-- mod_http_upload

--

-- Copyright (C) 2015-2017 Kim Alvefur

--

-- This file is MIT/X11 licensed.

--

-- Implementation of HTTP Upload file transfer mechanism used by Conversations

--

-- imports

local st = require"util.stanza";

local lfs = require"lfs";

local url = require "socket.url";

local dataform = require "util.dataforms".new;

local datamanager = require "util.datamanager";

local array = require "util.array";

local t_concat = table.concat;

local t_insert = table.insert;

local s_upper = string.upper;

local have_id, id = pcall(require, "util.id"); -- Only available in 0.10+

local uuid = require"util.uuid".generate;

if have_id then

	uuid = id.medium;

end

local function join_path(...) -- COMPAT util.path was added in 0.10

	return table.concat({ ... }, package.config:sub(1,1));

end

-- config

local file_size_limit = module:get_option_number(module.name .. "_file_size_limit", 1024 * 1024); -- 1 MB

local quota = module:get_option_number(module.name .. "_quota");

local max_age = module:get_option_number(module.name .. "_expire_after");

local allowed_file_types = module:get_option_set(module.name .. "_allowed_file_types");

--- sanity

local parser_body_limit = module:context("*"):get_option_number("http_max_content_size", 10*1024*1024);

if file_size_limit > parser_body_limit then

	module:log("warn", "%s_file_size_limit exceeds HTTP parser limit on body size, capping file size to %d B",

		module.name, parser_body_limit);

	file_size_limit = parser_body_limit;

end

-- depends

module:depends("http");

module:depends("disco");

local http_files = module:depends("http_files");

local mime_map = module:shared("/*/http_files/mime").types;

-- namespaces

local namespace = "urn:xmpp:http:upload:0";

local legacy_namespace = "urn:xmpp:http:upload";

-- identity and feature advertising

module:add_identity("store", "file", module:get_option_string("name", "HTTP File Upload"));

module:add_feature(namespace);

module:add_feature(legacy_namespace);

module:add_extension(dataform {

	{ name = "FORM_TYPE", type = "hidden", value = namespace },

	{ name = "max-file-size", type = "text-single" },

}:form({ ["max-file-size"] = tostring(file_size_limit) }, "result"));

module:add_extension(dataform {

	{ name = "FORM_TYPE", type = "hidden", value = legacy_namespace },

	{ name = "max-file-size", type = "text-single" },

}:form({ ["max-file-size"] = tostring(file_size_limit) }, "result"));

-- state

local pending_slots = module:shared("upload_slots");

local storage_path = module:get_option_string(module.name .. "_path", join_path(prosody.paths.data, module.name));

lfs.mkdir(storage_path);

local function expire(username, host)

	if not max_age then return true; end

	local uploads, err = datamanager.list_load(username, host, module.name);

	if not uploads then return true; end

	uploads = array(uploads);

	local expiry = os.time() - max_age;

	uploads:filter(function (item)

		if item.time < expiry then

			local deleted, whynot = os.remove(item.filename);

			if not deleted then

				module:log("warn", "Could not delete expired upload %s: %s", item.filename, whynot or "delete failed");

			end

			return false;

		end

		return true;

	end);

	return datamanager.list_store(username, host, module.name, uploads);

end

local function check_quota(username, host, does_it_fit)

	if not quota then return true; end

	local uploads, err = datamanager.list_load(username, host, module.name);

	if not uploads then return true; end

	local sum = does_it_fit or 0;

	for _, item in ipairs(uploads) do

		sum = sum + item.size;

	end

	return sum < quota;

end

local function handle_request(origin, stanza, xmlns, filename, filesize, mimetype)

	-- local clients only

	if origin.type ~= "c2s" then

		module:log("debug", "Request for upload slot from a %s", origin.type);

		origin.send(st.error_reply(stanza, "cancel", "not-authorized"));

		return true;

	end

	-- validate

	if not filename or filename:find("/") then

		module:log("debug", "Filename %q not allowed", filename or "");

		origin.send(st.error_reply(stanza, "modify", "bad-request", "Invalid filename"));

		return true;

	end

	expire(origin.username, origin.host);

	if not filesize then

		module:log("debug", "Missing file size");

		origin.send(st.error_reply(stanza, "modify", "bad-request", "Missing or invalid file size"));

		return true;

	elseif filesize > file_size_limit then

		module:log("debug", "File too large (%d > %d)", filesize, file_size_limit);

		origin.send(st.error_reply(stanza, "modify", "not-acceptable", "File too large")

			:tag("file-too-large", {xmlns=xmlns})

