path: root/modules/luci-base/luasrc/dispatcher.lua

-- Copyright 2008 Steven Barth <steven@midlink.org>
-- Copyright 2008-2015 Jo-Philipp Wich <jow@openwrt.org>
-- Licensed to the public under the Apache License 2.0.

local fs = require "nixio.fs"
local sys = require "luci.sys"
local util = require "luci.util"
local http = require "luci.http"
local nixio = require "nixio", require "nixio.util"

module("luci.dispatcher", package.seeall)
context = util.threadlocal()
uci = require "luci.model.uci"
i18n = require "luci.i18n"
_M.fs = fs

-- Index table
local index = nil

local function check_fs_depends(fs)
	local fs = require "nixio.fs"

	for path, kind in pairs(fs) do
		if kind == "directory" then
			local empty = true
			for entry in (fs.dir(path) or function() end) do
				empty = false
				break
			end
			if empty then
				return false
			end
		elseif kind == "executable" then
			if fs.stat(path, "type") ~= "reg" or not fs.access(path, "x") then
				return false
			end
		elseif kind == "file" then
			if fs.stat(path, "type") ~= "reg" then
				return false
			end
		end
	end

	return true
end

local function check_uci_depends_options(conf, s, opts)
	local uci = require "luci.model.uci"

	if type(opts) == "string" then
		return (s[".type"] == opts)
	elseif opts == true then
		for option, value in pairs(s) do
			if option:byte(1) ~= 46 then
				return true
			end
		end
	elseif type(opts) == "table" then
		for option, value in pairs(opts) do
			local sval = s[option]
			if type(sval) == "table" then
				local found = false
				for _, v in ipairs(sval) do
					if v == value then
						found = true
						break
					end
				end
				if not found then
					return false
				end
			elseif value == true then
				if sval == nil then
					return false
				end
			else
				if sval ~= value then
					return false
				end
			end
		end
	end

	return true
end

local function check_uci_depends_section(conf, sect)
	local uci = require "luci.model.uci"

	for section, options in pairs(sect) do
		local stype = section:match("^@([A-Za-z0-9_%-]+)$")
		if stype then
			local found = false
			uci:foreach(conf, stype, function(s)
				if check_uci_depends_options(conf, s, options) then
					found = true
					return false
				end
			end)
			if not found then
				return false
			end
		else
			local s = uci:get_all(conf, section)
			if not s or not check_uci_depends_options(conf, s, options) then
				return false
			end
		end
	end

	return true
end

local function check_uci_depends(conf)
	local uci = require "luci.model.uci"

	for config, values in pairs(conf) do
		if values == true then
			local found = false
			uci:foreach(config, nil, function(s)
				found = true
				return false
			end)
			if not found then
				return false
			end
		elseif type(values) == "table" then
			if not check_uci_depends_section(config, values) then
				return false
			end
		end
	end

	return true
end

local function check_depends(spec)
	if type(spec.depends) ~= "table" then
		return true
	end

	if type(spec.depends.fs) == "table" and not check_fs_depends(spec.depends.fs) then
		local satisfied = false
		local alternatives = (#spec.depends.fs > 0) and spec.depends.fs or { spec.depends.fs }
		for _, alternative in ipairs(alternatives) do
			if check_fs_depends(alternative) then
				satisfied = true
				break
			end
		end
		if not satisfied then
			return false
		end
	end

	if type(spec.depends.uci) == "table" then
		local satisfied = false
		local alternatives = (#spec.depends.uci > 0) and spec.depends.uci or { spec.depends.uci }
		for _, alternative in ipairs(alternatives) do
			if check_uci_depends(alternative) then
				satisfied = true
				break
			end
		end
		if not satisfied then
			return false
		end
	end

