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minetest/util/wireshark/minetest.lua

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-- minetest.lua
-- Packet dissector for the UDP-based Minetest protocol
-- Copy this to $HOME/.wireshark/plugins/
--
-- Minetest
-- Copyright (C) 2011 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 General Public License as published by
-- the Free Software Foundation; either version 2 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 General Public License for more details.
--
-- You should have received a copy of the GNU 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.
--
-- Wireshark documentation:
-- https://web.archive.org/web/20170711121726/https://www.wireshark.org/docs/wsdg_html_chunked/lua_module_Proto.html
-- https://web.archive.org/web/20170711121844/https://www.wireshark.org/docs/wsdg_html_chunked/lua_module_Tree.html
-- https://web.archive.org/web/20170711121917/https://www.wireshark.org/docs/wsdg_html_chunked/lua_module_Tvb.html
-- Table of Contents:
-- Part 1: Utility functions
-- Part 2: Client command dissectors (TOSERVER_*)
-- Part 3: Server command dissectors (TOCLIENT_*)
-- Part 4: Wrapper protocol subdissectors
-- Part 5: Wrapper protocol main dissector
-- Part 6: Utility functions part 2
-----------------------
-- Part 1 --
-- Utility functions --
-----------------------
-- Creates two ProtoFields to hold a length and variable-length text content
-- lentype must be either "uint16" or "uint32"
function minetest_field_helper(lentype, name, abbr)
local f_textlen = ProtoField[lentype](name .. "len", abbr .. " (length)", base.DEC)
local f_text = ProtoField.string(name, abbr)
return f_textlen, f_text
end
--------------------------------------------
-- Part 2 --
-- Client command dissectors (TOSERVER_*) --
--------------------------------------------
minetest_client_commands = {}
minetest_client_obsolete = {}
-- TOSERVER_INIT
do
local abbr = "minetest.client.init_"
local f_ser_fmt = ProtoField.uint8(abbr.."ser_version",
"Maximum serialization format version", base.DEC)
local f_comp_modes = ProtoField.uint16(abbr.."compression",
"Supported compression modes", base.DEC, { [0] = "No compression" })
local f_proto_min = ProtoField.uint16(abbr.."proto_min", "Minimum protocol version", base.DEC)
local f_proto_max = ProtoField.uint16(abbr.."_proto_max", "Maximum protocol version", base.DEC)
local f_player_namelen, f_player_name =
minetest_field_helper("uint16", abbr.."player_name", "Player Name")
minetest_client_commands[0x02] = {
"INIT", -- Command name
11, -- Minimum message length including code
{ f_ser_fmt, -- List of fields [optional]
f_comp_modes,
f_proto_min,
f_proto_max,
f_player_namelen,
f_player_name },
function(buffer, pinfo, tree, t) -- Dissector function [optional]
t:add(f_ser_fmt, buffer(2,1))
t:add(f_comp_modes, buffer(3,2))
t:add(f_proto_min, buffer(5,2))
t:add(f_proto_max, buffer(7,2))
minetest_decode_helper_ascii(buffer, t, "uint16", 9, f_player_namelen, f_player_name)
end
}
end
-- TOSERVER_INIT_LEGACY (obsolete)
minetest_client_commands[0x10] = { "INIT_LEGACY", 53 }
minetest_client_obsolete[0x10] = true
-- TOSERVER_INIT2
do
local f_langlen, f_lang =
minetest_field_helper("uint16", "minetest.client.init2_language", "Language Code")
minetest_client_commands[0x11] = {
"INIT2",
2,
{ f_langlen,
f_lang },
function(buffer, pinfo, tree, t)
minetest_decode_helper_ascii(buffer, t, "uint16", 2, f_langlen, f_lang)
end
}
end
-- TOSERVER_MODCHANNEL_JOIN
minetest_client_commands[0x17] = { "MODCHANNEL_JOIN", 2 }
-- TOSERVER_MODCHANNEL_LEAVE
minetest_client_commands[0x18] = { "MODCHANNEL_LEAVE", 2 }
-- TOSERVER_MODCHANNEL_MSG
minetest_client_commands[0x19] = { "MODCHANNEL_MSG", 2 }
-- TOSERVER_GETBLOCK (obsolete)
minetest_client_commands[0x20] = { "GETBLOCK", 2 }
minetest_client_obsolete[0x20] = true
-- TOSERVER_ADDNODE (obsolete)
minetest_client_commands[0x21] = { "ADDNODE", 2 }
minetest_client_obsolete[0x21] = true
-- TOSERVER_REMOVENODE (obsolete)
minetest_client_commands[0x22] = { "REMOVENODE", 2 }
minetest_client_obsolete[0x22] = true
-- TOSERVER_PLAYERPOS
do
local abbr = "minetest.client.playerpos_"
local f_x = ProtoField.int32(abbr.."x", "Position X", base.DEC)
local f_y = ProtoField.int32(abbr.."y", "Position Y", base.DEC)
local f_z = ProtoField.int32(abbr.."z", "Position Z", base.DEC)
local f_speed_x = ProtoField.int32(abbr.."speed_x", "Speed X", base.DEC)
local f_speed_y = ProtoField.int32(abbr.."speed_y", "Speed Y", base.DEC)
local f_speed_z = ProtoField.int32(abbr.."speed_z", "Speed Z", base.DEC)
local f_pitch = ProtoField.int32(abbr.."pitch", "Pitch", base.DEC)
local f_yaw = ProtoField.int32(abbr.."yaw", "Yaw", base.DEC)
local f_key_pressed = ProtoField.bytes(abbr.."key_pressed", "Pressed keys")
local f_fov = ProtoField.uint8(abbr.."fov", "FOV", base.DEC)
local f_wanted_range = ProtoField.uint8(abbr.."wanted_range", "Requested view range", base.DEC)
minetest_client_commands[0x23] = {
"PLAYERPOS", 34,
{ f_x, f_y, f_z, f_speed_x, f_speed_y, f_speed_z, f_pitch, f_yaw,
f_key_pressed, f_fov, f_wanted_range },
function(buffer, pinfo, tree, t)
t:add(f_x, buffer(2,4))
t:add(f_y, buffer(6,4))
t:add(f_z, buffer(10,4))
t:add(f_speed_x, buffer(14,4))
t:add(f_speed_y, buffer(18,4))
t:add(f_speed_z, buffer(22,4))
t:add(f_pitch, buffer(26,4))
t:add(f_yaw, buffer(30,4))
t:add(f_key_pressed, buffer(34,4))
t:add(f_fov, buffer(38,1))
t:add(f_wanted_range, buffer(39,1))
