Formatted (HTML) messages with markdown features are rendered incorrectly as markdown

[tulir]

When the formatted_body field of a "format": "org.matrix.custom.html" message contains special markdown characters, they're rendered as markdown instead of as plain text. This could be an actual problem if you escape markdown characters in a message that contains other formatting

Exaggerated example

Expected rendering

Actual rendering

Event source

{
  "type": "m.room.message",
  "sender": "@tulir:maunium.net",
  "content": {
    "msgtype": "m.text",
    "body": "Blank message (or is it? 🤔)",
    "format": "org.matrix.custom.html",
    "formatted_body": "---\n> * # [`RiotX` renders this message ***completely incorrectly***](https://github.com/vector-im/riotX-android/issues/289#issuecomment-510894293)\n---"
  },
  "event_id": "$156295723912295JSonL:maunium.net",
  "origin_server_ts": 1562957239380,
  "unsigned": {
    "age": 52
  },
  "room_id": "!tTIucwUZLRtKnXeurb:matrix.org"
}

Non-exaggerated example

Expected rendering

Actual rendering

Event source

{
  "type": "m.room.message",
  "sender": "@tulir:maunium.net",
  "content": {
    "msgtype": "m.text",
    "format": "org.matrix.custom.html",
    "body": "*less exaggerated example*: \\*\\*stars!**",
    "formatted_body": "<em>less exaggerated example</em>: **stars!**"
  },
  "event_id": "$156295796112315whymM:maunium.net",
  "origin_server_ts": 1562957961390,
  "unsigned": {
    "age": 170
  },
  "room_id": "!jhpZBTbckszblMYjMK:matrix.org"
}

Real-life example

matrix:room/riotx:matrix.org/event/$15630377604255dZoDF:hacklab.fi

This one was a reply sent from RiotX, which had indentation in the fallback format for some reason. The indentation of course turned into a code block because that's what a markdown parser does.

This specific example could be fixed by

• fixing whatever caused the indentation, or
• adding reply rendering to RiotX,

but of course neither of those is a proper fix to this issue.

Expected rendering

Actual rendering

Event source

{
  "content": {
    "body": "><@marmulak:converser.eu> Does the \"black\" theme work for reducing power consumption on oled displays?\n\nYes, the dark theme will reduce power consumption and the black theme will reduce it a bit more",
    "format": "org.matrix.custom.html",
    "formatted_body": "<mx-reply>\n               <blockquote>\n                   <a href=\"https://matrix.to/#/!tTIucwUZLRtKnXeurb:matrix.org/$1563036634937vaAEg:converser.eu\">In reply to</a>\n                   <a href=\"https://matrix.to/#/@marmulak:converser.eu\">@marmulak:converser.eu</a>\n                   <br />\n                   <p>Does the &quot;black&quot; theme work for reducing power consumption on oled displays?</p>\n\n               </blockquote>\n           </mx-reply>\n           Yes, the dark theme will reduce power consumption and the black theme will reduce it a bit more",
    "m.relates_to": {
      "m.in_reply_to": {
        "event_id": "$1563036634937vaAEg:converser.eu"
      }
    },
    "msgtype": "m.text"
  },
  "event_id": "$15630377604255dZoDF:hacklab.fi",
  "origin_server_ts": 1563037760897,
  "sender": "@vurpo:hacklab.fi",
  "type": "m.room.message",
  "unsigned": {
    "age": 630
  },
  "room_id": "!tTIucwUZLRtKnXeurb:matrix.org"
}

[bmarty]

I reopen the issue, we will close it once when we can confirm that we do not reproduce it

[jwh]

\/\/\/\/

[cloudrac3r]

I reopen the issue, we will close it once when we can confirm that we do not reproduce it

This really is fixed by #6357 and won't be reproduced anymore.

[bmarty]

@cloudrac3r OK, thanks!
#6357 is included in Element Android 1.4.26.