fix: unclean crash on provider resolution failure

Apparently go doesn't support those

go.mod

@@ -1,6 +1,6 @@
 module github.com/janishutz/oidclogin
 
-go 1.27.1
+go 1.26.0
 
 require (
 	github.com/coreos/go-oidc/v3 v3.21.0

handlers.go

@@ -128,6 +128,15 @@ func logoutHandler(c *gin.Context) {
 	session := sessions.Default(c)
 	session.Clear()
 	session.Save()
+	redir := ""
+	if c.Query("returnTo") != "" {
+		redir = c.Query("returnTo")
+	}
+	if redir != "" {
+		c.Redirect(307, redir)
+	} else {
+		c.Redirect(307, defaultRedirect)
+	}
 }
 
 // Ensure that a user is currently logged in.

main.go

@@ -29,18 +29,26 @@ var (
 	defaultRedirect string
 )
 
-// Configure and set up the login SDK. The user_function is used to create or update a user
+// Wraps the normal configure function, but also gives you access to change the User Function, which is called upon login.
-func Configure(r *gin.Engine, app_url string, default_redirect string, user_function UserFunc, stubs_on_unconfigured bool) {
+// It is used to create or update a user.
+// The check middleware may be nil, in which case a default is used. Otherwise should be a valid gin middleware, calling c.Next() if okay to proceed.
+func ConfigureFull(r *gin.Engine, app_url string, default_redirect string, user_function UserFunc, stubs_on_unconfigured bool, check_middleware func(c *gin.Context)) {
+	userFunc = user_function
+	Configure(r, app_url, default_redirect, stubs_on_unconfigured, check_middleware)
+}
+
+// Configure and set up the login SDK
+// The check middleware may be nil, in which case a default is used. Otherwise should be a valid gin middleware, calling c.Next() if okay to proceed.
+func Configure(r *gin.Engine, app_url string, default_redirect string, stubs_on_unconfigured bool, check_middleware func(c *gin.Context)) {
 	issuer := os.Getenv("OIDC_ISSUER")
 	clientID := os.Getenv("OIDC_CLIENT_ID")
 	clientSecret := os.Getenv("OIDC_CLIENT_SECRET")
 	defaultRedirect = default_redirect
-	userFunc = user_function
 
 	if issuer == "" || clientID == "" || clientSecret == "" {
 		if stubs_on_unconfigured {
 			log.Println("[JHID] WARNING: OIDC not set up due to missing environment variables. Falling back to stubs")
-			startStubs(r)
+			startStubs(r, check_middleware)
 			return
 		} else {
 			log.Fatal("[JHID] One or more requried environment variables are missing. See docs for more information")
@@ -48,12 +56,12 @@ func Configure(r *gin.Engine, app_url string, default_redirect string, user_func
 	}
 
 	provider, err := oidc.NewProvider(context.Background(), issuer)
-	verifier = *provider.Verifier(&oidc.Config{ClientID: clientID})
-
 	if err != nil {
 		log.Fatal("[JHID] Provider resolution failed with error", err)
 	}
 
+	verifier = *provider.Verifier(&oidc.Config{ClientID: clientID})
+
 	config = oauth2.Config{
 		ClientID:     clientID,
 		ClientSecret: clientSecret,
@@ -64,12 +72,19 @@ func Configure(r *gin.Engine, app_url string, default_redirect string, user_func
 
 	r.GET("/auth/v2/login", loginHandler)
 	r.GET("/auth/v2/verify", callbackHandler)
-	r.GET("/auth/v2/check", EnsureLogin(false), func(ctx *gin.Context) { ctx.JSON(200, gin.H{"success": "true"}) })
+	if check_middleware == nil {
+		r.GET("/auth/v2/check", EnsureLogin(false), check_finalizer)
+	} else {
+		log.Println("[JHID] Custom check middleware enabled")
+		r.GET("/auth/v2/check", EnsureLogin(false), check_middleware, check_finalizer)
+	}
 	r.GET("/auth/v2/logout", logoutHandler)
 
 	log.Println("[JHID] Configured successfully")
 }
 
+func check_finalizer(ctx *gin.Context) { ctx.JSON(200, gin.H{"success": "true"}) }
+
 func ErrorHandler() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		c.Next()

stubs.go

@@ -7,10 +7,15 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-func startStubs(r *gin.Engine) {
+func startStubs(r *gin.Engine, check_middleware func(c *gin.Context)) {
 	r.GET("/auth/v2/login", stubsHandler)
 	r.GET("/auth/v2/verify", stubsHandler)
-	r.GET("/auth/v2/check", EnsureLogin(false), func(ctx *gin.Context) { ctx.JSON(200, gin.H{"success": "true"}) })
+	if check_middleware == nil {
+		r.GET("/auth/v2/check", EnsureLogin(false), check_finalizer)
+	} else {
+		log.Println("[JHID] Custom check middleware enabled")
+		r.GET("/auth/v2/check", EnsureLogin(false), check_middleware, check_finalizer)
+	}
 	r.GET("/auth/v2/logout", logoutHandler)
 }