Enhance Next.js API endpoint handling for compatibility with both Pages and App Router structures.

javascript/ql/lib/semmle/javascript/frameworks/Next.qll

@@ -213,10 +213,12 @@ module NextJS {
   /**
    * Gets a folder that contains API endpoints for a Next.js application.
    * These API endpoints act as Express-like route-handlers.
+   * It matches both the Pages Router (`pages/api/`) Next.js 12 or earlier and
+   * the App Router (`app/api/`) Next.js 13+ structures.
    */
   Folder apiFolder() {
-    result = getANextPackage().getFile().getParentContainer().getFolder("pages").getFolder("api")
-    or
+    result =
+      getANextPackage().getFile().getParentContainer().getFolder(["pages", "app"]).getFolder("api") or
     result = apiFolder().getAFolder()
   }
 
@@ -271,4 +273,56 @@ module NextJS {
       override string getCredentialsKind() { result = "jwt key" }
     }
   }
+
+  /**
+   * A route handler for Next.js 13+ App Router API endpoints, which are defined by exporting
+   * HTTP method functions (like `GET`, `POST`, `PUT`, `DELETE`) from route.js files inside
+   * the `app/api/` directory.
+   */
+  class NextAppRouteHandler extends DataFlow::FunctionNode, Http::Servers::StandardRouteHandler {
+    NextAppRouteHandler() {
+      exists(Module mod | mod.getFile().getParentContainer() = apiFolder() |
+        this = mod.getAnExportedValue(any(Http::RequestMethodName m)).getAFunctionValue() and
+        (
+          this.getParameter(0).hasUnderlyingType("next/server", "NextRequest")
+          or
+          this.getParameter(0).hasUnderlyingType("Request")
+        )
+      )
+    }
+
+    /**
+     * Gets the request parameter, which is either a `NextRequest` object (from `next/server`) or a standard web `Request` object.
+     */
+    DataFlow::SourceNode getRequest() { result = this.getParameter(0) }
+  }
+
+  /**
+   * A source of user-controlled data from a `NextRequest` object (from `next/server`) or a standard web `Request` object
+   * in a Next.js App Router route handler.
+   */
+  class NextAppRequestSource extends Http::RequestInputAccess {
+    NextAppRouteHandler handler;
+    string kind;
+
+    NextAppRequestSource() {
+      (
+        this =
+          handler.getRequest().getAMethodCall(["json", "formData", "blob", "arrayBuffer", "text"])
+        or
+        this = handler.getRequest().getAPropertyRead("body")
+      ) and
+      kind = "body"
+      or
+      this = handler.getRequest().getAPropertyRead(["url", "nextUrl"]) and kind = "url"
+      or
+      this = handler.getRequest().getAPropertyRead("headers") and kind = "headers"
+    }
+
+    override string getKind() { result = kind }
+
+    override Http::RouteHandler getRouteHandler() { result = handler }
+
+    override string getSourceType() { result = "Next.js App Router request" }
+  }
 }