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43 lines
1.4 KiB
Diff
43 lines
1.4 KiB
Diff
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From: Uwe Kleine-König <uwe@kleine-koenig.org>
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Date: Sat, 8 Oct 2022 19:22:52 +0200
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Subject: [PATCH] nslookup: ensure unique transaction IDs for the DNS queries
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The transaction IDs generated by res_mkquery() for both glibc and musl only
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depends on the state of the monotonic clock.
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For some machines (here: a TP-Link RE200 powered by a MediaTek MT7620A)
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the monotonic clock has a coarse resolution (here: 20 µs) and it can happen
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that the requests for A and AAAA share the same transaction ID.
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In that case the mapping from received responses to the sent queries
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doesn't work and name resolution fails as follows:
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# /bin/busybox nslookup heise.de
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Server: 127.0.0.1
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Address: 127.0.0.1:53
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Non-authoritative answer:
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Name: heise.de
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Address: 193.99.144.80
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*** Can't find heise.de: No answer
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because the AAAA reply is dropped as a duplicate reply to the A query.
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To prevent this make sure the transaction IDs are unique.
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Forwarded: http://lists.busybox.net/pipermail/busybox/2022-October/089911.html
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---
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--- a/networking/nslookup.c
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+++ b/networking/nslookup.c
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@@ -978,6 +978,10 @@ int nslookup_main(int argc UNUSED_PARAM,
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}
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}
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+ /* Ensure the Transaction IDs are unique */
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+ for (rc = 1; rc < G.query_count; rc++)
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+ G.query[rc].query[1] = G.query[rc - 1].query[1] + 1;
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+
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for (rc = 0; rc < G.serv_count;) {
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int c;
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