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40 lines
2.0 KiB
Markdown
Executable File
40 lines
2.0 KiB
Markdown
Executable File
# Anti-censorship Solution for Russia on PAC-Script
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## Censorship in Russia
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Censorship in Russia plagues the Freedoms of
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[Information](https://en.wikipedia.org/wiki/Freedom_of_information) and [Speech](https://en.wikipedia.org/wiki/Freedom_of_speech),
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slowly building analogue of [China Golden Shield](https://en.wikipedia.org/wiki/Golden_Shield_Project).
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For good or bad, it blocks
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[Main Kampf](https://en.wikipedia.org/wiki/Mein_Kampf),
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[lolicon](https://en.wikipedia.org/wiki/Lolicon) (rearly distinguishing from hentai) and
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[critics of Putin](http://www.reuters.com/article/2014/03/13/us-russia-internet-idUSBREA2C21L20140313).
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Looking at how Russian government [distorts TV](https://therussianreader.wordpress.com/2015/11/22/russian-truckers-strike-dagestan/) and blocks Internet, I decided to write an Anti-Censorship extension for Chomium.
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I believe the freedom of information is a virtue and important __information mustn't be blocked based on political or other subjective views__.
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## Technical Titbits
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```javascript
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if (Is_subdomain_of( host, blocked_hosts ))
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return 'use proxy';
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```
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You have to make `Is_subdomain_of` very fast.
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This check is executed on each request. You should watch memeory consumption too.
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The naive solution is to keep array of blocked ips and check if the host resolves to one of the ips.
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You may do it with `indexOf`, binary search, etc.
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The shortcoming of every ip solution is that some providers resolve blocked hosts to wrong ips, so we eventually need list of hosts.
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I have tested different solutions, and depicted [results](./benchmark/Output.txt) in the following chart:
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![Host Lookup Chart: Time-Memory, Hits-Misses](./chart/host-lookup-chart.png)
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* __IPs indexOf__ – Blocked IP is search by `indexOf`
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* __IPs binary__ – Blocked IP is search by binary search. For some reason miss time slightly increased.
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* __IPs switch__ – Simply `switch(Blocked_IP) { case1: ... caseN: return true }`. Works even better than binary search. Magic.
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* __Hosts switch__ – Radix trie built on `switch`. Comparable to __IPs switch__.
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