openwrt/package/network/services/dnsmasq/patches/0009-Revert-68f6312d4bae30b78daafcd6f51dc441b8685b1e.patch
Kevin Darbyshire-Bryant 7541d30c9c dnsmasq: backport latest pre2.81 patches
f52bb5b fix previous commit
18eac67 Fix entries in /etc/hosts disabling static leases.
f8c77ed Fix removal of DHCP_CLIENT_MAC options from DHCPv6 relay replies.
4bf62f6 Tidy cache_blockdata_free()
9c0d445 Fix e7bfd556c079c8b5e7425aed44abc35925b24043 to actually work.
2896e24 Check for not(DS or DNSKEY) in is_outdated_cname_pointer()
a90f09d Fix crash freeing negative SRV cache entries.
5b99eae Cache SRV records.
2daca52 Fix typo in ra-param man page section.
2c59473 File logic bug in cache-marshalling code. Introduced a couple of commits back.
cc921df Remove nested struct/union in cache records and all_addr.
ab194ed Futher address union tidying.
65a01b7 Tidy address-union handling: move class into explicit argument.
bde4647 Tidy all_addr union, merge log and rcode fields.
e7bfd55 Alter DHCP address selection after DECLINE in consec-addr mode. Avoid offering the same address after a recieving a DECLINE message to stop an infinite protocol loop. This has long been done in default address allocation mode: this adds similar behaviour when allocaing addresses consecutively.

The most relevant fix for openwrt is 18eac67 (& my own local f52bb5b
which fixes a missing bracket silly) To quote the patch:

It is possible for a config entry to have one address family specified by a
dhcp-host directive and the other added from /etc/hosts. This is especially
common on OpenWrt because it uses odhcpd for DHCPv6 and IPv6 leases are
imported into dnsmasq via a hosts file.

To handle this case there need to be separate *_HOSTS flags for IPv4 and IPv6.
Otherwise when the hosts file is reloaded it will clear the CONFIG_ADDR(6) flag
which was set by the dhcp-host directive.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
2019-01-16 15:39:54 +00:00

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Diff

From 122392e0b352507cabb9e982208d35d2e56902e0 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Wed, 31 Oct 2018 22:24:02 +0000
Subject: [PATCH 09/30] Revert 68f6312d4bae30b78daafcd6f51dc441b8685b1e
The above is intended to increase robustness, but actually does the
opposite. The problem is that by ignoring SERVFAIL messages and hoping
for a better answer from another of the servers we've forwarded to,
we become vulnerable in the case that one or more of the configured
servers is down or not responding.
Consider the case that a domain is indeed BOGUS, and we've send the
query to n servers. With 68f6312d4bae30b78daafcd6f51dc441b8685b1e
we ignore the first n-1 SERVFAIL replies, and only return the
final n'th answer to the client. Now, if one of the servers we are
forwarding to is down, then we won't get all n replies, and the
client will never get an answer! This is a far more likely scenario
than a temporary SERVFAIL from only one of a set of notionally identical
servers, so, on the ground of robustness, we have to believe
any SERVFAIL answers we get, and return them to the client.
The client could be using the same recursive servers we are,
so it should, in theory, retry on SERVFAIL anyway.
Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
---
src/forward.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/src/forward.c
+++ b/src/forward.c
@@ -957,8 +957,7 @@ void reply_query(int fd, int family, tim
we get a good reply from another server. Kill it when we've
had replies from all to avoid filling the forwarding table when
everything is broken */
- if (forward->forwardall == 0 || --forward->forwardall == 1 ||
- (RCODE(header) != REFUSED && RCODE(header) != SERVFAIL))
+ if (forward->forwardall == 0 || --forward->forwardall == 1 || RCODE(header) != REFUSED)
{
int check_rebind = 0, no_cache_dnssec = 0, cache_secure = 0, bogusanswer = 0;