end
}
end
-- TOSERVER_GOTBLOCKS
do
local f_count = ProtoField.uint8("minetest.client.gotblocks_count", "Count", base.DEC)
local f_block = ProtoField.bytes("minetest.client.gotblocks_block", "Block", base.NONE)
local f_x = ProtoField.int16("minetest.client.gotblocks_x", "Block position X", base.DEC)
local f_y = ProtoField.int16("minetest.client.gotblocks_y", "Block position Y", base.DEC)
local f_z = ProtoField.int16("minetest.client.gotblocks_z", "Block position Z", base.DEC)
minetest_client_commands[0x24] = {
"GOTBLOCKS", 3,
{ f_count, f_block, f_x, f_y, f_z },
function(buffer, pinfo, tree, t)
t:add(f_count, buffer(2,1))
local count = buffer(2,1):uint()
if minetest_check_length(buffer, 3 + 6*count, t) then
pinfo.cols.info:append(" * " .. count)
local index
for index = 0, count - 1 do
local pos = 3 + 6*index
local t2 = t:add(f_block, buffer(pos, 6))
t2:set_text("Block, X: " .. buffer(pos, 2):int()
.. ", Y: " .. buffer(pos + 2, 2):int()
.. ", Z: " .. buffer(pos + 4, 2):int())
t2:add(f_x, buffer(pos, 2))
t2:add(f_y, buffer(pos + 2, 2))
t2:add(f_z, buffer(pos + 4, 2))
end
end
end
}
end
-- TOSERVER_DELETEDBLOCKS
do
local f_count = ProtoField.uint8("minetest.client.deletedblocks_count", "Count", base.DEC)
local f_block = ProtoField.bytes("minetest.client.deletedblocks_block", "Block", base.NONE)
local f_x = ProtoField.int16("minetest.client.deletedblocks_x", "Block position X", base.DEC)
local f_y = ProtoField.int16("minetest.client.deletedblocks_y", "Block position Y", base.DEC)
local f_z = ProtoField.int16("minetest.client.deletedblocks_z", "Block position Z", base.DEC)
minetest_client_commands[0x25] = {
"DELETEDBLOCKS", 3,
{ f_count, f_block, f_x, f_y, f_z },
function(buffer, pinfo, tree, t)
t:add(f_count, buffer(2,1))
local count = buffer(2,1):uint()
if minetest_check_length(buffer, 3 + 6*count, t) then
pinfo.cols.info:append(" * " .. count)
local index
for index = 0, count - 1 do
local pos = 3 + 6*index
local t2 = t:add(f_block, buffer(pos, 6))
t2:set_text("Block, X: " .. buffer(pos, 2):int()
.. ", Y: " .. buffer(pos + 2, 2):int()
.. ", Z: " .. buffer(pos + 4, 2):int())
t2:add(f_x, buffer(pos, 2))
t2:add(f_y, buffer(pos + 2, 2))
t2:add(f_z, buffer(pos + 4, 2))
end
end
end
}
end
-- TOSERVER_ADDNODE_FROM_INVENTORY (obsolete)
minetest_client_commands[0x26] = { "ADDNODE_FROM_INVENTORY", 2 }
minetest_client_obsolete[0x26] = true
-- TOSERVER_CLICK_OBJECT (obsolete)
minetest_client_commands[0x27] = { "CLICK_OBJECT", 2 }
minetest_client_obsolete[0x27] = true
-- TOSERVER_GROUND_ACTION (obsolete)
minetest_client_commands[0x28] = { "GROUND_ACTION", 2 }
minetest_client_obsolete[0x28] = true
-- TOSERVER_RELEASE (obsolete)
minetest_client_commands[0x29] = { "RELEASE", 2 }
minetest_client_obsolete[0x29] = true
-- TOSERVER_SIGNTEXT (obsolete)
minetest_client_commands[0x30] = { "SIGNTEXT", 2 }
minetest_client_obsolete[0x30] = true
-- TOSERVER_INVENTORY_ACTION
do
local f_action = ProtoField.string("minetest.client.inventory_action", "Action")
minetest_client_commands[0x31] = {
"INVENTORY_ACTION", 2,
{ f_action },
function(buffer, pinfo, tree, t)
t:add(f_action, buffer(2, buffer:len() - 2))
end
}
end
-- TOSERVER_CHAT_MESSAGE
do
local f_length = ProtoField.uint16("minetest.client.chat_message_length", "Length", base.DEC)
local f_message = ProtoField.string("minetest.client.chat_message", "Message")
minetest_client_commands[0x32] = {
"CHAT_MESSAGE", 4,
{ f_length, f_message },
function(buffer, pinfo, tree, t)
t:add(f_length, buffer(2,2))
local textlen = buffer(2,2):uint()
if minetest_check_length(buffer, 4 + textlen*2, t) then
t:add(f_message, buffer(4, textlen*2), buffer(4, textlen*2):ustring())
end
end
}
end
-- TOSERVER_SIGNNODETEXT (obsolete)
minetest_client_commands[0x33] = { "SIGNNODETEXT", 2 }
minetest_client_obsolete[0x33] = true
-- TOSERVER_CLICK_ACTIVEOBJECT (obsolete)
minetest_client_commands[0x34] = { "CLICK_ACTIVEOBJECT", 2 }
minetest_client_obsolete[0x34] = true
-- TOSERVER_DAMAGE
do
local f_amount = ProtoField.uint8("minetest.client.damage_amount", "Amount", base.DEC)
minetest_client_commands[0x35] = {
"DAMAGE", 3,
{ f_amount },
function(buffer, pinfo, tree, t)
t:add(f_amount, buffer(2,1))
end
}
end
-- TOSERVER_PASSWORD (obsolete)
minetest_client_commands[0x36] = { "CLICK_ACTIVEOBJECT", 2 }
minetest_client_obsolete[0x36] = true
-- TOSERVER_PLAYERITEM
do
local f_item = ProtoField.uint16("minetest.client.playeritem_item", "Wielded item")
minetest_client_commands[0x37] = {
"PLAYERITEM", 4,
{ f_item },
function(buffer, pinfo, tree, t)
t:add(f_item, buffer(2,2))
end
}
end
-- TOSERVER_RESPAWN
minetest_client_commands[0x38] = { "RESPAWN", 2 }
-- TOSERVER_INTERACT
do
local abbr = "minetest.client.interact_"
local vs_action = {
[0] = "Start digging",
[1] = "Stop digging",
[2] = "Digging completed",
[3] = "Place block or item",
[4] = "Use item",
[5] = "Activate held item",
}
local vs_pointed_type = {
[0] = "Nothing",
[1] = "Node",
[2] = "Object",
}
local f_action = ProtoField.uint8(abbr.."action", "Action", base.DEC, vs_action)
local f_item = ProtoField.uint16(abbr.."item", "Item Index", base.DEC)
local f_plen = ProtoField.uint32(abbr.."plen", "Length of pointed thing", base.DEC)
local f_pointed_version = ProtoField.uint8(abbr.."pointed_version",
"Pointed Thing Version", base.DEC)
local f_pointed_type = ProtoField.uint8(abbr.."pointed_version",
"Pointed Thing Type", base.DEC, vs_pointed_type)