				:tag("max-file-size"):text(tostring(file_size_limit)));

		return true;

	elseif not check_quota(origin.username, origin.host, filesize) then

		module:log("debug", "Upload of %dB by %s would exceed quota", filesize, origin.full_jid);

		origin.send(st.error_reply(stanza, "wait", "resource-constraint", "Quota reached"));

		return true;

	end

	if mime_map then

		local file_ext = filename:match("%.([^.]+)$");

		if (not file_ext and mimetype ~= "application/octet-stream") or (file_ext and mime_map[file_ext] ~= mimetype) then

			origin.send(st.error_reply(stanza, "modify", "bad-request", "MIME type does not match file extension"));

			return true;

		end

	end

	if allowed_file_types then

		if not (allowed_file_types:contains(mimetype) or allowed_file_types:contains(mimetype:gsub("/.*", "/*"))) then

			origin.send(st.error_reply(stanza, "cancel", "not-allowed", "File type not allowed"));

			return true;

		end

	end

	local reply = st.reply(stanza);

	reply:tag("slot", { xmlns = xmlns });

	local random_dir;

	repeat random_dir = uuid();

	until lfs.mkdir(join_path(storage_path, random_dir))

		or not lfs.attributes(join_path(storage_path, random_dir, filename))

	datamanager.list_append(origin.username, origin.host, module.name, {

		filename = join_path(storage_path, random_dir, filename), size = filesize, time = os.time() });

	local slot = random_dir.."/"..filename;

	pending_slots[slot] = origin.full_jid;

	module:add_timer(900, function()

		pending_slots[slot] = nil;

	end);

	local base_url = module:http_url();

	local slot_url = url.parse(base_url);

	slot_url.path = url.parse_path(slot_url.path or "/");

	t_insert(slot_url.path, random_dir);

	t_insert(slot_url.path, filename);

	slot_url.path.is_directory = false;

	slot_url.path = url.build_path(slot_url.path);

	slot_url = url.build(slot_url);

	reply:tag("get"):text(slot_url):up();

	reply:tag("put"):text(slot_url):up();

	origin.send(reply);

	origin.log("debug", "Given upload slot %q", slot);

	return true;

end

-- hooks

module:hook("iq/host/"..namespace..":request", function (event)

	local stanza, origin = event.stanza, event.origin;

	local request = stanza.tags[1];

	local filename = request.attr.filename;

	local filesize = tonumber(request.attr.size);

	local mimetype = request.attr["content-type"];

	return handle_request(origin, stanza, namespace, filename, filesize, mimetype);

end);

module:hook("iq/host/"..legacy_namespace..":request", function (event)

	local stanza, origin = event.stanza, event.origin;

	local request = stanza.tags[1];

	local filename = request:get_child_text("filename");

	local filesize = tonumber(request:get_child_text("size"));

	local mimetype = request:get_child_text("content-type");

	return handle_request(origin, stanza, legacy_namespace, filename, filesize, mimetype);

end);

-- http service

local function upload_data(event, path)

	local uploader = pending_slots[path];

	if not uploader then

		module:log("warn", "Attempt to upload to unknown slot %q", path);

		return; -- 404

	end

	local random_dir, filename = path:match("^([^/]+)/([^/]+)$");

	if not random_dir then

		module:log("warn", "Invalid file path %q", path);

		return 400;

	end

	if #event.request.body > file_size_limit then

		module:log("warn", "Uploaded file too large %d bytes", #event.request.body);

		return 400;

	end

	pending_slots[path] = nil;

	local full_filename = join_path(storage_path, random_dir, filename);

	if lfs.attributes(full_filename) then

		module:log("warn", "File %s exists already, not replacing it", full_filename);

		return 409;

	end

	local fh, ferr = io.open(full_filename, "w");

	if not fh then

		module:log("error", "Could not open file %s for upload: %s", full_filename, ferr);

		return 500;

	end

	local ok, err = fh:write(event.request.body);

	if not ok then

		module:log("error", "Could not write to file %s for upload: %s", full_filename, err);

		os.remove(full_filename);

		return 500;

	end

	ok, err = fh:close();

	if not ok then

		module:log("error", "Could not write to file %s for upload: %s", full_filename, err);

		os.remove(full_filename);

		return 500;

	end

	module:log("info", "File uploaded by %s to slot %s", uploader, random_dir);

	return 201;

end

-- FIXME Duplicated from net.http.server

local codes = require "net.http.codes";

local headerfix = setmetatable({}, {

	__index = function(t, k)

		local v = "\r\n"..k:gsub("_", "-"):gsub("%f[%w].", s_upper)..": ";

		t[k] = v;

		return v;

	end

});

local function send_response_sans_body(response, body)

	if response.finished then return; end

	response.finished = true;

	response.conn._http_open_response = nil;

	local status_line = "HTTP/"..response.request.httpversion.." "..(response.status or codes[response.status_code]);

	local headers = response.headers;

	body = body or response.body or "";

	headers.content_length = #body;

	local output = { status_line };

	for k,v in pairs(headers) do

		t_insert(output, headerfix[k]..v);

	end

	t_insert(output, "\r\n\r\n");

	-- Here we *don't* add the body to the output

	response.conn:write(t_concat(output));

	if response.on_destroy then

		response:on_destroy();

		response.on_destroy = nil;

	end

	if response.persistent then

		response:finish_cb();

	else

		response.conn:close();

	end

end

local serve_uploaded_files = http_files.serve(storage_path);

local function serve_head(event, path)

	event.response.send = send_response_sans_body;

	return serve_uploaded_files(event, path);

end

local function serve_hello(event)

	event.response.headers.content_type = "text/html;charset=utf-8"

	return "<!DOCTYPE html>\n<h1>Hello from mod_"..module.name.."!</h1>\n";

end

module:provides("http", {

	route = {

		["GET"] = serve_hello;

		["GET /"] = serve_hello;

		["GET /*"] = serve_uploaded_files;

		["HEAD /*"] = serve_head;

		["PUT /*"] = upload_data;

	};

});

module:log("info", "URL: <%s>; Storage path: %s", module:http_url(), storage_path);