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/*
This is an example application to demonstrate parsing an ID Token.
*/
package main
import (
"crypto/rand"
"encoding/base64"
"encoding/json"
"io"
"log"
"net/http"
"os"
"time"
"github.com/coreos/go-oidc/v3/oidc"
"golang.org/x/net/context"
"golang.org/x/oauth2"
)
var (
clientID = os.Getenv("GOOGLE_OAUTH2_CLIENT_ID")
clientSecret = os.Getenv("GOOGLE_OAUTH2_CLIENT_SECRET")
)
func randString(nByte int) (string, error) {
b := make([]byte, nByte)
if _, err := io.ReadFull(rand.Reader, b); err != nil {
return "", err
}
return base64.RawURLEncoding.EncodeToString(b), nil
}
func setCallbackCookie(w http.ResponseWriter, r *http.Request, name, value string) {
c := &http.Cookie{
Name: name,
Value: value,
MaxAge: int(time.Hour.Seconds()),
Secure: r.TLS != nil,
HttpOnly: true,
}
http.SetCookie(w, c)
}
func main() {
ctx := context.Background()
provider, err := oidc.NewProvider(ctx, "https://accounts.google.com")
if err != nil {
log.Fatal(err)
}
oidcConfig := &oidc.Config{
ClientID: clientID,
}
verifier := provider.Verifier(oidcConfig)
config := oauth2.Config{
ClientID: clientID,
ClientSecret: clientSecret,
Endpoint: provider.Endpoint(),
RedirectURL: "http://127.0.0.1:5556/auth/google/callback",
Scopes: []string{oidc.ScopeOpenID, "profile", "email"},
}
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
state, err := randString(16)
if err != nil {
http.Error(w, "Internal error", http.StatusInternalServerError)
return
}
nonce, err := randString(16)
if err != nil {
http.Error(w, "Internal error", http.StatusInternalServerError)
return
}
setCallbackCookie(w, r, "state", state)
setCallbackCookie(w, r, "nonce", nonce)
http.Redirect(w, r, config.AuthCodeURL(state, oidc.Nonce(nonce)), http.StatusFound)
})
http.HandleFunc("/auth/google/callback", func(w http.ResponseWriter, r *http.Request) {
state, err := r.Cookie("state")
if err != nil {
http.Error(w, "state not found", http.StatusBadRequest)
return
}
if r.URL.Query().Get("state") != state.Value {
http.Error(w, "state did not match", http.StatusBadRequest)
return
}
oauth2Token, err := config.Exchange(ctx, r.URL.Query().Get("code"))
if err != nil {
http.Error(w, "Failed to exchange token: "+err.Error(), http.StatusInternalServerError)
return
}
rawIDToken, ok := oauth2Token.Extra("id_token").(string)
if !ok {
http.Error(w, "No id_token field in oauth2 token.", http.StatusInternalServerError)
return
}
idToken, err := verifier.Verify(ctx, rawIDToken)
if err != nil {
http.Error(w, "Failed to verify ID Token: "+err.Error(), http.StatusInternalServerError)
return
}
nonce, err := r.Cookie("nonce")
if err != nil {
http.Error(w, "nonce not found", http.StatusBadRequest)
return
}
if idToken.Nonce != nonce.Value {
http.Error(w, "nonce did not match", http.StatusBadRequest)
return
}
oauth2Token.AccessToken = "*REDACTED*"
resp := struct {
OAuth2Token *oauth2.Token
IDTokenClaims *json.RawMessage // ID Token payload is just JSON.
}{oauth2Token, new(json.RawMessage)}
if err := idToken.Claims(&resp.IDTokenClaims); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
data, err := json.MarshalIndent(resp, "", " ")
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Write(data)
})
log.Printf("listening on http://%s/", "127.0.0.1:5556")
log.Fatal(http.ListenAndServe("127.0.0.1:5556", nil))
}
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