local datafiles = require "datafiles"
local nmap = require "nmap"
local shortport = require "shortport"
local snmp = require "snmp"
local stdnse = require "stdnse"
local string = require "string"
local table = require "table"
local target = require "target"

description = [[
Attempts to enumerate network interfaces through SNMP.

This script can also be run during Nmap's pre-scanning phase and can
attempt to add the SNMP server's interface addresses to the target
list.  The script argument <code>snmp-interfaces.host</code> is
required to know what host to probe.  To specify a port for the SNMP
server other than 161, use <code>snmp-interfaces.port</code>.  When
run in this way, the script's output tells how many new targets were
successfully added.
]]

---
-- @usage
-- nmap -sU -p 161 --script=snmp-interfaces <target>
-- @args snmp-interfaces.host  Specifies the SNMP server to probe when
--       running in the "pre-scanning phase".
-- @args snmp-interfaces.port  The optional port number corresponding
--       to the host script argument.  Defaults to 161.
--
-- @output
-- | snmp-interfaces:
-- |   eth0
-- |     IP address: 192.168.221.128
-- |     MAC address: 00:0c:29:01:e2:74 (VMware)
-- |     Type: ethernetCsmacd  Speed: 1 Gbps
-- |_    Traffic stats: 6.45 Mb sent, 15.01 Mb received
--

author = "Thomas Buchanan, Kris Katterjohn"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"default", "discovery", "safe"}
dependencies = {"snmp-brute"}

-- code borrowed heavily from Patrik Karlsson's excellent snmp scripts
-- Created 03/03/2010 - v0.1 - created by Thomas Buchanan <tbuchanan@thecompassgrp.net>
-- Revised 03/05/2010 - v0.2 - Reworked output slightly, moved iana_types to script scope. Suggested by David Fifield
-- Revised 04/11/2010 - v0.2 - moved snmp_walk to snmp library <patrik@cqure.net>
-- Revised 08/10/2010 - v0.3 - prerule; add interface addresses to Nmap's target list (Kris Katterjohn)
-- Revised 05/27/2011 - v0.4 - action; add MAC addresses to nmap.registry[host.ip]["mac-geolocation"] (Gorjan Petrovski)
-- Revised 07/31/2012 - v0.5 - action; remove mac-geolocation changes (script removed from trunk)




prerule = function()
  if not stdnse.get_script_args({"snmp-interfaces.host", "host"}) then
    stdnse.debug3("Skipping '%s' %s, 'snmp-interfaces.host' argument is missing.", SCRIPT_NAME, SCRIPT_TYPE)
    return false
  end

  return true
end

portrule = shortport.portnumber(161, "udp", {"open", "open|filtered"})

