mod_cloud_notify_encrypted: Ensure body substring remains valid UTF-8 The `body:sub()` call risks splitting the string in the middle of a multi-byte UTF-8 sequence. This should have been caught by util.stanza validation, but that would have caused some havoc, at the very least causing the notification to not be sent. There have been no reports of this happening. Likely because this module isn't widely deployed among users with languages that use many longer UTF-8 sequences. The util.encodings.utf8.valid() function is O(n) where only the last sequence really needs to be checked, but it's in C and expected to be fast.

# Groupchat 1.0 usage statistics gathering

Groupchat 1.0 was probably the protocol that predated
[XEP-0045: Multi-User Chat] and there is still some compatibility that
lives on, in the XEP and in implementations.

This module tries to detect clients still using the GC 1.0 protocol and
what software they run, to determine if support can be removed. 

Since joins in the GC 1.0 protocol are highly ambiguous, some hits
reported will be because of desynchronized MUC clients

# Compatibility

Should work with Prosody 0.10.x and earlier.

It will not work with current trunk, since the MUC code has had major
changes.