local f_pointed_under_x = ProtoField.int16(abbr.."pointed_under_x",
"Node position (under surface) X")
local f_pointed_under_y = ProtoField.int16(abbr.."pointed_under_y",
"Node position (under surface) Y")
local f_pointed_under_z = ProtoField.int16(abbr.."pointed_under_z",
"Node position (under surface) Z")
local f_pointed_above_x = ProtoField.int16(abbr.."pointed_above_x",
"Node position (above surface) X")
local f_pointed_above_y = ProtoField.int16(abbr.."pointed_above_y",
"Node position (above surface) Y")
local f_pointed_above_z = ProtoField.int16(abbr.."pointed_above_z",
"Node position (above surface) Z")
local f_pointed_object_id = ProtoField.int16(abbr.."pointed_object_id",
"Object ID")
-- mising: additional playerpos data just like in TOSERVER_PLAYERPOS
minetest_client_commands[0x39] = {
"INTERACT", 11,
{ f_action,
f_item,
f_plen,
f_pointed_version,
f_pointed_type,
f_pointed_under_x,
f_pointed_under_y,
f_pointed_under_z,
f_pointed_above_x,
f_pointed_above_y,
f_pointed_above_z,
f_pointed_object_id },
function(buffer, pinfo, tree, t)
t:add(f_action, buffer(2,1))
t:add(f_item, buffer(3,2))
t:add(f_plen, buffer(5,4))
local plen = buffer(5,4):uint()
if minetest_check_length(buffer, 9 + plen, t) then
t:add(f_pointed_version, buffer(9,1))
t:add(f_pointed_type, buffer(10,1))
local ptype = buffer(10,1):uint()
if ptype == 1 then -- Node
t:add(f_pointed_under_x, buffer(11,2))
t:add(f_pointed_under_y, buffer(13,2))
t:add(f_pointed_under_z, buffer(15,2))
t:add(f_pointed_above_x, buffer(17,2))
t:add(f_pointed_above_y, buffer(19,2))
t:add(f_pointed_above_z, buffer(21,2))
elseif ptype == 2 then -- Object
t:add(f_pointed_object_id, buffer(11,2))
end
end
end
}
end
-- ...
minetest_client_commands[0x3a] = { "REMOVED_SOUNDS", 2 }
minetest_client_commands[0x3b] = { "NODEMETA_FIELDS", 2 }
minetest_client_commands[0x3c] = { "INVENTORY_FIELDS", 2 }
minetest_client_commands[0x40] = { "REQUEST_MEDIA", 2 }
minetest_client_commands[0x41] = { "RECEIVED_MEDIA", 2 }
-- TOSERVER_BREATH (obsolete)
minetest_client_commands[0x42] = { "BREATH", 2 }
minetest_client_obsolete[0x42] = true
-- TOSERVER_CLIENT_READY
do
local abbr = "minetest.client.client_ready_"
local f_major = ProtoField.uint8(abbr.."major","Version Major")
local f_minor = ProtoField.uint8(abbr.."minor","Version Minor")
local f_patch = ProtoField.uint8(abbr.."patch","Version Patch")
local f_reserved = ProtoField.uint8(abbr.."reserved","Reserved")
local f_versionlen, f_version =
minetest_field_helper("uint16", abbr.."version", "Full Version String")
local f_formspec_ver = ProtoField.uint16(abbr.."formspec_version",
"Formspec API version")
minetest_client_commands[0x43] = {
"CLIENT_READY",
8,
{ f_major, f_minor, f_patch, f_reserved, f_versionlen,
f_version, f_formspec_ver },
function(buffer, pinfo, tree, t)
t:add(f_major, buffer(2,1))
t:add(f_minor, buffer(3,1))
t:add(f_patch, buffer(4,1))
t:add(f_reserved, buffer(5,1))
local off = minetest_decode_helper_ascii(buffer, t, "uint16", 6,
f_versionlen, f_version)
if off and minetest_check_length(buffer, off + 2, t) then
t:add(f_formspec_ver, buffer(off,2))
end
end
}
end
-- ...
minetest_client_commands[0x50] = { "FIRST_SRP", 2 }
minetest_client_commands[0x51] = { "SRP_BYTES_A", 2 }
minetest_client_commands[0x52] = { "SRP_BYTES_M", 2 }
--------------------------------------------
-- Part 3 --
-- Server command dissectors (TOCLIENT_*) --
--------------------------------------------
minetest_server_commands = {}
minetest_server_obsolete = {}
-- TOCLIENT_HELLO
do
local abbr = "minetest.server.hello_"
local f_ser_fmt = ProtoField.uint8(abbr.."ser_version",
"Deployed serialization format version", base.DEC)
local f_comp_mode = ProtoField.uint16(abbr.."compression",
"Deployed compression mode", base.DEC, { [0] = "No compression" })
local f_proto = ProtoField.uint16(abbr.."proto",
"Deployed protocol version", base.DEC)
local f_auth_methods = ProtoField.bytes(abbr.."auth_modes",
"Supported authentication modes")
local f_legacy_namelen, f_legacy_name = minetest_field_helper("uint16",
abbr.."legacy_name", "Legacy player name for hashing")
minetest_server_commands[0x02] = {
"HELLO",
13,
{ f_ser_fmt, f_comp_mode, f_proto, f_auth_methods,
f_legacy_namelen, f_legacy_name },
function(buffer, pinfo, tree, t)
t:add(f_ser_fmt, buffer(2,1))
t:add(f_comp_mode, buffer(3,2))
t:add(f_proto, buffer(5,2))
t:add(f_auth_methods, buffer(7,4))
minetest_decode_helper_ascii(buffer, t, "uint16", 11, f_legacy_namelen, f_legacy_name)
end
}
end
-- TOCLIENT_AUTH_ACCEPT
do
local abbr = "minetest.server.auth_accept_"
local f_player_x = ProtoField.float(abbr.."player_x", "Player position X")
local f_player_y = ProtoField.float(abbr.."player_y", "Player position Y")
local f_player_z = ProtoField.float(abbr.."player_z", "Player position Z")
local f_map_seed = ProtoField.uint64(abbr.."map_seed", "Map seed")
local f_send_interval = ProtoField.float(abbr.."send_interval",
"Recommended send interval")
local f_sudo_auth_methods = ProtoField.bytes(abbr.."sudo_auth_methods",
"Supported auth methods for sudo mode")
minetest_server_commands[0x03] = {
"AUTH_ACCEPT",
30,
{ f_player_x, f_player_y, f_player_z, f_map_seed,
f_send_interval, f_sudo_auth_methods },
function(buffer, pinfo, tree, t)
t:add(f_player_x, buffer(2,4))
t:add(f_player_y, buffer(6,4))
t:add(f_player_z, buffer(10,4))
t:add(f_map_seed, buffer(14,8))
t:add(f_send_interval, buffer(22,4))
t:add(f_sudo_auth_methods, buffer(26,4))
end
}
end
-- ...
