10. Hosts Engine, Blocklists & Smart Caching

The Hosts Engine (components/hosts.uc) provides automated background ingestion, normalization, deduplication, and caching of external host lists and static DNS overrides.

1. Architecture of Hosts Engine

graph TD
    Sources[External Remote URLs: AdAway, StevenBlack, Custom] --> Downloader[HTTP Fetcher with Mirror Retry]
    Static[Static dns_hosts in UCI] --> Downloader
    
    Downloader --> Parser[Multi-Format Parser: Hosts, AdBlock, Domains]
    Parser --> Deduper[Deduplication & Sorting Engine]
    Deduper --> Cache[Unified Cache: /tmp/tachyon/hosts/combined.txt]
    
    Cache --> DNSMasq[dnsmasq /etc/dnsmasq.d/tachyon-hosts.conf]
    Cache --> SingboxDNS[sing-box DNS hosts rule]

2. Multi-Format Ingestion

The parser automatically detects and normalizes multiple common blocklist formats:

Standard /etc/hosts format:

0.0.0.0 ads.example.com
127.0.0.1 tracker.adserver.net

Domain-only list format:
```
malware-domain.org
telemetry.app.com
```

AdBlock / DNSmasq syntax:

||badsite.com^
server=/blocked.com/
address=/ads.org/0.0.0.0

3. GitHub Mirror Retry Resiliency

When fetching blocklists hosted on GitHub (e.g. raw.githubusercontent.com), access may be blocked or throttled by regional DPI.

Tachyon implements an automated fallback retry chain:

Primary: Direct HTTPS request to target URL.
Mirror 1: https://gh-proxy.com/<original_url>
Mirror 2: https://ghfast.top/<original_url>
Mirror 3: https://ghproxy.net/<original_url>

If direct connection fails with timeout or SSL handshake error, Tachyon transparently cycles through available mirrors before reporting an error.

4. Dedicated Hosts Routing (`action = 'hosts'`)

Tachyon supports routing sections that operate purely as DNS-overriding engines without requiring an outbound proxy association.

Example UCI Configuration:

config rule 'adblock_section'
    option enabled '1'
    option name 'AdBlock & Anti-Tracker'
    option action 'hosts'
    list hosts_list_urls 'https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts'
    list hosts_list_urls 'https://adaway.org/hosts.txt'

Domains in this section are redirected directly to 0.0.0.0 or custom IPs in dnsmasq / sing-box DNS.
Zero traffic is routed to external proxies, preserving VPS bandwidth and minimizing latency.

2.4 KiB Raw Blame History