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-- CS168 Snowcast Protocol Dissector
snowcast_protocol = Proto("CS168Snowcast", "CS168 Snowcast Protocol")
message = ProtoField.uint8("cs168snowcast.messsage_type", "messageType", base.DEC)
-- HELLO fields
udp_port = ProtoField.uint16("cs168snowcast.udp_port", "udpPort", base.DEC)
-- SET_STATION fields
station_number = ProtoField.uint16("cs168snowcast.station_number", "stationNumber", base.DEC)
-- WELCOME fields
num_stations = ProtoField.uint16("cs168snowcast.num_stations", "numStations", base.DEC)
-- ANNOUNCE fields
song_name_size = ProtoField.uint8("cs168snowcast.song_name_size", "songnameSize", base.DEC)
song_name = ProtoField.string("cs168snowcast.song_name", "songname")
-- INVALID_COMMAND fields
reply_string_size = ProtoField.uint8("cs168snowcast.reply_string_size", "replyStringSize", base.DEC)
reply_string = ProtoField.string("cs168snowcast.reply_string", "replyString")
snowcast_protocol.fields = {
message,
udp_port,
station_number,
num_stations,
song_name_size,
song_name,
reply_string_size,
reply_string
}
function snowcast_protocol.dissector(buffer, pinfo, tree)
length = buffer:len()
if length == 0 then return end
pinfo.cols.protocol = snowcast_protocol.name
local subtree = tree:add(snowcast_protocol, buffer(), "Snowcast Protocol Data")
local packet_len = buffer:reported_length_remaining()
local message_num = buffer(0, 1):uint()
local message_name = get_message_name(message_num)
-- Add command ID and name
subtree:add(message, buffer(0, 1)):append_text(" (" .. message_name .. ") ")
-- Clear any existing info in the info column so the TCP stuff info isn't in the way
pinfo.cols.info = ""
pinfo.cols.info:append("Snowcast " .. message_name)
if message_num == 0 then
-- Handling HELLO command
local udpPort = buffer(1, 2):uint()
subtree:add(udp_port, buffer(1, 2))
pinfo.cols.info:append(" (UDP Port: " .. udpPort .. ") ")
elseif message_num == 1 then
-- Handling SET_STATION command
local stationNumber = buffer(1, 2):uint()
subtree:add(station_number, buffer(1, 2))
pinfo.cols.info:append(" (Station Number: " .. stationNumber .. ") ")
elseif message_num == 2 then
-- Handling WELCOME reply
local numStations = buffer(1, 2):uint()
subtree:add(num_stations, buffer(1, 2))
pinfo.cols.info:append(" (Station Number: " .. numStations .. ") ")
elseif message_num == 3 then
-- Handling ANNOUNCE reply
local songnameSize = buffer(1, 1):uint()
subtree:add(reply_string_size, buffer(1, 1))
local songname = buffer(2, songnameSize):string()
subtree:add(reply_string, buffer(2, songnameSize))
pinfo.cols.info:append(" (Song Name [" .. songnameSize .. " bytes]: " .. songname .. ") ")
elseif message_num == 4 then
-- Handling INVALID_COMMAND reply
local replyStringSize = buffer(1, 1):uint()
subtree:add(reply_string_size, buffer(1, 1))
local replyString = buffer(2, replyStringSize):string()
subtree:add(reply_string, buffer(2, replyStringSize))
pinfo.cols.info:append(" (Reply String [" .. replyStringSize .. " bytes]: " .. replyString .. ") ")
end
end
function get_message_name(message_num)
local message_name = "UNNOWN"
if message_num == 0 then
message_name = "HELLO"
elseif message_num == 1 then
message_name = "SET_STATION"
elseif message_num == 2 then
message_name = "WELCOME REPLY"
elseif message_num == 3 then
message_name = "ANNOUNCE REPLY"
elseif message_num == 4 then
message_name = "INVALID_COMMAND REPLY"
end
return message_name
end
local tcp_port = DissectorTable.get("tcp.port")
tcp_port:add(1680, snowcast_protocol)
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