Wireshark STOMP protocol dissector

For posterity's sake, below is a corrected version of the plugin with bugs fixed:

--
-- Original source: https://github.com/ficoos/wireshark-stomp-plugin
--
-- Modified to handle STOMP over HTTP/Websocket
--
-- Copyright 2009-2012 Red Hat, Inc.
--
-- 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
--
-- Refer to the README and COPYING files for full details of the license
--
local p_stomp = Proto("stomp", "STOMP")
local f_command = ProtoField.string("stomp.command", "Command", FT_STRING)
local f_body = ProtoField.string("stomp.body", "Body")
local f_header = ProtoField.string("stomp.header", "Header")
local f_header_key = ProtoField.string("stomp.header.key", "Key")
local f_header_value = ProtoField.string("stomp.header.value", "Value")
p_stomp.fields = {
f_command,
f_body,
f_header,
f_header_key,
f_header_value,
}
local settings = {
TCP_PORT = 54321,
WEBSOCKET_PORT = 9000
}
p_stomp.prefs["tcp_port"] = Pref.uint(
"Standards-based TCP Port",
settings.TCP_PORT,
"TCP Port for STOMP standards-compliant communication (0 to disable)"
)
p_stomp.prefs["websocket_port"] = Pref.uint(
"STOMP in Websocket for HTTP server TCP port",
settings.WEBSOCKET_PORT,
"The TCP server port number for STOMP in Websocket payload (0 to disable)"
)
p_stomp.prefs["warning_text"] = Pref.statictext(
"Warning: The Standards-based TCP port number must not be the "..
"same as the Websocket TCP port number."
)
local Headers = {
content_length = "content-length",
}
local function _partition(buf, s)
local buf_len = buf:len() - 1
local s_len = s:len()
for i=0,buf_len do
if buf(i, s_len):string() == s then
if (i + s_len) >= buf:len() then
return buf(0, i), buf(i, s_len), ByteArray.new()
else
return buf(0, i), buf(i, s_len), buf(i + s_len)
end
end
end
return nil, nil, buf
end
local function read_line(buf)
return _partition(buf, "\n")
end
local function read_command(buf)
return read_line(buf)
end
local KNOWN_COMMANDS = {
– client commands
["SEND"] = true,
["SUBSCRIBE"] = true,
["UNSUBSCRIBE"] = true,
["BEGIN"] = true,
["COMMIT"] = true,
["ABORT"] = true,
["ACK"] = true,
["NACK"] = true,
["DISCONNECT"] = true,
["CONNECT"] = true,
["STOMP"] = true,
-- server commands
["CONNECTED"] = true,
["MESSAGE"] = true,
["RECEIPT"] = true,
["ERROR"] = true,

}
function p_stomp.dissector(buf, pinfo, root)
local offset = pinfo.desegment_offset or 0
local command = nil
local headers = {}
local body = nil
local sep = nil
local rest = nil
local content_length = nil
rest = buf(offset)
command, sep, rest = read_command(rest)
if not sep then
if rest:len() > 12 then
return
else
pinfo.desegment_len = DESEGMENT_ONE_MORE_SEGMENT
return
end
end
offset = offset + command:len() + sep:len()
– This is here to fuzz out bad data that contains \n
if not KNOWN_COMMANDS[command:string()] then
return
end
do
    local header = nil
    while true do
        header, sep, rest = read_line(rest)
        if not sep then
            pinfo.desegment_len = DESEGMENT_ONE_MORE_SEGMENT
            return
        end
        offset = offset + header:len() + sep:len()

        if header:len() == 0 then
            break
        end

        local key, sep, value = _partition(header, ":")
        if
            content_length == nil
            and key
            and key:string() == Headers.content_length
        then
            content_length = tonumber(value:string())
        end
        table.insert(headers, {header, key, value})
    end
end
if content_length == nil then
    body, sep, rest = _partition(rest, "\0")
    if not sep then
        pinfo.desegment_len = DESEGMENT_ONE_MORE_SEGMENT
        return
    end
    offset = offset + body:len() + sep:len()
else
    if rest:len() < content_length then
        pinfo.desegment_len = DESEGMENT_ONE_MORE_SEGMENT
        return
    end
    body = rest(0, content_length)
    offset = offset + body:len() + 1
end

pinfo.cols.protocol = "STOMP"
pinfo.cols.info = command:string()
local subtree = root:add(p_stomp, buf(0))
subtree:add(f_command, command)
for _, header_info in ipairs(headers) do
    local header, key, value = unpack(header_info)
    local header_tree = subtree:add(f_header, header)
    if key then
        header_tree:add(f_header_key, key)
    end
    if value then
        header_tree:add(f_header_value, value)
    end
end
subtree:add(f_body, body)
pinfo.desegment_offset = offset

end
local errmsg = "Error: The STOMP Preferences setting has the same "..
"Standards-based TCP port number as the Websocket TCP "..
"port number!\n\nPlease correct this before continuing."
function p_stomp.prefs_changed()
– raw TCP and Websocket cannot use same port number
if (p_stomp.prefs.tcp_port == p_stomp.prefs.websocket_port) and
(p_stomp.prefs.tcp_port ~= 0) then
    if gui_enabled() then
        local tw = TextWindow.new("STOMP Preference Error")
        tw:set(errmsg)
    else
        print(errmsg)
    end
    return
end

if settings.TCP_PORT ~= p_stomp.prefs.tcp_port then
    -- the tcp port number preference changed
    local tcp_dissector_table = DissectorTable.get("tcp.port")
    if settings.TCP_PORT ~= 0 then
        -- remove our proto from the number it was previously dissecting
        tcp_dissector_table:remove(settings.TCP_PORT, p_stomp)
    end
    settings.TCP_PORT = p_stomp.prefs.tcp_port
    if settings.TCP_PORT ~= 0 then
        -- add our proto for the new port number
        tcp_dissector_table:add(settings.TCP_PORT, p_stomp)
    end
end

if settings.WEBSOCKET_PORT ~= p_stomp.prefs.websocket_port then
    -- the tcp port number preference changed
    local ws_dissector_table = DissectorTable.get("ws.port")
    if settings.WEBSOCKET_PORT ~= 0 then
        -- remove our proto from the number it was previously dissecting
        ws_dissector_table:remove(settings.WEBSOCKET_PORT, p_stomp)
    end
    settings.WEBSOCKET_PORT = p_stomp.prefs.websocket_port
    if settings.WEBSOCKET_PORT ~= 0 then
        -- add our proto for the new port number
        ws_dissector_table:add(settings.WEBSOCKET_PORT, p_stomp)
    end
end

end
if settings.TCP_PORT ~= 0 then
DissectorTable.get("tcp.port"):add(settings.TCP_PORT, p_stomp)
end
if settings.WEBSOCKET_PORT ~= 0 then
DissectorTable.get("ws.port"):add(settings.WEBSOCKET_PORT, p_stomp)
end