Add a way to set custom room version impls (#455)

We have this lovely room version abstraction, but... no one can actually
use it without getting it into this map. Let's fix that.

Author: kegsay

eventauth.go

@@ -1158,7 +1158,12 @@ func (m *membershipAllower) membershipAllowedSelf() error { // nolint: gocyclo
 	switch m.newMember.Membership {
 	case spec.Knock:
 		// Check if the given roomVersionImpl allows knocking.
-		return m.roomVersionImpl.CheckKnockingAllowed(m)
+		return m.roomVersionImpl.CheckKnockingAllowed(
+			string(m.roomVersionImpl.Version()),
+			m.senderID, m.targetID,
+			m.joinRule.JoinRule,
+			m.oldMember.Membership,
+		)
 	case spec.Join:
 		if m.joinRule.JoinRule == spec.Restricted || m.joinRule.JoinRule == spec.KnockRestricted {
 			if err := m.membershipAllowedSelfForRestrictedJoin(); err != nil {
@@ -1227,11 +1232,17 @@ func disallowRestrictedJoins() error {
 	return errorf("restricted joins are not supported in this room version")
 }
 
-func disallowKnocking(m *membershipAllower) error {
-	return m.membershipFailed(
-		"room version %q does not support knocking on rooms with join rule %q",
-		m.roomVersionImpl.Version(),
-		m.joinRule.JoinRule,
+func disallowKnocking(roomVer, sender, target, joinRule, prevMembership string) error {
+	if sender == target {
+		return errorf(
+			"%q is not allowed to change their membership from %q as room version %q does not support knocking on rooms with join rule %q",
+			sender, prevMembership, roomVer, joinRule,
+		)
+	}
+
+	return errorf(
+		"%q is not allowed to change the membership of %q from %q as room version %q does not support knocking on rooms with join rule %q",
+		sender, target, prevMembership, roomVer, joinRule,
 	)
 }
 
@@ -1242,23 +1253,25 @@ func disallowKnocking(m *membershipAllower) error {
 // MSC3787 extends this: the behaviour above is also permitted if the
 // join rules are "knock_restricted"
 // Spec: https://github.com/matrix-org/matrix-spec-proposals/pull/3787
-func checkKnocking(m *membershipAllower) error {
+func checkKnocking(roomVer, sender, target, joinRule, prevMembership string) error {
 	// If the join_rule is anything other than knock or knock_restricted, reject.
-	supported := m.joinRule.JoinRule == spec.Knock || m.joinRule.JoinRule == spec.KnockRestricted
+	supported := joinRule == spec.Knock || joinRule == spec.KnockRestricted
 	if !supported {
-		return m.membershipFailed(
-			"room version %q does not support knocking on rooms with join rule %q",
-			m.roomVersionImpl.Version(),
-			m.joinRule.JoinRule,
+		return errorf(
+			"%q is not allowed to change the membership of %q from %q as room version %q does not support knocking on rooms with join rule %q",
+			sender, target, prevMembership,
+			roomVer,
+			joinRule,
 		)
 	}
-	switch m.oldMember.Membership {
+	switch prevMembership {
 
 	case spec.Join, spec.Invite, spec.Ban:
 		// The user is already joined, invited or banned, therefore they
 		// can't knock.
-		return m.membershipFailed(
-			"sender is already joined/invited/banned",
+		return errorf(
+			"%q is not allowed to change the membership of %q from %q as sender is already joined/invited/banned",
+			sender, target, prevMembership,
 		)
 	}
 	// A non-joined, non-invited, non-banned user is allowed to knock.

eventauth_test.go

@@ -1999,3 +1999,21 @@ func TestJoinRuleKnockRestricted(t *testing.T) {
 		}]
 	}`, RoomVersionV10)
 }
+
+type CustomVer struct {
+	IRoomVersion
+}
+
+func (v CustomVer) Version() RoomVersion {
+	return "hello"
+}
+
+func TestSetRoomVersion(t *testing.T) {
+	// ensure we can set and get custom room versions.
+	// GMSL doesn't use this but users of GMSL do.
+	v := CustomVer{
+		IRoomVersion: MustGetRoomVersion("10"),
+	}
+	SetRoomVersion(v)
+	MustGetRoomVersion("hello")
+}

eventcontent.go

@@ -581,11 +581,11 @@ type RelatesTo struct {
 	RelationType string `json:"rel_type"`
 }
 
-func noCheckCreateEvent(event PDU, knownRoomVersion knownRoomVersionFunc) error {
+func noCheckCreateEvent(event PDU, knownRoomVersion KnownRoomVersionFunc) error {
 	return nil
 }
 
