fix: dispatch zeroconf addUser from the current user

zeroconf/zeroconf.go

@@ -212,8 +212,7 @@ func (z *Zeroconf) handleAddUser(writer http.ResponseWriter, request *http.Reque
 
 	z.userLock.Lock()
 
-	// check if we are authenticating the same user that is holding the session
-	if z.currentUser == username || z.authenticatingUser == username {
+	if z.authenticatingUser == username {
 		z.userLock.Unlock()
 
 		writer.WriteHeader(http.StatusOK)

zeroconf/zeroconf_test.go

@@ -0,0 +1,155 @@
+package zeroconf
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+	"time"
+
+	librespot "github.com/devgianlu/go-librespot"
+	"github.com/devgianlu/go-librespot/dh"
+)
+
+func newTestZeroconf(t *testing.T) *Zeroconf {
+	z := &Zeroconf{
+		log:      &librespot.NullLogger{},
+		reqsChan: make(chan NewUserRequest),
+	}
+
+	var err error
+	z.dh, err = dh.NewDiffieHellman()
+	if err != nil {
+		t.Fatalf("failed initializing diffiehellman: %v", err)
+	}
+
+	return z
+}
+
+func newAddUserRequest(t *testing.T, z *Zeroconf, username, deviceName string) *http.Request {
+	clientDh, err := dh.NewDiffieHellman()
+	if err != nil {
+		t.Fatalf("failed initializing client diffiehellman: %v", err)
+	}
+
+	sharedSecret := clientDh.Exchange(z.dh.PublicKeyBytes())
+	baseKey := func() []byte { sum := sha1.Sum(sharedSecret); return sum[:16] }()
+
+	mac := hmac.New(sha1.New, baseKey)
+	mac.Write([]byte("checksum"))
+	checksumKey := mac.Sum(nil)
+
+	mac.Reset()
+	mac.Write([]byte("encryption"))
+	encryptionKey := func() []byte { sum := mac.Sum(nil); return sum[:16] }()
+
+	iv := make([]byte, 16)
+	if _, err := rand.Read(iv); err != nil {
+		t.Fatalf("failed reading random iv: %v", err)
+	}
+
+	bc, err := aes.NewCipher(encryptionKey)
+	if err != nil {
+		t.Fatalf("failed initializing aes cipher: %v", err)
+	}
+
+	payload := []byte("auth-blob-payload")
+	encrypted := make([]byte, len(payload))
+	cipher.NewCTR(bc, iv).XORKeyStream(encrypted, payload)
+
+	mac = hmac.New(sha1.New, checksumKey)
+	mac.Write(encrypted)
+	checksum := mac.Sum(nil)
+
+	blob := append(append(append([]byte{}, iv...), encrypted...), checksum...)
+
+	req := httptest.NewRequest(http.MethodPost, "/?action=addUser", nil)
+	req.Form = url.Values{
+		"userName":   {username},
+		"blob":       {base64.StdEncoding.EncodeToString(blob)},
+		"clientKey":  {base64.StdEncoding.EncodeToString(clientDh.PublicKeyBytes())},
+		"deviceName": {deviceName},
+	}
+	return req
+}
+
+func TestHandleAddUserSameUserReauthenticates(t *testing.T) {
+	z := newTestZeroconf(t)
+	z.currentUser = "alice"
+
+	dispatched := make(chan NewUserRequest, 1)
+	go func() {
+		req := <-z.reqsChan
+		dispatched <- req
+		req.result <- true
+	}()
+
+	rec := httptest.NewRecorder()
+	if err := z.handleAddUser(rec, newAddUserRequest(t, z, "alice", "phone")); err != nil {
+		t.Fatalf("handleAddUser failed: %v", err)
+	}
+
+	select {
+	case req := <-dispatched:
+		if req.Username != "alice" {
+			t.Fatalf("dispatched request for wrong username: %s", req.Username)
+		}
+	default:
+		t.Fatal("add user request for the current user was not dispatched")
+	}
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status code: %d", rec.Code)
+	}
+
+	var resp AddUserResponse
+	if err := json.NewDecoder(rec.Body).Decode(&resp); err != nil {
+		t.Fatalf("failed decoding response: %v", err)
+	}
+	if resp.Status != 101 {
+		t.Fatalf("unexpected response status: %d", resp.Status)
+	}
+
+	if z.currentUser != "alice" {
+		t.Fatalf("unexpected current user: %s", z.currentUser)
+	}
+}
+
+func TestHandleAddUserAuthenticatingSameUserShortCircuits(t *testing.T) {
+	z := newTestZeroconf(t)
+	z.authenticatingUser = "alice"
+
+	rec := httptest.NewRecorder()
+	done := make(chan error, 1)
+	go func() { done <- z.handleAddUser(rec, newAddUserRequest(t, z, "alice", "phone")) }()
+
+	select {
+	case err := <-done:
+		if err != nil {
+			t.Fatalf("handleAddUser failed: %v", err)
+		}
+	case req := <-z.reqsChan:
+		t.Fatalf("unexpected dispatch for user %s", req.Username)
+	case <-time.After(time.Second):
+		t.Fatal("handleAddUser did not return")
+	}
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("unexpected status code: %d", rec.Code)
+	}
+
+	var resp AddUserResponse
+	if err := json.NewDecoder(rec.Body).Decode(&resp); err != nil {
+		t.Fatalf("failed decoding response: %v", err)
+	}
+	if resp.Status != 101 {
+		t.Fatalf("unexpected response status: %d", resp.Status)
+	}
+}