dnsmasq fork with fast ipset/server/address lookup
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Latest commit 15e4c18 Aug 24, 2018

README.md

DNSMASQ fork for improving --ipsets, --server, and --address performance

Dnsmasq matches domain names for --ipsets, --server, and --address options by iterates over linked list. It is good enough for general use, but slows down as the domain names to be matched grows.

Here introduce a modified dnsmasq for fast lookup ipset/server/address options. The match time is constant regardless the size of rules.

                   root
                    |
         +---------------------+
        com                   org
         |                     |
+------------------+     +-------------+
yahoo google twitter   debian       freebsd
  |      |               |             |
 www    mail          +---------+     www
                      cn jp uk us
                      |
                     ftp

The lookup steps over domain name hierarchy top-down. All labels are stored in open addressing hash tables. Sub-level labels that belong to different parent nodes are stored separately. e.g. yahoo, google, and twitter are in one hash table, while debian and freebsd are in another.

The hash table size is power of 2, two hash functions are used to compute hash bucket. For locating a particular label from hash table, two hash values are compared first, only if they are match, should the more expensive string comparison be used to confirm the search.

Precompiled OpenWrt packages

For OpenWrt Chaos Calmer 15.05 on ar71xx and mt7620 platform. DNSSEC is disabled.

sha1sum
0a1a7c13714e982b2cf98b33fe16d572f3d1a58d dnsmasq-full_2.72-5_ar71xx_Chaos_Calmer_15.05.ipk
58b1b3e9447f55ae26dc6a5834cea826ae7a51c1 dnsmasq-full_2.72-5_ramips_24kec_Chaos_Calmer_15.05.ipk

md5sum
5aa14fc279f182820b8462a5f38ca0f4 dnsmasq-full_2.72-5_ar71xx_Chaos_Calmer_15.05.ipk
f4b5b8c71f05efbf1f5b98ba1abb7ed8 dnsmasq-full_2.72-5_ramips_24kec_Chaos_Calmer_15.05.ipk

Example usage

Use DNS blackhole to block malware site:

address=/example.com/

Force google DNS as upstream server for special domain:

server=/example.com/8.8.8.8

Add all IPs of a paticular domain to IPSET:

ipset=/example.com/example-ipset