Show decryption errors more accurately. Fixes #174

2 files changed, 76 insertions, 9 deletions

diff --git a/matrix/matrix.go b/matrix/matrix.go
index 0553910..b07fa82 100644
--- a/matrix/matrix.go
+++ b/matrix/matrix.go
@@ -352,7 +352,7 @@ func (c *Container) OnLogin() {
 		})
 		c.syncer.OnEventType(event.EventEncrypted, c.HandleEncrypted)
 	} else {
-		c.syncer.OnEventType(event.EventEncrypted, c.HandleMessage)
+		c.syncer.OnEventType(event.EventEncrypted, c.HandleEncryptedUnsupported)
 	}
 	c.syncer.OnEventType(event.EventMessage, c.HandleMessage)
 	c.syncer.OnEventType(event.EventSticker, c.HandleMessage)
@@ -554,11 +554,23 @@ func (c *Container) HandleReaction(room *rooms.Room, reactsTo id.EventID, reactE
 	}
 }
 
+func (c *Container) HandleEncryptedUnsupported(source mautrix.EventSource, mxEvent *event.Event) {
+	mxEvent.Type = muksevt.EventEncryptionUnsupported
+	origContent, _ := mxEvent.Content.Parsed.(*event.EncryptedEventContent)
+	mxEvent.Content.Parsed = muksevt.EncryptionUnsupportedContent{Original: origContent}
+	c.HandleMessage(source, mxEvent)
+}
+
 func (c *Container) HandleEncrypted(source mautrix.EventSource, mxEvent *event.Event) {
 	evt, err := c.crypto.DecryptMegolmEvent(mxEvent)
 	if err != nil {
-		debug.Print("Failed to decrypt event:", err)
-		// TODO add decryption failed message instead of passing through directly
+		debug.Printf("Failed to decrypt event %s: %v", mxEvent.ID, err)
+		mxEvent.Type = muksevt.EventBadEncrypted
+		origContent, _ := mxEvent.Content.Parsed.(*event.EncryptedEventContent)
+		mxEvent.Content.Parsed = &muksevt.BadEncryptedContent{
+			Original: origContent,
+			Reason:   err.Error(),
+		}
 		c.HandleMessage(source, mxEvent)
 		return
 	}
@@ -987,13 +999,24 @@ func (c *Container) GetHistory(room *rooms.Room, limit int, dbPointer uint64) ([
 			debug.Printf("Failed to unmarshal content of event %s (type %s) by %s in %s: %v\n%s", evt.ID, evt.Type.Repr(), evt.Sender, evt.RoomID, err, string(evt.Content.VeryRaw))
 		}
 
-		if c.crypto != nil && evt.Type == event.EventEncrypted {
-			decrypted, err := c.crypto.DecryptMegolmEvent(evt)
-			if err != nil {
-				debug.Print("Failed to decrypt event:", err)
-				// TODO add decryption failed message instead of passing through directly
+		if evt.Type == event.EventEncrypted {
+			if c.crypto == nil {
+				evt.Type = muksevt.EventEncryptionUnsupported
+				origContent, _ := evt.Content.Parsed.(*event.EncryptedEventContent)
+				evt.Content.Parsed = muksevt.EncryptionUnsupportedContent{Original: origContent}
 			} else {
-				resp.Chunk[i] = decrypted
+				decrypted, err := c.crypto.DecryptMegolmEvent(evt)
+				if err != nil {
+					debug.Printf("Failed to decrypt event %s: %v", evt.ID, err)
+					evt.Type = muksevt.EventBadEncrypted
+					origContent, _ := evt.Content.Parsed.(*event.EncryptedEventContent)
+					evt.Content.Parsed = &muksevt.BadEncryptedContent{
+						Original: origContent,
+						Reason:   err.Error(),
+					}
+				} else {
+					resp.Chunk[i] = decrypted
+				}
 			}
 		}
 	}
diff --git a/matrix/muksevt/content.go b/matrix/muksevt/content.go
new file mode 100644
index 0000000..fb78323
--- /dev/null
+++ b/matrix/muksevt/content.go
@@ -0,0 +1,44 @@
+// gomuks - A terminal Matrix client written in Go.
+// Copyright (C) 2020 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package muksevt
+
+import (
+	"encoding/gob"
+	"reflect"
+
+	"maunium.net/go/mautrix/event"
+)
+
+var EventBadEncrypted = event.Type{Type: "net.maunium.gomuks.bad_encrypted", Class: event.MessageEventType}
+var EventEncryptionUnsupported = event.Type{Type: "net.maunium.gomuks.encryption_unsupported", Class: event.MessageEventType}
+
+type BadEncryptedContent struct {
+	Original *event.EncryptedEventContent `json:"-"`
+
+	Reason string `json:"-"`
+}
+
+type EncryptionUnsupportedContent struct {
+	Original *event.EncryptedEventContent `json:"-"`
+}
+
+func init() {
+	gob.Register(&BadEncryptedContent{})
+	gob.Register(&EncryptionUnsupportedContent{})
+	event.TypeMap[EventBadEncrypted] = reflect.TypeOf(&BadEncryptedContent{})
+	event.TypeMap[EventEncryptionUnsupported] = reflect.TypeOf(&EncryptionUnsupportedContent{})
+}