# HG changeset patch
# User Matthew Wild <mwild1@gmail.com>
# Date 1365001880 -3600
# Node ID c91cac3b823fb0c25e9da4969f28e13f63ad5da2
# Parent  2c5430ff1c11ee2691ebbdb71be6417a1043696c
mod_firewall: General stanza filtering plugin with a declarative rule-based syntax

diff -r 2c5430ff1c11 -r c91cac3b823f mod_firewall/actions.lib.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_firewall/actions.lib.lua	Wed Apr 03 16:11:20 2013 +0100
@@ -0,0 +1,158 @@
+local action_handlers = {};
+
+-- Takes an XML string and returns a code string that builds that stanza
+-- using st.stanza()
+local function compile_xml(data)
+	local code = {};
+	local first, short_close = true, nil;
+	for tagline, text in data:gmatch("<([^>]+)>([^<]*)") do
+		if tagline:sub(-1,-1) == "/" then
+			tagline = tagline:sub(1, -2);
+			short_close = true;
+		end
+		if tagline:sub(1,1) == "/" then
+			code[#code+1] = (":up()");
+		else
+			local name, attr = tagline:match("^(%S*)%s*(.*)$");
+			local attr_str = {};
+			for k, _, v in attr:gmatch("(%S+)=([\"'])([^%2]-)%2") do
+				if #attr_str == 0 then
+					table.insert(attr_str, ", { ");
+				else
+					table.insert(attr_str, ", ");
+				end
+				if k:match("^%a%w*$") then
+					table.insert(attr_str, string.format("%s = %q", k, v));
+				else
+					table.insert(attr_str, string.format("[%q] = %q", k, v));
+				end
+			end
+			if #attr_str > 0 then
+				table.insert(attr_str, " }");
+			end
+			if first then
+				code[#code+1] = (string.format("st.stanza(%q %s)", name, #attr_str>0 and table.concat(attr_str) or ", nil"));
+				first = nil;
+			else
+				code[#code+1] = (string.format(":tag(%q%s)", name, table.concat(attr_str)));
+			end
+		end
+		if text and text:match("%S") then
+			code[#code+1] = (string.format(":text(%q)", text));
+		elseif short_close then
+			short_close = nil;
+			code[#code+1] = (":up()");
+		end
+	end
+	return table.concat(code, "");
+end
+
+
+function action_handlers.DROP()
+	return "log('debug', 'Firewall dropping stanza: %s', tostring(stanza)); return true;";
+end
+
+function action_handlers.STRIP(tag_desc)
+	local code = {};
+	local name, xmlns = tag_desc:match("^(%S+) (.+)$");
+	if not name then
+		name, xmlns = tag_desc, nil;
+	end
+	if name == "*" then
+		name = nil;
+	end
+	code[#code+1] = ("local stanza_xmlns = stanza.attr.xmlns; ");
+	code[#code+1] = "stanza:maptags(function (tag) if ";
+	if name then
+		code[#code+1] = ("tag.name == %q and "):format(name);
+	end
+	if xmlns then
+		code[#code+1] = ("(tag.attr.xmlns or stanza_xmlns) == %q "):format(xmlns);
+	else
+		code[#code+1] = ("tag.attr.xmlns == stanza_xmlns ");
+	end
+	code[#code+1] = "then return nil; end return tag; end );";
+	return table.concat(code);
+end
+
+function action_handlers.INJECT(tag)
+	return "stanza:add_child("..compile_xml(tag)..")", { "st" };
+end
+
+local error_types = {
+	["bad-request"] = "modify";
+	["conflict"] = "cancel";
+	["feature-not-implemented"] = "cancel";
+	["forbidden"] = "auth";
+	["gone"] = "cancel";
+	["internal-server-error"] = "cancel";
+	["item-not-found"] = "cancel";
+	["jid-malformed"] = "modify";
+	["not-acceptable"] = "modify";
+	["not-allowed"] = "cancel";
