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// Copyright 2015 Google Inc. All rights reserved.
//
// 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 header
import (
"encoding/json"
"net/http"
"github.com/google/martian/v3"
"github.com/google/martian/v3/parse"
)
const idHeaderName string = "X-Martian-ID"
func init() {
parse.Register("header.Id", idModifierFromJSON)
}
type idModifier struct{}
type idModifierJSON struct {
Scope []parse.ModifierType `json:"scope"`
}
// NewIDModifier returns a request modifier that will set a header with the name
// X-Martian-ID with a value that is a unique identifier for the request. In the case
// that the X-Martian-ID header is already set, the header is unmodified.
func NewIDModifier() martian.RequestModifier {
return &idModifier{}
}
// ModifyRequest sets the X-Martian-ID header with a unique identifier. In the case
// that the X-Martian-ID header is already set, the header is unmodified.
func (im *idModifier) ModifyRequest(req *http.Request) error {
// Do not rewrite an ID if req already has one
if req.Header.Get(idHeaderName) != "" {
return nil
}
ctx := martian.NewContext(req)
req.Header.Set(idHeaderName, ctx.ID())
return nil
}
func idModifierFromJSON(b []byte) (*parse.Result, error) {
msg := &idModifierJSON{}
if err := json.Unmarshal(b, msg); err != nil {
return nil, err
}
modifier := NewIDModifier()
return parse.NewResult(modifier, msg.Scope)
}
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