After replying with stale data, dnsmasq sends the query upstream to
refresh the cache asynchronously and sometimes sends the wrong packet:
packet length can be wrong, and if an EDE marking stale data is added
to the answer that can end up in the query also. This bug only seems
to cause problems when the usptream server is a DOH/DOT proxy. Thanks
to Justin He for the bug report.
If there exists a --address=/<domain>/ or --server=/<domain>/#
configuration but no upstream server config unqualified by
domain then when a query which doesnt match the domain is
recieved it will use the qualfied server config and in the process
possibly make an out-of-bounds memory access.
Thanks to Daniel Danzberger for spotting the bug.
If there are multiple cache records with the same name but different
F_REVERSE and/or F_IMMORTAL flags, the code added in fe9a134b could
concievable break the REVERSE-FORWARD-IMMORTAL order invariant.
Reproducing this is damn near impossible, but it is responsible
for rare and otherwise inexplicable reversion between 2.87 and 2.88
which manifests itself as a cache internal error. All observed
cases have depended on DNSSEC being enabled, but the bug could in
theory manifest itself without DNSSEC
Thanks to Timo van Roermund for reporting the bug and huge
efforts to isolate it.
When re-reading upstream servers from /etc/resolv.conf or other
sources that can change dnsmasq tries to avoid memory fragmentation by
re-using existing records that are being re-read unchanged. This
involves seaching all the server records for each new one installed.
During startup this search is pointless, and can cause long start
times with thousands of --server options because the work needed is
O(n^2). Handle this case more intelligently. Thanks to Ye Zhou for
spotting the problem and an initial patch.
A bug, introduced in 2.87, which could result in DNS
servers being removed from the configuration when reloading
server configuration from DBus, or re-reading /etc/resolv.conf
Only servers from the same source should be replaced, but some
servers from other sources (ie hard coded or another dynamic source)
could mysteriously disappear.
This gives dnsmasq the ability to originate retries for upstream DNS
queries itself, rather than relying on the downstream client. This is
most useful when doing DNSSEC over unreliable upstream network. It
comes with some cost in memory usage and network bandwidth.
Tweak things so that packets relayed towards a server
have source address on the server-facing network, not the
client-facing network. Thanks to Luis Thomas for spotting this
and initial patch.
forwarded queries to the configured or default value of
edns-packet-max. There's no point letting a client set a larger
value if we're unable to return the answer.
This change also removes a previous bug
where --dhcp-alternate-port would affect the port used
to relay _to_ as well as the port being listened on.
The new feature allows configuration to provide bug-for-bug
compatibility, if required. Thanks to Damian Kaczkowski
for the feature suggestion.
This allows hosts get a domain which relects the interface they
are attached to in a way which doesn't require hard-coding addresses.
Thanks to Sten Spans for the idea.
To be treated as hex, the pattern must consist of only hex digits AND
contain at least one ':'. Thanks to Bengt-Erik Sandstrom who tripped
over a pattern consisting of a decimal number which was interpreted
surprisingly.
The sharing point for DNSSEC RR data used to be when it entered the
cache, having been validated. After that queries requiring the KEY or
DS records would share the cached values. There is a common case in
dual-stack hosts that queries for A and AAAA records for the same
domain are made simultaneously. If required keys were not in the
cache, this would result in two requests being sent upstream for the
same key data (and all the subsequent chain-of-trust queries.) Now we
combine these requests and elide the duplicates, resulting in fewer
queries upstream and better performance. To keep a better handle on
what's going on, the "extra" logging mode has been modified to
associate queries and answers for DNSSEC queries in the same way as
ordinary queries. The requesting address and port have been removed
from DNSSEC logging lines, since this is no longer strictly defined.
This used to have a global limit, but that has a problem when using
different servers for different upstream domains. Queries which are
routed by domain to an upstream server which is not responding will
build up and trigger the limit, which breaks DNS service for all other
domains which could be handled by other servers. The change is to make
the limit per server-group, where a server group is the set of servers
configured for a particular domain. In the common case, where only
default servers are declared, there is no effective change.
This should be largely transparent, but it drastically
improves performance and reduces memory foot-print when
configuring large numbers domains of the form
local=/adserver.com/
or
local=/adserver.com/#
Lookup times now grow as log-to-base-2 of the number of domains,
rather than greater than linearly, as before.
The change makes multiple addresses associated with a domain work
address=/example.com/1.2.3.4
address=/example.com/5.6.7.8
It also handles multiple upstream servers for a domain better; using
the same try/retry alogrithms as non domain-specific servers. This
also applies to DNSSEC-generated queries.
Finally, some of the oldest and gnarliest code in dnsmasq has had
a significant clean-up. It's far from perfect, but it _is_ better.
