Hostlist compiler

This is a simple tool that makes it easier to compile a hosts blocklist compatible with AdGuard Home or any other AdGuard product with DNS filtering.

• Usage
  • Configuration
  • Command-line
  • API
• Transformations
  • RemoveComments
  • Compress
  • RemoveModifiers
  • Validate
  • Deduplicate
  • InvertAllow
  • RemoveEmptyLines
  • TrimLines
  • InsertFinalNewLine
• How to build

Usage

First of all, install the hostlist-compiler:

npm i -g @adguard/hostlist-compiler

Prepare the list configuration (read more about that below) and run the compiler:

hostlist-compiler -c configuration.json -o output.txt

Configuration

Configuration defines your filter list sources, and the transformations that are applied to the sources.

Here is an example of this configuration:

{
  "name": "List name",
  "description": "List description",
  "homepage": "https://example.org/",
  "license": "GPLv3",
  "sources": [
    {
      "name": "Local rules",
      "source": "rules.txt",
      "type": "adblock",
      "transformations": ["RemoveComments", "Compress"],
      "exclusions": ["excluded rule 1"],
      "exclusions_sources": ["exclusions.txt"],
      "inclusions": ["*"],
      "inclusions_sources": ["inclusions.txt"]
    },
    {
      "name": "Remote rules",
      "source": "https://example.org/rules",
      "type": "hosts",
      "exclusions": ["excluded rule 1"]
    }
  ],
  "transformations": ["Deduplicate", "Compress"],
  "exclusions": ["excluded rule 1", "excluded rule 2"],
  "exclusions_sources": ["global_exclusions.txt"],
  "inclusions": ["*"],
  "inclusions_sources": ["global_inclusions.txt"]
}

• name - (mandatory) the list name.
• description - (optional) the list description.
• homepage - (optional) URL to the list homepage.
• license - (optional) Filter list license.
• sources - (mandatory) array of the list sources.
  • .source - (mandatory) path or URL of the source. It can be a traditional filter list or a hosts file.
  • .name - (optional) name of the source.
  • .type - (optional) type of the source. It could be adblock for Adblock-style lists or hosts for /etc/hosts style lists. If not specified, adblock is assumed.
  • .transformations - (optional) a list of transformations to apply to the source rules. By default, no transformations are applied. Learn more about possible transformations here.
  • .exclusions - (optional) a list of rules (or wildcards) to exclude from the source.
  • .exclusions_sources - (optional) a list of files with exclusions.
  • .inclusions - (optional) a list of wildcards to include from the source. All rules that don't match these wildcards won't be included.
  • .inclusions_sources - (optional) a list of files with inclusions.
• transformations - (optional) a list of transformations to apply to the final list of rules. By default, no transformations are applied. Learn more about possible transformations here.
• exclusions - (optional) a list of rules (or wildcards) to exclude from the source.
• exclusions_sources - (optional) a list of files with exclusions.
• .inclusions - (optional) a list of wildcards to include from the source. All rules that don't match these wildcards won't be included.
• .inclusions_sources - (optional) a list of files with inclusions.

Here is an example of a minimal configuration:

{
  "name": "test list",
  "sources": [
    {
      "source": "rules.txt"
    }
  ]
}

Exclusion and inclusion rules

Please note, that exclusion or inclusion rules may be a plain string, wildcard, or a regular expression.

• plainstring - every rule that contains plainstring will match the rule
• *.plainstring - every rule that matches this wildcard will match the rule
• /regex/ - every rule that matches this regular expression, will match the rule. By default, regular expressions are case-insensitive.
• ! comment - comments will be ignored.

Command-line

Command-line arguments.

Usage: hostlist-compiler [options]

Options:
  --version      Show version number                                   [boolean]
  --config, -c   Path to the compiler configuration file     [string] [required]
  --output, -o   Path to the output file                     [string] [required]
  --verbose, -v  Run with verbose logging                              [boolean]
  -h, --help     Show help                                             [boolean]

Examples:
  hostlist-compiler -c config.json -o       compile a blocklist and write the
  output.txt                                output to output.txt

API

Install: npm i @adguard/hostlist-compiler or yarn add @adguard/hostlist-compiler

JavaScript example:

const compile = require("@adguard/hostlist-compiler");

;(async () => {
    // Compile filters
    const result = await compile({
        name: 'Your Hostlist',
        sources: [
            {
                type: 'adblock',
                source: 'https://adguardteam.github.io/AdGuardSDNSFilter/Filters/filter.txt', // or local file
                transformations: ['RemoveComments', 'Validate'],
            },
        ],
        transformations: ['Deduplicate'],
    });
    
    // Write to file
    writeFileSync('your-hostlist.txt', result.join('\n'));
})();

TypeScript example:

import compile from '@adguard/hostlist-compiler';
import { writeFileSync } from 'fs';

