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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 stash provides a modifier that stores the request URL in a
// specified header.
package stash
import (
"encoding/json"
"fmt"
"net/http"
"github.com/google/martian/v3/parse"
)
func init() {
parse.Register("stash.Modifier", modifierFromJSON)
}
// Modifier adds a header to the request containing the current state of the URL.
// The header will be named with the value stored in headerName.
// There will be no validation done on this header name.
type Modifier struct {
headerName string
}
type modifierJSON struct {
HeaderName string `json:"headerName"`
Scope []parse.ModifierType `json:"scope"`
}
// NewModifier returns a RequestModifier that write the current URL into a header.
func NewModifier(headerName string) *Modifier {
return &Modifier{headerName: headerName}
}
// ModifyRequest writes the current URL into a header.
func (m *Modifier) ModifyRequest(req *http.Request) error {
req.Header.Set(m.headerName, req.URL.String())
return nil
}
// ModifyResponse writes the same header written in the request into the response.
func (m *Modifier) ModifyResponse(res *http.Response) error {
res.Header.Set(m.headerName, res.Request.Header.Get(m.headerName))
return nil
}
func modifierFromJSON(b []byte) (*parse.Result, error) {
// If you would like the saved state of the URL to be written in the response you must specify
// this modifier's scope as both request and response.
msg := &modifierJSON{}
if err := json.Unmarshal(b, msg); err != nil {
return nil, err
}
mod := NewModifier(msg.HeaderName)
r, err := parse.NewResult(mod, msg.Scope)
if err != nil {
return nil, err
}
if r.ResponseModifier() != nil && r.RequestModifier() == nil {
return nil, fmt.Errorf("to write header on a response, specify scope as both request and response")
}
return r, nil
}
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