	return true
end

local function target_to_json(target, module)
	local action

	if target.type == "call" then
		action = {
			["type"] = "call",
			["module"] = module,
			["function"] = target.name,
			["parameters"] = target.argv
		}
	elseif target.type == "view" then
		action = {
			["type"] = "view",
			["path"] = target.view
		}
	elseif target.type == "template" then
		action = {
			["type"] = "template",
			["path"] = target.view
		}
	elseif target.type == "cbi" then
		action = {
			["type"] = "cbi",
			["path"] = target.model
		}
	elseif target.type == "form" then
		action = {
			["type"] = "form",
			["path"] = target.model
		}
	elseif target.type == "firstchild" then
		action = {
			["type"] = "firstchild"
		}
	elseif target.type == "firstnode" then
		action = {
			["type"] = "firstchild",
			["recurse"] = true
		}
	elseif target.type == "arcombine" then
		if type(target.targets) == "table" then
			action = {
				["type"] = "arcombine",
				["targets"] = {
					target_to_json(target.targets[1], module),
					target_to_json(target.targets[2], module)
				}
			}
		end
	elseif target.type == "alias" then
		action = {
			["type"] = "alias",
			["path"] = table.concat(target.req, "/")
		}
	elseif target.type == "rewrite" then
		action = {
			["type"] = "rewrite",
			["path"] = table.concat(target.req, "/"),
			["remove"] = target.n
		}
	end

	if target.post and action then
		action.post = target.post
	end

	return action
end

local function tree_to_json(node, json)
	local fs = require "nixio.fs"
	local util = require "luci.util"

	if type(node.nodes) == "table" then
		for subname, subnode in pairs(node.nodes) do
			local spec = {
				title = util.striptags(subnode.title),
				order = subnode.order
			}

			if subnode.leaf then
				spec.wildcard = true
			end

			if subnode.cors then
				spec.cors = true
			end

			if subnode.setuser then
				spec.setuser = subnode.setuser
			end

			if subnode.setgroup then
				spec.setgroup = subnode.setgroup
			end

			if type(subnode.target) == "table" then
				spec.action = target_to_json(subnode.target, subnode.module)
			end

			if type(subnode.file_depends) == "table" then
				for _, v in ipairs(subnode.file_depends) do
					spec.depends = spec.depends or {}
					spec.depends.fs = spec.depends.fs or {}

					local ft = fs.stat(v, "type")
					if ft == "dir" then
						spec.depends.fs[v] = "directory"
					elseif v:match("/s?bin/") then
						spec.depends.fs[v] = "executable"
					else
						spec.depends.fs[v] = "file"
					end
				end
			end

			if type(subnode.uci_depends) == "table" then
				for k, v in pairs(subnode.uci_depends) do
					spec.depends = spec.depends or {}
					spec.depends.uci = spec.depends.uci or {}
					spec.depends.uci[k] = v
				end
			end

			if (subnode.sysauth_authenticator ~= nil) or
			   (subnode.sysauth ~= nil and subnode.sysauth ~= false)
			then
				if subnode.sysauth_authenticator == "htmlauth" then
					spec.auth = {
						login = true,
						methods = { "cookie:sysauth" }
					}
				elseif subname == "rpc" and subnode.module == "luci.controller.rpc" then
					spec.auth = {
						login = false,
						methods = { "param:auth", "cookie:sysauth" }
					}
				elseif subnode.module == "luci.controller.admin.uci" then
					spec.auth = {
						login = false,
						methods = { "param:sid" }
					}
				end
			elseif subnode.sysauth == false then
				spec.auth = {}
			end

			if not spec.action then
				spec.title = nil
			end

			spec.satisfied = check_depends(spec)
			json.children = json.children or {}
			json.children[subname] = tree_to_json(subnode, spec)
		end
	end

	return json
end

function build_url(...)
	local path = {...}
	local url = { http.getenv("SCRIPT_NAME") or "" }

	local p
	for _, p in ipairs(path) do
		if p:match("^[a-zA-Z0-9_%-%.%%/,;]+$") then
			url[#url+1] = "/"
			url[#url+1] = p
		end
	end

	if #path == 0 then
		url[#url+1] = "/"
	end

	return table.concat(url, "")
end


function error404(message)
	http.status(404, "Not Found")
	message = message or "Not Found"

	local function render()
		local template = require "luci.template"
		template.render("error404")
	end

	if not util.copcall(render) then
		http.prepare_content("text/plain")
		http.write(message)
	end

	return false
end

function error500(message)
	util.perror(message)
	if not context.template_header_sent then
		http.status(500, "Internal Server Error")
		http.prepare_content("text/plain")
		http.write(message)
	else
		require("luci.template")
		if not util.copcall(luci.template.render, "error500", {message=message}) then
			http.prepare_content("text/plain")
			http.write(message)
		end
	end
	return false
end

