From b4ba0be6bae33f21c723702e83483742540b3c8a Mon Sep 17 00:00:00 2001
From: Till Faelligen <tfaelligen@gmail.com>
Date: Thu, 15 Oct 2020 21:18:18 +0200
Subject: [PATCH] Make "Inbound federation rejects receipts from wrong remote"
 pass

---
 federationapi/routing/send.go | 72 +++++++++++++++++++++++++++++++++++
 sytest-whitelist              |  3 +-
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/federationapi/routing/send.go b/federationapi/routing/send.go
index 783fdc3b8..42c45d0e0 100644
--- a/federationapi/routing/send.go
+++ b/federationapi/routing/send.go
@@ -30,6 +30,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -322,12 +323,83 @@ func (t *txnReq) processEDUs(ctx context.Context) {
 			}
 		case gomatrixserverlib.MDeviceListUpdate:
 			t.processDeviceListUpdate(ctx, e)
+		case "m.receipt": // to be replaced by gomatrixserverlib.MReceipt
+			// https://matrix.org/docs/spec/server_server/r0.1.4#receipts
+			payload := receiptPayload{}
+
+			if err := json.Unmarshal(e.Content, &payload.Data); err != nil {
+				util.GetLogger(ctx).WithError(err).Error("Failed to unmarshal receipt event")
+				continue
+			}
+
+			for roomID, receipt := range payload.Data {
+				for userID := range receipt.MRead {
+					_, domain, err := gomatrixserverlib.SplitID('@', userID)
+					if err != nil {
+						util.GetLogger(ctx).WithError(err).Error("Failed to split domain from receipt event sender")
+						continue
+					}
+					if t.Origin != domain {
+						util.GetLogger(ctx).Warnf("Dropping receipt event where sender domain (%q) doesn't match origin (%q)", domain, t.Origin)
+						continue
+					}
+					ts := receipt.MRead[userID].Data.TS
+					events := receipt.MRead[userID].EventIDs
+					if err := t.processReceiptEvent(ctx, userID, roomID, "m.read", ts, events); err != nil {
+						util.GetLogger(ctx).WithError(err).WithFields(logrus.Fields{
+							"sender":  t.Origin,
+							"user_id": userID,
+							"room_id": roomID,
+							"events":  receipt.MRead[userID].EventIDs,
+						}).Error("Failed to send receipt event to edu server")
+						continue
+					}
+				}
+			}
 		default:
 			util.GetLogger(ctx).WithField("type", e.Type).Debug("Unhandled EDU")
 		}
 	}
 }
 
+// ReceiptPayload is the receipt payload passed between servers
+type receiptPayload struct {
+	Data map[string]struct {
+		MRead map[string]struct {
+			Data struct {
+				TS gomatrixserverlib.Timestamp `json:"ts"`
+			} `json:"data"`
+			EventIDs []string `json:"event_ids"`
+		} `json:"m.read"`
+	} `json:"data"`
+}
+
+// processReceiptEvent sends receipt events to the edu server
+func (t *txnReq) processReceiptEvent(ctx context.Context,
+	userID, roomID, receiptType string,
+	timestamp gomatrixserverlib.Timestamp,
+	eventIDs []string,
+) error {
+	// store every event
+	for _, eventID := range eventIDs {
+		req := eduserverAPI.InputReceiptEventRequest{
+			InputReceiptEvent: eduserverAPI.InputReceiptEvent{
+				UserID:    userID,
+				RoomID:    roomID,
+				EventID:   eventID,
+				Type:      receiptType,
+				Timestamp: timestamp,
+			},
+		}
+		resp := eduserverAPI.InputReceiptEventResponse{}
+		if err := t.eduAPI.InputReceiptEvent(ctx, &req, &resp); err != nil {
+			return errors.Wrap(err, "unable to set receipt event")
+		}
+	}
+
+	return nil
+}
+
 func (t *txnReq) processDeviceListUpdate(ctx context.Context, e gomatrixserverlib.EDU) {
 	var payload gomatrixserverlib.DeviceListUpdateEvent
 	if err := json.Unmarshal(e.Content, &payload); err != nil {
diff --git a/sytest-whitelist b/sytest-whitelist
index f31b5f0b7..f5ba5fce1 100644
--- a/sytest-whitelist
+++ b/sytest-whitelist
@@ -488,4 +488,5 @@ POST /rooms/:room_id/receipt can create receipts
 Receipts must be m.read
 Read receipts appear in initial v2 /sync
 New read receipts appear in incremental v2 /sync
-Outbound federation sends receipts
\ No newline at end of file
+Outbound federation sends receipts
+Inbound federation rejects receipts from wrong remote
\ No newline at end of file