158 lines
3.4 KiB
Go
158 lines
3.4 KiB
Go
package main
|
|
|
|
import (
|
|
"encoding/json"
|
|
"io"
|
|
"log"
|
|
"net"
|
|
"net/http"
|
|
"os"
|
|
|
|
"github.com/kardianos/service"
|
|
)
|
|
|
|
const (
|
|
port = "8999"
|
|
logFile = "hostname_service.log"
|
|
logFlags = log.Ldate | log.Ltime | log.Lshortfile
|
|
)
|
|
|
|
var logger *log.Logger
|
|
|
|
// Request structure
|
|
type Request struct {
|
|
IP string `json:"ip"`
|
|
}
|
|
|
|
// Response structure
|
|
type Response struct {
|
|
Hostname string `json:"hostname,omitempty"`
|
|
Error string `json:"error,omitempty"`
|
|
}
|
|
|
|
type program struct {
|
|
server *http.Server
|
|
}
|
|
|
|
func (p *program) Start(s service.Service) error {
|
|
// Start should not block
|
|
go p.run()
|
|
return nil
|
|
}
|
|
|
|
func (p *program) run() {
|
|
mux := http.NewServeMux()
|
|
mux.HandleFunc("/", handleRequest)
|
|
|
|
p.server = &http.Server{
|
|
Addr: ":" + port,
|
|
Handler: mux,
|
|
}
|
|
|
|
logger.Println("Starting server on port", port)
|
|
err := p.server.ListenAndServe()
|
|
if err != nil && err != http.ErrServerClosed {
|
|
logger.Fatalf("Server failed: %v", err)
|
|
}
|
|
}
|
|
|
|
func (p *program) Stop(s service.Service) error {
|
|
logger.Println("Stopping server...")
|
|
if p.server != nil {
|
|
return p.server.Close()
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func handleRequest(w http.ResponseWriter, r *http.Request) {
|
|
if r.Method != http.MethodPost {
|
|
logger.Printf("Rejected %s request from %s", r.Method, r.RemoteAddr)
|
|
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
|
|
return
|
|
}
|
|
|
|
body, err := io.ReadAll(r.Body)
|
|
if err != nil {
|
|
logger.Printf("Failed to read request: %v", err)
|
|
http.Error(w, "Invalid request", http.StatusBadRequest)
|
|
return
|
|
}
|
|
defer r.Body.Close()
|
|
|
|
var req Request
|
|
err = json.Unmarshal(body, &req)
|
|
if err != nil || req.IP == "" {
|
|
logger.Printf("Invalid JSON or missing IP: %s", string(body))
|
|
respond(w, Response{Error: "Invalid JSON or missing 'ip'"})
|
|
return
|
|
}
|
|
|
|
logger.Printf("Received IP lookup request: %s", req.IP)
|
|
names, err := net.LookupAddr(req.IP)
|
|
if err != nil || len(names) == 0 {
|
|
logger.Printf("Hostname not found for IP: %s", req.IP)
|
|
respond(w, Response{Error: "Hostname not found"})
|
|
return
|
|
}
|
|
|
|
hostname := names[0]
|
|
logger.Printf("Resolved %s to %s", req.IP, hostname)
|
|
respond(w, Response{Hostname: hostname})
|
|
}
|
|
|
|
func respond(w http.ResponseWriter, resp Response) {
|
|
w.Header().Set("Content-Type", "application/json")
|
|
json.NewEncoder(w).Encode(resp)
|
|
}
|
|
|
|
func setupLogging() {
|
|
file, err := os.OpenFile(logFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
|
|
if err != nil {
|
|
log.Fatalf("Unable to open log file: %v", err)
|
|
}
|
|
logger = log.New(file, "", logFlags)
|
|
}
|
|
|
|
func main() {
|
|
setupLogging()
|
|
|
|
svcConfig := &service.Config{
|
|
Name: "HostnameGoHTTPService",
|
|
DisplayName: "Hostname Go HTTP Resolver Service",
|
|
Description: "Resolves hostnames from IPs via POST JSON requests on port 8999.",
|
|
}
|
|
|
|
prg := &program{}
|
|
s, err := service.New(prg, svcConfig)
|
|
if err != nil {
|
|
logger.Fatalf("Failed to create service: %v", err)
|
|
}
|
|
|
|
// Logging via service (or fallback)
|
|
errs := make(chan error, 5)
|
|
loggerAdapter, err := s.Logger(errs)
|
|
if err == nil {
|
|
logger.SetOutput(serviceLogWriter{loggerAdapter})
|
|
}
|
|
|
|
if len(os.Args) > 1 && os.Args[1] == "run" {
|
|
// Standalone mode for testing
|
|
prg.run()
|
|
} else {
|
|
err = s.Run()
|
|
if err != nil {
|
|
logger.Fatalf("Service failed: %v", err)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Adapter to redirect standard logger to service log
|
|
type serviceLogWriter struct {
|
|
logger service.Logger
|
|
}
|
|
|
|
func (w serviceLogWriter) Write(p []byte) (n int, err error) {
|
|
w.logger.Info(string(p))
|
|
return len(p), nil
|
|
}
|