description = [[
Retrieves disk space statistics and information from the remote NFS
share. This script will try to emulate the behaviour of the "df" tool.

The script will provide pathconf information of the remote NFS if
the version used is NFSv3.
]]

---
-- @output
-- PORT    STATE SERVICE
-- | nfs-statfs:
-- |
-- |   Filesystem           1K-blocks  Used     Available  Use%  Blocksize
-- |   /mnt/nfs/files       5542276    2732012  2528728    52%   4096
-- |_  /mnt/nfs/opensource  5534416    620640   4632644    12%   4096
--
-- @args nfs-statfs.human If set to '1' or 'true' shows the filesystem
--       size in the human readable format.
--

-- Version 0.3

-- Created 01/25/2010 - v0.1 - created by Patrik Karlsson <patrik@cqure.net>
-- Revised 02/22/2010 - v0.2 - adapted to support new RPC library
-- Revised 03/13/2010 - v0.3 - converted host to port rule
-- Revised 06/28/2010 - v0.4 - added NFSv3 support and doc


author = "Patrik Karlsson, Djalal Harouni"
license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
categories = {"discovery", "safe"}

require("shortport")
require("rpc")
require("tab")

portrule = shortport.port_or_service(111, "rpcbind", {"tcp", "udp"} )

local function table_fsstat(nfs, mount, stats)
  local fs, err = rpc.Util.calc_fsstat_table(stats, nfs.version, nfs.human)
  if fs == nil then
    return false, err
  end
  fs.filesystem = string.format("%s", mount)
  return true, fs
end

local function table_fsinfo(nfs, fsinfo)
  local ret = {}
  local fs, err = rpc.Util.calc_fsinfo_table(fsinfo, nfs.version, nfs.human)
  if fs == nil then
    return false, err
  end

  ret.maxfilesize = fs.maxfilesize
  return true, ret
end

local function table_pathconf(nfs, pconf)
  local ret = {}
  local fs, err = rpc.Util.calc_pathconf_table(pconf, nfs.version)
  if fs == nil then
    return false, err
  end

  ret.linkmax = fs.linkmax
  return true, ret
end

local function report(nfs, tables)
  local outtab, tab_size, tab_avail
  local tab_filesys, tab_used, tab_use,
        tab_bs, tab_maxfs, tab_linkmax = "  Filesystem",
        "Used", "Use%", "Blocksize", "Maxfilesize", "Maxlink"

  if nfs.human then
    tab_size = "Size"
    tab_avail = "Avail"
  else
    tab_size = "1K-blocks"
    tab_avail = "Available"
  end

  if nfs.version == 2 then
    outtab = tab.new(6)
    tab.nextrow(outtab)
    tab.addrow(outtab, tab_filesys, tab_size, tab_used,
                       tab_avail, tab_use, tab_bs)
    for _, t in ipairs(tables) do
      tab.nextrow(outtab)
      tab.addrow(outtab, ("  %s"):format(t.filesystem), t.size,
                         t.used, t.available, t.use, t.bsize)
    end
  elseif nfs.version == 3 then
    outtab = tab.new(7)
    tab.nextrow(outtab)
    tab.addrow(outtab, tab_filesys, tab_size, tab_used,
                       tab_avail, tab_use, tab_maxfs, tab_linkmax)
    for _, t in ipairs(tables) do
      tab.nextrow(outtab)
      tab.addrow(outtab, ("  %s"):format(t.filesystem), t.size,
                         t.used, t.available, t.use, t.maxfilesize,
                         t.linkmax)
    end
  end

  return tab.dump(outtab)
end

local function nfs_filesystem_info(nfs, mount, filesystem)
  local results, res, status = {}, {}
  local nfsobj = rpc.NFS:new()
  local mnt_comm, nfs_comm, fhandle

  mnt_comm, fhandle = rpc.Helper.MountPath(nfs.host, nfs.port, mount)
  if mnt_comm == nil then
    return false, fhandle
  end

  local nfs_comm, status = rpc.Helper.NfsOpen(nfs.host, nfs.port)
  if nfs_comm == nil then
    rpc.Helper.UnmountPath(mnt_comm, mount)
    return false, status
  end 

  nfs.version = nfs_comm.version

  -- use simple check since NFSv1 is not used anymore.
  if (mnt_comm.version ~= nfs_comm.version) then
    rpc.Helper.UnmountPath(mnt_comm, mount)
    return false, string.format("versions mismatch, nfs v%d - mount v%d",
                                nfs_comm.version, mnt_comm.version)
  end

  if nfs_comm.version < 3 then
    status, res = nfsobj:StatFs(nfs_comm, fhandle)
  elseif nfs_comm.version == 3 then
    status, res = nfsobj:FsStat(nfs_comm, fhandle)
  end
  
  if status then 
    status, res = table_fsstat(nfs, mount, res)
    if status then
      for k, v in pairs(res) do
      	results[k] = v
      end
    end

    if nfs_comm.version == 3 then
      status, res = nfsobj:FsInfo(nfs_comm, fhandle)
      if status then
      	status, res = table_fsinfo(nfs, res)
      	if status then
      	  for k, v in pairs(res) do
      	    results[k] = v
      	  end
      	end
      end

      status, res = nfsobj:PathConf(nfs_comm, fhandle)
      if status then
        status, res = table_pathconf(nfs, res)
      	if status then
      	  for k, v in pairs(res) do
      	    results[k] = v
      	  end
      	end
      end

    end
  end

  rpc.Helper.NfsClose(nfs_comm)
  rpc.Helper.UnmountPath(mnt_comm, mount)
  if (not(status)) then
    return status, res
  end

  table.insert(filesystem, results)
  return true, nil
end

action = function(host, port)
  local o, fs_info, mounts, status = {}, {}, {}, {}
  local nfs_info =
  {
    host    = host,
    port    = port,
    human   = nmap.registry.args['nfs-statfs.human'] or nil,
  }

  status, mounts = rpc.Helper.ShowMounts( host, port )
  if (not(status)) then
    return stdnse.format_output(false, mounts)
  end

  for _, v in ipairs(mounts) do
    local err
    status, err = nfs_filesystem_info(nfs_info, v.name, fs_info)
    if (not(status)) then
      return stdnse.format_output(false, err)
    end
  end
  table.insert(o, report(nfs_info, fs_info))
  
  return stdnse.format_output(true, o)	
end