javascript - 在 Golang 回调函数中启用 CORS

Question

我有一个对 Google 的 oAuth2 api 的 AJAX 调用，如下所示:

$(document).on('click', '#signup', function() {
  var OAUTHURL        =  'https://accounts.google.com/o/oauth2/auth?';
  var SCOPE           =   'email profile';
  var STATE           =   'profile';
  var REDIRECT_URI    =   'https://localhost:8080/callback';
  var RESPONSE_TYPE   =   'token';
  var CLIENT_ID       =   '554886359117-8icq0dc9halr8rjd6bdtqcmagrdql9lr.apps.googleusercontent.com';
  var _url            =    OAUTHURL + 'scope=' + SCOPE + '&state=' + STATE + '&redirect_uri=' + REDIRECT_URI + '&response_type=' + RESPONSE_TYPE + '&client_id=' + CLIENT_ID;
  $.ajax({
    type: "POST",
    dataType: "text",
    url: _url,
    success: function(response)
    {
        console.log(response.url);
    },
    error: function(error)
    {
        console.log("ERROR: ", error);
    }
  });
});

这应该重定向回在 http://localhost/callback 上运行的服务器.

Redirect URIs:  http://localhost:8080/callback
Javascript Origins: http://localhost:8080

我还有如下定义的回调函数:

func init() {
    r := mux.NewRouter()

    r.HandleFunc("/", rootHandler)
    r.HandleFunc("/callback", callbackHandler)
    http.Handle("/", r)
}
func callbackHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "I am sent back from the server!"+time.Now().Format("Mon, 02 Jan 2006 15:04:05 MST"))
}

在 Debug模式下一切看起来都很好，除了我从谷歌的 api 返回这个错误:

XMLHttpRequest cannot load https://accounts.google.com/o/oauth2/auth?scope=email%20profile&state=profi…d=554886359117-8icq0dc9halr8rjd6bdtqcmagrdql9lr.apps.googleusercontent.com. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.

我已经做了一些调整，但我似乎无法找到解决方法。有什么想法吗？

Answer 1

就像 Not_a_Golfer 所说的那样，您的后端没有为响应设置正确的 header 。为了处理每种情况下的 CORS 问题，我做了这个小 handler包装您的路由器，因此您不必在每个回调中手动设置 header 。

像这样使用它:

import "github.com/heppu/simple-cors"

func init() {
    r := mux.NewRouter()
    r.HandleFunc("/", rootHandler)
    r.HandleFunc("/callback", callbackHandler)
    http.Handle("/", cors.CORS(r))
}
func callbackHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "I am sent back from the server!"+time.Now().Format("Mon, 02 Jan 2006 15:04:05 MST"))
}