+	}
+	parsedPolicy.Conditions.Policies = make(map[string]struct {
+		Operator string
+		Value    string
+	})
+
+	// Parse conditions.
+	for _, val := range rawPolicy.Conditions {
+		switch condt := val.(type) {
+		case map[string]interface{}: // Handle key:value map types.
+			for k, v := range condt {
+				if !isString(v) { // Pre-check value type.
+					// All values must be of type string.
+					return parsedPolicy, probe.NewError(fmt.Errorf("Unknown type ‘%s’ of conditional field value ‘%s’ found in POST policy form.",
+						reflect.TypeOf(condt).String(), condt))
+				}
+				// {"acl": "public-read" } is an alternate way to indicate - [ "eq", "$acl", "public-read" ]
+				// In this case we will just collapse this into "eq" for all use cases.
+				parsedPolicy.Conditions.Policies["$"+k] = struct {
+					Operator string
+					Value    string
+				}{
+					Operator: "eq",
+					Value:    toString(v),
+				}
+			}
+		case []interface{}: // Handle array types.
+			if len(condt) != 3 { // Return error if we have insufficient elements.
+				return parsedPolicy, probe.NewError(fmt.Errorf("Malformed conditional fields ‘%s’ of type ‘%s’ found in POST policy form.",
+					condt, reflect.TypeOf(condt).String()))
+			}
+			switch toString(condt[0]) {
+			case "eq", "starts-with":
+				for _, v := range condt { // Pre-check all values for type.
+					if !isString(v) {
+						// All values must be of type string.
+						return parsedPolicy, probe.NewError(fmt.Errorf("Unknown type ‘%s’ of conditional field value ‘%s’ found in POST policy form.",
+							reflect.TypeOf(condt).String(), condt))
+					}
+				}
+				operator, matchType, value := toString(condt[0]), toString(condt[1]), toString(condt[2])
+				parsedPolicy.Conditions.Policies[matchType] = struct {
+					Operator string
+					Value    string
+				}{
+					Operator: operator,
+					Value:    value,
+				}
+			case "content-length-range":
+				parsedPolicy.Conditions.ContentLengthRange = struct {
+					Min int
+					Max int
+				}{
+					Min: toInteger(condt[1]),
+					Max: toInteger(condt[2]),
+				}
+			default:
+				// Condition should be valid.
+				return parsedPolicy, probe.NewError(fmt.Errorf("Unknown type ‘%s’ of conditional field value ‘%s’ found in POST policy form.",
+					reflect.TypeOf(condt).String(), condt))
+			}
+		default:
+			return parsedPolicy, probe.NewError(fmt.Errorf("Unknown field ‘%s’ of type ‘%s’ found in POST policy form.",
+				condt, reflect.TypeOf(condt).String()))
+		}
+	}
+	return parsedPolicy, nil
+}