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302 lines
8.3 KiB
Lua
302 lines
8.3 KiB
Lua
---
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-- A minimalistic OSPF (Open Shortest Path First routing protocol) library, currently supporting IPv4 and the following
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-- OSPF message types: HELLO
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--
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-- The library consists of an OSPF class that contains code to handle OSPFv2 packets.
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--
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-- @author Patrik Karlsson <patrik@cqure.net>
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-- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html
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local bin = require "bin"
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local bit = require "bit"
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local math = require "math"
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local stdnse = require "stdnse"
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local table = require "table"
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local ipOps = require "ipOps"
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local packet = require "packet"
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_ENV = stdnse.module("ospf", stdnse.seeall)
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-- The OSPF class.
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OSPF = {
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-- Message Type constants
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Message = {
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HELLO = 1,
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DB_DESCRIPTION = 2,
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LS_UPDATE = 4,
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},
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LSUpdate = {
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},
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Header = {
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size = 24,
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new = function(self, type, area_id, router_id, auth_type, auth_data)
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local o = {
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ver = 2,
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type = type,
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length = 0,
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router_id = router_id or 0,
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area_id = area_id or 0,
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chksum = 0,
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auth_type = auth_type or 0,
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auth_data = auth_data or {},
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}
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setmetatable(o, self)
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self.__index = self
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return o
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end,
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parse = function(data)
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local header = OSPF.Header:new()
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local pos
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pos, header.ver, header.type, header.length = bin.unpack(">CCS", data)
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assert( header.ver == 2, "Invalid OSPF version detected")
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pos, header.router_id, header.area_id, header.chksum, header.auth_type
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= bin.unpack("<I>ISS", data, pos)
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-- No authentication
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if header.auth_type == 0x00 then
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header.auth_data.password = nil
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-- Clear text password
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elseif header.auth_type == 0x01 then
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pos, header.auth_data.password = bin.unpack(">A8", data, pos)
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-- MD5 hash authentication
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elseif header.auth_type == 0x02 then
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local _
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_, header.auth_data.keyid = bin.unpack(">C", data, pos+2)
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_, header.auth_data.length = bin.unpack(">C", data, pos+3)
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_, header.auth_data.seq = bin.unpack(">C", data, pos+4)
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_, header.auth_data.hash = bin.unpack(">H"..header.auth_data.length, data, header.length+1)
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else
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-- Shouldn't happen
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stdnse.debug1("Unknown authentication type " .. header.auth_type)
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return nil
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end
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header.router_id = ipOps.fromdword(header.router_id)
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return header
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end,
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--- Sets the OSPF Area ID
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-- @param areaid Area ID.
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setAreaID = function(self, areaid)
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self.area_id = (type(areaid) == "number") and areaid or ipOps.todword(areaid)
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end,
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--- Sets the OSPF Router ID
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-- @param router_id Router ID.
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setRouterId = function(self, router_id)
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self.router_id = router_id
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end,
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--- Sets the OSPF Packet length
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-- @param length Packet length.
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setLength = function(self, length)
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self.length = self.size + length
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end,
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__tostring = function(self)
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local auth
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if self.auth_type == 0x00 then
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auth = bin.pack(">L", 0x00)
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elseif self.auth_type == 0x01 then
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auth = bin.pack(">A8", self.auth_data.password)
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elseif self.auth_type == 0x02 then
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auth = bin.pack(">A".. self.auth_data.length, self.auth_data.hash)
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end
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local hdr = bin.pack(">CCS", self.ver, self.type, self.length )
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.. bin.pack(">IISS", ipOps.todword(self.router_id), self.area_id, self.chksum, self.auth_type)
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.. auth
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return hdr
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end,
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},
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Hello = {
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new = function(self)
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local o = {
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header = OSPF.Header:new(OSPF.Message.HELLO),
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options = 0x02,
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prio = 0,
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interval = 10,
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router_dead_interval = 40,
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neighbors = {},
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DR = "0.0.0.0",
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BDR = "0.0.0.0",
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}
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setmetatable(o, self)
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self.__index = self
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return o
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end,
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--- Adds a neighbor to the list of neighbors.
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-- @param neighbor IP Address of the neighbor.
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addNeighbor = function(self, neighbor)
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table.insert(self.neighbors, neighbor)
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end,
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--- Sets the OSPF netmask.
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-- @param netmask Netmask in A.B.C.D
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setNetmask = function(self, netmask)
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if netmask then
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self.netmask = netmask
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end
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end,
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--- Sets the OSPF designated Router.
