How to fix the "Malformed auth code" when trying to refreshToken on the second attempt?

In my case it was pretty stupid: google api changes the auth code coding between requests.

Step 1 - During the first request to obtain tokens google returns quite normal, not encoded string as the code.

Step 2 - During second and N-th request to obtain tokens (if they were not revoked) google returns the auth code as url-encoded. In my case the killing change was '/' -> '%2F'.

Solution: Always URL-Decode the auth code before exchanging it for the access tokens!

Finally I achieved refreshing the access token as times as needed. The problem was a misconception of how it works the Google Api.

The first time to update the token, it is needed to call this endpoint with these parameters and setting as {{refreshToken}} the value obtained from the response of the Consent Screen call (serverAuthCode)

https://oauth2.googleapis.com/token?code={{refreshToken}}&client_id={{googleClientId}}&client_secret={{googleClientSecret}}&grant_type=authorization_code

After the first refresh, any update to the token needs to be call to this other endpoint by setting as {{tokenUpdated}} the attribute {{refresh_token}} obtained from the response of the first call.

https://oauth2.googleapis.com/token?refresh_token={{tokenUpdated}}&client_id={{googleClientId}}&client_secret={{googleClientSecret}}&grant_type=refresh_token

Here I show you an example of my AuthenticationService

import { Injectable} from '@angular/core';
import { Router } from '@angular/router';
import { GooglePlus } from '@ionic-native/google-plus/ngx';

@Injectable({
  providedIn: 'root'
})
export class AuthenticationService {


static AUTH_INFO_GOOGLE = 'auth-info-google';
static CLIENT_ID = 'XXXXX-XXXX.apps.googleusercontent.com';
static CLIENT_SECRET = 'SecretPasswordClientId';


public authenticationState = new BehaviorSubject(false);

  constructor(
    private router: Router,
    private googlePlus: GooglePlus) {

  }

public isAuthenticated() {
    return this.authenticationState.value;
}

public logout(): Promise<void> {
    this.authenticationState.next(false);   
    return this.googlePlus.disconnect()
    .then(msg => {
      console.log('User logged out: ' + msg);
    }, err => {
      console.log('User already disconected');
    }); 
}

/**
* Performs the login
*/
public async login(): Promise<any> {
    return this.openGoogleConsentScreen().then(async (user) => {
      console.log(' ServerAuth Code: ' + user.serverAuthCode);
      user.updated = false;
      await this.setData(AuthenticationService.AUTH_INFO_GOOGLE, JSON.stringify(user));
      this.authenticationState.next(true);
      // Do more staff after successfully login
    }, err => {
        this.authenticationState.next(false);
        console.log('An error ocurred in the login process: ' + err);
        console.log(err);
    });

}

  /**
   * Gets the Authentication Token
   */
public async getAuthenticationToken(): Promise<string> {
      return this.getAuthInfoGoogle()
        .then(auth => {
          if (this.isTokenExpired(auth)) {
            return this.refreshToken(auth);
          } else {
            return 'Bearer ' + auth.accessToken;
          }
        });
}



private async openGoogleConsentScreen(): Promise<any> {
  return this.googlePlus.login({
    // optional, space-separated list of scopes, If not included or empty, defaults to `profile` and `email`.
    'scopes': 'profile email openid',
    'webClientId': AuthenticationService.CLIENT_ID,
    'offline': true
  });
}

private isTokenExpired(auth: any): Boolean {
    const expiresIn = auth.expires - (Date.now() / 1000);
     const extraSeconds = 60 * 59 + 1;
    // const extraSeconds = 0;
    const newExpiration = expiresIn - extraSeconds;
     console.log('Token expires in ' + newExpiration + ' seconds. Added ' + extraSeconds + ' seconds for debugging purpouses');
    return newExpiration < 0;
}

private async refreshToken(auth: any): Promise<any> {
      console.log('The authentication token has expired. Calling for renewing');
      if (auth.updated) {
        auth = await this.requestGoogleRefreshToken(auth.serverAuthCode, auth.userId, auth.email);
      } else {
        auth = await this.requestGoogleAuthorizationCode(auth.serverAuthCode, auth.userId, auth.email);
      }
      await this.setData(AuthenticationService.AUTH_INFO_GOOGLE, JSON.stringify(auth));
      return 'Bearer ' + auth.accessToken;
}


