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require "util"
local p = Proto("pcmeta", "PictoChat Meta")
local message_dissector = Dissector.get("pcmsg")
function p.init()
local dt = DissectorTable.get("dslmp")
dt:add(GAMEID.PICTOCHAT, p)
end
local MSG_TYPE = {
MSG_START = 1,
MSG_FRAG = 2,
-- There doesn't seem to be an actual difference between type 4 and 5, even
-- the sequence number is shared between these message types
STATUS_A = 4,
STATUS_B = 5,
}
local MSG_TYPE_MAP = {
[MSG_TYPE.MSG_START] = "msg start",
[MSG_TYPE.MSG_FRAG] = "msg fragment",
[MSG_TYPE.STATUS_A] = "status", -- constantly spammed, contains room users' addresses
[MSG_TYPE.STATUS_B] = "status",
}
p.fields.unknown = ProtoField.uint16("pcmeta.unknown", "Unknown")
local dissect_msg_type = { }
p.fields.msg_start_len = ProtoField.uint8("pcmeta.msg_start.len", "Total length")
p.fields.msg_start_id = ProtoField.uint32("pcmeta.msg_start.id", "ID")
p.fields.msg_start_seq = ProtoField.uint16("pcmeta.msg_start.seq", "Sequence")
p.fields.msg_start_new = ProtoField.bool("pcmeta.msg_start.new", "New")
dissect_msg_type[MSG_TYPE.MSG_START] = function (buffer, pinfo, tree)
local subtree = tree:add(p, buffer(), string.format("PictoChat Meta Message start: %d bytes", buffer:len()))
subtree:add_le(p.fields.unknown, buffer(0x00, 2))
subtree:add_le(p.fields.unknown, buffer(0x02, 2)) -- usu. ffffh
subtree:add_le(p.fields.msg_start_len, buffer(0x04, 2))
subtree:add_le(p.fields.unknown, buffer(0x06, 2)) -- usu. 0000h
subtree:add_le(p.fields.unknown, buffer(0x08, 2))
subtree:add_le(p.fields.unknown, buffer(0x0a, 2)) -- usu. 0000h
subtree:add_le(p.fields.msg_start_id, buffer(0x0c, 4))
local id = buffer(0x0c, 4):le_uint()
subtree:add_le(p.fields.msg_start_seq, buffer(0x10, 2))
subtree:add_le(p.fields.new, buffer(0x12, 2))
local new = buffer(0x12, 2):le_uint() ~= 0
if not pinfo.visited then
if new then
pc_global.mid = id
end
pc_global.pid_mid_map[pinfo.number] = pc_global.mid
pc_global.msg[pc_global.mid] = ByteArray.new()
end
end
p.fields.body_len = ProtoField.uint8("pcmeta.body.len", "Length")
p.fields.body_end = ProtoField.bool("pcmeta.body.end", "End")
p.fields.body_offset = ProtoField.uint16("pcmeta.body.offset", "Offset")
p.fields.body = ProtoField.bytes("pcmeta.body", "Data")
p.fields.body_seq = ProtoField.uint16("pcmeta.body.seq", "Sequence")
p.fields.body_new = ProtoField.bool("pcmeta.body.new", "New")
dissect_msg_type[MSG_TYPE.MSG_FRAG] = function (buffer, pinfo, tree)
local subtree = tree:add(p, buffer(), string.format("PictoChat Meta Message Fragment: %d bytes", buffer:len()))
subtree:add_le(p.fields.unknown, buffer(0x00, 2))
subtree:add_le(p.fields.body_len, buffer(0x02, 1))
local body_len = buffer(0x02, 1):le_uint()
subtree:add_le(p.fields.body_end, buffer(0x03, 1))
-- This appears to be some kind of offset for indicating where to store the
-- current frame's data in a larger buffer. Messages sent in multiple parts
-- increment this value by 160 for each new original (p.fields.original ==
-- True) message.
subtree:add_le(p.fields.body_offset, buffer(0x04, 2))
local body_offset = buffer(0x04, 2):le_uint()
subtree:add_le(p.fields.unknown, buffer(0x06, 2)) -- usually 0
buffer = buffer(0x08)
-- This appears to be the actual message data (the drawing) sent as an
-- array of 8x8 tiles.