+	["not-authorized"] = "auth";
+	["payment-required"] = "auth";
+	["policy-violation"] = "modify";
+	["recipient-unavailable"] = "wait";
+	["redirect"] = "modify";
+	["registration-required"] = "auth";
+	["remote-server-not-found"] = "cancel";
+	["remote-server-timeout"] = "wait";
+	["resource-constraint"] = "wait";
+	["service-unavailable"] = "cancel";
+	["subscription-required"] = "auth";
+	["undefined-condition"] = "cancel";
+	["unexpected-request"] = "wait";
+};
+
+
+local function route_modify(make_new, to, drop)
+	local reroute, deps = "session.send(newstanza)", { "st" };
+	if to then
+		reroute = ("newstanza.attr.to = %q; core_post_stanza(session, newstanza)"):format(to);
+		deps[#deps+1] = "core_post_stanza";
+	end
+	return ([[local newstanza = st.%s; %s; %s; ]])
+		:format(make_new, reroute, drop and "return true" or ""), deps;
+end
+	
+function action_handlers.BOUNCE(with)
+	local error = with and with:match("^%S+") or "service-unavailable";
+	local error_type = error:match(":(%S+)");
+	if not error_type then
+		error_type = error_types[error] or "cancel";
+	else
+		error = error:match("^[^:]+");
+	end
+	error, error_type = string.format("%q", error), string.format("%q", error_type);
+	local text = with and with:match(" %((.+)%)$");
+	if text then
+		text = string.format("%q", text);
+	else
+		text = "nil";
+	end
+	return route_modify(("error_reply(stanza, %s, %s, %s)"):format(error_type, error, text), nil, true);
+end
+
+function action_handlers.REDIRECT(where)
+	return route_modify("clone(stanza)", where, true, true);
+end
+
+function action_handlers.COPY(where)
+	return route_modify("clone(stanza)", where, true, false);
+end
+
+function action_handlers.LOG(string)
+	local level = string:match("^%[(%a+)%]") or "info";
+	string = string:gsub("^%[%a+%] ?", "");
+	return (("log(%q, %q)"):format(level, string)
+		:gsub("$top", [["..stanza:top_tag().."]])
+		:gsub("$stanza", [["..stanza.."]])
+		:gsub("$(%b())", [["..%1.."]]));
+end
+
+function action_handlers.RULEDEP(dep)
+	return "", { dep };
+end
+
+return action_handlers;
diff -r 2c5430ff1c11 -r c91cac3b823f mod_firewall/conditions.lib.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_firewall/conditions.lib.lua	Wed Apr 03 16:11:20 2013 +0100
@@ -0,0 +1,94 @@
+local condition_handlers = {};
+
+local jid = require "util.jid";
+
+-- Return a code string for a condition that checks whether the contents
+-- of variable with the name 'name' matches any of the values in the
+-- comma/space/pipe delimited list 'values'.
+local function compile_comparison_list(name, values)
+	local conditions = {};
+	for value in values:gmatch("[^%s,|]+") do
+		table.insert(conditions, ("%s == %q"):format(name, value));
+	end
+	return table.concat(conditions, " or ");
+end
+
+function condition_handlers.KIND(kind)
+	return compile_comparison_list("name", kind), { "name" };
+end
+
+local wildcard_equivs = { ["*"] = ".*", ["?"] = "." };
+
+local function compile_jid_match_part(part, match)
+	if not match then
+		return part.." == nil"
+	end
+	local pattern = match:match("<(.*)>");
+	-- TODO: Support Lua pattern matching (main issue syntax... << >>?)
