Add some roomserver UTs (#3067)

Adds tests for `QueryRestrictedJoinAllowed`, `IsServerAllowed` and
`PerformRoomUpgrade`. Refactors the `QueryRoomVersionForRoom` method to
accept a string and return a `gmsl.RoomVersion` instead of req/resp
structs.
Adds some more caching for `GetStateEvent`

This should also fix #2912 by ignoring state events belonging to other
users.

roomserver/auth/auth.go

@@ -26,6 +26,10 @@ func IsServerAllowed(
 	serverCurrentlyInRoom bool,
 	authEvents []*gomatrixserverlib.Event,
 ) bool {
+	// In practice should not happen, but avoids unneeded CPU cycles
+	if serverName == "" || len(authEvents) == 0 {
+		return false
+	}
 	historyVisibility := HistoryVisibilityForRoom(authEvents)
 
 	// 1. If the history_visibility was set to world_readable, allow.

roomserver/auth/auth_test.go

@@ -0,0 +1,85 @@
+package auth
+
+import (
+	"testing"
+
+	"github.com/matrix-org/dendrite/test"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/gomatrixserverlib/spec"
+)
+
+func TestIsServerAllowed(t *testing.T) {
+	alice := test.NewUser(t)
+
+	tests := []struct {
+		name                  string
+		want                  bool
+		roomFunc              func() *test.Room
+		serverName            spec.ServerName
+		serverCurrentlyInRoom bool
+	}{
+		{
+			name:     "no servername specified",
+			roomFunc: func() *test.Room { return test.NewRoom(t, alice) },
+		},
+		{
+			name:       "no authEvents specified",
+			serverName: "test",
+			roomFunc:   func() *test.Room { return &test.Room{} },
+		},
+		{
+			name:       "default denied",
+			serverName: "test2",
+			roomFunc:   func() *test.Room { return test.NewRoom(t, alice) },
+		},
+		{
+			name:       "world readable room",
+			serverName: "test",
+			roomFunc: func() *test.Room {
+				return test.NewRoom(t, alice, test.RoomHistoryVisibility(gomatrixserverlib.HistoryVisibilityWorldReadable))
+			},
+			want: true,
+		},
+		{
+			name:       "allowed due to alice being joined",
+			serverName: "test",
+			roomFunc:   func() *test.Room { return test.NewRoom(t, alice) },
+			want:       true,
+		},
+		{
+			name:                  "allowed due to 'serverCurrentlyInRoom'",
+			serverName:            "test2",
+			roomFunc:              func() *test.Room { return test.NewRoom(t, alice) },
+			want:                  true,
+			serverCurrentlyInRoom: true,
+		},
+		{
+			name:       "allowed due to pending invite",
+			serverName: "test2",
+			roomFunc: func() *test.Room {
+				bob := test.User{ID: "@bob:test2"}
+				r := test.NewRoom(t, alice, test.RoomHistoryVisibility(gomatrixserverlib.HistoryVisibilityInvited))
+				r.CreateAndInsert(t, alice, spec.MRoomMember, map[string]interface{}{
+					"membership": spec.Invite,
+				}, test.WithStateKey(bob.ID))
+				return r
+			},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.roomFunc == nil {
+				t.Fatalf("missing roomFunc")
+			}
+			var authEvents []*gomatrixserverlib.Event
+			for _, ev := range tt.roomFunc().Events() {
+				authEvents = append(authEvents, ev.Event)
+			}
+
+			if got := IsServerAllowed(tt.serverName, tt.serverCurrentlyInRoom, authEvents); got != tt.want {
+				t.Errorf("IsServerAllowed() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}