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-- @param router IP address of the designated router.
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setDesignatedRouter = function(self, router)
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if router then
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self.DR = router
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end
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end,
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--- Sets the OSPF backup Router.
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-- @param router IP Address of the backup router.
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setBackupRouter = function(self, router)
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if router then
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self.BDR = router
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end
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end,
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__tostring = function(self)
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self.neighbors = self.neighbors or {}
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local function tostr()
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local data = bin.pack(">ISCCIII", ipOps.todword(self.netmask), self.interval, self.options, self.prio, self.router_dead_interval, ipOps.todword(self.DR), ipOps.todword(self.BDR))
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for _, n in ipairs(self.neighbors) do
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data = data .. bin.pack(">I", ipOps.todword(n))
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end
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self.header:setLength(#data)
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return tostring(self.header) .. data
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end
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local data = tostr()
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self.header.chksum = packet.in_cksum(data:sub(1,12) .. data:sub(25))
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return tostr()
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end,
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parse = function(data)
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local hello = OSPF.Hello:new()
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local pos = OSPF.Header.size + 1
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hello.header = OSPF.Header.parse(data)
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assert( #data >= hello.header.length, "OSPF packet too short")
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pos, hello.netmask, hello.interval, hello.options, hello.prio,
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hello.router_dead_interval, hello.DR,
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hello.BDR = bin.unpack("<ISCCIII", data, pos)
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hello.netmask = ipOps.fromdword(hello.netmask)
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hello.DR = ipOps.fromdword(hello.DR)
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hello.BDR = ipOps.fromdword(hello.BDR)
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if ( ( #data - pos + 1 ) % 4 ~= 0 ) then
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stdnse.debug2("Unexpected OSPF packet length, aborting ...")
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return
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end
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local neighbor_count = ( hello.header.length - pos + 1 ) / 4
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local neighbor
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hello.neighbors = {}
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for i=1, neighbor_count do
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pos, neighbor = bin.unpack("<I", data, pos)
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neighbor = ipOps.fromdword(neighbor)
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table.insert(hello.neighbors, neighbor)
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end
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return hello
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end,
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},
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DBDescription = {
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LSAHeader = {
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new = function(self)
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local o = {
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age = 0,
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options = 0,
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type = 1,
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id = 0,
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adv_router = 0,
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sequence = 0,
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checksum = 0,
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length = 0,
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}
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setmetatable(o, self)
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self.__index = self
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return o
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end,
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},
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new = function(self)
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local o = {
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header = OSPF.Header:new(OSPF.Message.DB_DESCRIPTION),
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mtu = 1500,
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options = 2, -- external routing capability
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init = true,
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more = true,
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master = true,
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sequence = math.random(123456789)
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}
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setmetatable(o, self)
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self.__index = self
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return o
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end,
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__tostring = function(self)
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local function tostr()
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local flags = 0
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if ( self.init ) then flags = flags + 4 end
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if ( self.more ) then flags = flags + 2 end
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if ( self.master) then flags= flags + 1 end
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local data = bin.pack(">SCCI", self.mtu, self.options, flags, self.sequence)
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self.header:setLength(#data)
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return tostring(self.header) .. data
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end
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local data = tostr()
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self.header.chksum = packet.in_cksum(data:sub(1,12) .. data:sub(25))
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return tostr()
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end,
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parse = function(data)
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local desc = OSPF.DBDescription:new()
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local pos = OSPF.Header.size + 1
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desc.header = OSPF.Header.parse(data)
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assert( #data == desc.header.length, "OSPF packet too short")
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local flags = 0
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pos, desc.mtu, desc.options, flags, desc.sequence = bin.unpack(">SCCI", data, pos)
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desc.init = ( bit.band(flags, 4) == 4 )
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desc.more = ( bit.band(flags, 2) == 2 )
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desc.master = ( bit.band(flags, 1) == 1 )
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if ( desc.init or not(desc.more) ) then
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return desc
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end
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return desc
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end,
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},
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Response = {
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parse = function(data)
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local pos, ver, ospf_type = bin.unpack("CC", data)
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if ( ospf_type == OSPF.Message.HELLO ) then
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return OSPF.Hello.parse( data )
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elseif( ospf_type == OSPF.Message.DB_DESCRIPTION ) then
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return OSPF.DBDescription.parse(data)
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end
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return
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end,
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}
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}
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return _ENV;
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