[Feature Request] Custom response for unregistered HTTP vhost (rules, wildcard, headers) #4972
Description
Describe the feature request
Summary
Add support for configurable customResponse in FRPS HTTP vhost, so requests with unknown/unregistered Host header return a user-defined response (status, content-type, body, headers).
Why
Currently, FRPS always returns default 404 for unregistered hostnames. This is not customizable. Custom responses improve UX and debugging, especially in multi-tenant setups.
## Proposed config (TOML)
[customResponse]
enable = false
[[customResponse.rules]]
hostname = ["*.example.com", "example.com"]
statusCode = 503
contentType = "text/html"
body = """
<!doctype html><html><body>
<h1>Service Unavailable</h1>
<p>The server is currently unavailable.<br/>Please try again later.</p>
</body></html>
"""
[customResponse.rules.headers]
Cache-Control = "no-store"
X-Error-Code = "UNREGISTERED_HOST"
[[customResponse.rules]]
hostname = ["spesific.example2.com"]
statusCode = 404
contentType = "application/json"
body = "{\"error\":\"unregistered_host\",\"hint\":\"register frpc for this hostname\"}"
[customResponse.rules.headers]
Cache-Control = "no-store"
Behavior
- If feature disabled, behavior unchanged (default 404).
- Rules support exact, wildcard (
*.example.com), and"*"catch-all. - First match wins.
Next step
I can prepare a PR with implementation + unit tests if this direction is acceptable.
Describe alternatives you've considered
No response
Affected area
- Docs
- Installation
- Performance and Scalability
- Security
- User Experience
- Test and Release
- Developer Infrastructure
- Client Plugin
- Server Plugin
- Extensions
- Others