Google api token checker

main.go

package main

import (
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	"io/ioutil"
	"net/http"
	"strings"
)

const (
	GOOGLE_TOKEN_URL = "https://www.googleapis.com/oauth2/v3/tokeninfo?id_token={0}"
)

func init() {

}

func main() {
	r := mux.NewRouter()
	r.HandleFunc("/authUser", AuthHandler)
	http.Handle("/", r)
	http.ListenAndServe(":8443", nil)
}

func AuthHandler(w http.ResponseWriter, r *http.Request) {
	x, err := ioutil.ReadAll(r.Body)
	if err != nil {
		fmt.Println(err)
	}

	users_name := validateToken(string(x))
	if users_name == "" {
		//log that token was invalid
	}

	// in case of CORS issues.
	w.Header().Set("Access-Control-Allow-Origin", "*")
	w.Write([]byte(users_name))
}

func validateToken(token string) (name string) {
	token = strings.Replace(token, "idtoken=", "", 1)
	reqPath := strings.Replace(GOOGLE_TOKEN_URL, "{0}", token, 1)

	res, err := http.Get(reqPath)
	if err != nil {
		fmt.Println(err)
	}

	if res.StatusCode == http.StatusOK {
		x, err := ioutil.ReadAll(res.Body)
		if err != nil {
			fmt.Println(err)
		}

		tokenResponse := TokenResponse{}
		err = json.Unmarshal(x, &tokenResponse)
		if err != nil {
			fmt.Println(err)
		}
		fmt.Println(tokenResponse)
		name = tokenResponse.Name
	}

	return
}

token_response.go

package main

type TokenResponse struct {
	Iss           string `json:"iss"`
	Sub           string `json:"sub"`
	Azp           string `json:"azp"`
	Email         string `json:"email"`
	AtHash        string `json:"at_hash"`
	EmailVerified string `json:"email_verified"`
	Aud           string `json:"aud"`
	Iat           string `json:"iat"`
	Exp           string `json:"exp"`
	Name          string `json:"name"`
	Picture       string `json:"picture"`
	GivenName     string `json:"given_name"`
	FamilyName    string `json:"family_name"`
	Locale        string `json:"locale"`
	Alg           string `json:"alg"`
	Kid           string `json:"kid"`
	// Hosted Domain [only shows up for google eduction/for work/government domains]
	Hd	      string `json:"hd"`
}