minetest_server_commands[0x04] = {"ACCEPT_SUDO_MODE", 2}
minetest_server_commands[0x05] = {"DENY_SUDO_MODE", 2}
minetest_server_commands[0x0A] = {"ACCESS_DENIED", 2}
-- TOCLIENT_INIT (obsolete)
minetest_server_commands[0x10] = { "INIT", 2 }
minetest_server_obsolete[0x10] = true
-- TOCLIENT_BLOCKDATA
do
local f_x = ProtoField.int16("minetest.server.blockdata_x", "Block position X", base.DEC)
local f_y = ProtoField.int16("minetest.server.blockdata_y", "Block position Y", base.DEC)
local f_z = ProtoField.int16("minetest.server.blockdata_z", "Block position Z", base.DEC)
local f_data = ProtoField.bytes("minetest.server.blockdata_block", "Serialized MapBlock")
minetest_server_commands[0x20] = {
"BLOCKDATA", 8,
{ f_x, f_y, f_z, f_data },
function(buffer, pinfo, tree, t)
t:add(f_x, buffer(2,2))
t:add(f_y, buffer(4,2))
t:add(f_z, buffer(6,2))
t:add(f_data, buffer(8, buffer:len() - 8))
end
}
end
-- TOCLIENT_ADDNODE
do
local f_x = ProtoField.int16("minetest.server.addnode_x", "Position X", base.DEC)
local f_y = ProtoField.int16("minetest.server.addnode_y", "Position Y", base.DEC)
local f_z = ProtoField.int16("minetest.server.addnode_z", "Position Z", base.DEC)
local f_data = ProtoField.bytes("minetest.server.addnode_node", "Serialized MapNode")
minetest_server_commands[0x21] = {
"ADDNODE", 8,
{ f_x, f_y, f_z, f_data },
function(buffer, pinfo, tree, t)
t:add(f_x, buffer(2,2))
t:add(f_y, buffer(4,2))
t:add(f_z, buffer(6,2))
t:add(f_data, buffer(8, buffer:len() - 8))
end
}
end
-- TOCLIENT_REMOVENODE
do
local f_x = ProtoField.int16("minetest.server.removenode_x", "Position X", base.DEC)
local f_y = ProtoField.int16("minetest.server.removenode_y", "Position Y", base.DEC)
local f_z = ProtoField.int16("minetest.server.removenode_z", "Position Z", base.DEC)
minetest_server_commands[0x22] = {
"REMOVENODE", 8,
{ f_x, f_y, f_z },
function(buffer, pinfo, tree, t)
t:add(f_x, buffer(2,2))
t:add(f_y, buffer(4,2))
t:add(f_z, buffer(6,2))
end
}
end
-- TOCLIENT_PLAYERPOS (obsolete)
minetest_server_commands[0x23] = { "PLAYERPOS", 2 }
minetest_server_obsolete[0x23] = true
-- TOCLIENT_PLAYERINFO (obsolete)
minetest_server_commands[0x24] = { "PLAYERINFO", 2 }
minetest_server_obsolete[0x24] = true
-- TOCLIENT_OPT_BLOCK_NOT_FOUND (obsolete)
minetest_server_commands[0x25] = { "OPT_BLOCK_NOT_FOUND", 2 }
minetest_server_obsolete[0x25] = true
-- TOCLIENT_SECTORMETA (obsolete)
minetest_server_commands[0x26] = { "SECTORMETA", 2 }
minetest_server_obsolete[0x26] = true
-- TOCLIENT_INVENTORY
do
local f_inventory = ProtoField.string("minetest.server.inventory", "Inventory")
minetest_server_commands[0x27] = {
"INVENTORY", 2,
{ f_inventory },
function(buffer, pinfo, tree, t)
t:add(f_inventory, buffer(2, buffer:len() - 2))
end
}
end
-- TOCLIENT_OBJECTDATA (obsolete)
minetest_server_commands[0x28] = { "OBJECTDATA", 2 }
minetest_server_obsolete[0x28] = true
-- TOCLIENT_TIME_OF_DAY
do
local f_time = ProtoField.uint16("minetest.server.time_of_day", "Time", base.DEC)
local f_time_speed = ProtoField.float("minetest.server.time_speed", "Time Speed", base.DEC)
minetest_server_commands[0x29] = {
"TIME_OF_DAY", 4,
{ f_time, f_time_speed },
function(buffer, pinfo, tree, t)
t:add(f_time, buffer(2,2))
t:add(f_time_speed, buffer(4,4))
end
}
end
-- TOCLIENT_CSM_RESTRICTION_FLAGS
minetest_server_commands[0x2a] = { "CSM_RESTRICTION_FLAGS", 2 }
-- TOCLIENT_PLAYER_SPEED
minetest_server_commands[0x2b] = { "PLAYER_SPEED", 2 }
-- TOCLIENT_CHAT_MESSAGE
do
local abbr = "minetest.server.chat_message_"
local vs_type = {
[0] = "Raw",
[1] = "Normal",
[2] = "Announce",
[3] = "System",
}
local f_version = ProtoField.uint8(abbr.."version", "Version")
local f_type = ProtoField.uint8(abbr.."type", "Message Type", base.DEC, vs_type)
local f_senderlen, f_sender = minetest_field_helper("uint16", abbr.."sender",
"Message sender")
local f_messagelen, f_message = minetest_field_helper("uint16", abbr:sub(1,-2),
"Message")
minetest_server_commands[0x2f] = {
"CHAT_MESSAGE", 8,
{ f_version, f_type, f_senderlen, f_sender,
f_messagelen, f_message },
function(buffer, pinfo, tree, t)
t:add(f_version, buffer(2,1))
t:add(f_type, buffer(3,1))
local off = 4
off = minetest_decode_helper_utf16(buffer, t, "uint16", off, f_senderlen, f_sender)
if off then
off = minetest_decode_helper_utf16(buffer, t, "uint16", off, f_messagelen, f_message)
end
end
}
end
-- TOCLIENT_CHAT_MESSAGE_OLD (obsolete)
minetest_server_commands[0x30] = { "CHAT_MESSAGE_OLD", 2 }
minetest_server_obsolete[0x30] = true
-- TOCLIENT_ACTIVE_OBJECT_REMOVE_ADD
do
local f_removed_count = ProtoField.uint16(
"minetest.server.active_object_remove_add_removed_count",
