fix: handle CORS correctly for endpoints that SPAs need (#513)

backend/internal/controller/oidc_controller.go

@@ -129,9 +129,6 @@ func (oc *OidcController) authorizationConfirmationRequiredHandler(c *gin.Contex
 // @Success 200 {object} dto.OidcTokenResponseDto "Token response with access_token and optional id_token and refresh_token"
 // @Router /api/oidc/token [post]
 func (oc *OidcController) createTokensHandler(c *gin.Context) {
-	// Disable cors for this endpoint
-	c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
-
 	var input dto.OidcCreateTokensDto
 	if err := c.ShouldBind(&input); err != nil {
 		_ = c.Error(err)

backend/internal/middleware/cors.go

@@ -4,7 +4,6 @@ import (
 	"net/http"
 
 	"github.com/gin-gonic/gin"
-	"github.com/pocket-id/pocket-id/backend/internal/common"
 )
 
 type CorsMiddleware struct{}
@@ -15,17 +14,21 @@ func NewCorsMiddleware() *CorsMiddleware {
 
 func (m *CorsMiddleware) Add() gin.HandlerFunc {
 	return func(c *gin.Context) {
-		// Allow all origins for the token endpoint
-		switch c.FullPath() {
-		case "/api/oidc/token", "/api/oidc/introspect":
-			c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
-		default:
-			c.Writer.Header().Set("Access-Control-Allow-Origin", common.EnvConfig.AppURL)
+		path := c.FullPath()
+		if path == "" {
+			// The router doesn't map preflight requests, so we need to use the raw URL path
+			path = c.Request.URL.Path
 		}
 
-		c.Writer.Header().Set("Access-Control-Allow-Headers", "*")
-		c.Writer.Header().Set("Access-Control-Allow-Methods", "POST, OPTIONS, GET, PUT")
+		if !isCorsPath(path) {
+			c.Next()
+			return
+		}
 
+		c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
+		c.Writer.Header().Set("Access-Control-Allow-Methods", "GET, POST")
+
+		// Preflight request
 		if c.Request.Method == http.MethodOptions {
 			c.AbortWithStatus(204)
 			return
@@ -34,3 +37,17 @@ func (m *CorsMiddleware) Add() gin.HandlerFunc {
 		c.Next()
 	}
 }
+
+func isCorsPath(path string) bool {
+	switch path {
+	case "/api/oidc/token",
+		"/api/oidc/userinfo",
+		"/oidc/end-session",
+		"/api/oidc/introspect",
+		"/.well-known/jwks.json",
+		"/.well-known/openid-configuration":
+		return true
+	default:
+		return false
+	}
+}