;(async () => {
    // Compile filters
    const result = await compile({
        name: 'Your Hostlist',
        sources: [
            {
                type: 'adblock',
                source: 'https://adguardteam.github.io/AdGuardSDNSFilter/Filters/filter.txt',
                transformations: ['RemoveComments', 'Validate'],
            },
        ],
        transformations: ['Deduplicate'],
    });

    // Write to file
    writeFileSync('your-hostlist.txt', result.join('\n'));
})();

or:

import HostlistCompiler, { IConfiguration as HostlistCompilerConfiguration } from '@adguard/hostlist-compiler';
import { writeFileSync } from 'fs';

;(async () => {
    // Configuration
    const config: HostlistCompilerConfiguration = {
        name: 'Your Hostlist',
        sources: [
            {
                type: 'adblock',
                source: 'https://adguardteam.github.io/AdGuardSDNSFilter/Filters/filter.txt',
                transformations: ['RemoveComments', 'Validate'],
            },
        ],
        transformations: ['Deduplicate'],
    };

    // Compile filters
    const result = await HostlistCompiler(config);

    // Write to file
    writeFileSync('your-hostlist.txt', result.join('\n'));
})();

Transformations

Here is the full list of transformations that are available:

1. RemoveComments
2. Compress
3. RemoveModifiers
4. Validate
5. Deduplicate
6. InvertAllow
7. RemoveEmptyLines
8. TrimLines
9. InsertFinalNewLine

Please note that these transformations are are always applied in the order specified here.

RemoveComments

This is a very simple transformation that simply removes comments (e.g. all rules starting with ! or #).

Compress

IMPORTANT: this transformation converts hosts lists into adblock lists.

Here's what it does:

1. It converts all rules to adblock-style rules. For instance, 0.0.0.0 example.org will be converted to ||example.org^.
2. It discards the rules that are now redundant because of other existing rules. For instance, ||example.org blocks example.org and all it's subdomains, therefore additional rules for the subdomains are now redundant.

RemoveModifiers

By default, AdGuard Home will ignore rules with unsupported modifiers, and all of the modifiers listed here are unsupported. However, the rules with these modifiers are likely to be okay for DNS-level blocking, that's why you might want to remove them when importing rules from a traditional filter list.

Here is the list of modifiers that will be removed:

• $third-party and $3p modifiers
• $document and $doc modifiers
• $all modifier
• $popup modifier

IMPORTANT: please, be cautious with this. Blindly removing $third-party from traditional ad blocking rules leads to lots of false-positives. This is exactly why there is an option to exclude rules - you may need to use it.

Validate

This transformation is really crucial if you're using a filter list for a traditional ad blocker as a source.

It removes dangerous or incompatible rules from the list.

So here's what it does:

• Discards domain-specific rules (e.g. ||example.org^$domain=example.com). You don't want to have domain-specific rules working globally.
• Discards rules with unsupported modifiers. Click here to learn more about which modifiers are supported.
• Discards rules that are too short.

If there are comments preceding the invalid rule, they will be removed as well.

Deduplicate

This transformation simply removes the duplicates from the specified source.

There are two important notes about this transformation:

1. It keeps the original rules order.
2. It ignores comments. However, if the comments precede the rule that is being removed, the comments will be also removed.

For instance:

! rule1 comment 1
rule1
! rule1 comment 2
rule1

Here's what will be left after the transformation:

! rule1 comment 2
rule1

InvertAllow

This transformation converts blocking rules to "allow" rules. Note, that it does nothing to /etc/hosts rules (unless they were previously converted to adblock-style syntax by a different transformation, for example Compress).

There are two important notes about this transformation:

1. It keeps the original rules order.
2. It ignores comments, empty lines, /etc/hosts rules and existing "allow" rules.

Example:

Original list:

! comment 1
rule1

# comment 2
192.168.11.11   test.local
@@rule2

Here's what we will have after applying this transformation:

! comment 1
@@rule1

# comment 2
192.168.11.11   test.local
@@rule2

RemoveEmptyLines

This is a very simple transformation that removes empty lines.

Example:

Original list:

rule1

rule2


rule3

Here's what we will have after applying this transformation:

rule1
rule2
rule3

TrimLines

This is a very simple transformation that removes leading and trailing spaces/tabs.

Example:

Original list:

rule1
   rule2
rule3
		rule4

Here's what we will have after applying this transformation:

rule1
rule2
rule3
rule4

InsertFinalNewLine

This is a very simple transformation that inserts a final newline.

Example:

Original list:

rule1
rule2
rule3

Here's what we will have after applying this transformation:

rule1
rule2
rule3

RemoveEmptyLines doesn't delete this empty row due to the execution order.

How to build

• yarn install - installs dependencies
• yarn lint - runs eslint
• yarn test - runs tests
• node src/cli.js -c examples/sdn/configuration.json -o filter.txt - runs compiler with the example configuration