-- List of IANA-assigned network interface types
-- Taken from IANAifType-MIB
-- Available at http://www.iana.org/assignments/ianaiftype-mib
-- REVISION     "201002110000Z"
local iana_types = { "other", "regular1822", "hdh1822", "ddnX25", "rfc877x25", "ethernetCsmacd",
  "iso88023Csmacd", "iso88024TokenBus", "iso88025TokenRing", "iso88026Man", "starLan",
  "proteon10Mbit", "proteon80Mbit", "hyperchannel", "fddi", "lapb", "sdlc", "ds1", "e1",
  "basicISDN", "primaryISDN", "propPointToPointSerial", "ppp", "softwareLoopback", "eon",
  "ethernet3Mbit", "nsip", "slip", "ultra", "ds3", "sip", "frameRelay", "rs232", "para",
  "arcnet", "arcnetPlus", "atm", "miox25", "sonet", "x25ple", "iso88022llc", "localTalk",
  "smdsDxi", "frameRelayService", "v35", "hssi", "hippi", "modem", "aal5", "sonetPath",
  "sonetVT", "smdsIcip", "propVirtual", "propMultiplexor", "ieee80212", "fibreChannel",
  "hippiInterface", "frameRelayInterconnect", "aflane8023", "aflane8025", "cctEmul",
  "fastEther", "isdn", "v11", "v36", "g703at64k", "g703at2mb", "qllc", "fastEtherFX",
  "channel", "ieee80211", "ibm370parChan", "escon", "dlsw", "isdns", "isdnu", "lapd",
  "ipSwitch", "rsrb", "atmLogical", "ds0", "ds0Bundle", "bsc", "async", "cnr",
  "iso88025Dtr", "eplrs", "arap", "propCnls", "hostPad", "termPad", "frameRelayMPI",
  "x213", "adsl", "radsl", "sdsl", "vdsl", "iso88025CRFPInt", "myrinet", "voiceEM",
  "voiceFXO", "voiceFXS", "voiceEncap", "voiceOverIp", "atmDxi", "atmFuni", "atmIma",
  "pppMultilinkBundle", "ipOverCdlc", "ipOverClaw", "stackToStack", "virtualIpAddress",
  "mpc", "ipOverAtm", "iso88025Fiber", "tdlc", "gigabitEthernet", "hdlc", "lapf", "v37",
  "x25mlp", "x25huntGroup", "trasnpHdlc", "interleave", "fast", "ip", "docsCableMaclayer",
  "docsCableDownstream", "docsCableUpstream", "a12MppSwitch", "tunnel", "coffee", "ces",
  "atmSubInterface", "l2vlan", "l3ipvlan", "l3ipxvlan", "digitalPowerlinev", "mediaMailOverIp",
  "dtm", "dcn", "ipForward", "msdsl", "ieee1394", "if-gsn", "dvbRccMacLayer", "dvbRccDownstream",
  "dvbRccUpstream", "atmVirtual", "mplsTunnel", "srp", "voiceOverAtm", "voiceOverFrameRelay",
  "idsl", "compositeLink", "ss7SigLink", "propWirelessP2P", "frForward", "rfc1483", "usb",
  "ieee8023adLag", "bgppolicyaccounting", "frf16MfrBundle", "h323Gatekeeper", "h323Proxy",
  "mpls", "mfSigLink", "hdsl2", "shdsl", "ds1FDL", "pos", "dvbAsiIn", "dvbAsiOut", "plc",
  "nfas", "tr008", "gr303RDT", "gr303IDT", "isup", "propDocsWirelessMaclayer",
  "propDocsWirelessDownstream", "propDocsWirelessUpstream", "hiperlan2", "propBWAp2Mp",
  "sonetOverheadChannel", "digitalWrapperOverheadChannel", "aal2", "radioMAC", "atmRadio",
  "imt", "mvl", "reachDSL", "frDlciEndPt", "atmVciEndPt", "opticalChannel", "opticalTransport",
  "propAtm", "voiceOverCable", "infiniband", "teLink", "q2931", "virtualTg", "sipTg", "sipSig",
  "docsCableUpstreamChannel", "econet", "pon155", "pon622", "bridge", "linegroup", "voiceEMFGD",
  "voiceFGDEANA", "voiceDID", "mpegTransport", "sixToFour", "gtp", "pdnEtherLoop1",
  "pdnEtherLoop2", "opticalChannelGroup", "homepna", "gfp", "ciscoISLvlan", "actelisMetaLOOP",
  "fcipLink", "rpr", "qam", "lmp", "cblVectaStar", "docsCableMCmtsDownstream", "adsl2",
  "macSecControlledIF", "macSecUncontrolledIF", "aviciOpticalEther", "atmbond", "voiceFGDOS",
  "mocaVersion1", "ieee80216WMAN", "adsl2plus", "dvbRcsMacLayer", "dvbTdm", "dvbRcsTdma",
  "x86Laps", "wwanPP", "wwanPP2", "voiceEBS", "ifPwType", "ilan", "pip", "aluELP", "gpon",
  "vdsl2", "capwapDot11Profile", "capwapDot11Bss", "capwapWtpVirtualRadio" }

--- Gets a value for the specified oid
--
-- @param tbl table containing <code>oid</code> and <code>value</code>
-- @param oid string containing the object id for which the value should be extracted
-- @return value of relevant type or nil if oid was not found
function get_value_from_table( tbl, oid )

  for _, v in ipairs( tbl ) do
    if v.oid == oid then
      return v.value
    end
  end

  return nil
end

--- Gets the network interface type from a list of IANA approved types
--
-- @param iana integer interface type returned from snmp result
-- @return string description of interface type, or "Unknown" if type not found
function get_iana_type( iana )
  -- 254 types are currently defined
  -- if the requested type falls outside that range, reset to "other"
  if iana > 254 or iana < 1 then
    iana = 1
  end

  return iana_types[iana]
end

--- Calculates the speed of the interface based on the snmp value
--
-- @param speed value from IF-MIB::ifSpeed
-- @return string description of speed
function get_if_speed( speed )
  local result

  -- GigE or 10GigE speeds
  if speed >= 1000000000 then
    result = string.format( "%d Gbps", speed / 1000000000)
  -- Common for 10 or 100 Mbit ethernet
  elseif speed >= 1000000 then
    result = string.format( "%d Mbps", speed / 1000000)
  -- Anything slower report in Kbps
  else
    result = string.format( "%d Kbps", speed / 1000)
  end

  return result
end

--- Calculates the amount of traffic passed through an interface based on the snmp value
--
-- @param amount value from IF-MIB::ifInOctets or IF-MIB::ifOutOctets
-- @return string description of traffic amount
function get_traffic( amount )
  local result