"Count of removed objects", base.DEC)
local f_removed = ProtoField.bytes(
"minetest.server.active_object_remove_add_removed",
"Removed object")
local f_removed_id = ProtoField.uint16(
"minetest.server.active_object_remove_add_removed_id",
"ID", base.DEC)
local f_added_count = ProtoField.uint16(
"minetest.server.active_object_remove_add_added_count",
"Count of added objects", base.DEC)
local f_added = ProtoField.bytes(
"minetest.server.active_object_remove_add_added",
"Added object")
local f_added_id = ProtoField.uint16(
"minetest.server.active_object_remove_add_added_id",
"ID", base.DEC)
local f_added_type = ProtoField.uint8(
"minetest.server.active_object_remove_add_added_type",
"Type", base.DEC)
local f_added_init_length = ProtoField.uint32(
"minetest.server.active_object_remove_add_added_init_length",
"Initialization data length", base.DEC)
local f_added_init_data = ProtoField.bytes(
"minetest.server.active_object_remove_add_added_init_data",
"Initialization data")
minetest_server_commands[0x31] = {
"ACTIVE_OBJECT_REMOVE_ADD", 6,
{ f_removed_count, f_removed, f_removed_id,
f_added_count, f_added, f_added_id,
f_added_type, f_added_init_length, f_added_init_data },
function(buffer, pinfo, tree, t)
local t2, index, pos
local removed_count_pos = 2
local removed_count = buffer(removed_count_pos, 2):uint()
t:add(f_removed_count, buffer(removed_count_pos, 2))
local added_count_pos = removed_count_pos + 2 + 2 * removed_count
if not minetest_check_length(buffer, added_count_pos + 2, t) then
return
end
-- Loop through removed active objects
for index = 0, removed_count - 1 do
pos = removed_count_pos + 2 + 2 * index
t2 = t:add(f_removed, buffer(pos, 2))
t2:set_text("Removed object, ID = " .. buffer(pos, 2):uint())
t2:add(f_removed_id, buffer(pos, 2))
end
local added_count = buffer(added_count_pos, 2):uint()
t:add(f_added_count, buffer(added_count_pos, 2))
-- Loop through added active objects
pos = added_count_pos + 2
for index = 0, added_count - 1 do
if not minetest_check_length(buffer, pos + 7, t) then
return
end
local init_length = buffer(pos + 3, 4):uint()
if not minetest_check_length(buffer, pos + 7 + init_length, t) then
return
end
t2 = t:add(f_added, buffer(pos, 7 + init_length))
t2:set_text("Added object, ID = " .. buffer(pos, 2):uint())
t2:add(f_added_id, buffer(pos, 2))
t2:add(f_added_type, buffer(pos + 2, 1))
t2:add(f_added_init_length, buffer(pos + 3, 4))
t2:add(f_added_init_data, buffer(pos + 7, init_length))
pos = pos + 7 + init_length
end
pinfo.cols.info:append(" * " .. (removed_count + added_count))
end
}
end
-- TOCLIENT_ACTIVE_OBJECT_MESSAGES
do
local f_object_count = ProtoField.uint16(
"minetest.server.active_object_messages_object_count",
"Count of objects", base.DEC)
local f_object = ProtoField.bytes(
"minetest.server.active_object_messages_object",
"Object")
local f_object_id = ProtoField.uint16(
"minetest.server.active_object_messages_id",
"ID", base.DEC)
local f_message_length = ProtoField.uint16(
"minetest.server.active_object_messages_message_length",
"Message length", base.DEC)
local f_message = ProtoField.bytes(
"minetest.server.active_object_messages_message",
"Message")
minetest_server_commands[0x32] = {
"ACTIVE_OBJECT_MESSAGES", 2,
{ f_object_count, f_object, f_object_id, f_message_length, f_message },
function(buffer, pinfo, tree, t)
local t2, count, pos, message_length
count = 0
pos = 2
while pos < buffer:len() do
if not minetest_check_length(buffer, pos + 4, t) then
return
end
message_length = buffer(pos + 2, 2):uint()
if not minetest_check_length(buffer, pos + 4 + message_length, t) then
return
end
count = count + 1
pos = pos + 4 + message_length
end
pinfo.cols.info:append(" * " .. count)
t:add(f_object_count, count):set_generated()
pos = 2
while pos < buffer:len() do
message_length = buffer(pos + 2, 2):uint()
t2 = t:add(f_object, buffer(pos, 4 + message_length))
t2:set_text("Object, ID = " .. buffer(pos, 2):uint())
t2:add(f_object_id, buffer(pos, 2))
t2:add(f_message_length, buffer(pos + 2, 2))
t2:add(f_message, buffer(pos + 4, message_length))
pos = pos + 4 + message_length
end
end
}
end
-- TOCLIENT_HP
do
local f_hp = ProtoField.uint16("minetest.server.hp", "Health points", base.DEC)
minetest_server_commands[0x33] = {
"HP", 4,
{ f_hp },
function(buffer, pinfo, tree, t)
t:add(f_hp, buffer(2,2))
end
}
end
-- TOCLIENT_MOVE_PLAYER
do
local abbr = "minetest.server.move_player_"
local f_x = ProtoField.float(abbr.."x", "Position X")
local f_y = ProtoField.float(abbr.."y", "Position Y")
local f_z = ProtoField.float(abbr.."z", "Position Z")
local f_pitch = ProtoField.float(abbr.."_pitch", "Pitch")
