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package source
import (
"fmt"
"io"
"log/slog"
"net/http"
"net/netip"
"strings"
"time"
)
type Kind string
const (
// only the simple generic sources for now!
KindStatic Kind = "static"
KindURL Kind = "url"
KindFile Kind = "file"
)
type Family string
const (
IPv4 Family = "ipv4"
IPv6 Family = "ipv6"
)
type Config struct {
Kind Kind `json:"kind"`
Family Family `json:"family,omitempty"`
URL string `json:"url,omitempty"`
Path string `json:"path,omitempty"`
Value string `json:"value,omitempty"`
}
type Source interface {
Supports(Family) bool
Lookup(Family) (netip.Addr, error)
}
func New(log *slog.Logger, cfg Config) (Source, error) {
if cfg.Family != IPv4 && cfg.Family != IPv6 {
return nil, fmt.Errorf("%s source needs family set to ipv4 or ipv6", cfg.Kind)
}
if cfg.Kind == KindStatic {
return newStatic(log, cfg)
}
if cfg.Kind == KindURL {
return newURL(log, cfg)
}
if cfg.Kind == KindFile {
return newFile(log, cfg)
}
return nil, fmt.Errorf("unknown source kind %q", cfg.Kind)
}
// parsing function for ipv4 and ipv6 strings
func parse(raw string, family Family) (netip.Addr, error) {
addr, err := netip.ParseAddr(strings.TrimSpace(raw))
if err != nil {
return netip.Addr{}, err
}
if addr.Is6() != (family == IPv6) {
return netip.Addr{}, fmt.Errorf("%s is not an %s address", addr, family)
}
return addr, nil
}
// generic http fetching helper since a lot of sources will need it.
func fetch(url string, family Family) (netip.Addr, error) {
client := http.Client{Timeout: 15 * time.Second}
resp, err := client.Get(url)
if err != nil {
return netip.Addr{}, err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return netip.Addr{}, fmt.Errorf("%s: %s", url, resp.Status)
}
raw, err := io.ReadAll(io.LimitReader(resp.Body, 256))
if err != nil {
return netip.Addr{}, err
}
return parse(string(raw), family)
}
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