Refactor utils/http.go, fixes #11899

Signed-off-by: Antonio Murdaca <me@runcom.ninja>

requestdecorator/requestdecorator.go

@@ -0,0 +1,172 @@
+// 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
+}