+	if pattern then
+		if pattern ~= "*" then
+			return ("%s:match(%q)"):format(part, pattern:gsub(".", wildcard_equivs));
+		end
+	else
+		return ("%s == %q"):format(part, match);
+	end
+end
+
+local function compile_jid_match(which, match_jid)
+	local match_node, match_host, match_resource = jid.split(match_jid);
+	local conditions = {
+		compile_jid_match_part(which.."_node", match_node);
+		compile_jid_match_part(which.."_host", match_host);
+		match_resource and compile_jid_match_part(which.."_resource", match_resource) or nil;
+	};
+	return table.concat(conditions, " and ");
+end
+
+function condition_handlers.TO(to)
+	return compile_jid_match("to", to), { "split_to" };
+end
+
+function condition_handlers.FROM(from)
+	return compile_jid_match("from", from), { "split_from" };
+end
+
+function condition_handlers.TYPE(type)
+	return compile_comparison_list("type", type), { "type" };
+end
+
+function condition_handlers.ENTERING(zone)
+	return ("(zones[%q] and (zones[%q][to_host] or "
+		.."zones[%q][to] or "
+		.."zones[%q][bare_to]))"
+		)
+		:format(zone, zone, zone, zone), { "split_to", "bare_to" };
+end
+
+function condition_handlers.LEAVING(zone)
+	return ("zones[%q] and (zones[%q][from_host] or "
+		.."(zones[%q][from] or "
+		.."zones[%q][bare_from]))")
+		:format(zone, zone, zone, zone), { "split_from", "bare_from" };
+end
+
+function condition_handlers.PAYLOAD(payload_ns)
+	return ("stanza:get_child(nil, %q)"):format(payload_ns);
+end
+
+function condition_handlers.FROM_GROUP(group_name)
+	return ("group_contains(%q, bare_from)"):format(group_name), { "group_contains", "bare_from" };
+end
+
+function condition_handlers.TO_GROUP(group_name)
+	return ("group_contains(%q, bare_to)"):format(group_name), { "group_contains", "bare_to" };
+end
+
+function condition_handlers.FROM_ADMIN_OF(host)
+	return ("is_admin(bare_from, %s)"):format(host ~= "*" and host or nil), { "is_admin", "bare_from" };
+end
+
+function condition_handlers.TO_ADMIN_OF(host)
+	return ("is_admin(bare_to, %s)"):format(host ~= "*" and host or nil), { "is_admin", "bare_to" };
+end
+
+return condition_handlers;
diff -r 2c5430ff1c11 -r c91cac3b823f mod_firewall/mod_firewall.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_firewall/mod_firewall.lua	Wed Apr 03 16:11:20 2013 +0100
@@ -0,0 +1,271 @@
+
+local resolve_relative_path = require "core.configmanager".resolve_relative_path;
+local logger = require "util.logger".init;
+local set = require "util.set";
+local add_filter = require "util.filters".add_filter;
+
+
+zones = {};
+local zones = zones;
+setmetatable(zones, {
+	__index = function (zones, zone)
+		local t = { [zone] = true };
+		rawset(zones, zone, t);
+		return t;
+	end;
+});
+
+local chains = {
+	preroute = {
+		type = "event";
+		priority = 0.1;
+		"pre-message/bare", "pre-message/full", "pre-message/host";
+		"pre-presence/bare", "pre-presence/full", "pre-presence/host";
+		"pre-iq/bare", "pre-iq/full", "pre-iq/host";
+	};
+	deliver = {
+		type = "event";
+		priority = 0.1;
+		"message/bare", "message/full", "message/host";
+		"presence/bare", "presence/full", "presence/host";
+		"iq/bare", "iq/full", "iq/host";
+	};
+	deliver_remote = {
+		type = "event"; "route/remote";
+		priority = 0.1;
+	};
+};
+
+-- Dependency locations:
+-- <type lib>
+-- <type global>
+-- function handler()
+--   <local deps>
+--   if <conditions> then
+--     <actions>
+--   end
+-- end
+
+local available_deps = {
+	st = { global_code = [[local st = require "util.stanza"]]};
+	jid_split = {
+		global_code = [[local jid_split = require "util.jid".split;]];
+	};
+	jid_bare = {
+		global_code = [[local jid_bare = require "util.jid".bare;]];
+	};
+	to = { local_code = [[local to = stanza.attr.to;]] };
