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moby--moby/pkg/requestdecorator/requestdecorator.go

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// Package requestdecorator provides helper functions to decorate a request with
// user agent versions, auth, meta headers.
package requestdecorator
import (
"errors"
"io"
"net/http"
"strings"
"github.com/Sirupsen/logrus"
)
var (
ErrNilRequest = errors.New("request cannot be nil")
)
// UAVersionInfo is used to model UserAgent versions.
type UAVersionInfo struct {
Name string
Version string
}
func NewUAVersionInfo(name, version string) UAVersionInfo {
return UAVersionInfo{
Name: name,
Version: version,
}
}
func (vi *UAVersionInfo) isValid() bool {
const stopChars = " \t\r\n/"
name := vi.Name
vers := vi.Version
if len(name) == 0 || strings.ContainsAny(name, stopChars) {
return false
}
if len(vers) == 0 || strings.ContainsAny(vers, stopChars) {
return false
}
return true
}
// Convert versions to a string and append the string to the string base.
//
// Each UAVersionInfo will be converted to a string in the format of
// "product/version", where the "product" is get from the name field, while
// version is get from the version field. Several pieces of verson information
// will be concatinated and separated by space.
func appendVersions(base string, versions ...UAVersionInfo) string {
if len(versions) == 0 {
return base
}
verstrs := make([]string, 0, 1+len(versions))
if len(base) > 0 {
verstrs = append(verstrs, base)
}
for _, v := range versions {
if !v.isValid() {
continue
}
verstrs = append(verstrs, v.Name+"/"+v.Version)
}
return strings.Join(verstrs, " ")
}
// Decorator is used to change an instance of
// http.Request. It could be used to add more header fields,
// change body, etc.
type Decorator interface {
// ChangeRequest() changes the request accordingly.
// The changed request will be returned or err will be non-nil
// if an error occur.
ChangeRequest(req *http.Request) (newReq *http.Request, err error)
}
// UserAgentDecorator appends the product/version to the user agent field
// of a request.
type UserAgentDecorator struct {
Versions []UAVersionInfo
}
func (h *UserAgentDecorator) ChangeRequest(req *http.Request) (*http.Request, error) {
if req == nil {
return req, ErrNilRequest
}
userAgent := appendVersions(req.UserAgent(), h.Versions...)
if len(userAgent) > 0 {
req.Header.Set("User-Agent", userAgent)
}
return req, nil
}
type MetaHeadersDecorator struct {
Headers map[string][]string
}
func (h *MetaHeadersDecorator) ChangeRequest(req *http.Request) (*http.Request, error) {
if h.Headers == nil {
return req, ErrNilRequest
}
for k, v := range h.Headers {
req.Header[k] = v
}
return req, nil
}
type AuthDecorator struct {
login string
password string
}
func NewAuthDecorator(login, password string) Decorator {
return &AuthDecorator{
login: login,
password: password,
}
}
func (self *AuthDecorator) ChangeRequest(req *http.Request) (*http.Request, error) {
if req == nil {
return req, ErrNilRequest
}
req.SetBasicAuth(self.login, self.password)
return req, nil
}
// RequestFactory creates an HTTP request
// and applies a list of decorators on the request.
type RequestFactory struct {
decorators []Decorator
}
func NewRequestFactory(d ...Decorator) *RequestFactory {
return &RequestFactory{
decorators: d,
}
}
func (f *RequestFactory) AddDecorator(d ...Decorator) {
f.decorators = append(f.decorators, d...)
}
func (f *RequestFactory) GetDecorators() []Decorator {
return f.decorators
}
// NewRequest() creates a new *http.Request,
// applies all decorators in the Factory on the request,
// then applies decorators provided by d on the request.
func (h *RequestFactory) NewRequest(method, urlStr string, body io.Reader, d ...Decorator) (*http.Request, error) {
req, err := http.NewRequest(method, urlStr, body)
if err != nil {
return nil, err
}
// By default, a nil factory should work.
if h == nil {
return req, nil
}
for _, dec := range h.decorators {
req, _ = dec.ChangeRequest(req)
}
for _, dec := range d {
req, _ = dec.ChangeRequest(req)
}
logrus.Debugf("%v -- HEADERS: %v", req.URL, req.Header)
return req, err
}