oidc: use 'end_session_endpoint' from discovery, remove 'OIDC_LOGOUT_URL'

internal/api/v1/auth/oidc.go

@@ -4,31 +4,42 @@ import (
 	"context"
 	"crypto/rand"
 	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"mime"
 	"net/http"
 	"net/url"
 	"slices"
+	"strings"
 	"time"
 
 	"github.com/coreos/go-oidc/v3/oidc"
 	"github.com/yusing/go-proxy/internal/common"
 	"github.com/yusing/go-proxy/internal/net/gphttp"
-	CE "github.com/yusing/go-proxy/internal/utils"
+	"github.com/yusing/go-proxy/internal/utils"
 	"github.com/yusing/go-proxy/internal/utils/strutils"
 	"golang.org/x/oauth2"
 )
 
-type OIDCProvider struct {
+type (
+	OIDCProvider struct {
 		oauthConfig       *oauth2.Config
 		oidcProvider      *oidc.Provider
 		oidcVerifier      *oidc.IDTokenVerifier
-	oidcLogoutURL *url.URL
+		oidcEndSessionURL *url.URL
 		allowedUsers      []string
 		allowedGroups     []string
 		isMiddleware      bool
 	}
 
+	providerJSON struct {
+		oidc.ProviderConfig
+		EndSessionURL string `json:"end_session_endpoint"`
+	}
+)
+
 const CookieOauthState = "godoxy_oidc_state"
 
 const (
@@ -36,25 +47,50 @@ const (
 	OIDCLogoutPath             = "/auth/logout"
 )
 
-func NewOIDCProvider(issuerURL, clientID, clientSecret, redirectURL, logoutURL string, allowedUsers, allowedGroups []string) (*OIDCProvider, error) {
+func NewOIDCProvider(issuerURL, clientID, clientSecret, redirectURL string, allowedUsers, allowedGroups []string) (*OIDCProvider, error) {
 	if len(allowedUsers)+len(allowedGroups) == 0 {
 		return nil, errors.New("OIDC users, groups, or both must not be empty")
 	}
 
-	var logout *url.URL
-	var err error
-	if logoutURL != "" {
-		logout, err = url.Parse(logoutURL)
+	wellKnown := strings.TrimSuffix(issuerURL, "/") + "/.well-known/openid-configuration"
+	resp, err := gphttp.Get(wellKnown)
 	if err != nil {
-			return nil, fmt.Errorf("failed to parse logout URL: %w", err)
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: unable to read response body: %v", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("oidc: %s: %s", resp.Status, body)
+	}
+
+	var p providerJSON
+	err = json.Unmarshal(body, &p)
+	if err != nil {
+		mimeType, _, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
+		if err == nil && mimeType != "application/json" {
+			return nil, fmt.Errorf("oidc: unexpected content type: %q from OIDC provider discovery, have you configured the correct issuer URL?", mimeType)
+		}
+		return nil, fmt.Errorf("oidc: failed to decode provider discovery object: %v", err)
+	}
+
+	if p.IssuerURL != issuerURL {
+		return nil, fmt.Errorf("oidc: issuer did not match the issuer returned by provider, expected %q got %q", issuerURL, p.IssuerURL)
+	}
+
+	var endSessionURL *url.URL
+	if p.EndSessionURL != "" {
+		endSessionURL, err = url.Parse(p.EndSessionURL)
+		if err != nil {
+			return nil, fmt.Errorf("oidc: failed to parse end session URL: %w", err)
 		}
 	}
 
-	provider, err := oidc.NewProvider(context.Background(), issuerURL)
-	if err != nil {
-		return nil, fmt.Errorf("failed to initialize OIDC provider: %w", err)
-	}
-
+	provider := p.NewProvider(context.Background())
 	return &OIDCProvider{
 		oauthConfig: &oauth2.Config{
 			ClientID:     clientID,
@@ -67,7 +103,7 @@ func NewOIDCProvider(issuerURL, clientID, clientSecret, redirectURL, logoutURL s
 		oidcVerifier: provider.Verifier(&oidc.Config{
 			ClientID: clientID,
 		}),
-		oidcLogoutURL: logout,
+		oidcEndSessionURL: endSessionURL,
 		allowedUsers:      allowedUsers,
 		allowedGroups:     allowedGroups,
 	}, nil
@@ -80,7 +116,6 @@ func NewOIDCProviderFromEnv() (*OIDCProvider, error) {
 		common.OIDCClientID,
 		common.OIDCClientSecret,
 		common.OIDCRedirectURL,
-		common.OIDCLogoutURL,
 		common.OIDCAllowedUsers,
 		common.OIDCAllowedGroups,
 	)
@@ -130,7 +165,7 @@ func (auth *OIDCProvider) CheckToken(r *http.Request) error {
 
 	// Logical AND between allowed users and groups.
 	allowedUser := slices.Contains(auth.allowedUsers, claims.Username)
-	allowedGroup := len(CE.Intersect(claims.Groups, auth.allowedGroups)) > 0
+	allowedGroup := len(utils.Intersect(claims.Groups, auth.allowedGroups)) > 0
 	if !allowedUser && !allowedGroup {
 		return ErrUserNotAllowed
 	}
@@ -235,7 +270,7 @@ func (auth *OIDCProvider) LoginCallbackHandler(w http.ResponseWriter, r *http.Re
 }
 
 func (auth *OIDCProvider) LogoutCallbackHandler(w http.ResponseWriter, r *http.Request) {
-	if auth.oidcLogoutURL == nil {
+	if auth.oidcEndSessionURL == nil {
 		DefaultLogoutCallbackHandler(auth, w, r)
 		return
 	}
@@ -247,7 +282,7 @@ func (auth *OIDCProvider) LogoutCallbackHandler(w http.ResponseWriter, r *http.R
 	}
 	clearTokenCookie(w, r, auth.TokenCookieName())
 
-	logoutURL := *auth.oidcLogoutURL
+	logoutURL := *auth.oidcEndSessionURL
 	logoutURL.Query().Add("id_token_hint", token.Value)
 
 	http.Redirect(w, r, logoutURL.String(), http.StatusFound)

internal/common/env.go

@@ -46,7 +46,6 @@ var (
 
 	// OIDC Configuration.
 	OIDCIssuerURL     = GetEnvString("OIDC_ISSUER_URL", "")
-	OIDCLogoutURL     = GetEnvString("OIDC_LOGOUT_URL", "")
 	OIDCClientID      = GetEnvString("OIDC_CLIENT_ID", "")
 	OIDCClientSecret  = GetEnvString("OIDC_CLIENT_SECRET", "")
 	OIDCRedirectURL   = GetEnvString("OIDC_REDIRECT_URL", "")

internal/net/gphttp/middleware/oidc.go

@@ -80,11 +80,12 @@ func (amw *oidcMiddleware) before(w http.ResponseWriter, r *http.Request) (proce
 		return false
 	}
 
+	if r.URL.Path == auth.OIDCLogoutPath {
+		amw.auth.LogoutCallbackHandler(w, r)
+	}
 	if err := amw.auth.CheckToken(r); err != nil {
 		if errors.Is(err, auth.ErrMissingToken) {
 			amw.authMux.ServeHTTP(w, r)
-		} else if r.URL.Path == auth.OIDCLogoutPath {
-			amw.auth.LogoutCallbackHandler(w, r)
 		} else {
 			auth.WriteBlockPage(w, http.StatusForbidden, err.Error(), auth.OIDCLogoutPath)
 		}