local body = buffer(0, body_len)
subtree:add(p.fields.body, body)
buffer = buffer(body_len)
subtree:add_le(p.fields.body_seq, buffer(0x00, 2))
subtree:add_le(p.fields.body_new, buffer(0x02, 2))
local new = buffer(0x02, 2):le_uint() ~= 0
if not pinfo.visited then
pc_global.pid_mid_map[pinfo.number] = pc_global.mid
-- reassembly
if pc_global.msg[pc_global.mid]:len() == body_offset and new == true then
pc_global.msg[pc_global.mid]:append(body:bytes())
end
end
end
p.fields.status_id = ProtoField.uint32("pcmeta.status.id", "ID")
p.fields.status_addr = ProtoField.bytes("pcmeta.status.addr", "Address", base.COLON)
p.fields.status_seq = ProtoField.uint16("pcmeta.status.seq", "Sequence")
p.fields.status_new = ProtoField.bool("pcmeta.status.new", "New")
dissect_msg_type[MSG_TYPE.STATUS_A] = function (buffer, pinfo, tree)
local subtree = tree:add(p, buffer(), string.format("PictoChat Meta Status: %d bytes", buffer:len()))
subtree:add_le(p.fields.status_id, buffer(0x00, 4))
local id = buffer(0x00, 4):le_uint()
buffer = buffer(0x04)
for _ = 0, 15 do
add_addr_le(subtree, p.fields.status_addr, buffer(0, 6))
buffer = buffer(6)
end
subtree:add_le(p.fields.status_seq, buffer(0x00, 2))
subtree:add_le(p.fields.status_new, buffer(0x02, 2))
pc_global.pid_mid_map[pinfo.number] = id
end
dissect_msg_type[MSG_TYPE.STATUS_B] = dissect_msg_type[MSG_TYPE.STATUS_A]
p.fields.magic = ProtoField.bytes("pcmeta.magic", "Magic")
p.fields.new = ProtoField.bool("pcmeta.new", "New")
p.fields.type = ProtoField.uint8("pcmeta.type", "Content type", base.DEC, MSG_TYPE_MAP)
p.fields.len = ProtoField.uint16("pcmeta.len", "Payload length")
p.fields.data = ProtoField.bytes("pcmeta.data", "Payload")
function p.dissector(buffer, pinfo, tree)
-- check magic
if buffer(0x00, 2):uint() ~= GAMEID.PICTOCHAT then return 0 end
-- check length (avoid errors)
if buffer:len() < 6 then return 0 end
pinfo.cols.protocol = p.name
local buffer_len = math.min(buffer:len(), 0x0a)
local subtree = tree:add(p, buffer(0, buffer_len), string.format("PictoChat Meta Header: %d bytes", buffer_len))
subtree:add_le(p.fields.magic, buffer(0x00, 2))
subtree:add_le(p.fields.new, buffer(0x02, 2))
subtree:add_le(p.fields.unknown, buffer(0x04, 2))
local unknown = buffer(0x04, 2):le_uint()
if unknown == 0 then
-- no idea what this field means but if it is 0 then this is the last field
-- in the pictochat body, and we must return in order to prevent lua errors
pinfo.cols.info = "???"
return buffer_len
end
subtree:add_le(p.fields.type, buffer(0x06, 2))
local type = buffer(0x06, 2):le_uint()
local type_str = MSG_TYPE_MAP[type]
if type_str ~= nil then
pinfo.cols.info = type_str
end
subtree:add_le(p.fields.len, buffer(0x08, 2))
local payload_length = buffer(0x08, 2):le_uint()
local payload = buffer(0x0a, payload_length)
subtree:add(p.fields.data, payload)
local subdissector = dissect_msg_type[type]
if subdissector ~= nil then
subdissector(payload, pinfo, tree)
end
-- prefix info field with message ID
local mid = pc_global.pid_mid_map[pinfo.number] or 0
pinfo.cols.info = string.format("[%08x] %s", mid, pinfo.cols.info)
-- add reassembly to current frame if current frame is part of the complete message
local reassembly = pc_global.msg[mid]
if reassembly ~= nil then
local tvb = ByteArray.tvb(reassembly, string.format("msg %08x", mid))
message_dissector:call(tvb, pinfo, tree)
end
return buffer_len
end
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