254 lines
6.4 KiB
Go
254 lines
6.4 KiB
Go
|
package main
|
||
|
|
||
|
import (
|
||
|
"crypto/hmac"
|
||
|
"encoding/hex"
|
||
|
"encoding/json"
|
||
|
"errors"
|
||
|
"fmt"
|
||
|
"log"
|
||
|
"net/http"
|
||
|
"strconv"
|
||
|
"strings"
|
||
|
"time"
|
||
|
|
||
|
"github.com/julienschmidt/httprouter"
|
||
|
"golang.org/x/crypto/blake2b"
|
||
|
)
|
||
|
|
||
|
const IPgwDMZ = "172.23.200.1"
|
||
|
|
||
|
type Challenge struct {
|
||
|
Accessible []func(*Student, *http.Request) error
|
||
|
Check func(*Student, *givenToken, int) error
|
||
|
}
|
||
|
|
||
|
/* Restrictions */
|
||
|
|
||
|
func noAccessRestriction(*Student, *http.Request) error {
|
||
|
return nil
|
||
|
}
|
||
|
|
||
|
func accessFrom(ip string) func(_ *Student, r *http.Request) error {
|
||
|
return func(_ *Student, r *http.Request) error {
|
||
|
if r.Header.Get("X-Forwarded-By") != ip {
|
||
|
return errors.New("This challenge is not accessible this way.")
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func notAccessFrom(ip string) func(_ *Student, r *http.Request) error {
|
||
|
return func(_ *Student, r *http.Request) error {
|
||
|
if r.Header.Get("X-Forwarded-By") == ip {
|
||
|
return errors.New("This challenge is not accessible this way.")
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func maxProxy(nb int) func(_ *Student, r *http.Request) error {
|
||
|
return func(_ *Student, r *http.Request) error {
|
||
|
if len(strings.Split(r.Header.Get("X-Forwarded-For"), ",")) > nb {
|
||
|
return errors.New("This challenge is not accessible this way.")
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func sslOnly(_ *Student, r *http.Request) error {
|
||
|
if r.Header.Get("X-Forwarded-Proto") != "https" {
|
||
|
return errors.New("This challenge should be performed over TLS.")
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
|
||
|
|
||
|
/* Challenges */
|
||
|
|
||
|
func challenge42(s *Student, t *givenToken, chid int) error {
|
||
|
pkey := s.GetPKey()
|
||
|
if expectedToken, err := GenerateToken(pkey, chid, []byte("42")); err != nil {
|
||
|
return err
|
||
|
} else if ! hmac.Equal(expectedToken, t.token) {
|
||
|
return errors.New("This is not the expected token.")
|
||
|
} else {
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func challengeDNS(s *Student, t *givenToken, chid int) error {
|
||
|
pkey := s.GetPKey()
|
||
|
if expectedToken, err := GenerateToken(pkey, chid, []byte("8dde678132d6c558fc6adaeb9f1d53bf6ec7b876308cf98c48604caa9138523c1ce58b672c87c7e7d9b7248b81804d3940dbf20bf263eeb683244f7c1143712d")); err != nil {
|
||
|
return err
|
||
|
} else if ! hmac.Equal(expectedToken, t.token) {
|
||
|
return errors.New("This is not the expected token.")
|
||
|
} else {
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func challengeTime(s *Student, t *givenToken, chid int) error {
|
||
|
pkey := s.GetPKey()
|
||
|
if expectedToken, err := GenerateToken(pkey, chid, []byte(t.Data[0])); err != nil {
|
||
|
return err
|
||
|
} else if ! hmac.Equal(expectedToken, t.token) {
|
||
|
return errors.New("This is not the expected token.")
|
||
|
} else if t, err := strconv.ParseInt(t.Data[0], 10, 64); err != nil {
|
||
|
return err
|
||
|
} else {
|
||
|
var rt time.Time
|
||
|
if t > 3000000000 {
|
||
|
rt = time.Unix(t / 1000000000, t % 1000000000)
|
||
|
} else {
|
||
|
rt = time.Unix(t, 0)
|
||
|
}
|
||
|
if rt.After(time.Now()) {
|
||
|
return errors.New("You seem to live in the future...")
|
||
|
} else if d := rt.Sub(time.Now()); d.Minutes() < -10 {
|
||
|
return errors.New(fmt.Sprintf("Your time is %.0f minutes from us", d.Minutes()))
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func challengeDisk(s *Student, t *givenToken, chid int) error {
|
||
|
pkey := s.GetPKey()
|
||
|
|
||
|
n1, err := strconv.Atoi(t.Token[0:2])
|
||
|
if err != nil {
|
||
|
return err
|
||
|
}
|
||
|
n2, err := strconv.Atoi(t.Token[2:4])
|
||
|
if err != nil {
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
sum := make([]byte, hex.DecodedLen(len(t.Token[4:])))
|
||
|
if _, err := hex.Decode(t.token, []byte(t.Token[4:])); err != nil {
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
expectedToken := blake2b.Sum512([]byte(pkey[n1:n2]))
|
||
|
|
||
|
if ! hmac.Equal(expectedToken[:], sum) {
|
||
|
return errors.New("This is not the expected token.")
