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Difference between revisions of "XEP-Remarks/XEP-0280: Message Carbons"
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XEP-Remarks/XEP-0280: Message Carbons (view source)
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In the long term, Carbons+MAM might be replaced/updated by some common mechanism that also ensures that a client knows the MAM-ID of sent messages. | In the long term, Carbons+MAM might be replaced/updated by some common mechanism that also ensures that a client knows the MAM-ID of sent messages. | ||
= | = Client-Side Processing = | ||
'''Carbons MUST NOT be accepted from JIDs other than the user's bare account JID''', or else: | |||
* [https://op-co.de/tmp/CVE-2017-5589.html CVE-2017-5589+ Multiple XMPP Clients User Impersonation Vulnerability] | |||
* [https://gultsch.de/dino_multiple.html CVE-2019-16235+ Multiple Vulnerabilities found in Dino] | |||
* [https://monal.im/blog/cve-2020-26547/ CVE-2020-26547 Missing verification of origin of Carbons in Monal] | |||
Before processing a Carbon, the client must determine whether the message was a MUC-PM or a regular chat message (this might require an IQ round-trip to the sending entity). | |||
Possible MUC-PM resolution, "partner" is the sender JID of "received" and the recipient JID of "sent" Carbons: | |||
# If the forwarded message contains an <tt><x xmlns='http://jabber.org/protocol/muc'></tt> payload, it's a PM | |||
# If the partner's bare JID is a known MUC (joined, listed in bookmarks), it's a PM | |||
# If the partner's bare JID is in the roster, it's '''probably''' a normal message (shakes fist at Gajim) | |||
# If still undetermined, send a <tt>disco#info</tt> IQ to the partner's bare JID and delay processing of the Carbon (yes, ewwww!) | |||
# If the <tt>disco#info</tt> response contains <tt><feature var='http://jabber.org/protocol/muc'/></tt> then it's a PM, otherwise it's a normal message. Cache the disco result for next time! | |||
For regular messsages, the client should process the Carbon similarly to a normal message (it might modify notification behavior, but this is not guaranteed to work). | For regular messsages, the client should process the Carbon similarly to a normal message (it might modify notification behavior, but this is not guaranteed to work). | ||
= Handling of MUC-PMs = | = Handling of MUC-PMs = | ||