Some Telegram channels copied to Mattermost always show user as [Unknown]

[nikkilocke]

See #1430 (comment)
I have opened a new conversation, because the subject of that one did not reflect the remaining problem.

I am copying messages from a broadcast only channel on Telegram into Mattermost. Every message shows the user as [Unknown].

The debug log for a typical message looks like this:

time="2021-03-26T15:08:12Z" level=debug msg="== Receiving event: (*tgbotapi.Message)(nil)" func=handleRecv file="bridge/telegram/handlers.go:121" prefix=telegram
time="2021-03-26T15:08:12Z" level=debug msg="<= Sending message from unknown on telegram.digital-reb to gateway" func=handleRecv file="bridge/telegram/handlers.go:173" prefix=telegram
time="2021-03-26T15:08:12Z" level=debug msg="<= Message is config.Message{Text:"Forwarded from unknown: United for Black Lives is a coalition of BLM Groups from across the UK. We are reclaiming the 21st March back to its origin, as a vehicle for change to inspire Black youths and Black communities.\nJoin us for an amazing event, with speakers from across the diaspora and the continent. \nPlease register here: https://buytickets.at/unitedforblacklives/493138\n#BlackYouthMatter #IDERD #UnitedForBlackLives", Channel:"-1001469059055", Username:"unknown", UserID:"", Avatar:"", Account:"telegram.digital-reb", Event:"", Protocol:"", Gateway:"", ParentID:"", Timestamp:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}, ID:"6", Extra:map[string][]interface {}{}}" func=handleRecv file="bridge/telegram/handlers.go:174" prefix=telegram
time="2021-03-26T15:08:12Z" level=debug msg="=> Sending config.Message{Text:"Forwarded from unknown: United for Black Lives is a coalition of BLM Groups from across the UK. We are reclaiming the 21st March back to its origin, as a vehicle for change to inspire Black youths and Black communities.\nJoin us for an amazing event, with speakers from across the diaspora and the continent. \nPlease register here: https://buytickets.at/unitedforblacklives/493138\n#BlackYouthMatter #IDERD #UnitedForBlackLives", Channel:"-1001469059055", Username:"unknown", UserID:"", Avatar:"", Account:"telegram.digital-reb", Event:"", Protocol:"telegram", Gateway:"test", ParentID:"", Timestamp:time.Time{wall:0xc00f9c1734aa097d, ext:63924141941, loc:(*time.Location)(0x33419a0)}, ID:"6", Extra:map[string][]interface {}{}} from telegram.digital-reb (-1001469059055) to mattermost.test (rollout)" func=SendMessage file="gateway/gateway.go:421" prefix=gateway
time="2021-03-26T15:08:12Z" level=debug msg="=> Receiving config.Message{Text:"Forwarded from unknown: United for Black Lives is a coalition of BLM Groups from across the UK. We are reclaiming the 21st March back to its origin, as a vehicle for change to inspire Black youths and Black communities.\nJoin us for an amazing event, with speakers from across the diaspora and the continent. \nPlease register here: https://buytickets.at/unitedforblacklives/493138\n#BlackYouthMatter #IDERD #UnitedForBlackLives", Channel:"rollout", Username:"[unknown] ", UserID:"", Avatar:"", Account:"telegram.digital-reb", Event:"", Protocol:"telegram", Gateway:"test", ParentID:"", Timestamp:time.Time{wall:0xc00f9c1734aa097d, ext:63924141941, loc:(*time.Location)(0x33419a0)}, ID:"", Extra:map[string][]interface {}{}}" func=Send file="bridge/mattermost/mattermost.go:99" prefix=mattermost
time="2021-03-26T15:08:14Z" level=debug msg="map[string]interface {}{"channel_display_name":"Rollout", "channel_name":"rollout", "channel_type":"O", "post":"{\"id\":\"6i87ag471fydzbs7mkgpabzudy\",\"create_at\":1616771292978,\"update_at\":1616771292978,\"edit_at\":0,\"delete_at\":0,\"is_pinned\":false,\"user_id\":\"oxthbu6y3pyc8ptmmux6hyg49y\",\"channel_id\":\"pdbkt9nft3b1xfqiobuf64nn3y\",\"root_id\":\"\",\"parent_id\":\"\",\"original_id\":\"\",\"message\":\"[unknown] Forwarded from unknown: United for Black Lives is a coalition of BLM Groups from across the UK. We are reclaiming the 21st March back to its origin, as a vehicle for change to inspire Black youths and Black communities.\\nJoin us for an amazing event, with speakers from across the diaspora and the continent. \\nPlease register here: https://buytickets.at/unitedforblacklives/493138\\n#BlackYouthMatter #IDERD #UnitedForBlackLives\",\"type\":\"\",\"props\":{},\"hashtags\":\"#BlackYouthMatter #IDERD #UnitedForBlackLives\",\"pending_post_id\":\"\",\"reply_count\":0,\"metadata\":{}}", "sender_name":"@matterbridge", "set_online":true, "team_id":"nc8q5ufmb7ryzdarzjto94ugtw"}" func=handleMatterClient file="bridge/mattermost/handlers.go:91" prefix=mattermost
time="2021-03-26T15:08:14Z" level=debug msg="Skipped message: &matterclient.Message{Raw:(*model.WebSocketEvent)(0xc000683f50), Post:(*model.Post)(0xc000c40000), Team:"migration-team", Channel:"rollout", Username:"matterbridge", Text:"[unknown] Forwarded from unknown: United for Black Lives is a coalition of BLM Groups from across the UK. We are reclaiming the 21st March back to its origin, as a vehicle for change to inspire Black youths and Black communities.\nJoin us for an amazing event, with speakers from across the diaspora and the continent. \nPlease register here: https://buytickets.at/unitedforblacklives/493138\n#BlackYouthMatter #IDERD #UnitedForBlackLives", Type:"", UserID:"oxthbu6y3pyc8ptmmux6hyg49y"}" func=handleMatterClient file="bridge/mattermost/handlers.go:94" prefix=mattermost
time="2021-03-26T15:08:14Z" level=debug msg="mID mattermost.test: 6i87ag471fydzbs7mkgpabzudy" func=SendMessage file="gateway/gateway.go:464" prefix=gateway

