fix(security): harden open proxy fallback against SSRF and key leak

app/api/proxy.ts

@@ -1,5 +1,72 @@
 import { NextRequest, NextResponse } from "next/server";
 import { getServerSideConfig } from "@/app/config/server";
+import { ModelProvider } from "@/app/constant";
+import { auth } from "./auth";
+
+function parseBaseUrl(raw: string | null): URL | null {
+  if (!raw) return null;
+  try {
+    const url = new URL(raw);
+    if (url.protocol !== "http:" && url.protocol !== "https:") {
+      return null;
+    }
+    return url;
+  } catch {
+    return null;
+  }
+}
+
+/** Block obvious SSRF targets (loopback / RFC1918 / link-local / CGNAT / metadata-ish). */
+function isBlockedHostname(hostname: string): boolean {
+  const host = hostname.toLowerCase().replace(/\.$/, "");
+
+  if (
+    host === "localhost" ||
+    host.endsWith(".localhost") ||
+    host === "0.0.0.0" ||
+    host === "::1" ||
+    host === "metadata.google.internal" ||
+    host.endsWith(".internal")
+  ) {
+    return true;
+  }
+
+  // IPv6 ULA / link-local
+  if (
+    host.startsWith("fe80:") ||
+    host.startsWith("fc") ||
+    host.startsWith("fd") ||
+    host.startsWith("[fe80:") ||
+    host.startsWith("[fc") ||
+    host.startsWith("[fd")
+  ) {
+    return true;
+  }
+
+  const m = host.match(/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/);
+  if (!m) return false;
+
+  const a = Number(m[1]);
+  const b = Number(m[2]);
+  const c = Number(m[3]);
+  const d = Number(m[4]);
+  if ([a, b, c, d].some((n) => n > 255)) return true;
+
+  if (a === 0 || a === 10 || a === 127) return true;
+  if (a === 169 && b === 254) return true; // link-local / cloud metadata
+  if (a === 172 && b >= 16 && b <= 31) return true;
+  if (a === 192 && b === 168) return true;
+  if (a === 100 && b >= 64 && b <= 127) return true; // CGNAT 100.64/10
+  if (a >= 224) return true; // multicast / reserved
+
+  return false;
+}
+
+/** Only inject the server OpenAI key for the real OpenAI API host (not substring matches). */
+function isOpenAIApiHost(hostname: string): boolean {
+  const host = hostname.toLowerCase().replace(/\.$/, "");
+  return host === "api.openai.com";
+}
 
 export async function handle(
   req: NextRequest,
@@ -10,16 +77,40 @@ export async function handle(
   if (req.method === "OPTIONS") {
     return NextResponse.json({ body: "OK" }, { status: 200 });
   }
+
+  // Match named provider handlers: do not leave the fallback proxy unauthenticated.
+  const authResult = auth(req, ModelProvider.GPT);
+  if (authResult.error) {
+    return NextResponse.json(authResult, {
+      status: 401,
+    });
+  }
+
   const serverConfig = getServerSideConfig();
 
   // remove path params from searchParams
   req.nextUrl.searchParams.delete("path");
   req.nextUrl.searchParams.delete("provider");
 
+  const baseUrl = parseBaseUrl(req.headers.get("x-base-url"));
+  if (!baseUrl) {
+    return NextResponse.json(
+      { error: true, msg: "invalid or missing x-base-url" },
+      { status: 400 },
+    );
+  }
+
+  if (isBlockedHostname(baseUrl.hostname)) {
+    return NextResponse.json(
+      { error: true, msg: "x-base-url target is not allowed" },
+      { status: 400 },
+    );
+  }
+
   const subpath = params.path.join("/");
-  const fetchUrl = `${req.headers.get(
-    "x-base-url",
-  )}/${subpath}?${req.nextUrl.searchParams.toString()}`;
+  const base = baseUrl.toString().replace(/\/$/, "");
+  const fetchUrl = `${base}/${subpath}?${req.nextUrl.searchParams.toString()}`;
+
   const skipHeaders = ["connection", "host", "origin", "referer", "cookie"];
   const headers = new Headers(
     Array.from(req.headers.entries()).filter((item) => {
@@ -33,17 +124,18 @@ export async function handle(
       return true;
     }),
   );
-  // if dalle3 use openai api key
-    const baseUrl = req.headers.get("x-base-url");
-    if (baseUrl?.includes("api.openai.com")) {
-      if (!serverConfig.apiKey) {
-        return NextResponse.json(
-          { error: "OpenAI API key not configured" },
-          { status: 500 },
-        );
-      }
-      headers.set("Authorization", `Bearer ${serverConfig.apiKey}`);
+
+  // Inject server OpenAI key only when the hostname is exactly api.openai.com.
+  // Substring checks (includes) allowed key exfiltration via attacker hosts.
+  if (isOpenAIApiHost(baseUrl.hostname)) {
+    if (!serverConfig.apiKey) {
+      return NextResponse.json(
+        { error: "OpenAI API key not configured" },
+        { status: 500 },
+      );
     }
+    headers.set("Authorization", `Bearer ${serverConfig.apiKey}`);
+  }
 
   const controller = new AbortController();
   const fetchOptions: RequestInit = {