refactor(ouath): use oauth2 library to get token

api/oauth/oauth.go

@@ -1,12 +1,10 @@
 package oauth
 
 import (
+	"context"
 	"encoding/json"
-	"errors"
 	"fmt"
-	"io"
 	"io/ioutil"
-	"log"
 	"mime"
 	"net/http"
 	"net/url"
@@ -26,84 +24,9 @@ type Service struct{}
 
 // GetAccessToken takes an access code and exchanges it for an access token from portainer OAuthSettings token endpoint
 func (*Service) GetAccessToken(code string, settings *portainer.OAuthSettings) (string, error) {
-	v := url.Values{}
-	v.Set("client_id", settings.ClientID)
-	v.Set("client_secret", settings.ClientSecret)
-	v.Set("redirect_uri", settings.RedirectURI)
-	v.Set("code", code)
-	v.Set("grant_type", "authorization_code")
-
-	req, err := http.NewRequest("POST", settings.AccessTokenURI, strings.NewReader(v.Encode()))
-	if err != nil {
-		return "", err
-	}
-
-	client := &http.Client{}
-	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-	r, err := client.Do(req)
-	if err != nil {
-		return "", err
-	}
-
-	body, err := ioutil.ReadAll(io.LimitReader(r.Body, 1<<20))
-	if err != nil {
-		return "", fmt.Errorf("oauth2: cannot fetch token: %v", err)
-	}
-
-	if r.StatusCode != http.StatusOK {
-		type ErrorMessage struct {
-			Message string
-			Type    string
-			Code    int
-		}
-		type ErrorResponse struct {
-			Error ErrorMessage
-		}
-
-		var response ErrorResponse
-		if err = json.Unmarshal(body, &response); err != nil {
-			// report also error
-			log.Printf("[Error] - Failed parsing error body: %v", err)
-			return "", errors.New("oauth2: cannot fetch token")
-		}
-
-		return "", errors.New(response.Error.Message)
-	}
-
-	content, _, _ := mime.ParseMediaType(r.Header.Get("Content-Type"))
-	if content == "application/x-www-form-urlencoded" || content == "text/plain" {
-		values, err := url.ParseQuery(string(body))
-		if err != nil {
-			return "", err
-		}
-
-		token := values.Get("access_token")
-		log.Printf("[DEBUG] - returned body %v", values)
-
-		if token == "" {
-			log.Printf("[DEBUG] - access token returned empty - %v", values)
-			return "", errors.New("oauth2: cannot fetch token")
-		}
-
-		return token, nil
-	}
-
-	type tokenJSON struct {
-		AccessToken string `json:"access_token"`
-	}
-
-	var tj tokenJSON
-	if err = json.Unmarshal(body, &tj); err != nil {
-		return "", err
-	}
-
-	token := tj.AccessToken
-
-	if token == "" {
-		log.Printf("[DEBUG] - access token returned empty - %v with status code", string(body), r.StatusCode)
-		return "", errors.New("oauth2: cannot fetch token")
-	}
-	return token, nil
+	config := buildConfig(settings)
+	token, err := config.Exchange(context.Background(), code)
+	return token.AccessToken, err
 }
 
 // GetUsername takes a token and retrieves the portainer OAuthSettings user identifier from resource server.
@@ -167,19 +90,22 @@ func (*Service) GetUsername(token string, settings *portainer.OAuthSettings) (st
 }
 
 // BuildLoginURL creates a login url for the oauth provider
-func (*Service) BuildLoginURL(oauthSettings portainer.OAuthSettings) string {
+func (*Service) BuildLoginURL(oauthSettings *portainer.OAuthSettings) string {
+	oauthConfig := buildConfig(oauthSettings)
+	return oauthConfig.AuthCodeURL("portainer")
+}
+
+func buildConfig(oauthSettings *portainer.OAuthSettings) *oauth2.Config {
 	endpoint := oauth2.Endpoint{
 		AuthURL:  oauthSettings.AuthorizationURI,
 		TokenURL: oauthSettings.AccessTokenURI,
 	}
 
-	oauthConfig := &oauth2.Config{
+	return &oauth2.Config{
 		ClientID:     oauthSettings.ClientID,
 		ClientSecret: oauthSettings.ClientSecret,
 		Endpoint:     endpoint,
 		RedirectURL:  oauthSettings.RedirectURI,
 		Scopes:       strings.Split(oauthSettings.Scopes, ","),
 	}
-
-	return oauthConfig.AuthCodeURL("portainer")
 }