-func checkCreateEvent(event PDU, knownRoomVersion knownRoomVersionFunc) error {
+func checkCreateEvent(event PDU, knownRoomVersion KnownRoomVersionFunc) error {
 	c := struct {
 		Creator     *string      `json:"creator"`
 		RoomVersion *RoomVersion `json:"room_version"`

eventversion.go

@@ -12,6 +12,8 @@ import (
 // RoomVersion refers to the room version for a specific room.
 type RoomVersion string
 
+// The interface which needs to be implemented to register a room version with gomatrixserverlib.
+// All types should be public to allow for extensibility.
 type IRoomVersion interface {
 	Version() RoomVersion
 	Stable() bool
@@ -29,14 +31,14 @@ type IRoomVersion interface {
 
 	RestrictedJoinServername(content []byte) (spec.ServerName, error)
 	CheckRestrictedJoinsAllowed() error
-	CheckKnockingAllowed(m *membershipAllower) error
+	CheckKnockingAllowed(roomVer, sender, target, joinRule, prevMembership string) error
 	CheckNotificationLevels(senderLevel int64, oldPowerLevels, newPowerLevels PowerLevelContent) error
 	CheckCanonicalJSON(input []byte) error
 	ParsePowerLevels(contentBytes []byte, c *PowerLevelContent) error
-	CheckCreateEvent(event PDU, knownRoomVersion knownRoomVersionFunc) error
+	CheckCreateEvent(event PDU, knownRoomVersion KnownRoomVersionFunc) error
 }
 
-type knownRoomVersionFunc func(RoomVersion) bool
+type KnownRoomVersionFunc func(RoomVersion) bool
 
 // StateResAlgorithm refers to a version of the state resolution algorithm.
 type StateResAlgorithm int
@@ -416,6 +418,14 @@ func StableRoomVersions() map[RoomVersion]IRoomVersion {
 	return versions
 }
 
+// SetRoomVersion sets a room version implementation so it is recognised by gomatrixserverlib.
+// This is useful when you are testing custom room versions which gomatrixserverlib may be unaware of,
+// e.g for Complement usage. Full room version impls should be defined in gomatrixserverlib, but
+// partial impls for testing can be set here.
+func SetRoomVersion(ver IRoomVersion) {
+	roomVersionMeta[ver.Version()] = ver
+}
+
 // RoomVersionDescription contains information about a room version,
 // namely whether it is marked as supported or stable in this server
 // version, along with the state resolution algorithm, event ID etc
@@ -440,8 +450,8 @@ type RoomVersionImpl struct {
 	checkRestrictedJoin                    restrictedJoinCheckFunc
 	restrictedJoinServernameFunc           func(content []byte) (spec.ServerName, error)
 	checkRestrictedJoinAllowedFunc         func() error
-	checkKnockingAllowedFunc               func(m *membershipAllower) error
-	checkCreateEvent                       func(e PDU, knownRoomVersion knownRoomVersionFunc) error
+	checkKnockingAllowedFunc               func(roomVer, sender, target, joinRule, prevMembership string) error
+	checkCreateEvent                       func(e PDU, knownRoomVersion KnownRoomVersionFunc) error
 	newEventFromUntrustedJSONFunc          func(eventJSON []byte, roomVersion IRoomVersion) (result PDU, err error)
 	newEventFromTrustedJSONFunc            func(eventJSON []byte, redacted bool, roomVersion IRoomVersion) (result PDU, err error)
 	newEventFromTrustedJSONWithEventIDFunc func(eventID string, eventJSON []byte, redacted bool, roomVersion IRoomVersion) (result PDU, err error)
@@ -483,8 +493,8 @@ func (v RoomVersionImpl) CheckNotificationLevels(senderLevel int64, oldPowerLeve
 }
 
 // CheckKnockingAllowed checks if this room version supports knocking on rooms.
-func (v RoomVersionImpl) CheckKnockingAllowed(m *membershipAllower) error {
-	return v.checkKnockingAllowedFunc(m)
+func (v RoomVersionImpl) CheckKnockingAllowed(roomVer, sender, target, joinRule, prevMembership string) error {
+	return v.checkKnockingAllowedFunc(roomVer, sender, target, joinRule, prevMembership)
 }
 
 // CheckRestrictedJoinsAllowed checks if this room version allows restricted joins.
@@ -508,7 +518,7 @@ func (v RoomVersionImpl) ParsePowerLevels(contentBytes []byte, c *PowerLevelCont
 	return v.parsePowerLevelsFunc(contentBytes, c)
 }
 
-func (v RoomVersionImpl) CheckCreateEvent(event PDU, knownRoomVersion knownRoomVersionFunc) error {
+func (v RoomVersionImpl) CheckCreateEvent(event PDU, knownRoomVersion KnownRoomVersionFunc) error {
 	return v.checkCreateEvent(event, knownRoomVersion)
 }