Hi, we are getting these Tracebacks from time to time in the prosody logfile: Oct 01 11:33:07 mod_c2s error Traceback[c2s]: /usr/lib/prosody/modules/mod_presence.lua:67: invalid value (table) at index 2 in table for 'concat' stack traceback: [C]: in function 't_concat' /usr/lib/prosody/modules/mod_presence.lua:67: in function 'handle_normal_presence' /usr/lib/prosody/modules/mod_presence.lua:325: in function '?' /usr/lib/prosody/util/events.lua:67: in function 'fire_event' /usr/lib/prosody/core/stanza_router.lua:187: in function 'core_post_stanza' /usr/lib/prosody/core/stanza_router.lua:135: in function </usr/lib/prosody/core/stanza_router.lua:56> (tail call): ? [C]: in function 'xpcall' /usr/lib/prosody/modules/mod_c2s.lua:123: in function 'cb_handlestanza' /usr/lib/prosody/util/xmppstream.lua:187: in function </usr/lib/prosody/util/xmppstream.lua:167> [C]: in function 'parse' /usr/lib/prosody/util/xmppstream.lua:255: in function 'feed' /usr/lib/prosody/modules/mod_c2s.lua:230: in function 'data' /usr/lib/prosody/modules/mod_c2s.lua:252: in function </usr/lib/prosody/modules/mod_c2s.lua:249> (tail call): ? /usr/lib/prosody/net/server_select.lua:854: in function </usr/lib/prosody/net/server_select.lua:836> [C]: in function 'xpcall' /usr/bin/prosody:376: in function 'loop' /usr/bin/prosody:407: in main chunk [C]: ? Is there anything bad happening? Regards Robert

This seems to be what happens if someone sends a broken presence stanza. E.g: <presence><priority>123<cause-traceback/></priority></presence>

• title Invalid presence causes traceback
• tag Status-Accepted

Also happened to me today, running 0.9.10 on Debian.

• owner Zash
• tags Milestone-0.10 Status-Started

Fixed in https://hg.prosody.im/0.10/rev/194409dcba22 Clients triggering this would be breaking a MUST. If we ever do any more careful stanza validation, this would could be rejected. For now it will be forwarded. https://xmpp.org/rfcs/rfc6121.html#presence-syntax-children-priority

• tags Status-Fixed

"Be conservative in what you do, be liberal in what you accept from others." https://en.wikipedia.org/wiki/Robustness_principle Do not rely on any standard when dealing with external input.

https://tools.ietf.org/html/draft-thomson-postel-was-wrong-00