Create accounts automatically when authenticating from HTTP header (#2087)

* Create accounts automatically when authenticating from HTTP header

* Disable password check when header auth is enabled

* Formatting

* Password change is valid when no password (old or new) is provided

* Test suite runs with header auth disabled (mock config)
Prevents nil pointer access (panic) while testing password validating logic

* Use a constant prefix for autogenerated passwords (header auth case)

* Add tests

* Add context to log messages

Co-authored-by: Deluan <deluan@navidrome.org>

server/auth.go

@@ -285,8 +285,25 @@ func handleLoginFromHeaders(ds model.DataStore, r *http.Request) map[string]inte
 	userRepo := ds.User(r.Context())
 	user, err := userRepo.FindByUsernameWithPassword(username)
 	if user == nil || err != nil {
-		log.Warn(r, "User passed in header not found", "user", username)
-		return nil
+		log.Info(r, "User passed in header not found", "user", username)
+		newUser := model.User{
+			ID:          uuid.NewString(),
+			UserName:    username,
+			Name:        username,
+			Email:       "",
+			NewPassword: consts.PasswordAutogenPrefix + uuid.NewString(),
+			IsAdmin:     false,
+		}
+		err := userRepo.Put(&newUser)
+		if err != nil {
+			log.Error(r, "Could not create new user", "user", username, err)
+			return nil
+		}
+		user, err = userRepo.FindByUsernameWithPassword(username)
+		if user == nil || err != nil {
+			log.Error(r, "Created user but failed to fetch it", "user", username)
+			return nil
+		}
 	}
 
 	err = userRepo.UpdateLastLoginAt(user.ID)