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package main
import (
"fmt"
"html/template"
"io"
"log"
"net"
"net/http"
"regexp"
)
type Client struct {
IP net.IP
}
func isCli(userAgent string) bool {
match, _ := regexp.MatchString("^(?i)(curl|wget|fetch\\slibfetch)\\/.*$",
userAgent)
return match
}
func handler(w http.ResponseWriter, req *http.Request) {
if req.Method != "GET" {
http.Error(w, "Invalid request method", 405)
return
}
var host string
var err error
realIP := req.Header.Get("X-Real-IP")
if realIP != "" {
host = realIP
} else {
host, _, err = net.SplitHostPort(req.RemoteAddr)
}
ip := net.ParseIP(host)
if err != nil {
log.Printf("Failed to parse remote address: %s\n", req.RemoteAddr)
http.Error(w, "Failed to parse remote address", 500)
return
}
if isCli(req.UserAgent()) {
io.WriteString(w, fmt.Sprintf("%s\n", ip))
} else {
t, _ := template.ParseFiles("index.html")
client := &Client{IP: ip}
t.Execute(w, client)
}
}
func main() {
http.HandleFunc("/", handler)
err := http.ListenAndServe(":8080", nil)
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}
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