[Bug] Rule-set download fails because DNS lookup is performed via `::1:53` (localhost), causing `connection refused`

[FSSocrates]

Environment

• App: SingCast
• Version: Latest release (also reproduced on previous release)
• Device: Realme 9
• Android: 14

Description

When importing or starting any configuration that requires downloading remote rule sets, SingCast fails before the rule sets are downloaded.

The Rule-Set Proxy is set to:

https://gh-proxy.org

The app forces this field to be non-empty.

Opening https://gh-proxy.org in a browser works correctly (it redirects to https://gh-proxy.com), so the proxy itself appears to be reachable.

Error

PlatformException(
CORE_ERROR,
start instance:
(initialize rule-set[0]:
initial rule-set: geoip-sg:
Get "https://gh-proxy.org/https://raw.githubusercontent.com/SagerNet/sing-geoip/rule-set/geoip-sg.srs":
lookup gh-proxy.org:
(exchange4: gh-proxy.org.: read response: read udp [::1]:41429->[::1]:53: read: connection refused |
exchange6: gh-proxy.org.: read response: read udp [::1]:38136->[::1]:53: read: connection refused)
...
),
null,
null
)

Changing the Rule-Set Proxy to:

https://raw.githubusercontent.com

produces:

https://raw.githubusercontent.com/https://raw.githubusercontent.com/...

which confirms that the Rule-Set Proxy is simply prepended to the original URL.

However, the failure still occurs during DNS resolution:

lookup raw.githubusercontent.com
read udp [::1]:xxxxx->[::1]:53
connection refused

Troubleshooting already performed

• Disabled all VPN applications.
• Disabled all DNS applications.
• Disabled Android Private DNS.
• Verified https://gh-proxy.org is reachable in a web browser.
• Reproduced on both the latest and previous SingCast releases.

Expected behavior

SingCast should resolve the hostname using the Android system DNS (or a valid configured DNS server) and download the rule sets successfully.

Likely cause

The embedded sing-box core appears to be attempting DNS resolution through the localhost IPv6 resolver (::1:53), but no DNS server is running there, resulting in connection refused.

Could you check whether SingCast is unintentionally configuring DNS to ::1/localhost before rule-set initialization, or whether the DNS initialization order is causing rule-set downloads to occur before a resolver is available?

[mapleafgo]

Is it possible to set the log level to debug on the settings page, and then export a log on the about page after reproduction?

[FSSocrates]

I've set the log level to Debug, reproduced the issue, and attached the exported log.

One additional note: Exporting the log was surprisingly difficult. The standard save/share methods repeatedly failed. After trying many different approaches, I was finally able to save it by extracting it with ZipXtract.

I also reproduced the issue with both the Clash and sing-box subscription links from @Au1rxx, and the same error occurred in both cases.

Please let me know if you need any additional logs or if you'd like me to test anything else.

[mapleafgo]

I’ve released a fixed version. You can give it a try.

[FSSocrates]

I investigated this further.

The downloaded subscription itself does not contain geosite-bd. I checked both of these subscriptions manually:

• https://github.com/Au1rxx/free-vpn-subscriptions/raw/main/output/clash.yaml
• https://github.com/Au1rxx/free-vpn-subscriptions/raw/main/output/singbox.json

Neither contains the string geosite-bd.

However, the debug log shows SingCast generating the following request during startup:

router: updating rule-set geosite-bd from URL:
https://raw.githubusercontent.com/SagerNet/sing-geosite/rule-set/geosite-bd.srs

This URL returns HTTP 404 because geosite-bd.srs does not exist in the SagerNet/sing-geosite rule-set branch.

So it appears geosite-bd is being generated or injected by SingCast during profile conversion or initialization, rather than coming from the subscription itself.

[mapleafgo]

Hey, friend, it was my oversight. You are the first foreign friend to give feedback. I use the rules of Singbox internally to replace the rules of Clash, but it doesn't work in non-Chinese environments. I will carefully study the rules of your country and try to make it compatible and adaptable.