+	from = { local_code = [[local from = stanza.attr.from;]] };
+	type = { local_code = [[local type = stanza.attr.type;]] };
+	name = { local_code = [[local name = stanza.name]] };
+	split_to = { -- The stanza's split to address
+		depends = { "jid_split", "to" };
+		local_code = [[local to_node, to_host, to_resource = jid_split(to);]];
+	};
+	split_from = { -- The stanza's split from address
+		depends = { "jid_split", "from" };
+		local_code = [[local from_node, from_host, from_resource = jid_split(from);]];
+	};
+	bare_to = { depends = { "jid_bare", "to" }, local_code = "local bare_to = jid_bare(to)"};
+	bare_from = { depends = { "jid_bare", "from" }, local_code = "local bare_from = jid_bare(from)"};
+	group_contains = {
+		global_code = [[local group_contains = module:depends("groups").group_contains]];
+	};
+	is_admin = { global_code = [[local is_admin = require "core.usermanager".is_admin]]};
+	core_post_stanza = { global_code = [[local core_post_stanza = prosody.core_post_stanza]] };
+};
+
+local function include_dep(dep, code)
+	local dep_info = available_deps[dep];
+	if not dep_info then
+		module:log("error", "Dependency not found: %s", dep);
+		return;
+	end
+	if code.included_deps[dep] then
+		if code.included_deps[dep] ~= true then
+			module:log("error", "Circular dependency on %s", dep);
+		end
+		return;
+	end
+	code.included_deps[dep] = false; -- Pending flag (used to detect circular references)
+	for _, dep_dep in ipairs(dep_info.depends or {}) do
+		include_dep(dep_dep, code);
+	end
+	if dep_info.global_code then
+		table.insert(code.global_header, dep_info.global_code);
+	end
+	if dep_info.local_code then
+		table.insert(code, "\n\t-- "..dep.."\n\t"..dep_info.local_code.."\n\n\t");
+	end
+	code.included_deps[dep] = true;
+end
+
+local condition_handlers = module:require("conditions");
+local action_handlers = module:require("actions");
+
+local function new_rule(ruleset, chain)
+	assert(chain, "no chain specified");
+	local rule = { conditions = {}, actions = {}, deps = {} };
+	table.insert(ruleset[chain], rule);
+	return rule;
+end
+
+local function compile_firewall_rules(filename)
+	local line_no = 0;
+	
+	local ruleset = {
+		deliver = {};
+	};
+
+	local chain = "deliver"; -- Default chain
+	local rule;
+	
+	local file, err = io.open(filename);
+	if not file then return nil, err; end
+	
+	local state; -- nil -> "rules" -> "actions" -> nil -> ...
+	
+	local line_hold;
+	for line in file:lines() do
+		line = line:match("^%s*(.-)%s*$");
+		if line_hold and line:sub(-1,-1) ~= "\\" then
+			line = line_hold..line;
+			line_hold = nil;
+		elseif line:sub(-1,-1) == "\\" then
+			line_hold = (line_hold or "")..line:sub(1,-2);
+		end
+		line_no = line_no + 1;
+		
+		if line_hold or line:match("^[#;]") then
+			-- No action; comment or partial line
+		elseif line == "" then
+			if state == "rules" then
+				return nil, ("Expected an action on line %d for preceding criteria")
+					:format(line_no);
+			end
+			state = nil;
+		elseif not(state) and line:match("^::") then
+			chain = line:gsub("^::%s*", "");
+			ruleset[chain] = ruleset[chain] or {};
+		elseif not(state) and line:match("^ZONE ") then
+			local zone_name = line:match("^ZONE ([^:]+)");
+			local zone_members = line:match("^ZONE .-: ?(.*)");
+			local zone_member_list = {};
+			for member in zone_members:gmatch("[^, ]+") do
+				zone_member_list[#zone_member_list+1] = member;
+			end
+			zones[zone_name] = set.new(zone_member_list)._items;
+		elseif line:match("^[^%s:]+[%.=]") then
+			-- Action
+			if state == nil then
+				-- This is a standalone action with no conditions
+				rule = new_rule(ruleset, chain);
+			end
+			state = "actions";
+			-- Action handlers?