  -- Gigabytes
  if amount >= 1000000000 then
    result = string.format( "%.2f Gb", amount / 1000000000)
  -- Megabytes
  elseif amount >= 1000000 then
    result = string.format( "%.2f Mb", amount / 1000000)
  -- Anything lower report in kb
  else
    result = string.format( "%.2f Kb", amount / 1000)
  end

  return result
end

--- Converts a 6 byte string into the familiar MAC address formatting
--
-- @param mac string containing the MAC address
-- @return formatted string suitable for printing
function get_mac_addr( mac )
  local catch = function() return end
  local try = nmap.new_try(catch)
  local mac_prefixes = try(datafiles.parse_mac_prefixes())

  if mac:len() ~= 6 then
    return "Unknown"
  else
    local prefix = string.upper(string.format("%02x%02x%02x", mac:byte(1), mac:byte(2), mac:byte(3)))
    local manuf = mac_prefixes[prefix] or "Unknown"
    return string.format("%s (%s)", stdnse.format_mac(mac:sub(1,6)), manuf )
  end
end

--- Processes the list of network interfaces
--
-- @param tbl table containing <code>oid</code> and <code>value</code>
-- @return table with network interfaces described in key / value pairs
function process_interfaces( tbl )

  -- Add the %. escape character to prevent matching the index on e.g. "1.3.6.1.2.1.2.2.1.10."
  local if_index = "1.3.6.1.2.1.2.2.1.1%."
  local if_descr = "1.3.6.1.2.1.2.2.1.2."
  local if_type = "1.3.6.1.2.1.2.2.1.3."
  local if_speed = "1.3.6.1.2.1.2.2.1.5."
  local if_phys_addr = "1.3.6.1.2.1.2.2.1.6."
  local if_status = "1.3.6.1.2.1.2.2.1.8."
  local if_in_octets = "1.3.6.1.2.1.2.2.1.10."
  local if_out_octets = "1.3.6.1.2.1.2.2.1.16."
  local new_tbl = {}

  -- Some operating systems (such as MS Windows) don't list interfaces with consecutive indexes
  -- Therefore we keep an index list so we can iterate over the indexes later on
  new_tbl.index_list = {}

  for _, v in ipairs( tbl ) do

    if ( v.oid:match("^" .. if_index) ) then
      local item = {}
      item.index = get_value_from_table( tbl, v.oid )

      local objid = v.oid:gsub( "^" .. if_index, if_descr)
      local value = get_value_from_table( tbl, objid )

      if value and value:len() > 0 then
        item.descr = value
      end

      objid = v.oid:gsub( "^" .. if_index, if_type )
      value = get_value_from_table( tbl, objid )

      if value then
        item.type = get_iana_type(value)
      end

      objid = v.oid:gsub( "^" .. if_index, if_speed )
      value = get_value_from_table( tbl, objid )

      if value then
        item.speed = get_if_speed( value )
      end

      objid = v.oid:gsub( "^" .. if_index, if_phys_addr )
      value = get_value_from_table( tbl, objid )

      if value and value:len() > 0 then
        item.phys_addr = get_mac_addr( value )
      end

      objid = v.oid:gsub( "^" .. if_index, if_status )
      value = get_value_from_table( tbl, objid )

      if value == 1 then
        item.status = "up"
      elseif value == 2 then
        item.status = "down"
      end

      objid = v.oid:gsub( "^" .. if_index, if_in_octets )
      value = get_value_from_table( tbl, objid )

      if value then
        item.received = get_traffic( value )
      end

      objid = v.oid:gsub( "^" .. if_index, if_out_octets )
      value = get_value_from_table( tbl, objid )

      if value then
        item.sent = get_traffic( value )
      end

      new_tbl[item.index] = item
      -- Add this interface index to our master list
      table.insert( new_tbl.index_list, item.index )

    end

  end

  return new_tbl

end

--- Processes the list of network interfaces and finds associated IP addresses
--
-- @param if_tbl table containing network interfaces
-- @param ip_tbl table containing <code>oid</code> and <code>value</code> pairs from IP::MIB
-- @return table with network interfaces described in key / value pairs
function process_ips( if_tbl, ip_tbl )
  local ip_index = "1.3.6.1.2.1.4.20.1.2."
  local ip_addr = "1.3.6.1.2.1.4.20.1.1."
  local ip_netmask = "1.3.6.1.2.1.4.20.1.3."
  local index
  local item

  for _, v in ipairs( ip_tbl ) do
    if ( v.oid:match("^" .. ip_index) ) then
      index = get_value_from_table( ip_tbl, v.oid )
      item = if_tbl[index]