local function determine_request_language()
	local conf = require "luci.config"
	assert(conf.main, "/etc/config/luci seems to be corrupt, unable to find section 'main'")

	local lang = conf.main.lang or "auto"
	if lang == "auto" then
		local aclang = http.getenv("HTTP_ACCEPT_LANGUAGE") or ""
		for aclang in aclang:gmatch("[%w_-]+") do
			local country, culture = aclang:match("^([a-z][a-z])[_-]([a-zA-Z][a-zA-Z])$")
			if country and culture then
				local cc = "%s_%s" %{ country, culture:lower() }
				if conf.languages[cc] then
					lang = cc
					break
				elseif conf.languages[country] then
					lang = country
					break
				end
			elseif conf.languages[aclang] then
				lang = aclang
				break
			end
		end
	end

	if lang == "auto" then
		lang = i18n.default
	end

	i18n.setlanguage(lang)
end

function httpdispatch(request, prefix)
	http.context.request = request

	local r = {}
	context.request = r

	local pathinfo = http.urldecode(request:getenv("PATH_INFO") or "", true)

	if prefix then
		for _, node in ipairs(prefix) do
			r[#r+1] = node
		end
	end

	local node
	for node in pathinfo:gmatch("[^/%z]+") do
		r[#r+1] = node
	end

	determine_request_language()

	local stat, err = util.coxpcall(function()
		dispatch(context.request)
	end, error500)

	http.close()

	--context._disable_memtrace()
end

local function require_post_security(target, args)
	if type(target) == "table" and target.type == "arcombine" and type(target.targets) == "table" then
		return require_post_security((type(args) == "table" and #args > 0) and target.targets[2] or target.targets[1], args)
	end

	if type(target) == "table" then
		if type(target.post) == "table" then
			local param_name, required_val, request_val

			for param_name, required_val in pairs(target.post) do
				request_val = http.formvalue(param_name)

				if (type(required_val) == "string" and
				    request_val ~= required_val) or
				   (required_val == true and request_val == nil)
				then
					return false
				end
			end

			return true
		end

		return (target.post == true)
	end

	return false
end

function test_post_security()
	if http.getenv("REQUEST_METHOD") ~= "POST" then
		http.status(405, "Method Not Allowed")
		http.header("Allow", "POST")
		return false
	end

	if http.formvalue("token") ~= context.authtoken then
		http.status(403, "Forbidden")
		luci.template.render("csrftoken")
		return false
	end

	return true
end

local function session_retrieve(sid, allowed_users)
	local sdat = util.ubus("session", "get", { ubus_rpc_session = sid })

	if type(sdat) == "table" and
	   type(sdat.values) == "table" and
	   type(sdat.values.token) == "string" and
	   (not allowed_users or
	    util.contains(allowed_users, sdat.values.username))
	then
		uci:set_session_id(sid)
		return sid, sdat.values
	end

	return nil, nil
end

local function session_setup(user, pass, allowed_users)
	if util.contains(allowed_users, user) then
		local login = util.ubus("session", "login", {
			username = user,
			password = pass,
			timeout  = tonumber(luci.config.sauth.sessiontime)
		})

		local rp = context.requestpath
			and table.concat(context.requestpath, "/") or ""

		if type(login) == "table" and
		   type(login.ubus_rpc_session) == "string"
		then
			util.ubus("session", "set", {
				ubus_rpc_session = login.ubus_rpc_session,
				values = { token = sys.uniqueid(16) }
			})

			io.stderr:write("luci: accepted login on /%s for %s from %s\n"
				%{ rp, user, http.getenv("REMOTE_ADDR") or "?" })

			return session_retrieve(login.ubus_rpc_session)
		end

		io.stderr:write("luci: failed login on /%s for %s from %s\n"
			%{ rp, user, http.getenv("REMOTE_ADDR") or "?" })
	end

	return nil, nil
end

local function check_authentication(method)
	local auth_type, auth_param = method:match("^(%w+):(.+)$")
	local sid, sdat

	if auth_type == "cookie" then
		sid = http.getcookie(auth_param)
	elseif auth_type == "param" then
		sid = http.formvalue(auth_param)
	end

	return session_retrieve(sid)
end

local function get_children(node)
	local children = {}

	if not node.wildcard and type(node.children) == "table" then
		for name, child in pairs(node.children) do
			children[#children+1] = {
				name  = name,
				node  = child,
				order = child.order or 1000
			}
		end

