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.
---
networking/nslookup.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/networking/nslookup.c b/networking/nslookup.c
index 6da97baf4216..61e3eb6052ab 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -978,6 +978,10 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
}
}
+ /* 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;
--
2.37.2
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