+			local action = line:match("^%P+");
+			if not action_handlers[action] then
+				return nil, ("Unknown action on line %d: %s"):format(line_no, action or "<unknown>");
+			end
+			table.insert(rule.actions, "-- "..line)
+			local action_string, action_deps = action_handlers[action](line:match("=(.+)$"));
+			table.insert(rule.actions, action_string);
+			for _, dep in ipairs(action_deps or {}) do
+				table.insert(rule.deps, dep);
+			end
+		elseif state == "actions" then -- state is actions but action pattern did not match
+			state = nil; -- Awaiting next rule, etc.
+			table.insert(ruleset[chain], rule);
+			rule = nil;
+		else
+			if not state then
+				state = "rules";
+				rule = new_rule(ruleset, chain);
+			end
+			-- Check standard modifiers for the condition (e.g. NOT)
+			local negated;
+			local condition = line:match("^[^:=%.]*");
+			if condition:match("%f[%w]NOT%f[^%w]") then
+				local s, e = condition:match("%f[%w]()NOT()%f[^%w]");
+				condition = (condition:sub(1,s-1)..condition:sub(e+1, -1)):match("^%s*(.-)%s*$");
+				negated = true;
+			end
+			condition = condition:gsub(" ", "");
+			if not condition_handlers[condition] then
+				return nil, ("Unknown condition on line %d: %s"):format(line_no, condition);
+			end
+			-- Get the code for this condition
+			local condition_code, condition_deps = condition_handlers[condition](line:match(":%s?(.+)$"));
+			if negated then condition_code = "not("..condition_code..")"; end
+			table.insert(rule.conditions, condition_code);
+			for _, dep in ipairs(condition_deps or {}) do
+				table.insert(rule.deps, dep);
+			end
+		end
+	end
+	
+	-- Compile ruleset and return complete code
+	
+	local chain_handlers = {};
+
+	-- Loop through the chains in the parsed ruleset (e.g. incoming, outgoing)
+	for chain_name, rules in pairs(ruleset) do
+		local code = { included_deps = {}, global_header = {} };
+		-- This inner loop assumes chain is an event-based, not a filter-based
+		-- chain (filter-based will be added later)
+		for _, rule in ipairs(rules) do
+			for _, dep in ipairs(rule.deps) do
+				include_dep(dep, code);
+			end
+			local rule_code = "if ("..table.concat(rule.conditions, ") and (")..") then\n\t"
+			..table.concat(rule.actions, "\n\t")
+			.."\n end\n";
+			table.insert(code, rule_code);
+		end
+
+		assert(chains[chain_name].type == "event", "Only event chains supported at the moment")
+
+		local code_string = [[return function (zones, log)
+			]]..table.concat(code.global_header, "\n")..[[
+			local db = require 'util.debug'
+			return function (event)
+				local stanza, session = event.stanza, event.origin;
+
+				]]..table.concat(code, " ")..[[
+			end;
+		end]];
+
+		print(code_string)
+
+		-- Prepare event handler function
+		local chunk, err = loadstring(code_string, "="..filename);
+		if not chunk then
+			return nil, "Error compiling (probably a compiler bug, please report): "..err;
+		end
+		chunk = chunk()(zones, logger(filename)); -- Returns event handler with 'zones' upvalue.
+		chain_handlers[chain_name] = chunk;
+	end
+		
+	return chain_handlers;
+end
+
+function module.load()
+	local firewall_scripts = module:get_option_set("firewall_scripts", {});
+	for script in firewall_scripts do
+		script = resolve_relative_path(script) or script;
+		local chain_functions, err = compile_firewall_rules(script)
+		
+		if not chain_functions then
+			module:log("error", "Error compiling %s: %s", script, err or "unknown error");
+		else
+			for chain, handler in pairs(chain_functions) do
+				local chain_definition = chains[chain];
+				if chain_definition.type == "event" then
+					for _, event_name in ipairs(chain_definition) do
+						module:hook(event_name, handler, chain_definition.priority);
+					end
+				end
+			end
+		end
+	end
+end