		table.sort(children, function(a, b)
			if a.order == b.order then
				return a.name < b.name
			else
				return a.order < b.order
			end
		end)
	end

	return children
end

local function find_subnode(root, prefix, recurse, descended)
	local children = get_children(root)

	if #children > 0 and (not descended or recurse) then
		local sub_path = { unpack(prefix) }

		if recurse == false then
			recurse = nil
		end

		for _, child in ipairs(children) do
			sub_path[#prefix+1] = child.name

			local res_path = find_subnode(child.node, sub_path, recurse, true)

			if res_path then
				return res_path
			end
		end
	end

	if descended then
		if not recurse or
		   root.action.type == "cbi" or
		   root.action.type == "form" or
		   root.action.type == "view" or
		   root.action.type == "template" or
		   root.action.type == "arcombine"
		then
			return prefix
		end
	end
end

function menu_json()
	local tree = context.tree or createtree()
	return tree_to_json(tree, {
		action = {
			["type"] = "firstchild",
			["recurse"] = true
		}
	})
end

local function init_template_engine(ctx)
	local tpl = require "luci.template"
	local media = luci.config.main.mediaurlbase

	if not pcall(tpl.Template, "themes/%s/header" % fs.basename(media)) then
		media = nil
		for name, theme in pairs(luci.config.themes) do
			if name:sub(1,1) ~= "." and pcall(tpl.Template,
			 "themes/%s/header" % fs.basename(theme)) then
				media = theme
			end
		end
		assert(media, "No valid theme found")
	end

	local function _ifattr(cond, key, val, noescape)
		if cond then
			local env = getfenv(3)
			local scope = (type(env.self) == "table") and env.self
			if type(val) == "table" then
				if not next(val) then
					return ''
				else
					val = util.serialize_json(val)
				end
			end

			val = tostring(val or
				(type(env[key]) ~= "function" and env[key]) or
				(scope and type(scope[key]) ~= "function" and scope[key]) or "")

			if noescape ~= true then
				val = util.pcdata(val)
			end

			return string.format(' %s="%s"', tostring(key), val)
		else
			return ''
		end
	end

	tpl.context.viewns = setmetatable({
		write       = http.write;
		include     = function(name) tpl.Template(name):render(getfenv(2)) end;
		translate   = i18n.translate;
		translatef  = i18n.translatef;
		export      = function(k, v) if tpl.context.viewns[k] == nil then tpl.context.viewns[k] = v end end;
		striptags   = util.striptags;
		pcdata      = util.pcdata;
		media       = media;
		theme       = fs.basename(media);
		resource    = luci.config.main.resourcebase;
		ifattr      = function(...) return _ifattr(...) end;
		attr        = function(...) return _ifattr(true, ...) end;
		url         = build_url;
	}, {__index=function(tbl, key)
		if key == "controller" then
			return build_url()
		elseif key == "REQUEST_URI" then
			return build_url(unpack(ctx.requestpath))
		elseif key == "FULL_REQUEST_URI" then
			local url = { http.getenv("SCRIPT_NAME") or "", http.getenv("PATH_INFO") }
			local query = http.getenv("QUERY_STRING")
			if query and #query > 0 then
				url[#url+1] = "?"
				url[#url+1] = query
			end
			return table.concat(url, "")
		elseif key == "token" then
			return ctx.authtoken
		else
			return rawget(tbl, key) or _G[key]
		end
	end})

	return tpl
end

function dispatch(request)
	--context._disable_memtrace = require "luci.debug".trap_memtrace("l")
	local ctx = context

	local auth, cors, suid, sgid
	local menu = menu_json()
	local page = menu

	local requested_path_full = {}
	local requested_path_node = {}
	local requested_path_args = {}

	for i, s in ipairs(request) do
		if type(page.children) ~= "table" or not page.children[s] then
			page = nil
			break
		end

		if not page.children[s].satisfied then
			page = nil
			break
		end

		page = page.children[s]
		auth = page.auth or auth
		cors = page.cors or cors
		suid = page.setuser or suid
		sgid = page.setgroup or sgid

		requested_path_full[i] = s
		requested_path_node[i] = s

		if page.wildcard then
			for j = i + 1, #request do
				requested_path_args[j - i] = request[j]
				requested_path_full[j] = request[j]
			end
			break
		end
	end

