Add Lua interface to HTTPFetchRequest

This allows mods to perform both asynchronous and synchronous HTTP
requests. Mods are only granted access to HTTP APIs if either mod
security is disabled or if they are whitelisted in any of the
the secure.http_mods and secure.trusted_mods settings.

Adds httpfetch_caller_alloc_secure to generate random, non-predictable
caller IDs so that lua mods cannot spy on each others HTTP queries.

1 files changed, 176 insertions, 0 deletions

diff --git a/src/script/lua_api/l_http.cpp b/src/script/lua_api/l_http.cpp
new file mode 100644
index 000000000..b0357e3e0
--- /dev/null
+++ b/src/script/lua_api/l_http.cpp
@@ -0,0 +1,176 @@
+/*
+Minetest
+Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "lua_api/l_internal.h"
+#include "common/c_converter.h"
+#include "common/c_content.h"
+#include "lua_api/l_http.h"
+#include "httpfetch.h"
+#include "settings.h"
+#include "log.h"
+
+#include <algorithm>
+#include <iomanip>
+#include <cctype>
+
+#define HTTP_API(name) \
+	lua_pushstring(L, #name); \
+	lua_pushcfunction(L, l_http_##name); \
+	lua_settable(L, -3);
+
+#if USE_CURL
+void ModApiHttp::read_http_fetch_request(lua_State *L, HTTPFetchRequest &req)
+{
+	luaL_checktype(L, 1, LUA_TTABLE);
+
+	req.caller = httpfetch_caller_alloc_secure();
+	getstringfield(L, 1, "url", req.url);
+	lua_getfield(L, 1, "user_agent");
+	if (lua_isstring(L, -1))
+		req.useragent = getstringfield_default(L, 1, "user_agent", "");
+	lua_pop(L, 1);
+	req.multipart = getboolfield_default(L, 1, "multipart", false);
+	req.timeout = getintfield_default(L, 1, "timeout", 3) * 1000;
+
+	// post_data: if table, post form data, otherwise raw data
+	lua_getfield(L, 1, "post_data");
+	if (lua_istable(L, 2)) {
+		lua_pushnil(L);
+		while (lua_next(L, 2) != 0)
+		{
+			req.post_fields[luaL_checkstring(L, -2)] = luaL_checkstring(L, -1);
+			lua_pop(L, 1);
+		}
+	} else if (lua_isstring(L, 2)) {
+		req.post_data = lua_tostring(L, 2);
+	}
+	lua_pop(L, 1);
+
+	lua_getfield(L, 1, "extra_headers");
+	if (lua_istable(L, 2)) {
+		lua_pushnil(L);
+		while (lua_next(L, 2) != 0)
+		{
+			const char *header = luaL_checkstring(L, -1);
+			req.extra_headers.push_back(header);
+			lua_pop(L, 1);
+		}
+	}
+	lua_pop(L, 1);
+}
+
+void ModApiHttp::push_http_fetch_result(lua_State *L, HTTPFetchResult &res, bool completed)
+{
+	lua_newtable(L);
+	setboolfield(L, -1, "succeeded", res.succeeded);
+	setboolfield(L, -1, "timeout", res.timeout);
+	setboolfield(L, -1, "completed", completed);
+	setintfield(L, -1, "code", res.response_code);
+	setstringfield(L, -1, "data", res.data.c_str());
+}
+
+// http_api.fetch_async(HTTPRequest definition)
+int ModApiHttp::l_http_fetch_async(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	HTTPFetchRequest req;
+	read_http_fetch_request(L, req);
+
+	actionstream << "Mod performs HTTP request with URL " << req.url << std::endl;
+	httpfetch_async(req);
+
+	// Convert handle to hex string since lua can't handle 64-bit integers
+	std::stringstream handle_conversion_stream;
+	handle_conversion_stream << std::hex << req.caller;
+	std::string caller_handle(handle_conversion_stream.str());
+
+	lua_pushstring(L, caller_handle.c_str());
+	return 1;
+}
+
+// http_api.fetch_async_get(handle)
+int ModApiHttp::l_http_fetch_async_get(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	std::string handle_str = luaL_checkstring(L, 1);
+
+	// Convert hex string back to 64-bit handle
+	u64 handle;
+	std::stringstream handle_conversion_stream;
+	handle_conversion_stream << std::hex << handle_str;
+	handle_conversion_stream >> handle;
+
+	HTTPFetchResult res;
+	bool completed = httpfetch_async_get(handle, res);
+
+	push_http_fetch_result(L, res, completed);
+
+	return 1;
+}
+
+int ModApiHttp::l_request_http_api(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	// Mod must be listed in secure.http_mods or secure.trusted_mods
+	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
+	if (!lua_isstring(L, -1)) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	const char *mod_name = lua_tostring(L, -1);
+	std::string http_mods = g_settings->get("secure.http_mods");
+	http_mods.erase(std::remove(http_mods.begin(), http_mods.end(), ' '), http_mods.end());
+	std::vector<std::string> mod_list_http = str_split(http_mods, ',');
+
+	std::string trusted_mods = g_settings->get("secure.trusted_mods");
+	trusted_mods.erase(std::remove(trusted_mods.begin(), trusted_mods.end(), ' '), trusted_mods.end());
+	std::vector<std::string> mod_list_trusted = str_split(trusted_mods, ',');
+
+	mod_list_http.insert(mod_list_http.end(), mod_list_trusted.begin(), mod_list_trusted.end());
+	if (std::find(mod_list_http.begin(), mod_list_http.end(), mod_name) == mod_list_http.end()) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	lua_getglobal(L, "core");
+	lua_getfield(L, -1, "http_add_fetch");
+
+	lua_newtable(L);
+	HTTP_API(fetch_async);
+	HTTP_API(fetch_async_get);
+
+	// Stack now looks like this:
+	// <core.http_add_fetch> <table with fetch_async, fetch_async_get>
+	// Now call core.http_add_fetch to append .fetch(request, callback) to table
+	lua_call(L, 1, 1);
+
+	return 1;
+}
+#endif
+
+void ModApiHttp::Initialize(lua_State *L, int top)
+{
+#if USE_CURL
+	API_FCT(request_http_api);
+#endif
+}