FR: Initial WRP Validation Framework

.gitignore

@@ -20,3 +20,7 @@ report.json
 
 # Images
 *.png
+
+# VSCode
+*.code-workspace
+.vscode/*

go.mod

@@ -12,4 +12,5 @@ require (
 	github.com/ugorji/go/codec v1.2.6
 	github.com/xmidt-org/httpaux v0.3.0
 	github.com/xmidt-org/webpa-common v1.3.2
+	go.uber.org/multierr v1.8.0
 )

go.sum

@@ -25,6 +25,10 @@ github.com/xmidt-org/httpaux v0.3.0 h1:JdV4QceiE8EMA1Qf5rnJzHdkIPzQV12ddARHLU8hr
 github.com/xmidt-org/httpaux v0.3.0/go.mod h1:mviIlg5fHGb3lAv3l0sbiwVG/q9rqvXaudEYxVrzXdE=
 github.com/xmidt-org/webpa-common v1.3.2 h1:dE1Fi+XVnkt3tMGMjH7/hN/UGcaQ/ukKriXuMDyCWnM=
 github.com/xmidt-org/webpa-common v1.3.2/go.mod h1:oCpKzOC+9h2vYHVzAU/06tDTQuBN4RZz+rhgIXptpOI=
+go.uber.org/atomic v1.7.0 h1:ADUqmZGgLDDfbSL9ZmPxKTybcoEYHgpYfELNoN+7hsw=
+go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
+go.uber.org/multierr v1.8.0 h1:dg6GjLku4EH+249NNmoIciG9N/jURbDG+pFlTkhzIC8=
+go.uber.org/multierr v1.8.0/go.mod h1:7EAYxJLBy9rStEaz58O2t4Uvip6FSURkq8/ppBp95ak=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

header_wrp.go

@@ -17,10 +17,6 @@
 
 package wrp
 
-import (
-	"errors"
-)
-
 // Constant HTTP header strings representing WRP fields
 const (
 	MsgTypeHeader         = "X-Midt-Msg-Type"
@@ -34,8 +30,6 @@ const (
 	SourceHeader          = "X-Midt-Source"
 )
 
-var ErrInvalidMsgType = errors.New("Invalid Message Type")
-
 // Map string to MessageType int
 /*
 func StringToMessageType(str string) MessageType {

validator.go

@@ -0,0 +1,101 @@
+/**
+ *  Copyright (c) 2022  Comcast Cable Communications Management, LLC
+ *
+ * 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 wrp
+
+import (
+	"errors"
+
+	"go.uber.org/multierr"
+)
+
+var (
+	ErrInvalidTypeValidator = errors.New("invalid TypeValidator")
+	ErrInvalidValidator     = errors.New("invalid WRP message type validator")
+	ErrInvalidMsgType       = errors.New("invalid WRP message type")
+)
+
+// AlwaysInvalid doesn't validate anything about the message and always returns an error.
+var AlwaysInvalid ValidatorFunc = func(m Message) error { return ErrInvalidMsgType }
+
+// AlwaysValid doesn't validate anything about the message and always returns nil.
+var AlwaysValid ValidatorFunc = func(msg Message) error { return nil }
+
+// Validator is a WRP validator that allows access to the Validate function.
+type Validator interface {
+	Validate(m Message) error
+}
+
+// Validators is a WRP validator that ensures messages are valid based on
+// message type and each validator in the list.
+type Validators []Validator
+
+// Validate runs messages through each validator in the validators list.
+// It returns as soon as the message is considered invalid, otherwise returns nil if valid.
+func (vs Validators) Validate(m Message) error {
+	var err error
+	for _, v := range vs {
+		if v != nil {
+			err = multierr.Append(err, v.Validate(m))
+		}
+	}
+
+	return err
+}
+
+// ValidatorFunc is a WRP validator that takes messages and validates them
+// against functions.
+type ValidatorFunc func(Message) error
+
+// Validate executes its own ValidatorFunc receiver and returns the result.
+func (vf ValidatorFunc) Validate(m Message) error {
+	return vf(m)
+}
+
+// TypeValidator is a WRP validator that validates based on message type
+// or using the defaultValidator if message type is unfound.
+type TypeValidator struct {
+	m                map[MessageType]Validator
+	defaultValidator Validator
+}
+
+// Validate validates messages based on message type or using the defaultValidator
+// if message type is unfound.
+func (m TypeValidator) Validate(msg Message) error {
+	vs := m.m[msg.MessageType()]
+	if vs == nil {
+		return m.defaultValidator.Validate(msg)
+	}
+
+	return vs.Validate(msg)
+}
+
+// NewTypeValidator is a TypeValidator factory.
+func NewTypeValidator(m map[MessageType]Validator, defaultValidator Validator) (TypeValidator, error) {
+	if m == nil {
+		return TypeValidator{}, ErrInvalidValidator
+	}
+
+	if defaultValidator == nil {
+		defaultValidator = AlwaysInvalid
+	}
+
+	return TypeValidator{
+		m:                m,
+		defaultValidator: defaultValidator,
+	}, nil
+}