	local tpl = init_template_engine(ctx)

	ctx.args = requested_path_args
	ctx.path = requested_path_node
	ctx.dispatched = page

	ctx.requestpath = ctx.requestpath or requested_path_full
	ctx.requestargs = ctx.requestargs or requested_path_args
	ctx.requested = ctx.requested or page

	if type(auth) == "table" and type(auth.methods) == "table" and #auth.methods > 0 then
		local sid, sdat
		for _, method in ipairs(auth.methods) do
			sid, sdat = check_authentication(method)

			if sid and sdat then
				break
			end
		end

		if not (sid and sdat) and auth.login then
			local user = http.getenv("HTTP_AUTH_USER")
			local pass = http.getenv("HTTP_AUTH_PASS")

			if user == nil and pass == nil then
				user = http.formvalue("luci_username")
				pass = http.formvalue("luci_password")
			end

			sid, sdat = session_setup(user, pass, { "root" })

			if not sid then
				context.path = {}

				http.status(403, "Forbidden")
				http.header("X-LuCI-Login-Required", "yes")

				return tpl.render("sysauth", { duser = "root", fuser = user })
			end

			http.header("Set-Cookie", 'sysauth=%s; path=%s; HttpOnly%s' %{
				sid, build_url(), http.getenv("HTTPS") == "on" and "; secure" or ""
			})

			http.redirect(build_url(unpack(ctx.requestpath)))
			return
		end

		if not sid or not sdat then
			http.status(403, "Forbidden")
			http.header("X-LuCI-Login-Required", "yes")
			return
		end

		ctx.authsession = sid
		ctx.authtoken = sdat.token
		ctx.authuser = sdat.username
	end

	local action = (page and type(page.action) == "table") and page.action or {}

	if action.type == "arcombine" then
		action = (#requested_path_args > 0) and action.targets[2] or action.targets[1]
	end

	if cors and http.getenv("REQUEST_METHOD") == "OPTIONS" then
		luci.http.status(200, "OK")
		luci.http.header("Access-Control-Allow-Origin", http.getenv("HTTP_ORIGIN") or "*")
		luci.http.header("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
		return
	end

	if require_post_security(action) then
		if not test_post_security() then
			return
		end
	end

	if sgid then
		sys.process.setgroup(sgid)
	end

	if suid then
		sys.process.setuser(suid)
	end

	if action.type == "view" then
		tpl.render("view", { view = action.path })

	elseif action.type == "call" then
		local ok, mod = util.copcall(require, action.module)
		if not ok then
			error500(mod)
			return
		end

		local func = mod[action["function"]]

		assert(func ~= nil,
		       'Cannot resolve function "' .. action["function"] .. '". Is it misspelled or local?')

		assert(type(func) == "function",
		       'The symbol "' .. action["function"] .. '" does not refer to a function but data ' ..
		       'of type "' .. type(func) .. '".')

		local argv = (type(action.parameters) == "table" and #action.parameters > 0) and { unpack(action.parameters) } or {}
		for _, s in ipairs(requested_path_args) do
			argv[#argv + 1] = s
		end

		local ok, err = util.copcall(func, unpack(argv))
		if not ok then
			error500(err)
		end

	elseif action.type == "firstchild" then
		local sub_request = find_subnode(page, requested_path_full, action.recurse)
		if sub_request then
			dispatch(sub_request)
		else
			tpl.render("empty_node_placeholder", getfenv(1))
		end

	elseif action.type == "alias" then
		local sub_request = {}
		for name in action.path:gmatch("[^/]+") do
			sub_request[#sub_request + 1] = name
		end

		for _, s in ipairs(requested_path_args) do
			sub_request[#sub_request + 1] = s
		end

		dispatch(sub_request)

	elseif action.type == "rewrite" then
		local sub_request = { unpack(request) }
		for i = 1, action.remove do
			table.remove(sub_request, 1)
		end

		local n = 1
		for s in action.path:gmatch("[^/]+") do
			table.insert(sub_request, n, s)
			n = n + 1
		end

		for _, s in ipairs(requested_path_args) do
			sub_request[#sub_request + 1] = s
		end

		dispatch(sub_request)

	elseif action.type == "template" then
		tpl.render(action.path, getfenv(1))

