File

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−local ip = require "util.ip";
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−local jid_bare = require "util.jid".bare;
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−local jid_split = require "util.jid".split;
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−local set = require "util.set";
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−local sha256 = require "util.hashes".sha256;
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−local st = require"util.stanza";
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−local is_contact_subscribed = require "core.rostermanager".is_contact_subscribed;
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−local full_sessions = prosody.full_sessions;
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−
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−local user_exists = require "core.usermanager".user_exists;
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−
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−local new_rtbl_subscription = module:require("rtbl").new_rtbl_subscription;
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−local trie = module:require("trie");
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−
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−local spam_source_domains = set.new();
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−local spam_source_ips = trie.new();
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−local spam_source_jids = set.new();
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−
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−local count_spam_blocked = module:metric("counter", "anti_spam_blocked", "stanzas", "Stanzas blocked as spam", {"reason"});
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−
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−local hosts = prosody.hosts;
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−
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−local reason_messages = {
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−	default = "Rejected as spam";
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−	["known-spam-source"] = "Rejected as spam. Your server is listed as a known source of spam. Please contact your server operator.";
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−};
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−
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−function block_spam(event, reason, action)
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−	event.spam_reason = reason;
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−	event.spam_action = action;
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−	if module:fire_event("spam-blocked", event) == false then
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−		module:log("debug", "Spam allowed by another module");
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−		return;
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−	end
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−
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−	count_spam_blocked:with_labels(reason):add(1);
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−
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−	if action == "bounce" then
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−		module:log("debug", "Bouncing likely spam %s from %s (%s)", event.stanza.name, event.stanza.attr.from, reason);
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−		event.origin.send(st.error_reply("cancel", "policy-violation", reason_messages[reason] or reason_messages.default));
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−	else
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−		module:log("debug", "Discarding likely spam %s from %s (%s)", event.stanza.name, event.stanza.attr.from, reason);
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−	end
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−
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−	return true;
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−end
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−
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−function is_from_stranger(from_jid, event)
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−	local stanza = event.stanza;
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−	local to_user, to_host, to_resource = jid_split(stanza.attr.to);
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−
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−	if not to_user then return false; end
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−
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−	local to_session = full_sessions[stanza.attr.to];
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−	if to_session then return false; end
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−
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−	if not is_contact_subscribed(to_user, to_host, from_jid) then
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−		-- Allow all messages from your own jid
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−		if from_jid == to_user.."@"..to_host then
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−			return false; -- Pass through
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−		end
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−		if to_resource and stanza.attr.type == "groupchat" then
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−			return false; -- Pass through
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−		end
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−		return true; -- Stranger danger
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−	end
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−end
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−
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−function is_spammy_server(session)
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−	if spam_source_domains:contains(session.from_host) then
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−		return true;
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−	end
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−	local raw_ip = session.ip;
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−	local parsed_ip = raw_ip and ip.new_ip(session.ip);
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−	-- Not every session has an ip - for example, stanzas sent from a
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−	-- local host session
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−	if parsed_ip and spam_source_ips:contains_ip(parsed_ip) then
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−		return true;
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−	end
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−end
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−
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−function is_spammy_sender(sender_jid)
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−	return spam_source_jids:contains(sha256(sender_jid, true));
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−end
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−
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−local spammy_strings = module:get_option_array("anti_spam_block_strings");
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−local spammy_patterns = module:get_option_array("anti_spam_block_patterns");
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−
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−function is_spammy_content(stanza)
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−	-- Only support message content
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−	if stanza.name ~= "message" then return; end
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−	if not (spammy_strings or spammy_patterns) then return; end
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−
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−	local body = stanza:get_child_text("body");
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−	if not body then return; end
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−
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−	if spammy_strings then
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−		for _, s in ipairs(spammy_strings) do
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−			if body:find(s, 1, true) then
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−				return true;
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−			end
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−		end
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−	end
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−	if spammy_patterns then
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−		for _, s in ipairs(spammy_patterns) do
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−			if body:find(s) then
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−				return true;
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−			end
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−		end
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−	end
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−end
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−
+
−-- Set up RTBLs
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−
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−local anti_spam_services = module:get_option_array("anti_spam_services", {});
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−
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−for _, rtbl_service_jid in ipairs(anti_spam_services) do
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−	new_rtbl_subscription(rtbl_service_jid, "spam_source_domains", {
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−		added = function (item)
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−			spam_source_domains:add(item);
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−		end;
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−		removed = function (item)
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−			spam_source_domains:remove(item);
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−		end;
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−	});
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−	new_rtbl_subscription(rtbl_service_jid, "spam_source_ips", {
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−		added = function (item)
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−			local subnet_ip, subnet_bits = ip.parse_cidr(item);
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−			if not subnet_ip then
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−				return;
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−			end
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−			spam_source_ips:add_subnet(subnet_ip, subnet_bits);
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−		end;
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−		removed = function (item)
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−			local subnet_ip, subnet_bits = ip.parse_cidr(item);
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−			if not subnet_ip then
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−				return;
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−			end
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−			spam_source_ips:remove_subnet(subnet_ip, subnet_bits);
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−		end;
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−	});
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−	new_rtbl_subscription(rtbl_service_jid, "spam_source_jids_sha256", {
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−		added = function (item)
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−			spam_source_jids:add(item);
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−		end;
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−		removed = function (item)
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−			spam_source_jids:remove(item);
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−		end;
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−	});
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−end
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−
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−module:hook("message/bare", function (event)
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−	local to_user, to_host = jid_split(event.stanza.attr.to);
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−
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−	if not hosts[to_host] then
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−		module:log("warn", "Skipping filtering of message to unknown host <%s>", to_host);
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−		return;
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−	end
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−
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−	if not user_exists(to_user, to_host) then return; end
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−
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−	local from_bare = jid_bare(event.stanza.attr.from);
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−	if not is_from_stranger(from_bare, event) then return; end
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−
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−	module:log("debug", "Processing message from stranger...");
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−
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−	if is_spammy_server(event.origin) then
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−		return block_spam(event, "known-spam-source", "drop");
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−	end
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−
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−	if is_spammy_sender(from_bare) then
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−		return block_spam(event, "known-spam-jid", "drop");
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−	end
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−
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−	if is_spammy_content(event.stanza) then
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−		return block_spam(event, "spam-content", "drop");
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−	end
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−
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−	module:log("debug", "Allowing message through");
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−end, 500);
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−
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−module:hook("presence/bare", function (event)
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−	if event.stanza.attr.type ~= "subscribe" then
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−		return;
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−	end
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−
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−	module:log("debug", "Processing subscription request...");
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−
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−	if is_spammy_server(event.origin) then
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−		return block_spam(event, "known-spam-source", "drop");
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−	end
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−
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−	module:log("debug", "Not from known spam source server");
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−
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−	if is_spammy_sender(jid_bare(event.stanza.attr.from)) then
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−		return block_spam(event, "known-spam-jid", "drop");
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−	end
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−
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−	module:log("debug", "Not from known spam source JID");
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−
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−	module:log("debug", "Allowing subscription request through");
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−end, 500);