2022-10-14 10:23:07 +00:00
|
|
|
From: Uwe Kleine-König <uwe@kleine-koenig.org>
|
|
|
|
Date: Sat, 8 Oct 2022 19:22:52 +0200
|
|
|
|
Subject: [PATCH] nslookup: ensure unique transaction IDs for the DNS queries
|
|
|
|
|
|
|
|
The transaction IDs generated by res_mkquery() for both glibc and musl only
|
|
|
|
depends on the state of the monotonic clock.
|
|
|
|
For some machines (here: a TP-Link RE200 powered by a MediaTek MT7620A)
|
|
|
|
the monotonic clock has a coarse resolution (here: 20 µs) and it can happen
|
|
|
|
that the requests for A and AAAA share the same transaction ID.
|
|
|
|
|
|
|
|
In that case the mapping from received responses to the sent queries
|
|
|
|
doesn't work and name resolution fails as follows:
|
|
|
|
|
|
|
|
# /bin/busybox nslookup heise.de
|
|
|
|
Server: 127.0.0.1
|
|
|
|
Address: 127.0.0.1:53
|
|
|
|
|
|
|
|
Non-authoritative answer:
|
|
|
|
Name: heise.de
|
|
|
|
Address: 193.99.144.80
|
|
|
|
|
|
|
|
*** Can't find heise.de: No answer
|
|
|
|
|
|
|
|
because the AAAA reply is dropped as a duplicate reply to the A query.
|
|
|
|
|
|
|
|
To prevent this make sure the transaction IDs are unique.
|
|
|
|
|
|
|
|
Forwarded: http://lists.busybox.net/pipermail/busybox/2022-October/089911.html
|
|
|
|
---
|
|
|
|
--- a/networking/nslookup.c
|
|
|
|
+++ b/networking/nslookup.c
|
2024-11-28 18:41:37 +00:00
|
|
|
@@ -1370,6 +1370,10 @@ int nslookup_main(int argc UNUSED_PARAM,
|
2022-10-14 10:23:07 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
+ /* Ensure the Transaction IDs are unique */
|
|
|
|
+ for (rc = 1; rc < G.query_count; rc++)
|
|
|
|
+ G.query[rc].query[1] = G.query[rc - 1].query[1] + 1;
|
|
|
|
+
|
|
|
|
for (rc = 0; rc < G.serv_count;) {
|
|
|
|
int c;
|
|
|
|
|