	elseif action.type == "cbi" then
		_cbi({ config = action.config, model = action.path }, unpack(requested_path_args))

	elseif action.type == "form" then
		_form({ model = action.path }, unpack(requested_path_args))

	else
		local root = find_subnode(menu, {}, true)
		if not root then
			error404("No root node was registered, this usually happens if no module was installed.\n" ..
			         "Install luci-mod-admin-full and retry. " ..
			         "If the module is already installed, try removing the /tmp/luci-indexcache file.")
		else
			error404("No page is registered at '/" .. table.concat(requested_path_full, "/") .. "'.\n" ..
			         "If this url belongs to an extension, make sure it is properly installed.\n" ..
			         "If the extension was recently installed, try removing the /tmp/luci-indexcache file.")
		end
	end
end

function createindex()
	local controllers = { }
	local base = "%s/controller/" % util.libpath()
	local _, path

	for path in (fs.glob("%s*.lua" % base) or function() end) do
		controllers[#controllers+1] = path
	end

	for path in (fs.glob("%s*/*.lua" % base) or function() end) do
		controllers[#controllers+1] = path
	end

	if indexcache then
		local cachedate = fs.stat(indexcache, "mtime")
		if cachedate then
			local realdate = 0
			for _, obj in ipairs(controllers) do
				local omtime = fs.stat(obj, "mtime")
				realdate = (omtime and omtime > realdate) and omtime or realdate
			end

			if cachedate > realdate and sys.process.info("uid") == 0 then
				assert(
					sys.process.info("uid") == fs.stat(indexcache, "uid")
					and fs.stat(indexcache, "modestr") == "rw-------",
					"Fatal: Indexcache is not sane!"
				)

				index = loadfile(indexcache)()
				return index
			end
		end
	end

	index = {}

	for _, path in ipairs(controllers) do
		local modname = "luci.controller." .. path:sub(#base+1, #path-4):gsub("/", ".")
		local mod = require(modname)
		assert(mod ~= true,
		       "Invalid controller file found\n" ..
		       "The file '" .. path .. "' contains an invalid module line.\n" ..
		       "Please verify whether the module name is set to '" .. modname ..
		       "' - It must correspond to the file path!")

		local idx = mod.index
		assert(type(idx) == "function",
		       "Invalid controller file found\n" ..
		       "The file '" .. path .. "' contains no index() function.\n" ..
		       "Please make sure that the controller contains a valid " ..
		       "index function and verify the spelling!")

		index[modname] = idx
	end

	if indexcache then
		local f = nixio.open(indexcache, "w", 600)
		f:writeall(util.get_bytecode(index))
		f:close()
	end
end

-- Build the index before if it does not exist yet.
function createtree()
	if not index then
		createindex()
	end

	local ctx  = context
	local tree = {nodes={}, inreq=true}

	ctx.treecache = setmetatable({}, {__mode="v"})
	ctx.tree = tree

	local scope = setmetatable({}, {__index = luci.dispatcher})

	for k, v in pairs(index) do
		scope._NAME = k
		setfenv(v, scope)
		v()
	end

	return tree
end

function assign(path, clone, title, order)
	local obj  = node(unpack(path))
	obj.nodes  = nil
	obj.module = nil

	obj.title = title
	obj.order = order

	setmetatable(obj, {__index = _create_node(clone)})

	return obj
end

function entry(path, target, title, order)
	local c = node(unpack(path))

	c.target = target
	c.title  = title
	c.order  = order
	c.module = getfenv(2)._NAME

	return c
end

-- enabling the node.
function get(...)
	return _create_node({...})
end

function node(...)
	local c = _create_node({...})

	c.module = getfenv(2)._NAME
	c.auto = nil

	return c
end

function lookup(...)
	local i, path = nil, {}
	for i = 1, select('#', ...) do
		local name, arg = nil, tostring(select(i, ...))
		for name in arg:gmatch("[^/]+") do
			path[#path+1] = name
		end
	end

	for i = #path, 1, -1 do
		local node = context.treecache[table.concat(path, ".", 1, i)]
		if node and (i == #path or node.leaf) then
			return node, build_url(unpack(path))
		end
	end
end

function _create_node(path)
	if #path == 0 then
		return context.tree
	end

	local name = table.concat(path, ".")
	local c = context.treecache[name]

	if not c then
		local last = table.remove(path)
		local parent = _create_node(path)

