Handle guest access [1/2?] (#2872)

Needs https://github.com/matrix-org/sytest/pull/1315, as otherwise the
membership events aren't persisted yet when hitting `/state` after
kicking guest users.

Makes the following tests pass:
```
Guest users denied access over federation if guest access prohibited
Guest users are kicked from guest_access rooms on revocation of guest_access
Guest users are kicked from guest_access rooms on revocation of guest_access over federation
```

Todo (in a follow up PR):
- Restrict access to CS API Endpoints as per
https://spec.matrix.org/v1.4/client-server-api/#client-behaviour-14

Co-authored-by: kegsay <kegan@matrix.org>

clientapi/clientapi.go

@@ -15,6 +15,8 @@
 package clientapi
 
 import (
+	"github.com/matrix-org/gomatrixserverlib"
+
 	appserviceAPI "github.com/matrix-org/dendrite/appservice/api"
 	"github.com/matrix-org/dendrite/clientapi/api"
 	"github.com/matrix-org/dendrite/clientapi/producers"
@@ -26,7 +28,6 @@ import (
 	"github.com/matrix-org/dendrite/setup/base"
 	"github.com/matrix-org/dendrite/setup/jetstream"
 	userapi "github.com/matrix-org/dendrite/userapi/api"
-	"github.com/matrix-org/gomatrixserverlib"
 )
 
 // AddPublicRoutes sets up and registers HTTP handlers for the ClientAPI component.

clientapi/routing/joinroom.go

@@ -37,6 +37,7 @@ func JoinRoomByIDOrAlias(
 	joinReq := roomserverAPI.PerformJoinRequest{
 		RoomIDOrAlias: roomIDOrAlias,
 		UserID:        device.UserID,
+		IsGuest:       device.AccountType == api.AccountTypeGuest,
 		Content:       map[string]interface{}{},
 	}
 	joinRes := roomserverAPI.PerformJoinResponse{}
@@ -84,7 +85,14 @@ func JoinRoomByIDOrAlias(
 		if err := rsAPI.PerformJoin(req.Context(), &joinReq, &joinRes); err != nil {
 			done <- jsonerror.InternalAPIError(req.Context(), err)
 		} else if joinRes.Error != nil {
-			done <- joinRes.Error.JSONResponse()
+			if joinRes.Error.Code == roomserverAPI.PerformErrorNotAllowed && device.AccountType == api.AccountTypeGuest {
+				done <- util.JSONResponse{
+					Code: http.StatusForbidden,
+					JSON: jsonerror.GuestAccessForbidden(joinRes.Error.Msg),
+				}
+			} else {
+				done <- joinRes.Error.JSONResponse()
+			}
 		} else {
 			done <- util.JSONResponse{
 				Code: http.StatusOK,

