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I am trying to write a simple program using the golang.org/x/oauth2 package. But I can't seem to exchange code for an access token. The following error is a bit misleading as it says the authorisation code has been used but I see a new code every time I invoke the login dialog. I am new to golang and I might be making a basic mistake, any pointers would be really helpful :)
clientOptions, err = oauth2.New(
oauth2.Client("xxxxxx", "22222222222222"),
oauth2.RedirectURL("http://localhost:3000/auth/cb/fb2"),
oauth2.Scope("public_profile", "email", "user_friends"),
oauth2.Endpoint(
"https://www.facebook.com/dialog/oauth",
"https://graph.facebook.com/oauth/access_token",
),
)
func handleFBSetupOauth(w http.ResponseWriter, r *http.Request) {
url := clientOptions.AuthCodeURL("state", "online", "auto")
fmt.Printf("Visit the URL for the auth dialog: %v", url)
http.Redirect(w, r, url, http.StatusFound)
}
func handleFBOauthCB(w http.ResponseWriter, r *http.Request) (int, string) {
var err error
code := r.FormValue("code")
if code == "" {
return 500, "No code!"
}
fmt.Printf("code - %s", code)
t, err := clientOptions.NewTransportFromCode(code)
if err != nil {
log.Fatal(err)
}
client := http.Client{Transport: t}
url := "https://graph.facebook.com/oauth/access_token?client_id=xxxxxxx&redirect_uri=http://localhost:3000/auth/cb/fb2&client_secret=22222222&code=" + code + ""
resp, err := client.Get(url)
I get the following error from the last get request -
{"error":{"message":"This authorization code has been used.","type":"OAuthException","code":100}}
I am following these 2 guides - Facebook login flow - https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.2
Latest goauth doc - https://godoc.org/golang.org/x/oauth2
758
Here is a simple example to get you started:
package main
import (
"fmt"
"io/ioutil"
"log"
"net/http"
"net/url"
"strings"
"golang.org/x/oauth2"
"golang.org/x/oauth2/facebook"
)
var (
oauthConf = &oauth2.Config{
ClientID: "YOUR_CLIENT_ID",
ClientSecret: "YOUR_CLIENT_SECRET",
RedirectURL: "YOUR_REDIRECT_URL_CALLBACK",
Scopes: []string{"public_profile"},
Endpoint: facebook.Endpoint,
}
oauthStateString = "thisshouldberandom"
)
const htmlIndex = `<html><body>
Logged in with <a href="/login">facebook</a>
</body></html>
`
func handleMain(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(http.StatusOK)
w.Write([]byte(htmlIndex))
}
func handleFacebookLogin(w http.ResponseWriter, r *http.Request) {
Url, err := url.Parse(oauthConf.Endpoint.AuthURL)
if err != nil {
log.Fatal("Parse: ", err)
}
parameters := url.Values{}
parameters.Add("client_id", oauthConf.ClientID)
parameters.Add("scope", strings.Join(oauthConf.Scopes, " "))
parameters.Add("redirect_uri", oauthConf.RedirectURL)
parameters.Add("response_type", "code")
parameters.Add("state", oauthStateString)
Url.RawQuery = parameters.Encode()
url := Url.String()
http.Redirect(w, r, url, http.StatusTemporaryRedirect)
}
func handleFacebookCallback(w http.ResponseWriter, r *http.Request) {
state := r.FormValue("state")
if state != oauthStateString {
fmt.Printf("invalid oauth state, expected '%s', got '%s'\n", oauthStateString, state)
http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
return
}
code := r.FormValue("code")
token, err := oauthConf.Exchange(oauth2.NoContext, code)
if err != nil {
fmt.Printf("oauthConf.Exchange() failed with '%s'\n", err)
http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
return
}
resp, err := http.Get("https://graph.facebook.com/me?access_token=" +
url.QueryEscape(token.AccessToken))
if err != nil {
fmt.Printf("Get: %s\n", err)
http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
return
}
defer resp.Body.Close()
response, err := ioutil.ReadAll(resp.Body)
if err != nil {
fmt.Printf("ReadAll: %s\n", err)
http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
return
}
log.Printf("parseResponseBody: %s\n", string(response))
http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
}
func main() {
http.HandleFunc("/", handleMain)
http.HandleFunc("/login", handleFacebookLogin)
http.HandleFunc("/oauth2callback", handleFacebookCallback)
fmt.Print("Started running on http://localhost:9090\n")
log.Fatal(http.ListenAndServe(":9090", nil))
}
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