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55 lines
1.8 KiB
Diff
55 lines
1.8 KiB
Diff
From 4139298d287eb5c57f4aa53c459cb02fc5be2495 Mon Sep 17 00:00:00 2001
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From: Simon Kelley <simon@thekelleys.org.uk>
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Date: Wed, 19 Sep 2018 22:27:11 +0100
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Subject: [PATCH 2/2] Change behavior when RD bit unset in queries.
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Change anti cache-snooping behaviour with queries with the
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recursion-desired bit unset. Instead to returning SERVFAIL, we
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now always forward, and never answer from the cache. This
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allows "dig +trace" command to work.
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Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
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---
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CHANGELOG | 7 ++++++-
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src/rfc1035.c | 8 +++-----
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2 files changed, 9 insertions(+), 6 deletions(-)
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--- a/CHANGELOG
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+++ b/CHANGELOG
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@@ -59,7 +59,12 @@ version 2.80
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Returning null addresses is a useful technique for ad-blocking.
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Thanks to Peter Russell for the suggestion.
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-
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+ Change anti cache-snooping behaviour with queries with the
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+ recursion-desired bit unset. Instead to returning SERVFAIL, we
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+ now always forward, and never answer from the cache. This
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+ allows "dig +trace" command to work.
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+
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+
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version 2.79
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Fix parsing of CNAME arguments, which are confused by extra spaces.
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Thanks to Diego Aguirre for spotting the bug.
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--- a/src/rfc1035.c
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+++ b/src/rfc1035.c
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@@ -1293,16 +1293,14 @@ size_t answer_request(struct dns_header
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struct mx_srv_record *rec;
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size_t len;
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- if (ntohs(header->ancount) != 0 ||
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+ /* never answer queries with RD unset, to avoid cache snooping. */
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+ if (!(header->hb3 & HB3_RD) ||
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+ ntohs(header->ancount) != 0 ||
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ntohs(header->nscount) != 0 ||
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ntohs(header->qdcount) == 0 ||
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OPCODE(header) != QUERY )
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return 0;
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- /* always servfail queries with RD unset, to avoid cache snooping. */
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- if (!(header->hb3 & HB3_RD))
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- return setup_reply(header, qlen, NULL, F_SERVFAIL, 0);
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-
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/* Don't return AD set if checking disabled. */
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if (header->hb4 & HB4_CD)
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sec_data = 0;
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