server

type Config struct {
	Addr           string        // e.g. ":8080"
	MaxDownloadMiB int64         // safety cap, default 1024 (1 GiB)
	MaxUploadMiB   int64         // safety cap, default 1024
	ReadTimeout    time.Duration // per request, default 60s — uploads can be large
	IPInfoToken    string        // optional ipinfo.io token for richer ISP data

	// TrustProxyHeaders, when true, makes the server honor
	// X-Forwarded-For / X-Real-IP for client-IP determination. OFF by
	// default to prevent header-spoofing attacks: any direct caller can
	// otherwise force /api/info to issue an outbound ipinfo.io lookup
	// for an IP of their choosing and read the result, draining the
	// operator's quota and acting as an SSRF-style oracle. Only enable
	// this when running behind a reverse proxy that *strips and re-sets*
	// these headers itself.
	TrustProxyHeaders bool
}

type InfoResponse struct {
	ClientIP   string `json:"client_ip"`
	ISP        string `json:"isp,omitempty"`
	City       string `json:"city,omitempty"`
	Region     string `json:"region,omitempty"`
	Country    string `json:"country,omitempty"`
	ServerHost string `json:"server_host"`
	ServerTime string `json:"server_time"`
}

type WSPingConfig struct {
	// Samples is the number of ping/pong round-trips to perform.
	Samples int
	// Spacing is the delay between successive pings.
	Spacing time.Duration
	// PingTimeout bounds an individual ping/pong. Treated as a hard error
	// if exceeded — typically only happens when the network or peer is
	// gone.
	PingTimeout time.Duration
	// MaxLifetime caps the entire connection. Defends against clients
	// that open the WS and stop reading.
	MaxLifetime time.Duration
}