view mod_http_upload_external/mod_http_upload_external.lua @ 5186:fa3059e653fa

mod_http_oauth2: Implement the Implicit flow Everyone says this is insecure and bad, but it's also the only thing that makes sense for e.g. pure JavaScript clients, but hey implement this even more complicated thing instead!
author Kim Alvefur <zash@zash.se>
date Thu, 02 Mar 2023 22:06:50 +0100
parents 16995e7624f0
children
line wrap: on
line source

-- mod_http_upload_external
--
-- Copyright (C) 2015-2016 Kim Alvefur
--
-- This file is MIT/X11 licensed.
--

-- imports
local st = require"util.stanza";
local uuid = require"util.uuid".generate;
local http = require "util.http";
local dataform = require "util.dataforms".new;
local HMAC = require "util.hashes".hmac_sha256;
local jid = require "util.jid";

-- config
local file_size_limit = module:get_option_number(module.name .. "_file_size_limit", 100 * 1024 * 1024); -- 100 MB
local base_url = assert(module:get_option_string(module.name .. "_base_url"),
	module.name .. "_base_url is a required option");
local secret = assert(module:get_option_string(module.name .. "_secret"),
	module.name .. "_secret is a required option");
local access = module:get_option_set(module.name .. "_access", {});

local token_protocol = module:get_option_string(module.name .. "_protocol", "v1");

-- depends
module:depends("disco");

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

-- 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"));

local function magic_crypto_dust(random, filename, filesize, filetype)
	local param, message;
	if token_protocol == "v1" then
		param, message = "v", string.format("%s/%s %d", random, filename, filesize);
	else
		param, message = "v2", string.format("%s/%s\0%d\0%s", random, filename, filesize, filetype);
	end
	local digest = HMAC(secret, message, true);
	random, filename = http.urlencode(random), http.urlencode(filename);
	return base_url .. random .. "/" .. filename, "?"..param.."=" .. digest;
end

local function handle_request(origin, stanza, xmlns, filename, filesize, filetype)
	local user_bare = jid.bare(stanza.attr.from);
	local user_host = jid.host(user_bare);

	-- local clients or whitelisted jids/hosts only
	if not (origin.type == "c2s" or access:contains(user_bare) or access:contains(user_host)) then
		module:log("debug", "Request for upload slot from a %s", origin.type);
		origin.send(st.error_reply(stanza, "cancel", "not-authorized"));
		return nil, nil;
	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 nil, nil;
	end
	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 nil, nil;
	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",
			st.stanza("file-too-large", {xmlns=xmlns})
				:tag("max-size"):text(tostring(file_size_limit))));
		return nil, nil;
	end
	local random = uuid();
	local get_url, verify = magic_crypto_dust(random, filename, filesize, filetype);
	local put_url = get_url .. verify;

	module:log("debug", "Handing out upload slot %s to %s@%s [%d %s]", get_url, origin.username, origin.host, filesize, filetype);

	return get_url, put_url;
end

-- hooks
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 filetype = request:get_child_text("content-type") or "application/octet-stream";

	local get_url, put_url = handle_request(
		origin, stanza, legacy_namespace, filename, filesize, filetype);

	if not get_url then
		-- error was already sent
		return true;
	end

	local reply = st.reply(stanza)
		:tag("slot", { xmlns = legacy_namespace })
			:tag("get"):text(get_url):up()
			:tag("put"):text(put_url):up()
		:up();
	origin.send(reply);
	return true;
end);

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 filetype = request.attr["content-type"] or "application/octet-stream";

	local get_url, put_url = handle_request(
		origin, stanza, namespace, filename, filesize, filetype);

	if not get_url then
		-- error was already sent
		return true;
	end

	local reply = st.reply(stanza)
		:tag("slot", { xmlns = namespace})
			:tag("get", { url = get_url }):up()
			:tag("put", { url = put_url }):up()
		:up();
	origin.send(reply);
	return true;
end);