mod_muc_markers: Add option for @id rewriting, default off (may break some clients) XEP-0333 was updated to clarify that stanza-id should be used instead of the 'id' attribute when in a MUC. Some clients still use the id attribute, which is why we were rewriting it. Rewriting is bad because mod_muc advertises stable_id, indicating that Prosody does *not* rewrite ids. Recent versions of Conversations actually depend on this being true. All clients should migrate to using stanza-id for markers. See XEP-0333.

local base64_encode = require"util.encodings".base64.encode;
local random_bytes = require"util.random".bytes;

local b64url = { ["+"] = "-", ["/"] = "_", ["="] = "" };
local function random_resource()
	return base64_encode(random_bytes(8)):gsub("[+/=]", b64url);
end

module:hook("pre-resource-bind", function (event)
	event.resource = random_resource();
end);