Add User-Interactive Authentication (#1193)

* Add User-Interactive Authentication

And use it when deleting a device. With tests.

* Make remaining sytest pass

* Linting

* 403 not 401 on wrong user/pass

clientapi/auth/password.go

@@ -0,0 +1,75 @@
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package auth
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/clientapi/userutil"
+	"github.com/matrix-org/dendrite/internal/config"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+type GetAccountByPassword func(ctx context.Context, localpart, password string) (*api.Account, error)
+
+type PasswordRequest struct {
+	Login
+	Password string `json:"password"`
+}
+
+// LoginTypePassword implements https://matrix.org/docs/spec/client_server/r0.6.1#password-based
+type LoginTypePassword struct {
+	GetAccountByPassword GetAccountByPassword
+	Config               *config.Dendrite
+}
+
+func (t *LoginTypePassword) Name() string {
+	return "m.login.password"
+}
+
+func (t *LoginTypePassword) Request() interface{} {
+	return &PasswordRequest{}
+}
+
+func (t *LoginTypePassword) Login(ctx context.Context, req interface{}) (*Login, *util.JSONResponse) {
+	r := req.(*PasswordRequest)
+	username := r.Username()
+	if username == "" {
+		return nil, &util.JSONResponse{
+			Code: http.StatusUnauthorized,
+			JSON: jsonerror.BadJSON("'user' must be supplied."),
+		}
+	}
+	localpart, err := userutil.ParseUsernameParam(username, &t.Config.Matrix.ServerName)
+	if err != nil {
+		return nil, &util.JSONResponse{
+			Code: http.StatusUnauthorized,
+			JSON: jsonerror.InvalidUsername(err.Error()),
+		}
+	}
+	_, err = t.GetAccountByPassword(ctx, localpart, r.Password)
+	if err != nil {
+		// Technically we could tell them if the user does not exist by checking if err == sql.ErrNoRows
+		// but that would leak the existence of the user.
+		return nil, &util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("username or password was incorrect, or the account does not exist"),
+		}
+	}
+	return &r.Login, nil
+}