Properly forward status codes from streams

src/endpoints/novelai.js

@@ -1,9 +1,8 @@
 const fetch = require('node-fetch').default;
 const express = require('express');
 const util = require('util');
-const { Readable } = require('stream');
 const { readSecret, SECRET_KEYS } = require('./secrets');
-const { readAllChunks, extractFileFromZipBuffer } = require('../util');
+const { readAllChunks, extractFileFromZipBuffer, forwardFetchResponse } = require('../util');
 const { jsonParser } = require('../express-common');
 
 const API_NOVELAI = 'https://api.novelai.net';
@@ -188,17 +187,7 @@ router.post('/generate', jsonParser, async function (req, res) {
 
         if (req.body.streaming) {
             // Pipe remote SSE stream to Express response
-            response.body.pipe(res);
-
-            req.socket.on('close', function () {
-                if (response.body instanceof Readable) response.body.destroy(); // Close the remote stream
-                res.end(); // End the Express response
-            });
-
-            response.body.on('end', function () {
-                console.log('Streaming request finished');
-                res.end();
-            });
+            forwardFetchResponse(response, res);
         } else {
             if (!response.ok) {
                 const text = await response.text();

src/util.js

@@ -6,6 +6,7 @@ const yauzl = require('yauzl');
 const mime = require('mime-types');
 const yaml = require('yaml');
 const { default: simpleGit } = require('simple-git');
+const { Readable } = require('stream');
 
 const { DIRECTORIES } = require('./constants');
 
@@ -346,6 +347,27 @@ function getImages(path) {
         .sort(Intl.Collator().compare);
 }
 
+/**
+ * Pipe a fetch() response to an Express.js Response, including status code.
+ * @param {Response} from The Fetch API response to pipe from.
+ * @param {Express.Response} to The Express response to pipe to.
+ */
+function forwardFetchResponse(from, to) {
+    to.statusCode = from.status;
+    to.statusMessage = from.statusText;
+    from.body.pipe(to);
+
+    to.socket.on('close', function () {
+        if (from.body instanceof Readable) from.body.destroy(); // Close the remote stream
+        to.end(); // End the Express response
+    });
+
+    from.body.on('end', function () {
+        console.log('Streaming request finished');
+        to.end();
+    });
+}
+
 module.exports = {
     getConfig,
     getConfigValue,
@@ -365,4 +387,5 @@ module.exports = {
     generateTimestamp,
     removeOldBackups,
     getImages,
+    forwardFetchResponse,
 };