		c = {nodes={}, auto=true, inreq=true}

		parent.nodes[last] = c
		context.treecache[name] = c
	end

	return c
end

-- Subdispatchers --

function firstchild()
	return { type = "firstchild" }
end

function firstnode()
	return { type = "firstnode" }
end

function alias(...)
	return { type = "alias", req = { ... } }
end

function rewrite(n, ...)
	return { type = "rewrite", n = n, req = { ... } }
end

function call(name, ...)
	return { type = "call", argv = {...}, name = name }
end

function post_on(params, name, ...)
	return {
		type = "call",
		post = params,
		argv = { ... },
		name = name
	}
end

function post(...)
	return post_on(true, ...)
end


function template(name)
	return { type = "template", view = name }
end

function view(name)
	return { type = "view", view = name }
end


function _cbi(self, ...)
	local cbi = require "luci.cbi"
	local tpl = require "luci.template"
	local http = require "luci.http"

	local config = self.config or {}
	local maps = cbi.load(self.model, ...)

	local state = nil

	local i, res
	for i, res in ipairs(maps) do
		if util.instanceof(res, cbi.SimpleForm) then
			io.stderr:write("Model %s returns SimpleForm but is dispatched via cbi(),\n"
				% self.model)

			io.stderr:write("please change %s to use the form() action instead.\n"
				% table.concat(context.request, "/"))
		end

		res.flow = config
		local cstate = res:parse()
		if cstate and (not state or cstate < state) then
			state = cstate
		end
	end

	local function _resolve_path(path)
		return type(path) == "table" and build_url(unpack(path)) or path
	end

	if config.on_valid_to and state and state > 0 and state < 2 then
		http.redirect(_resolve_path(config.on_valid_to))
		return
	end

	if config.on_changed_to and state and state > 1 then
		http.redirect(_resolve_path(config.on_changed_to))
		return
	end

	if config.on_success_to and state and state > 0 then
		http.redirect(_resolve_path(config.on_success_to))
		return
	end

	if config.state_handler then
		if not config.state_handler(state, maps) then
			return
		end
	end

	http.header("X-CBI-State", state or 0)

	if not config.noheader then
		tpl.render("cbi/header", {state = state})
	end

	local redirect
	local messages
	local applymap   = false
	local pageaction = true
	local parsechain = { }

	for i, res in ipairs(maps) do
		if res.apply_needed and res.parsechain then
			local c
			for _, c in ipairs(res.parsechain) do
				parsechain[#parsechain+1] = c
			end
			applymap = true
		end

		if res.redirect then
			redirect = redirect or res.redirect
		end

		if res.pageaction == false then
			pageaction = false
		end

		if res.message then
			messages = messages or { }
			messages[#messages+1] = res.message
		end
	end

	for i, res in ipairs(maps) do
		res:render({
			firstmap   = (i == 1),
			redirect   = redirect,
			messages   = messages,
			pageaction = pageaction,
			parsechain = parsechain
		})
	end

	if not config.nofooter then
		tpl.render("cbi/footer", {
			flow          = config,
			pageaction    = pageaction,
			redirect      = redirect,
			state         = state,
			autoapply     = config.autoapply,
			trigger_apply = applymap
		})
	end
end

function cbi(model, config)
	return {
		type = "cbi",
		post = { ["cbi.submit"] = true },
		config = config,
		model = model
	}
end


function arcombine(trg1, trg2)
	return {
		type = "arcombine",
		env = getfenv(),
		targets = {trg1, trg2}
	}
end


function _form(self, ...)
	local cbi = require "luci.cbi"
	local tpl = require "luci.template"
	local http = require "luci.http"

	local maps = luci.cbi.load(self.model, ...)
	local state = nil

	local i, res
	for i, res in ipairs(maps) do
		local cstate = res:parse()
		if cstate and (not state or cstate < state) then
			state = cstate
		end
	end

	http.header("X-CBI-State", state or 0)
	tpl.render("header")
	for i, res in ipairs(maps) do
		res:render()
	end
	tpl.render("footer")
end

function form(model)
	return {
		type = "form",
		post = { ["cbi.submit"] = true },
		model = model
	}
end

translate = i18n.translate

-- This function does not actually translate the given argument but
-- is used by build/i18n-scan.pl to find translatable entries.
function _(text)
	return text
end