local f_yaw = ProtoField.float(abbr.."yaw", "Yaw")
minetest_server_commands[0x34] = {
"MOVE_PLAYER", 22,
{ f_x, f_y, f_z, f_pitch, f_yaw, f_garbage },
function(buffer, pinfo, tree, t)
t:add(f_x, buffer(2, 4))
t:add(f_y, buffer(6, 4))
t:add(f_z, buffer(10, 4))
t:add(f_pitch, buffer(14, 4))
t:add(f_yaw, buffer(18, 4))
end
}
end
-- TOCLIENT_ACCESS_DENIED_LEGACY
do
local f_reason_length = ProtoField.uint16("minetest.server.access_denied_reason_length", "Reason length", base.DEC)
local f_reason = ProtoField.string("minetest.server.access_denied_reason", "Reason")
minetest_server_commands[0x35] = {
"ACCESS_DENIED_LEGACY", 4,
{ f_reason_length, f_reason },
function(buffer, pinfo, tree, t)
t:add(f_reason_length, buffer(2,2))
local reason_length = buffer(2,2):uint()
if minetest_check_length(buffer, 4 + reason_length * 2, t) then
t:add(f_reason, minetest_convert_utf16(buffer(4, reason_length * 2), "Converted reason message"))
end
end
}
end
-- TOCLIENT_FOV
minetest_server_commands[0x36] = { "FOV", 2 }
-- TOCLIENT_DEATHSCREEN
do
local f_set_camera_point_target = ProtoField.bool(
"minetest.server.deathscreen_set_camera_point_target",
"Set camera point target")
local f_camera_point_target_x = ProtoField.int32(
"minetest.server.deathscreen_camera_point_target_x",
"Camera point target X", base.DEC)
local f_camera_point_target_y = ProtoField.int32(
"minetest.server.deathscreen_camera_point_target_y",
"Camera point target Y", base.DEC)
local f_camera_point_target_z = ProtoField.int32(
"minetest.server.deathscreen_camera_point_target_z",
"Camera point target Z", base.DEC)
minetest_server_commands[0x37] = {
"DEATHSCREEN", 15,
{ f_set_camera_point_target, f_camera_point_target_x,
f_camera_point_target_y, f_camera_point_target_z},
function(buffer, pinfo, tree, t)
t:add(f_set_camera_point_target, buffer(2,1))
t:add(f_camera_point_target_x, buffer(3,4))
t:add(f_camera_point_target_y, buffer(7,4))
t:add(f_camera_point_target_z, buffer(11,4))
end
}
end
-- TOCLIENT_MEDIA
minetest_server_commands[0x38] = {"MEDIA", 2}
-- TOCLIENT_TOOLDEF (obsolete)
minetest_server_commands[0x39] = {"TOOLDEF", 2}
minetest_server_obsolete[0x39] = true
-- TOCLIENT_NODEDEF
minetest_server_commands[0x3a] = {"NODEDEF", 2}
-- TOCLIENT_CRAFTITEMDEF (obsolete)
minetest_server_commands[0x3b] = {"CRAFTITEMDEF", 2}
minetest_server_obsolete[0x3b] = true
-- ...
minetest_server_commands[0x3c] = {"ANNOUNCE_MEDIA", 2}
minetest_server_commands[0x3d] = {"ITEMDEF", 2}
minetest_server_commands[0x3f] = {"PLAY_SOUND", 2}
minetest_server_commands[0x40] = {"STOP_SOUND", 2}
minetest_server_commands[0x41] = {"PRIVILEGES", 2}
minetest_server_commands[0x42] = {"INVENTORY_FORMSPEC", 2}
minetest_server_commands[0x43] = {"DETACHED_INVENTORY", 2}
minetest_server_commands[0x44] = {"SHOW_FORMSPEC", 2}
minetest_server_commands[0x45] = {"MOVEMENT", 2}
minetest_server_commands[0x46] = {"SPAWN_PARTICLE", 2}
minetest_server_commands[0x47] = {"ADD_PARTICLE_SPAWNER", 2}
-- TOCLIENT_DELETE_PARTICLESPAWNER_LEGACY (obsolete)
minetest_server_commands[0x48] = {"DELETE_PARTICLESPAWNER_LEGACY", 2}
minetest_server_obsolete[0x48] = true
-- ...
minetest_server_commands[0x49] = {"HUDADD", 2}
minetest_server_commands[0x4a] = {"HUDRM", 2}
minetest_server_commands[0x4b] = {"HUDCHANGE", 2}
minetest_server_commands[0x4c] = {"HUD_SET_FLAGS", 2}
minetest_server_commands[0x4d] = {"HUD_SET_PARAM", 2}
minetest_server_commands[0x4e] = {"BREATH", 2}
minetest_server_commands[0x4f] = {"SET_SKY", 2}
minetest_server_commands[0x50] = {"OVERRIDE_DAY_NIGHT_RATIO", 2}
minetest_server_commands[0x51] = {"LOCAL_PLAYER_ANIMATIONS", 2}
minetest_server_commands[0x52] = {"EYE_OFFSET", 2}
minetest_server_commands[0x53] = {"DELETE_PARTICLESPAWNER", 2}
minetest_server_commands[0x54] = {"CLOUD_PARAMS", 2}
minetest_server_commands[0x55] = {"FADE_SOUND", 2}
-- TOCLIENT_UPDATE_PLAYER_LIST
do
local abbr = "minetest.server.update_player_list_"
local vs_type = {
[0] = "Init",
[1] = "Add",
[2] = "Remove",
}
local f_type = ProtoField.uint8(abbr.."type", "Type", base.DEC, vs_type)
local f_count = ProtoField.uint16(abbr.."count", "Number of players", base.DEC)
local f_name = ProtoField.string(abbr.."name", "Name")
minetest_server_commands[0x56] = {
"UPDATE_PLAYER_LIST",
5,
{ f_type, f_count, f_name },
function(buffer, pinfo, tree, t)
t:add(f_type, buffer(2,1))
t:add(f_count, buffer(3,2))
local count = buffer(3,2):uint()
local off = 5
for i = 1, count do
if not minetest_check_length(buffer, off + 2, t) then
return
end
off = minetest_decode_helper_ascii(buffer, t, "uint16", off, nil, f_name)
if not off then
return
end
end
end
}
end
-- ...