The exact same message forwarded to json Dump Bot shows:
{
"update_id": 144017831,
"message": {
"message_id": 332567,
"from": {
"id": 983940580,
"is_bot": false,
"first_name": "Nikki",
"language_code": "en"
},
"chat": {
"id": 983940580,
"first_name": "Nikki",
"type": "private"
},
"date": 1617037191,
"forward_from_chat": {
"id": -1001448546101,
"title": "Rebellion Broadcast",
"username": "rebellionbroadcast",
"type": "channel"
},
"forward_from_message_id": 447,
"forward_date": 1616181859,
"text": "✊🏿 ✊🏾✊🏼 People power works! -...",
"entities": [
{
"offset": 11,
"length": 69,
"type": "bold"
},
{
"offset": 471,
"length": 12,
"type": "hashtag"
},
{
"offset": 632,
"length": 62,
"type": "url"
},
{
"offset": 772,
"length": 95,
"type": "url"
},
{
"offset": 880,
"length": 12,
"type": "hashtag"
},
{
"offset": 919,
"length": 38,
"type": "url"
}
]
}
}

So the poster information is there, somewhere, it's just not getting through to Matterbridge.

[nikkilocke]

My matterbridge copies a lot of different channels, copying to the same Mattermost Team - some always have the user as Unknown, and others show it fine. I have no idea what the difference is.
I attempted to work round the problem by creating two entries for the team, under different names, one with PrefixMessagesWithNick=true and the other with PrefixMessagesWithNick=false. But Matterbridge didn't like that.

[nikkilocke]

Aha! Looks like its the difference between a channel (no user names) and a group (user names).

[nikkilocke]

Also, I discovered what the problem was with having two different entries for the same team - I had called them mattermost.uk and mattermost.uk.nonick. It seems dot (.) is significant in some way - if I use mattermost.uk and mattermost.uk-nonick it works fine, so I now have a workround.

[nikkilocke]

Sorry if I'm being a pain with my questions - if there is some documentation that would tell me all this, please send me a link!

[42wim]

@nikkilocke using 2 dots in [mattermost.team.somethingelse] isn't possible, I should document that.
About telegram it was in #1172 and linked on https://github.com/42wim/matterbridge/wiki/Gateway-config-(channel-rules)
I'll add it to the telegram FAQ also.

Telegram channels will always return unknown users. Telegram groups will show usernames if possible

[nikkilocke]

Thanks for all your help. I am finding some minor issues with the conversion of telegram messages to markdown. Do you want examples?