private getAuthInfoGoogle(): Promise<any> {
    return this.getData(AuthenticationService.AUTH_INFO_GOOGLE)
    .then(oauthInfo => {
      return JSON.parse(oauthInfo);
    }, err => {
      this.clearStorage();
      throw err;
    });
}

private async requestGoogleAuthorizationCode(serverAuthCode: string, userId: string, email: string): Promise<any> {
    let headers = new HttpHeaders();
    headers = headers.set('Content-Type', 'application/x-www-form-urlencoded');
    let params: HttpParams = new HttpParams();
    params = params.set('code', serverAuthCode);
    params = params.set('client_id', AuthenticationService.CLIENT_ID);
    params = params.set('client_secret', AuthenticationService.CLIENT_SECRET);
    params = params.set('grant_type', 'authorization_code');
    const options = {
      headers: headers,
      params: params
    };
    const url = 'https://oauth2.googleapis.com/token';
    const renewalTokenRequestPromise: Promise<any> = this.http.post(url, {}, options).toPromise()
      .then((response: any) => {
        const auth: any = {};
        auth.accessToken = response.access_token;
        console.log('RefreshToken: ' + response.refresh_token);
        auth.serverAuthCode = response.refresh_token;
        auth.expires = Date.now() / 1000 + response.expires_in;
        auth.userId = userId;
        auth.email = email;
        auth.updated = true;
        return auth;
      }, (error) => {
        console.error('Error renewing the authorization code: ' + JSON.stringify(error));
        return {};
      });
    return await renewalTokenRequestPromise;
}

private async requestGoogleRefreshToken(serverAuthCode: string, userId: string, email: string): Promise<any> {
    let headers = new HttpHeaders();
    headers = headers.set('Content-Type', 'application/x-www-form-urlencoded');
    let params: HttpParams = new HttpParams();
    params = params.set('refresh_token', serverAuthCode);
    params = params.set('client_id', AuthenticationService.CLIENT_ID);
    params = params.set('client_secret', AuthenticationService.CLIENT_SECRET);
    params = params.set('grant_type', 'refresh_token');
    const options = {
      headers: headers,
      params: params
    };
    const url = 'https://oauth2.googleapis.com/token';
    const renewalTokenRequestPromise: Promise<any> = this.http.post(url, {}, options).toPromise()
      .then((response: any) => {
        const auth: any = {};
        auth.accessToken = response.access_token;
        console.log('RefreshToken: ' + serverAuthCode);
        auth.serverAuthCode = serverAuthCode;
        auth.expires = Date.now() / 1000 + response.expires_in;
        auth.userId = userId;
        auth.email = email;
        auth.updated = true;
        return auth;
      }, (error) => {
        console.error('Error renewing refresh token: ' + JSON.stringify(error));
        return {};
      });
    return await renewalTokenRequestPromise;
}

private setData(key: string, value: any): Promise<any> {
    console.log('Store the value at key entry in the DDBB, Cookies, LocalStorage, etc')
}

private getData(key: string): Promise<string> {
    console.log('Retrieve the value from the key entry from DDBB, Cookies, LocalStorage, etc')
}

private clearStorage(): Promise<string> {
    console.log('Remove entries from DDBB, Cookies, LocalStorage, etc related to authentication')
}



}

This is an Authorization grant flow. To keep it simple that it follows.I request access token for web app. In my case the killing change was '%2F' to '/'. This should work

u need to decode your code like this

    String code = "4%2F0AX************...";
    String decodedCode = "";
    try {
      decodedCode = java.net.URLDecoder.decode(code, StandardCharsets.UTF_8.name());
    } catch (UnsupportedEncodingException e) {
      //do nothing
    }

then use decodedCode as param

This is an Authorization grant flow. To keep it simple following are steps that it follows.

1. First request gets authorizatio_code (This one with param authorization_code)
2. Once you receive the code use it to get access_token and refresh_token
3. After a while when access token is expired use the refresh_token from Step 2 to get new access token and new refresh token. (When you use the code from step 1 you will see the error.)

Hope this helps, please change your code and try again.

Your codes both have a "/" as their second character. You should probably url-encode it before you put it in a query string.

By adding URLDecode will work. But now it is not working anymore.

Must add prompt=consent then only return the refresh token when using authorization code to claim it.