token-validator: handle remote-validator authentication + new student features

token-validator/handler.go

@@ -1,11 +1,16 @@
 package main
 
 import (
+	"crypto/hmac"
+	"crypto/sha512"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
 	"log"
 	"net/http"
+	"strconv"
+	"time"
 
 	"github.com/julienschmidt/httprouter"
 )
@@ -18,6 +23,21 @@ func Router() *httprouter.Router {
 
 type DispatchFunction func(httprouter.Params, []byte) (interface{}, error)
 
+func remoteValidatorHandler(f func(http.ResponseWriter, *http.Request, httprouter.Params)) func(http.ResponseWriter, *http.Request, httprouter.Params) {
+	return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
+		expectedMAC := hmac.New(sha512.New, []byte(sharedSecret)).Sum([]byte(fmt.Sprintf("%d", time.Now().Unix()/10)))
+		previousMAC := hmac.New(sha512.New, []byte(sharedSecret)).Sum([]byte(fmt.Sprintf("%d", time.Now().Unix()/10-1)))
+
+		if aauth, err := base64.StdEncoding.DecodeString(r.Header.Get("X-ADLIN-Authentication")); err != nil {
+			http.Error(w, fmt.Sprintf("{\"errmsg\":%q}", err), http.StatusUnauthorized)
+		} else if !hmac.Equal(expectedMAC, aauth) && !hmac.Equal(previousMAC, aauth) {
+			http.Error(w, fmt.Sprintf("{\"errmsg\":%q}", "Bad authentication header"), http.StatusUnauthorized)
+		} else {
+			f(w, r, ps)
+		}
+	}
+}
+
 func apiHandler(f DispatchFunction) func(http.ResponseWriter, *http.Request, httprouter.Params) {
 	return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
 		if addr := r.Header.Get("X-Forwarded-For"); addr != "" {
@@ -78,3 +98,19 @@ func apiHandler(f DispatchFunction) func(http.ResponseWriter, *http.Request, htt
 		}
 	}
 }
+
+func studentHandler(f func(Student, []byte) (interface{}, error)) func(httprouter.Params, []byte) (interface{}, error) {
+	return func(ps httprouter.Params, body []byte) (interface{}, error) {
+		if sid, err := strconv.Atoi(string(ps.ByName("sid"))); err != nil {
+			if student, err := getStudentByLogin(ps.ByName("sid")); err != nil {
+				return nil, err
+			} else {
+				return f(student, body)
+			}
+		} else if student, err := getStudent(sid); err != nil {
+			return nil, err
+		} else {
+			return f(student, body)
+		}
+	}
+}