clientapi/routing/joinroom_test.go

@@ -0,0 +1,158 @@
+package routing
+
+import (
+	"bytes"
+	"context"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/matrix-org/gomatrixserverlib"
+
+	"github.com/matrix-org/dendrite/appservice"
+	"github.com/matrix-org/dendrite/keyserver"
+	"github.com/matrix-org/dendrite/roomserver"
+	"github.com/matrix-org/dendrite/test"
+	"github.com/matrix-org/dendrite/test/testrig"
+	"github.com/matrix-org/dendrite/userapi"
+	uapi "github.com/matrix-org/dendrite/userapi/api"
+)
+
+func TestJoinRoomByIDOrAlias(t *testing.T) {
+	alice := test.NewUser(t)
+	bob := test.NewUser(t)
+	charlie := test.NewUser(t, test.WithAccountType(uapi.AccountTypeGuest))
+
+	ctx := context.Background()
+	test.WithAllDatabases(t, func(t *testing.T, dbType test.DBType) {
+		base, baseClose := testrig.CreateBaseDendrite(t, dbType)
+		defer baseClose()
+
+		rsAPI := roomserver.NewInternalAPI(base)
+		keyAPI := keyserver.NewInternalAPI(base, &base.Cfg.KeyServer, nil, rsAPI)
+		userAPI := userapi.NewInternalAPI(base, &base.Cfg.UserAPI, nil, keyAPI, rsAPI, nil)
+		asAPI := appservice.NewInternalAPI(base, userAPI, rsAPI)
+		rsAPI.SetFederationAPI(nil, nil) // creates the rs.Inputer etc
+
+		// Create the users in the userapi
+		for _, u := range []*test.User{alice, bob, charlie} {
+			localpart, serverName, _ := gomatrixserverlib.SplitID('@', u.ID)
+			userRes := &uapi.PerformAccountCreationResponse{}
+			if err := userAPI.PerformAccountCreation(ctx, &uapi.PerformAccountCreationRequest{
+				AccountType: u.AccountType,
+				Localpart:   localpart,
+				ServerName:  serverName,
+				Password:    "someRandomPassword",
+			}, userRes); err != nil {
+				t.Errorf("failed to create account: %s", err)
+			}
+
+		}
+
+		aliceDev := &uapi.Device{UserID: alice.ID}
+		bobDev := &uapi.Device{UserID: bob.ID}
+		charlieDev := &uapi.Device{UserID: charlie.ID, AccountType: uapi.AccountTypeGuest}
+
+		// create a room with disabled guest access and invite Bob
+		resp := createRoom(ctx, createRoomRequest{
+			Name:          "testing",
+			IsDirect:      true,
+			Topic:         "testing",
+			Visibility:    "public",
+			Preset:        presetPublicChat,
+			RoomAliasName: "alias",
+			Invite:        []string{bob.ID},
+			GuestCanJoin:  false,
+		}, aliceDev, &base.Cfg.ClientAPI, userAPI, rsAPI, asAPI, time.Now())
+		crResp, ok := resp.JSON.(createRoomResponse)
+		if !ok {
+			t.Fatalf("response is not a createRoomResponse: %+v", resp)
+		}
+
+		// create a room with guest access enabled and invite Charlie
+		resp = createRoom(ctx, createRoomRequest{
+			Name:         "testing",
+			IsDirect:     true,
+			Topic:        "testing",
+			Visibility:   "public",
+			Preset:       presetPublicChat,
+			Invite:       []string{charlie.ID},
+			GuestCanJoin: true,
+		}, aliceDev, &base.Cfg.ClientAPI, userAPI, rsAPI, asAPI, time.Now())
+		crRespWithGuestAccess, ok := resp.JSON.(createRoomResponse)
+		if !ok {
+			t.Fatalf("response is not a createRoomResponse: %+v", resp)
+		}
+
+		// Dummy request
+		body := &bytes.Buffer{}
+		req, err := http.NewRequest(http.MethodPost, "/?server_name=test", body)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		testCases := []struct {
+			name        string
+			device      *uapi.Device
+			roomID      string
+			wantHTTP200 bool
+		}{
+			{
+				name:        "User can join successfully by alias",
+				device:      bobDev,
+				roomID:      crResp.RoomAlias,
+				wantHTTP200: true,
+			},
+			{
+				name:        "User can join successfully by roomID",
+				device:      bobDev,
+				roomID:      crResp.RoomID,
+				wantHTTP200: true,
+			},
+			{
+				name:   "join is forbidden if user is guest",
+				device: charlieDev,
+				roomID: crResp.RoomID,
+			},
+			{
+				name:   "room does not exist",
+				device: aliceDev,
+				roomID: "!doesnotexist:test",
+			},
+			{
+				name:   "user from different server",
+				device: &uapi.Device{UserID: "@wrong:server"},
+				roomID: crResp.RoomAlias,
+			},
+			{
+				name:   "user doesn't exist locally",
+				device: &uapi.Device{UserID: "@doesnotexist:test"},
+				roomID: crResp.RoomAlias,
+			},
+			{
+				name:   "invalid room ID",
+				device: aliceDev,
+				roomID: "invalidRoomID",
+			},
+			{
+				name:   "roomAlias does not exist",
+				device: aliceDev,
+				roomID: "#doesnotexist:test",
+			},
+			{
+				name:   "room with guest_access event",
+				device: charlieDev,
+				roomID: crRespWithGuestAccess.RoomID,
+			},
+		}
+
+		for _, tc := range testCases {
+			t.Run(tc.name, func(t *testing.T) {
+				joinResp := JoinRoomByIDOrAlias(req, tc.device, rsAPI, userAPI, tc.roomID)
+				if tc.wantHTTP200 && !joinResp.Is2xx() {
+					t.Fatalf("expected join room to succeed, but didn't: %+v", joinResp)
+				}
+			})
+		}
+	})
+}