      local objid = v.oid:gsub( "^" .. ip_index, ip_addr )
      local value = get_value_from_table( ip_tbl, objid )

      if value then
        item.ip_addr = value
      end

      objid = v.oid:gsub( "^" .. ip_index, ip_netmask )
      value = get_value_from_table( ip_tbl, objid )

      if value then
        item.netmask = value
      end
    end
  end

  return if_tbl
end

--- Creates a table of IP addresses from the table of network interfaces
--
-- @param tbl table containing network interfaces
-- @return table containing only IP addresses
function list_addrs( tbl )
  local new_tbl = {}

  for _, index in ipairs( tbl.index_list ) do
    local interface = tbl[index]
    if interface.ip_addr then
      table.insert( new_tbl, interface.ip_addr )
    end
  end

  return new_tbl
end

--- Process the table of network interfaces for reporting
--
-- @param tbl table containing network interfaces
-- @return table suitable for <code>stdnse.format_output</code>
function build_results( tbl )
  local new_tbl = {}
  local verbose = nmap.verbosity()

  -- For each interface index previously discovered, format the relevant information for output
  for _, index in ipairs( tbl.index_list ) do
    local interface = tbl[index]
    local item = {}
    local status = interface.status
    local if_type = interface.type

    if interface.descr then
      item.name = interface.descr
    else
      item.name = string.format("Interface %d", index)
    end

    if interface.ip_addr and interface.netmask then
      table.insert( item, ("IP address: %s  Netmask: %s"):format( interface.ip_addr, interface.netmask ) )
    end

    if interface.phys_addr then
      table.insert( item, ("MAC address: %s"):format( interface.phys_addr ) )
    end

    if interface.type and interface.speed then
      table.insert( item, ("Type: %s  Speed: %s"):format( interface.type, interface.speed ) )
    end

    if ( verbose > 0 ) and interface.status then
      table.insert( item, ("Status: %s"):format( interface.status ) )
    end

    if interface.sent and interface.received then
      table.insert( item, ("Traffic stats: %s sent, %s received"):format( interface.sent, interface.received ) )
    end

    if ( verbose > 0 ) or status == "up" then
      table.insert( new_tbl, item )
    end
  end

  return new_tbl
end

action = function(host, port)

  -- IF-MIB - used to look up network interfaces
  local if_oid = "1.3.6.1.2.1.2.2.1"
  -- IP-MIB - used to determine IP address information
  local ip_oid = "1.3.6.1.2.1.4.20"
  local interfaces = {}
  local ips = {}
  local status
  local srvhost, srvport

  if SCRIPT_TYPE == "prerule" then
    srvhost = stdnse.get_script_args({"snmp-interfaces.host", "host"})
    if not srvhost then
      -- Shouldn't happen; checked in prerule.
      return
    end

    srvport = stdnse.get_script_args({"snmp-interfaces.port", "port"})
    if srvport then
      srvport = { number=tonumber(srvport), protocol="udp" }
    else
      srvport = { number=tonumber(srvport), protocol="udp" }
    end
  else
    srvhost = host.ip
    srvport = port.number
  end

  local snmpHelper = snmp.Helper:new(host, port)
  snmpHelper:connect()

  -- retrieve network interface information from IF-MIB
  status, interfaces = snmpHelper:walk(if_oid)

  if (not(status)) or ( interfaces == nil ) or ( #interfaces == 0 ) then
    return
  end

  stdnse.debug1("SNMP walk of IF-MIB returned %d lines", #interfaces)

  -- build a table of network interfaces from the IF-MIB table
  interfaces = process_interfaces( interfaces )

  -- retrieve IP address information from IP-MIB
  status, ips = snmpHelper:walk( ip_oid )

  -- associate that IP address information with the correct interface
  if (not(status)) or ( ips ~= nil ) and ( #ips ~= 0 ) then
    interfaces = process_ips( interfaces, ips )
  end

  local output = stdnse.format_output( true, build_results(interfaces) )

  if SCRIPT_TYPE == "prerule" and target.ALLOW_NEW_TARGETS then
    local sum = 0

    ips = list_addrs(interfaces)

    -- Could add all of the addresses at once, but count
    -- successful additions instead for script output
    for _, i in ipairs(ips) do
      local st, err = target.add(i)
      if st then
        sum = sum + 1
      else
        stdnse.debug1("Couldn't add target " .. i .. ": " .. err)
      end
    end

    if sum ~= 0 then
      output = output .. "\nSuccessfully added " .. tostring(sum) .. " new targets"
    end
  elseif SCRIPT_TYPE == "portrule" then
    nmap.set_port_state(host, port, "open")
  end

  return output
end