To take a different approach I developed this patch in attachment that adds two new directives: block-file and allow-file. Summary of the functionality:
- Uses mmap() to load domain lists into RAM. - Multiple block-file directives are supported. - Multiple allow-file directives are supported. - Example syntax: block-file=/path/to/blockfile#NX,1NX is optional and can be replaced with any IP address to return instead of NX.
The trailing ,1 is optional too, and enables logging when domains from that file are matched (useful to log only blocked domains).
allow-file=/mnt/USB/blockfile-override,1- Mapped files must be pre-sorted (sorting is not included in this patch to keep the code minimal).
- Blocking/allowing behaviour mimics dnsmasq’s current semantics. For example:
dnsmasq config: local=/example.com/ (blocked) server=/www.example.com/ (unblocked) After the patch: example.com → listed in block-file www.example.com → listed in allow-file- Files are loaded one at a time and assesses against the amount of RAM available. If Current RAM usage + blockfile >= 80% of Total RAM, the loading is skipped and logged as a warning.
- This code does not change DNS resolution itself; it performs a very fast name match to decide whether a query should proceed or be answered with NX or a custom IP.
I developed this patch for FreshTomato router (dnsmasq v2.93rc1). On those small devices I performed a functional test loading 2.2M domains (55 MB blockfile) and reload the configuration without interruptions; no packet drops were observed during a config when reloading. This is already 3 time the current limit, but I haven't performed any proper capacity testing yet, which is expected to be much higher.
Any comments or considerations are greatly appreciated. Thanks.
<<attachment: dnsmasq-block-file.zip>>
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