discord: strip short-lived URL, pass attachment as raw bytes

Author: selfhoster1312

bridge/discord/handlers.go

@@ -211,7 +211,9 @@ func (b *Bdiscord) messageCreate(s *discordgo.Session, m *discordgo.MessageCreat
 	go func() {
 		count := 0
 		for _, attach := range m.Attachments {
-			err := b.AddAttachmentFromURL(&rmsg, attach.Filename, attach.ID, "", attach.URL)
+			// The URL isn't technically private, but it's short-lived so we
+			// strip it so other networks don't rely on it (attachment passed as bytes).
+			err := b.AddAttachmentFromProtectedURL(&rmsg, attach.Filename, attach.ID, "", attach.URL)
 			if err != nil {
 				b.Log.WithError(err).Warnf("Failed to download attachment %s", attach.Filename)
 				continue

changelog.md

@@ -23,6 +23,8 @@
 - irc: Leading colon messages are no longer doubled by default as an undocumented hack (eg `:D` -> `::D`); it's now enabled by the `DoubleColonPrefix` setting.
   If you are using this setting please help us understand the usecase by commenting
   on [issue #122](https://github.com/matterbridge-org/matterbridge/issues/122), otherwise this setting may be deprecated in the near-future.
+- discord: Attachments are now passed as raw bytes and reuploaded either to the mediaserver, or to the destination bridges,
+  as discord CDN URLs are short-lived and people from other bridges would complain about broken URLs
 
 ## New Features