dns: use length for building TXT string

Rely on the length reported by C-Ares rather than `\0`-termination
for creating the JS string for a dns TXT response.
Fixes: #30688
PR-URL: #30690
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: addaleax

src/cares_wrap.cc

@@ -906,7 +906,8 @@ int ParseTxtReply(Environment* env,
 uint32_t i = 0, j;
 uint32_t offset = ret->Length();
 for (j = 0; current != nullptr; current = current->next) {
- Local<String> txt = OneByteString(env->isolate(), current->txt);
+ Local<String> txt =
+OneByteString(env->isolate(), current->txt, current->length);
 
 // New record found - write out the current chunk
 if (current->record_start) {

test/parallel/test-dns-resolveany.js

@@ -11,7 +11,7 @@ const answers = [
 {type: 'AAAA',address: '::42',ttl: 123},
 {type: 'MX',priority: 42,exchange: 'foobar.com',ttl: 124},
 {type: 'NS',value: 'foobar.org',ttl: 457},
-{type: 'TXT',entries: ['v=spf1 ~all','xyz']},
+{type: 'TXT',entries: ['v=spf1 ~all','xyz\0foo']},
 {type: 'PTR',value: 'baz.org',ttl: 987},
 {
 type: 'SOA',