minetest_server_commands[0x57] = {"MODCHANNEL_MSG", 2}
minetest_server_commands[0x58] = {"MODCHANNEL_SIGNAL", 2}
minetest_server_commands[0x59] = {"NODEMETA_CHANGED", 2}
minetest_server_commands[0x5a] = {"SET_SUN", 2}
minetest_server_commands[0x5b] = {"SET_MOON", 2}
minetest_server_commands[0x5c] = {"SET_STARS", 2}
minetest_server_commands[0x60] = {"SRP_BYTES_S_B", 2}
minetest_server_commands[0x61] = {"FORMSPEC_PREPEND", 2}
------------------------------------
-- Part 4 --
-- Wrapper protocol subdissectors --
------------------------------------
-- minetest.control dissector
do
local p_control = Proto("minetest.control", "Minetest Control")
local vs_control_type = {
[0] = "Ack",
[1] = "Set Peer ID",
[2] = "Ping",
[3] = "Disco"
}
local f_control_type = ProtoField.uint8("minetest.control.type", "Control Type", base.DEC, vs_control_type)
local f_control_ack = ProtoField.uint16("minetest.control.ack", "ACK sequence number", base.DEC)
local f_control_peerid = ProtoField.uint8("minetest.control.peerid", "New peer ID", base.DEC)
p_control.fields = { f_control_type, f_control_ack, f_control_peerid }
local data_dissector = Dissector.get("data")
function p_control.dissector(buffer, pinfo, tree)
local t = tree:add(p_control, buffer(0,1))
t:add(f_control_type, buffer(0,1))
pinfo.cols.info = "Control message"
local pos = 1
if buffer(0,1):uint() == 0 then
pos = 3
t:set_len(3)
t:add(f_control_ack, buffer(1,2))
pinfo.cols.info = "Ack " .. buffer(1,2):uint()
elseif buffer(0,1):uint() == 1 then
pos = 3
t:set_len(3)
t:add(f_control_peerid, buffer(1,2))
pinfo.cols.info = "Set peer ID " .. buffer(1,2):uint()
elseif buffer(0,1):uint() == 2 then
pinfo.cols.info = "Ping"
elseif buffer(0,1):uint() == 3 then
pinfo.cols.info = "Disco"
end
data_dissector:call(buffer(pos):tvb(), pinfo, tree)
end
end
-- minetest.client dissector
-- minetest.server dissector
-- Defines the minetest.client or minetest.server Proto. These two protocols
-- are created by the same function because they are so similar.
-- Parameter: proto: the Proto object
-- Parameter: this_peer: "Client" or "Server"
-- Parameter: other_peer: "Server" or "Client"
-- Parameter: commands: table of command information, built above
-- Parameter: obsolete: table of obsolete commands, built above
function minetest_define_client_or_server_proto(is_client)
-- Differences between minetest.client and minetest.server
local proto_name, this_peer, other_peer, empty_message_info
local commands, obsolete
if is_client then
proto_name = "minetest.client"
this_peer = "Client"
other_peer = "Server"
empty_message_info = "Empty message / Connect"
commands = minetest_client_commands -- defined in Part 2
obsolete = minetest_client_obsolete -- defined in Part 2
else
proto_name = "minetest.server"
this_peer = "Server"
other_peer = "Client"
empty_message_info = "Empty message"
commands = minetest_server_commands -- defined in Part 3
obsolete = minetest_server_obsolete -- defined in Part 3
end
-- Create the protocol object.
local proto = Proto(proto_name, "Minetest " .. this_peer .. " to " .. other_peer)
-- Create a table vs_command that maps command codes to command names.
local vs_command = {}
local code, command_info
for code, command_info in pairs(commands) do
local command_name = command_info[1]
vs_command[code] = "TO" .. other_peer:upper() .. "_" .. command_name
end
-- Field definitions
local f_command = ProtoField.uint16(proto_name .. ".command", "Command", base.HEX, vs_command)
local f_empty = ProtoField.bool(proto_name .. ".empty", "Is empty", BASE_NONE)
proto.fields = { f_command, f_empty }
-- Add command-specific fields to the protocol
for code, command_info in pairs(commands) do
local command_fields = command_info[3]
if command_fields ~= nil then
for index, field in ipairs(command_fields) do
assert(field ~= nil)
table.insert(proto.fields, field)
end
end
end
-- minetest.client or minetest.server dissector function
function proto.dissector(buffer, pinfo, tree)
local t = tree:add(proto, buffer)
pinfo.cols.info = this_peer
if buffer:len() == 0 then
-- Empty message.
t:add(f_empty, 1):set_generated()
pinfo.cols.info:append(": " .. empty_message_info)
elseif minetest_check_length(buffer, 2, t) then
-- Get the command code.
t:add(f_command, buffer(0,2))
local code = buffer(0,2):uint()
local command_info = commands[code]
if command_info == nil then
-- Error: Unknown command.
pinfo.cols.info:append(": Unknown command")
t:add_expert_info(PI_UNDECODED, PI_WARN, "Unknown " .. this_peer .. " to " .. other_peer .. " command")
else
-- Process a known command
local command_name = command_info[1]
local command_min_length = command_info[2]
local command_fields = command_info[3]
local command_dissector = command_info[4]
if minetest_check_length(buffer, command_min_length, t) then
pinfo.cols.info:append(": " .. command_name)
if command_dissector ~= nil then
command_dissector(buffer, pinfo, tree, t)
end
end
if obsolete[code] then
t:add_expert_info(PI_REQUEST_CODE, PI_WARN, "Obsolete command.")