|
||
|
} else {
|
||
|
return nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
var challenges []Challenge
|
||
|
|
||
|
func init() {
|
||
|
challenges = []Challenge{
|
||
|
/* Challenge 1 : 42 */
|
||
|
Challenge{
|
||
|
Accessible: []func(*Student, *http.Request) error{noAccessRestriction},
|
||
|
Check: challenge42,
|
||
|
},
|
||
|
|
||
|
/* Challenge 2 : 42 from DMZ */
|
||
|
Challenge{
|
||
|
Accessible: []func(*Student, *http.Request) error{accessFrom(IPgwDMZ)},
|
||
|
Check: challenge42,
|
||
|
},
|
||
|
|
||
|
/* Challenge 3 : ssl (+ ntp) */
|
||
|
Challenge{
|
||
|
Accessible: []func(*Student, *http.Request) error{accessFrom(IPgwDMZ), sslOnly},
|
||
|
Check: challengeTime,
|
||
|
},
|
||
|
|
||
|
/* Challenge 4 : disk */
|
||
|
Challenge{
|
||
|
Accessible: []func(*Student, *http.Request) error{noAccessRestriction},
|
||
|
Check: challengeDisk,
|
||
|
},
|
||
|
|
||
|
/* Challenge 5 : DNS TXT */
|
||
|
Challenge{
|
||
|
Accessible: []func(*Student, *http.Request) error{accessFrom(IPgwDMZ), sslOnly},
|
||
|
Check: challengeDNS,
|
||
|
},
|
||
|
|
||
|
/* Challenge 6 : time net */
|
||
|
Challenge{
|
||
|
Accessible: []func(*Student, *http.Request) error{maxProxy(1)},
|
||
|
Check: challengeTime,
|
||
|
},
|
||
|
}
|
||
|
|
||
|
router.GET("/challenge", apiHandler(getChallengeList))
|
||
|
router.GET("/challenge/:chid", rawHandler(accessibleChallenge))
|
||
|
router.POST("/challenge", rawHandler(receiveToken))
|
||
|
}
|
||
|
|
||
|
type givenToken struct {
|
||
|
Login string `json:"login"`
|
||
|
Challenge int `json:"challenge"`
|
||
|
Token string `json:"token"`
|
||
|
token []byte
|
||
|
Data []string `json:"data"`
|
||
|
}
|
||
|
|
||
|
func getChallengeList(_ httprouter.Params, _ []byte) (interface{}, error) {
|
||
|
var ret []int
|
||
|
for i := range challenges {
|
||
|
ret = append(ret, i)
|
||
|
}
|
||
|
return ret, nil
|
||
|
}
|
||
|
|
||
|
func accessibleChallenge(r *http.Request, ps httprouter.Params, _ []byte) (interface{}, error) {
|
||
|
if chid, err := strconv.Atoi(string(ps.ByName("chid"))); err != nil {
|
||
|
return nil, err
|
||
|
} else if chid == 0 || chid >= len(challenges) {
|
||
|
return nil, errors.New("This challenge doesn't exist")
|
||
|
} else {
|
||
|
for _, a := range challenges[chid - 1].Accessible {
|
||
|
if err := a(nil, r); err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
}
|
||
|
return true, nil
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func receiveToken(r *http.Request, ps httprouter.Params, body []byte) (interface{}, error) {
|
||
|
if _, err := accessibleChallenge(r, ps, body); err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
var gt givenToken
|
||
|
if err := json.Unmarshal(body, >); err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
gt.token = make([]byte, hex.DecodedLen(len(gt.Token)))
|
||
|
if _, err := hex.Decode(gt.token, []byte(gt.Token)); err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
if chid, err := strconv.Atoi(string(ps.ByName("chid"))); err != nil {
|
||
|
return nil, err
|
||
|
} else if chid == 0 || chid > len(challenges) {
|
||
|
return nil, errors.New("This challenge doesn't exist")
|
||
|
} else if std, err := getStudentByLogin(gt.Login); err != nil {
|
||
|
return nil, err
|
||
|
} else {
|
||
|
if err := challenges[chid - 1].Check(&std, >, chid); err != nil {
|
||
|
log.Printf("%s just try ch#%d: %s\n", std.Login, chid, err)
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
if _, err := std.UnlockNewChallenge(chid, gt.Token); err != nil {
|
||
|
log.Println(err)
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
log.Printf("%s just unlock ch#%d\n", std.Login, chid)
|
||
|
return "Success", nil
|
||
|
}
|
||
|
}
|