Add a challenge for shadow password

pkg/login-validator/cmd/passwd.go

@@ -1,7 +1,10 @@
 package main
 
 import (
+	"bytes"
 	"compress/gzip"
+	"encoding/json"
+	"fmt"
 	"io"
 	"log"
 	"net/http"
@@ -157,6 +160,48 @@ func passwd(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	err = RegisterShadowChallenge(initrd)
+	if err != nil {
+		log.Printf("%s: Unable to register shadow challenge: %s", r.RemoteAddr, err.Error())
+	}
+
 	log.Println("Registered shadow for", r.RemoteAddr)
 	http.Error(w, "Success", http.StatusOK)
 }
+
+func RegisterShadowChallenge(initrd string) error {
+	// Retrieve username
+	fdlogin, err := os.Open(path.Join(tftpDir, "shadows", initrd, "whois"))
+	if err != nil {
+		return err
+	}
+	defer fdlogin.Close()
+
+	cnt, err := io.ReadAll(fdlogin)
+	if err != nil {
+		return err
+	}
+
+	tmp := bytes.Split(cnt, []byte("\n"))
+	if len(tmp) < 0 {
+		return fmt.Errorf("Too few fields in whois file")
+	}
+
+	login := tmp[0]
+
+	// Register shadow challenge
+	if j, err := json.Marshal(struct {
+		Token string
+		Login string
+	}{Token: loginSalt, Login: string(login)}); err != nil {
+		return err
+	} else if r, err := http.NewRequest("POST", "https://adlin.nemunai.re/challenge/0", bytes.NewReader(j)); err != nil {
+		return err
+	} else if resp, err := http.DefaultClient.Do(r); err == nil {
+		resp.Body.Close()
+	} else {
+		return err
+	}
+
+	return nil
+}