end
end
end
end
end
minetest_define_client_or_server_proto(true) -- minetest.client
minetest_define_client_or_server_proto(false) -- minetest.server
-- minetest.split dissector
do
local p_split = Proto("minetest.split", "Minetest Split Message")
local f_split_seq = ProtoField.uint16("minetest.split.seq", "Sequence number", base.DEC)
local f_split_chunkcount = ProtoField.uint16("minetest.split.chunkcount", "Chunk count", base.DEC)
local f_split_chunknum = ProtoField.uint16("minetest.split.chunknum", "Chunk number", base.DEC)
local f_split_data = ProtoField.bytes("minetest.split.data", "Split message data")
p_split.fields = { f_split_seq, f_split_chunkcount, f_split_chunknum, f_split_data }
function p_split.dissector(buffer, pinfo, tree)
local t = tree:add(p_split, buffer(0,6))
t:add(f_split_seq, buffer(0,2))
t:add(f_split_chunkcount, buffer(2,2))
t:add(f_split_chunknum, buffer(4,2))
t:add(f_split_data, buffer(6))
pinfo.cols.info:append(" " .. buffer(0,2):uint() .. " chunk " .. buffer(4,2):uint() .. "/" .. buffer(2,2):uint())
end
end
-------------------------------------
-- Part 5 --
-- Wrapper protocol main dissector --
-------------------------------------
-- minetest dissector
do
local p_minetest = Proto("minetest", "Minetest")
local minetest_id = 0x4f457403
local vs_id = {
[minetest_id] = "Valid"
}
local vs_peer = {
[0] = "Inexistent",
[1] = "Server"
}
local vs_type = {
[0] = "Control",
[1] = "Original",
[2] = "Split",
[3] = "Reliable"
}
local f_id = ProtoField.uint32("minetest.id", "ID", base.HEX, vs_id)
local f_peer = ProtoField.uint16("minetest.peer", "Peer", base.DEC, vs_peer)
local f_channel = ProtoField.uint8("minetest.channel", "Channel", base.DEC)
local f_type = ProtoField.uint8("minetest.type", "Type", base.DEC, vs_type)
local f_seq = ProtoField.uint16("minetest.seq", "Sequence number", base.DEC)
local f_subtype = ProtoField.uint8("minetest.subtype", "Subtype", base.DEC, vs_type)
p_minetest.fields = { f_id, f_peer, f_channel, f_type, f_seq, f_subtype }
local data_dissector = Dissector.get("data")
local control_dissector = Dissector.get("minetest.control")
local client_dissector = Dissector.get("minetest.client")
local server_dissector = Dissector.get("minetest.server")
local split_dissector = Dissector.get("minetest.split")
function p_minetest.dissector(buffer, pinfo, tree)
-- Defer if payload doesn't have Minetest's magic number
if buffer(0,4):uint() ~= minetest_id then
return false
end
-- Add Minetest tree item
local t = tree:add(p_minetest, buffer(0,8))
t:add(f_id, buffer(0,4))
-- ID is valid, so replace packet's shown protocol
pinfo.cols.protocol = "Minetest"
pinfo.cols.info = "Minetest"
-- Set the other header fields
t:add(f_peer, buffer(4,2))
t:add(f_channel, buffer(6,1))
t:add(f_type, buffer(7,1))
t:set_text("Minetest, Peer: " .. buffer(4,2):uint() .. ", Channel: " .. buffer(6,1):uint())
local reliability_info
local pos
if buffer(7,1):uint() == 3 then
-- Reliable message
reliability_info = "Seq=" .. buffer(8,2):uint()
t:set_len(11)
t:add(f_seq, buffer(8,2))
t:add(f_subtype, buffer(10,1))
pos = 10
else
-- Unreliable message
reliability_info = "Unrel"
pos = 7
end
if buffer(pos,1):uint() == 0 then
-- Control message, possibly reliable
control_dissector:call(buffer(pos+1):tvb(), pinfo, tree)
elseif buffer(pos,1):uint() == 1 then
-- Original message, possibly reliable
if buffer(4,2):uint() == 1 then
server_dissector:call(buffer(pos+1):tvb(), pinfo, tree)
else
client_dissector:call(buffer(pos+1):tvb(), pinfo, tree)
end
elseif buffer(pos,1):uint() == 2 then
-- Split message, possibly reliable
if buffer(4,2):uint() == 1 then
pinfo.cols.info = "Server: Split message"
else
pinfo.cols.info = "Client: Split message"
end
split_dissector:call(buffer(pos+1):tvb(), pinfo, tree)
elseif buffer(pos,1):uint() == 3 then
-- Doubly reliable message??
t:add_expert_info(PI_MALFORMED, PI_ERROR, "Reliable message wrapped in reliable message")
else
data_dissector:call(buffer(pos+1):tvb(), pinfo, tree)
end
pinfo.cols.info:append(" (" .. reliability_info .. ")")
return true
end
p_minetest:register_heuristic("udp", p_minetest.dissector)
end
------------------------------
-- Part 6 --
-- Utility functions part 2 --
------------------------------
-- Checks if a (sub-)Tvb is long enough to be further dissected.
-- If it is long enough, sets the dissector tree item length to min_len
-- and returns true. If it is not long enough, adds expert info to the
-- dissector tree and returns false.
-- Parameter: tvb: the Tvb
-- Parameter: min_len: required minimum length
-- Parameter: t: dissector tree item
-- Returns: true if tvb:len() >= min_len, false otherwise
function minetest_check_length(tvb, min_len, t)
if tvb:len() >= min_len then
t:set_len(min_len)
return true
-- TODO: check if other parts of
-- the dissector could benefit from reported_length_remaining
elseif tvb:reported_length_remaining() >= min_len then
t:add_expert_info(PI_UNDECODED, PI_INFO, "Only part of this packet was captured, unable to decode.")
return false
else
t:add_expert_info(PI_MALFORMED, PI_ERROR, "Message is too short")
return false
end
end
-- Decodes a variable-length string as ASCII text
-- t_textlen, t_text should be the ProtoFields created by minetest_field_helper
-- alternatively t_text can be a ProtoField.string and t_textlen can be nil
-- lentype must be the type of the length field (as passed to minetest_field_helper)
-- returns nil if length check failed
function minetest_decode_helper_ascii(tvb, t, lentype, offset, f_textlen, f_text)
local n = ({uint16 = 2, uint32 = 4})[lentype]
assert(n)
if f_textlen then
t:add(f_textlen, tvb(offset, n))
end
local textlen = tvb(offset, n):uint()
if minetest_check_length(tvb, offset + n + textlen, t) then
t:add(f_text, tvb(offset + n, textlen))
return offset + n + textlen
end
end
-- Decodes a variable-length string as UTF-16 text
-- (see minetest_decode_helper_ascii)
function minetest_decode_helper_utf16(tvb, t, lentype, offset, f_textlen, f_text)
local n = ({uint16 = 2, uint32 = 4})[lentype]
assert(n)
if f_textlen then
t:add(f_textlen, tvb(offset, n))
end
local textlen = tvb(offset, n):uint() * 2
if minetest_check_length(tvb, offset + n + textlen, t) then
t:add(f_text, tvb(offset + n, textlen), tvb(offset + n, textlen):ustring())
return offset + n + textlen
end
end
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