dns: fix TTL value for AAAA replies to `resolveAny()`

We were previously reading from the wrong offset, namely
the one into the final results array, not the one for the
AAAA results itself, which could have lead to reading
uninitialized or out-of-bounds data.

Also, adjust the test accordingly; TTL values are not
modified by c-ares, but are only exposed for a subset
of all DNS record types.

PR-URL: https://github.com/nodejs/node/pull/25187
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

2 files changed, 12 insertions, 5 deletions

diff --git a/src/cares_wrap.cc b/src/cares_wrap.cc
index a3bcdf8953..9d7af47dcd 100644
--- a/src/cares_wrap.cc
+++ b/src/cares_wrap.cc
@@ -1265,6 +1265,7 @@ class QueryAnyWrap: public QueryWrap {
     }
 
     CHECK_EQ(aaaa_count, naddr6ttls);
+    CHECK_EQ(ret->Length(), a_count + aaaa_count);
     for (uint32_t i = a_count; i < ret->Length(); i++) {
       Local<Object> obj = Object::New(env()->isolate());
       obj->Set(context,
@@ -1272,7 +1273,8 @@ class QueryAnyWrap: public QueryWrap {
                ret->Get(context, i).ToLocalChecked()).FromJust();
       obj->Set(context,
                env()->ttl_string(),
-               Integer::New(env()->isolate(), addr6ttls[i].ttl)).FromJust();
+               Integer::New(env()->isolate(), addr6ttls[i - a_count].ttl))
+          .FromJust();
       obj->Set(context,
                env()->type_string(),
                env()->dns_aaaa_string()).FromJust();
diff --git a/test/parallel/test-dns-resolveany.js b/test/parallel/test-dns-resolveany.js
index 46694f2403..bb15b1a38b 100644
--- a/test/parallel/test-dns-resolveany.js
+++ b/test/parallel/test-dns-resolveany.js
@@ -53,8 +53,13 @@ server.bind(0, common.mustCall(async () => {
 }));
 
 function validateResults(res) {
-  // Compare copies with ttl removed, c-ares fiddles with that value.
-  assert.deepStrictEqual(
-    res.map((r) => Object.assign({}, r, { ttl: null })),
-    answers.map((r) => Object.assign({}, r, { ttl: null })));
+  // TTL values are only provided for A and AAAA entries.
+  assert.deepStrictEqual(res.map(maybeRedactTTL), answers.map(maybeRedactTTL));
+}
+
+function maybeRedactTTL(r) {
+  const ret = { ...r };
+  if (!['A', 'AAAA'].includes(r.type))
+    delete ret.ttl;
+  return ret;
 }