feat: enhance error handling in batch processing & fix ip leaking

apps_script/Code.gs

@@ -1,10 +1,5 @@
 /**
- * DomainFront Relay — Google Apps Script
- *
- * TWO modes:
- *   1. Single:  POST { k, m, u, h, b, ct, r }       → { s, h, b }
- *   2. Batch:   POST { k, q: [{m,u,h,b,ct,r}, ...] } → { q: [{s,h,b}, ...] }
- *      Uses UrlFetchApp.fetchAll() — all URLs fetched IN PARALLEL.
+ * MasterHttpRelay — Google Apps Script
  * 
  * DEPLOYMENT:
  *   1. Go to https://script.google.com → New project
@@ -20,12 +15,20 @@ const AUTH_KEY = "CHANGE_ME_TO_A_STRONG_SECRET";
 
 // Keep browser capability headers (sec-ch-ua*, sec-fetch-*) intact.
 // Some modern apps, notably Google Meet, use them for browser gating.
+// Headers that reveal the user's real IP are also stripped here as a
+// second line of defence (the Python client strips them first).
 const SKIP_HEADERS = {
   host: 1, connection: 1, "content-length": 1,
   "transfer-encoding": 1, "proxy-connection": 1, "proxy-authorization": 1,
   "priority": 1, te: 1,
+  // IP-leaking / proxy-metadata headers
+  "x-forwarded-for": 1, "x-forwarded-host": 1, "x-forwarded-proto": 1,
+  "x-forwarded-port": 1, "x-real-ip": 1, "forwarded": 1, "via": 1,
 };
 
+// If fetchAll fails, only retry methods that are safe to replay.
+const SAFE_REPLAY_METHODS = { GET: 1, HEAD: 1, OPTIONS: 1 };
+
 function doPost(e) {
   try {
     var req = JSON.parse(e.postData.contents);
@@ -56,37 +59,80 @@ function _doSingle(req) {
 
 function _doBatch(items) {
   var fetchArgs = [];
+  var fetchIndex = [];
+  var fetchMethods = [];
   var errorMap = {};
 
   for (var i = 0; i < items.length; i++) {
     var item = items[i];
+    if (!item || typeof item !== "object") {
+      errorMap[i] = "bad item";
+      continue;
+    }
     if (!item.u || typeof item.u !== "string" || !item.u.match(/^https?:\/\//i)) {
       errorMap[i] = "bad url";
       continue;
     }
-    var opts = _buildOpts(item);
-    opts.url = item.u;
-    fetchArgs.push({ _i: i, _o: opts });
+    try {
+      var opts = _buildOpts(item);
+      opts.url = item.u;
+      fetchArgs.push(opts);
+      fetchIndex.push(i);
+      fetchMethods.push(String(item.m || "GET").toUpperCase());
+    } catch (err) {
+      errorMap[i] = String(err);
+    }
   }
 
   // fetchAll() processes all requests in parallel inside Google
   var responses = [];
   if (fetchArgs.length > 0) {
-    responses = UrlFetchApp.fetchAll(fetchArgs.map(function(x) { return x._o; }));
+    try {
+      responses = UrlFetchApp.fetchAll(fetchArgs);
+    } catch (err) {
+      // If fetchAll fails as a whole, degrade to per-item fetch so one bad
+      // request does not poison the full batch.
+      responses = [];
+      for (var j = 0; j < fetchArgs.length; j++) {
+        try {
+          if (!SAFE_REPLAY_METHODS[fetchMethods[j]]) {
+            errorMap[fetchIndex[j]] = "batch fetchAll failed; unsafe method not replayed";
+            responses[j] = null;
+            continue;
+          }
+          var fallbackReq = fetchArgs[j];
+          var fallbackUrl = fallbackReq.url;
+          var fallbackOpts = {};
+          for (var key in fallbackReq) {
+            if (Object.prototype.hasOwnProperty.call(fallbackReq, key) && key !== "url") {
+              fallbackOpts[key] = fallbackReq[key];
+            }
+          }
+          responses[j] = UrlFetchApp.fetch(fallbackUrl, fallbackOpts);
+        } catch (singleErr) {
+          errorMap[fetchIndex[j]] = String(singleErr);
+          responses[j] = null;
+        }
+      }
+    }
   }
 
   var results = [];
   var rIdx = 0;
   for (var i = 0; i < items.length; i++) {
-    if (errorMap.hasOwnProperty(i)) {
+    if (Object.prototype.hasOwnProperty.call(errorMap, i)) {
       results.push({ e: errorMap[i] });
     } else {
       var resp = responses[rIdx++];
-      results.push({
-        s: resp.getResponseCode(),
-        h: _respHeaders(resp),
-        b: Utilities.base64Encode(resp.getContent()),
-      });
+      if (!resp) {
+        results.push({ e: "fetch failed" });
+      } else {
+        results.push({
+          s: resp.getResponseCode(),
+          h: _respHeaders(resp),
+          b: Utilities.base64Encode(resp.getContent()),
+        });
+      }
     }
   }
   return _json({ q: results });